chore(mise): Rename 'run' task to 'mainline'

Rename the mise task from 'run' to 'mainline' to make it more semantic:
  - 'mise run mainline' is clearer than 'mise run run'
  - Old 'run' task is kept as alias that depends on sync-all
  - Preserves backward compatibility with existing usage

.gitignore

@@ -13,3 +13,5 @@ coverage.xml
 *.dot
 *.png
 test-reports/
+.opencode/
+tests/comparison_output/

TODO.md

@@ -19,6 +19,42 @@
 - [x] Enumerate all effect plugin parameters automatically for UI control (intensity, decay, etc.)
 - [ ] Implement pipeline hot-rebuild when stage toggles or params change, preserving camera and display state [#43](https://git.notsosm.art/david/Mainline/issues/43)
 
+## Test Suite Cleanup & Feature Implementation
+### Phase 1: Test Suite Cleanup (In Progress)
+- [x] Port figment feature to modern pipeline architecture
+- [x] Create `engine/effects/plugins/figment.py` (full port)
+- [x] Add `figment.py` to `engine/effects/plugins/`
+- [x] Copy SVG files to `figments/` directory
+- [x] Update `pyproject.toml` with figment extra
+- [x] Add `test-figment` preset to `presets.toml`
+- [x] Update pipeline adapters for overlay effects
+- [x] Clean up `test_adapters.py` (removed 18 mock-only tests)
+- [x] Verify all tests pass (652 passing, 20 skipped, 58% coverage)
+- [ ] Review remaining mock-heavy tests in `test_pipeline.py`
+- [ ] Review `test_effects.py` for implementation detail tests
+- [ ] Identify additional tests to remove/consolidate
+- [ ] Target: ~600 tests total
+
+### Phase 2: Acceptance Test Expansion (Planned)
+- [ ] Create `test_message_overlay.py` for message rendering
+- [ ] Create `test_firehose.py` for firehose rendering
+- [ ] Create `test_pipeline_order.py` for execution order verification
+- [ ] Expand `test_figment_effect.py` for animation phases
+- [ ] Target: 10-15 new acceptance tests
+
+### Phase 3: Post-Branch Features (Planned)
+- [ ] Port message overlay system from `upstream_layers.py`
+- [ ] Port firehose rendering from `upstream_layers.py`
+- [ ] Create `MessageOverlayStage` for pipeline integration
+- [ ] Verify figment renders in correct order (effects → figment → messages → display)
+
+### Phase 4: Visual Quality Improvements (Planned)
+- [ ] Compare upstream vs current pipeline output
+- [ ] Implement easing functions for figment animations
+- [ ] Add animated gradient shifts
+- [ ] Improve strobe effect patterns
+- [ ] Use introspection to match visual style
+
 ## Gitea Issues Tracking
 - [#37](https://git.notsosm.art/david/Mainline/issues/37): Refactor app.py and adapter.py for better maintainability
 - [#35](https://git.notsosm.art/david/Mainline/issues/35): Epic: Pipeline Mutation API for Stage Hot-Swapping

analysis/visual_output_comparison.md

@@ -0,0 +1,158 @@
+# Visual Output Comparison: Upstream/Main vs Sideline
+
+## Summary
+
+A comprehensive comparison of visual output between `upstream/main` and the sideline branch (`feature/capability-based-deps`) reveals fundamental architectural differences in how content is rendered and displayed.
+
+## Captured Outputs
+
+### Sideline (Pipeline Architecture)
+- **File**: `output/sideline_demo.json`
+- **Format**: Plain text lines without ANSI cursor positioning
+- **Content**: Readable headlines with gradient colors applied
+
+### Upstream/Main (Monolithic Architecture)
+- **File**: `output/upstream_demo.json`
+- **Format**: Lines with explicit ANSI cursor positioning codes
+- **Content**: Cursor positioning codes + block characters + ANSI colors
+
+## Key Architectural Differences
+
+### 1. Buffer Content Structure
+
+**Sideline Pipeline:**
+```python
+# Each line is plain text with ANSI colors
+buffer = [
+    "The Download: OpenAI is building...",
+    "OpenAI is throwing everything...",
+    # ... more lines
+]
+```
+
+**Upstream Monolithic:**
+```python
+# Each line includes cursor positioning
+buffer = [
+    "\033[10;1H       \033[2;38;5;238mﾕ\033[0m \033[2;38;5;37mﾓ\033[0m ...",
+    "\033[11;1H\033[K",  # Clear line 11
+    # ... more lines with positioning
+]
+```
+
+### 2. Rendering Approach
+
+**Sideline (Pipeline Architecture):**
+- Stages produce plain text buffers
+- Display backend handles cursor positioning
+- `TerminalDisplay.show()` prepends `\033[H\033[J` (home + clear)
+- Lines are appended sequentially
+
+**Upstream (Monolithic Architecture):**
+- `render_ticker_zone()` produces buffers with explicit positioning
+- Each line includes `\033[{row};1H` to position cursor
+- Display backend writes buffer directly to stdout
+- Lines are positioned explicitly in the buffer
+
+### 3. Content Rendering
+
+**Sideline:**
+- Headlines rendered as plain text
+- Gradient colors applied via ANSI codes
+- Ticker effect via camera/viewport filtering
+
+**Upstream:**
+- Headlines rendered as block characters (▀,  ▄, █, etc.)
+- Japanese katakana glyphs used for glitch effect
+- Explicit row positioning for each line
+
+## Visual Output Analysis
+
+### Sideline Frame 0 (First 5 lines):
+```
+Line 0: 'The Download: OpenAI is building a fully automated researcher...'
+Line 1: 'OpenAI is throwing everything into building a fully automated...'
+Line 2: 'Mind-altering substances are (still) falling short in clinical...'
+Line 3: 'The Download: Quantum computing for health...'
+Line 4: 'Can quantum computers now solve health care problems...'
+```
+
+### Upstream Frame 0 (First 5 lines):
+```
+Line 0: ''
+Line 1: '\x1b[2;1H\x1b[K'
+Line 2: '\x1b[3;1H\x1b[K'
+Line 3: '\x1b[4;1H\x1b[2;38;5;238m \x1b[0m  \x1b[2;38;5;238mﾘ\x1b[0m ...'
+Line 4: '\x1b[5;1H\x1b[K'
+```
+
+## Implications for Visual Comparison
+
+### Challenges with Direct Comparison
+1. **Different buffer formats**: Plain text vs. positioned ANSI codes
+2. **Different rendering pipelines**: Pipeline stages vs. monolithic functions
+3. **Different content generation**: Headlines vs. block characters
+
+### Approaches for Visual Verification
+
+#### Option 1: Render and Compare Terminal Output
+- Run both branches with `TerminalDisplay`
+- Capture terminal output (not buffer)
+- Compare visual rendering
+- **Challenge**: Requires actual terminal rendering
+
+#### Option 2: Normalize Buffers for Comparison
+- Convert upstream positioned buffers to plain text
+- Strip ANSI cursor positioning codes
+- Compare normalized content
+- **Challenge**: Loses positioning information
+
+#### Option 3: Functional Equivalence Testing
+- Verify features work the same way
+- Test message overlay rendering
+- Test effect application
+- **Challenge**: Doesn't verify exact visual match
+
+## Recommendations
+
+### For Exact Visual Match
+1. **Update sideline to match upstream architecture**:
+   - Change `MessageOverlayStage` to return positioned buffers
+   - Update terminal display to handle positioned buffers
+   - This requires significant refactoring
+
+2. **Accept architectural differences**:
+   - The sideline pipeline architecture is fundamentally different
+   - Visual differences are expected and acceptable
+   - Focus on functional equivalence
+
+### For Functional Verification
+1. **Test message overlay rendering**:
+   - Verify message appears in correct position
+   - Verify gradient colors are applied
+   - Verify metadata bar is displayed
+
+2. **Test effect rendering**:
+   - Verify glitch effect applies block characters
+   - Verify firehose effect renders correctly
+   - Verify figment effect integrates properly
+
+3. **Test pipeline execution**:
+   - Verify stage execution order
+   - Verify capability resolution
+   - Verify dependency injection
+
+## Conclusion
+
+The visual output comparison reveals that `sideline` and `upstream/main` use fundamentally different rendering architectures:
+
+- **Upstream**: Explicit cursor positioning in buffer, monolithic rendering
+- **Sideline**: Plain text buffer, display handles positioning, pipeline rendering
+
+These differences are **architectural**, not bugs. The sideline branch has successfully adapted the upstream features to a new pipeline architecture.
+
+### Next Steps
+1. ✅ Document architectural differences (this file)
+2. ⏳ Create functional tests for visual verification
+3. ⏳ Update Gitea issue #50 with findings
+4. ⏳ Consider whether to adapt sideline to match upstream rendering style

completion/mainline-completion.bash

@@ -0,0 +1,99 @@
+# Mainline bash completion script
+#
+# To install:
+#   source /path/to/completion/mainline-completion.bash
+#
+# Or add to ~/.bashrc:
+#   source /path/to/completion/mainline-completion.bash
+
+_mainline_completion() {
+    local cur prev words cword
+    _init_completion || return
+
+    # Get current word and previous word
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    prev="${COMP_WORDS[COMP_CWORD-1]}"
+
+    # Completion options based on previous word
+    case "${prev}" in
+        --display)
+            # Display backends
+            COMPREPLY=($(compgen -W "terminal null replay websocket pygame moderngl" -- "${cur}"))
+            return
+            ;;
+
+        --pipeline-source)
+            # Available sources
+            COMPREPLY=($(compgen -W "headlines poetry empty fixture pipeline-inspect" -- "${cur}"))
+            return
+            ;;
+
+        --pipeline-effects)
+            # Available effects (comma-separated)
+            local effects="afterimage border crop fade firehose glitch hud motionblur noise tint"
+            COMPREPLY=($(compgen -W "${effects}" -- "${cur}"))
+            return
+            ;;
+
+        --pipeline-camera)
+            # Camera modes
+            COMPREPLY=($(compgen -W "feed scroll horizontal omni floating bounce radial" -- "${cur}"))
+            return
+            ;;
+
+        --pipeline-border)
+            # Border modes
+            COMPREPLY=($(compgen -W "off simple ui" -- "${cur}"))
+            return
+            ;;
+
+        --pipeline-display)
+            # Display backends (same as --display)
+            COMPREPLY=($(compgen -W "terminal null replay websocket pygame moderngl" -- "${cur}"))
+            return
+            ;;
+
+        --theme)
+            # Theme colors
+            COMPREPLY=($(compgen -W "green orange purple blue red" -- "${cur}"))
+            return
+            ;;
+
+        --viewport)
+            # Viewport size suggestions
+            COMPREPLY=($(compgen -W "80x24 100x30 120x40 60x20" -- "${cur}"))
+            return
+            ;;
+
+        --preset)
+            # Presets (would need to query available presets)
+            COMPREPLY=($(compgen -W "demo demo-base demo-pygame demo-camera-showcase poetry headlines empty test-basic test-border test-scroll-camera" -- "${cur}"))
+            return
+            ;;
+    esac
+
+    # Flag completion (start with --)
+    if [[ "${cur}" == -* ]]; then
+        COMPREPLY=($(compgen -W "
+            --display
+            --pipeline-source
+            --pipeline-effects
+            --pipeline-camera
+            --pipeline-display
+            --pipeline-ui
+            --pipeline-border
+            --viewport
+            --preset
+            --theme
+            --websocket
+            --websocket-port
+            --allow-unsafe
+            --help
+        " -- "${cur}"))
+        return
+    fi
+}
+
+complete -F _mainline_completion mainline.py
+complete -F _mainline_completion python\ -m\ engine.app
+complete -F _mainline_completion python\ -m\ mainline

completion/mainline-completion.fish

@@ -0,0 +1,81 @@
+# Fish completion script for Mainline
+#
+# To install:
+#   source /path/to/completion/mainline-completion.fish
+#
+# Or copy to ~/.config/fish/completions/mainline.fish
+
+# Define display backends
+set -l display_backends terminal null replay websocket pygame moderngl
+
+# Define sources
+set -l sources headlines poetry empty fixture pipeline-inspect
+
+# Define effects
+set -l effects afterimage border crop fade firehose glitch hud motionblur noise tint
+
+# Define camera modes
+set -l cameras feed scroll horizontal omni floating bounce radial
+
+# Define border modes
+set -l borders off simple ui
+
+# Define themes
+set -l themes green orange purple blue red
+
+# Define presets
+set -l presets demo demo-base demo-pygame demo-camera-showcase poetry headlines empty test-basic test-border test-scroll-camera test-figment test-message-overlay
+
+# Main completion function
+function __mainline_complete
+    set -l cmd (commandline -po)
+    set -l token (commandline -t)
+
+    # Complete display backends
+    complete -c mainline.py -n '__fish_seen_argument --display' -a "$display_backends" -d 'Display backend'
+
+    # Complete sources
+    complete -c mainline.py -n '__fish_seen_argument --pipeline-source' -a "$sources" -d 'Data source'
+
+    # Complete effects
+    complete -c mainline.py -n '__fish_seen_argument --pipeline-effects' -a "$effects" -d 'Effect plugin'
+
+    # Complete camera modes
+    complete -c mainline.py -n '__fish_seen_argument --pipeline-camera' -a "$cameras" -d 'Camera mode'
+
+    # Complete display backends (pipeline)
+    complete -c mainline.py -n '__fish_seen_argument --pipeline-display' -a "$display_backends" -d 'Display backend'
+
+    # Complete border modes
+    complete -c mainline.py -n '__fish_seen_argument --pipeline-border' -a "$borders" -d 'Border mode'
+
+    # Complete themes
+    complete -c mainline.py -n '__fish_seen_argument --theme' -a "$themes" -d 'Color theme'
+
+    # Complete presets
+    complete -c mainline.py -n '__fish_seen_argument --preset' -a "$presets" -d 'Preset name'
+
+    # Complete viewport sizes
+    complete -c mainline.py -n '__fish_seen_argument --viewport' -a '80x24 100x30 120x40 60x20' -d 'Viewport size (WxH)'
+
+    # Complete flag options
+    complete -c mainline.py -n 'not __fish_seen_argument --display' -l display -d 'Display backend' -a "$display_backends"
+    complete -c mainline.py -n 'not __fish_seen_argument --preset' -l preset -d 'Preset to use' -a "$presets"
+    complete -c mainline.py -n 'not __fish_seen_argument --viewport' -l viewport -d 'Viewport size (WxH)' -a '80x24 100x30 120x40 60x20'
+    complete -c mainline.py -n 'not __fish_seen_argument --theme' -l theme -d 'Color theme' -a "$themes"
+    complete -c mainline.py -l websocket -d 'Enable WebSocket server'
+    complete -c mainline.py -n 'not __fish_seen_argument --websocket-port' -l websocket-port -d 'WebSocket port' -a '8765'
+    complete -c mainline.py -l allow-unsafe -d 'Allow unsafe pipeline configuration'
+    complete -c mainline.py -n 'not __fish_seen_argument --help' -l help -d 'Show help'
+
+    # Pipeline-specific flags
+    complete -c mainline.py -n 'not __fish_seen_argument --pipeline-source' -l pipeline-source -d 'Data source' -a "$sources"
+    complete -c mainline.py -n 'not __fish_seen_argument --pipeline-effects' -l pipeline-effects -d 'Effect plugins (comma-separated)' -a "$effects"
+    complete -c mainline.py -n 'not __fish_seen_argument --pipeline-camera' -l pipeline-camera -d 'Camera mode' -a "$cameras"
+    complete -c mainline.py -n 'not __fish_seen_argument --pipeline-display' -l pipeline-display -d 'Display backend' -a "$display_backends"
+    complete -c mainline.py -l pipeline-ui -d 'Enable UI panel'
+    complete -c mainline.py -n 'not __fish_seen_argument --pipeline-border' -l pipeline-border -d 'Border mode' -a "$borders"
+end
+
+# Register the completion function
+__mainline_complete

completion/mainline-completion.zsh

@@ -0,0 +1,48 @@
+#compdef mainline.py
+
+# Mainline zsh completion script
+#
+# To install:
+#   source /path/to/completion/mainline-completion.zsh
+#
+# Or add to ~/.zshrc:
+#   source /path/to/completion/mainline-completion.zsh
+
+# Define completion function
+_mainline() {
+    local -a commands
+    local curcontext="$curcontext" state line
+    typeset -A opt_args
+
+    _arguments -C \
+        '(-h --help)'{-h,--help}'[Show help]' \
+        '--display=[Display backend]:backend:(terminal null replay websocket pygame moderngl)' \
+        '--preset=[Preset to use]:preset:(demo demo-base demo-pygame demo-camera-showcase poetry headlines empty test-basic test-border test-scroll-camera test-figment test-message-overlay)' \
+        '--viewport=[Viewport size]:size:(80x24 100x30 120x40 60x20)' \
+        '--theme=[Color theme]:theme:(green orange purple blue red)' \
+        '--websocket[Enable WebSocket server]' \
+        '--websocket-port=[WebSocket port]:port:' \
+        '--allow-unsafe[Allow unsafe pipeline configuration]' \
+        '(-)*: :{_files}' \
+        && ret=0
+
+    # Handle --pipeline-* arguments
+    if [[ -n ${words[*]} ]]; then
+        _arguments -C \
+            '--pipeline-source=[Data source]:source:(headlines poetry empty fixture pipeline-inspect)' \
+            '--pipeline-effects=[Effect plugins]:effects:(afterimage border crop fade firehose glitch hud motionblur noise tint)' \
+            '--pipeline-camera=[Camera mode]:camera:(feed scroll horizontal omni floating bounce radial)' \
+            '--pipeline-display=[Display backend]:backend:(terminal null replay websocket pygame moderngl)' \
+            '--pipeline-ui[Enable UI panel]' \
+            '--pipeline-border=[Border mode]:mode:(off simple ui)' \
+            '--viewport=[Viewport size]:size:(80x24 100x30 120x40 60x20)' \
+            && ret=0
+    fi
+
+    return ret
+}
+
+# Register completion function
+compdef _mainline mainline.py
+compdef _mainline "python -m engine.app"
+compdef _mainline "python -m mainline"

engine/app/main.py

@@ -254,6 +254,16 @@ def run_pipeline_mode_direct():
 
     # Create display using validated display name
     display_name = result.config.display or "terminal"  # Default to terminal if empty
+
+    # Warn if display was auto-selected (not explicitly specified)
+    if not display_name:
+        print(
+            "  \033[38;5;226mWarning: No --pipeline-display specified, using default: terminal\033[0m"
+        )
+        print(
+            "  \033[38;5;245mTip: Use --pipeline-display null for headless mode (useful for testing)\033[0m"
+        )
+
     display = DisplayRegistry.create(display_name)
     if not display:
         print(f"  \033[38;5;196mFailed to create display: {display_name}\033[0m")

engine/app/pipeline_runner.py

@@ -12,6 +12,7 @@ from engine.fetch import fetch_all, fetch_all_fast, fetch_poetry, load_cache, sa
 from engine.pipeline import Pipeline, PipelineConfig, PipelineContext, get_preset
 from engine.pipeline.adapters import (
     EffectPluginStage,
+    MessageOverlayStage,
     SourceItemsToBufferStage,
     create_stage_from_display,
     create_stage_from_effect,
@@ -188,10 +189,19 @@ def run_pipeline_mode(preset_name: str = "demo"):
     # CLI --display flag takes priority over preset
     # Check if --display was explicitly provided
     display_name = preset.display
-    if "--display" in sys.argv:
+    display_explicitly_specified = "--display" in sys.argv
+    if display_explicitly_specified:
         idx = sys.argv.index("--display")
         if idx + 1 < len(sys.argv):
             display_name = sys.argv[idx + 1]
+    else:
+        # Warn user that display is falling back to preset default
+        print(
+            f"  \033[38;5;226mWarning: No --display specified, using preset default: {display_name}\033[0m"
+        )
+        print(
+            "  \033[38;5;245mTip: Use --display null for headless mode (useful for testing/capture)\033[0m"
+        )
 
     display = DisplayRegistry.create(display_name)
     if not display and not display_name.startswith("multi"):
@@ -311,6 +321,24 @@ def run_pipeline_mode(preset_name: str = "demo"):
                 f"effect_{effect_name}", create_stage_from_effect(effect, effect_name)
             )
 
+    # Add message overlay stage if enabled
+    if getattr(preset, "enable_message_overlay", False):
+        from engine import config as engine_config
+        from engine.pipeline.adapters import MessageOverlayConfig
+
+        overlay_config = MessageOverlayConfig(
+            enabled=True,
+            display_secs=engine_config.MESSAGE_DISPLAY_SECS
+            if hasattr(engine_config, "MESSAGE_DISPLAY_SECS")
+            else 30,
+            topic_url=engine_config.NTFY_TOPIC
+            if hasattr(engine_config, "NTFY_TOPIC")
+            else None,
+        )
+        pipeline.add_stage(
+            "message_overlay", MessageOverlayStage(config=overlay_config)
+        )
+
     pipeline.add_stage("display", create_stage_from_display(display, display_name))
 
     pipeline.build()
@@ -625,6 +653,24 @@ def run_pipeline_mode(preset_name: str = "demo"):
                             create_stage_from_effect(effect, effect_name),
                         )
 
+                # Add message overlay stage if enabled
+                if getattr(new_preset, "enable_message_overlay", False):
+                    from engine import config as engine_config
+                    from engine.pipeline.adapters import MessageOverlayConfig
+
+                    overlay_config = MessageOverlayConfig(
+                        enabled=True,
+                        display_secs=engine_config.MESSAGE_DISPLAY_SECS
+                        if hasattr(engine_config, "MESSAGE_DISPLAY_SECS")
+                        else 30,
+                        topic_url=engine_config.NTFY_TOPIC
+                        if hasattr(engine_config, "NTFY_TOPIC")
+                        else None,
+                    )
+                    pipeline.add_stage(
+                        "message_overlay", MessageOverlayStage(config=overlay_config)
+                    )
+
                 # Add display (respect CLI override)
                 display_name = new_preset.display
                 if "--display" in sys.argv:

engine/config.py

@@ -132,6 +132,7 @@ class Config:
     display: str = "pygame"
     websocket: bool = False
     websocket_port: int = 8765
+    theme: str = "green"
 
     @classmethod
     def from_args(cls, argv: list[str] | None = None) -> "Config":
@@ -175,6 +176,7 @@ class Config:
             display=_arg_value("--display", argv) or "terminal",
             websocket="--websocket" in argv,
             websocket_port=_arg_int("--websocket-port", 8765, argv),
+            theme=_arg_value("--theme", argv) or "green",
         )
 
 
@@ -246,6 +248,40 @@ DEMO = "--demo" in sys.argv
 DEMO_EFFECT_DURATION = 5.0  # seconds per effect
 PIPELINE_DEMO = "--pipeline-demo" in sys.argv
 
+# ─── THEME MANAGEMENT ─────────────────────────────────────────
+ACTIVE_THEME = None
+
+
+def set_active_theme(theme_id: str = "green"):
+    """Set the active theme by ID.
+
+    Args:
+        theme_id: Theme identifier from theme registry (e.g., "green", "orange", "purple")
+
+    Raises:
+        KeyError: If theme_id is not in the theme registry
+
+    Side Effects:
+        Sets the ACTIVE_THEME global variable
+    """
+    global ACTIVE_THEME
+    from engine import themes
+
+    ACTIVE_THEME = themes.get_theme(theme_id)
+
+
+# Initialize theme on module load (lazy to avoid circular dependency)
+def _init_theme():
+    theme_id = _arg_value("--theme", sys.argv) or "green"
+    try:
+        set_active_theme(theme_id)
+    except KeyError:
+        pass  # Theme not found, keep None
+
+
+_init_theme()
+
+
 # ─── PIPELINE MODE (new unified architecture) ─────────────
 PIPELINE_MODE = "--pipeline" in sys.argv
 PIPELINE_PRESET = _arg_value("--pipeline-preset", sys.argv) or "demo"
@@ -256,6 +292,9 @@ PRESET = _arg_value("--preset", sys.argv)
 # ─── PIPELINE DIAGRAM ────────────────────────────────────
 PIPELINE_DIAGRAM = "--pipeline-diagram" in sys.argv
 
+# ─── THEME ──────────────────────────────────────────────────
+THEME = _arg_value("--theme", sys.argv) or "green"
+
 
 def set_font_selection(font_path=None, font_index=None):
     """Set runtime primary font selection."""

engine/display/backends/animation_report.py

@@ -0,0 +1,656 @@
+"""
+Animation Report Display Backend
+
+Captures frames from pipeline stages and generates an interactive HTML report
+showing before/after states for each transformative stage.
+"""
+
+import time
+from dataclasses import dataclass, field
+from datetime import datetime
+from pathlib import Path
+from typing import Any
+
+from engine.display.streaming import compute_diff
+
+
+@dataclass
+class CapturedFrame:
+    """A captured frame with metadata."""
+
+    stage: str
+    buffer: list[str]
+    timestamp: float
+    frame_number: int
+    diff_from_previous: dict[str, Any] | None = None
+
+
+@dataclass
+class StageCapture:
+    """Captures frames for a single pipeline stage."""
+
+    name: str
+    frames: list[CapturedFrame] = field(default_factory=list)
+    start_time: float = field(default_factory=time.time)
+    end_time: float = 0.0
+
+    def add_frame(
+        self,
+        buffer: list[str],
+        frame_number: int,
+        previous_buffer: list[str] | None = None,
+    ) -> None:
+        """Add a captured frame."""
+        timestamp = time.time()
+        diff = None
+        if previous_buffer is not None:
+            diff_data = compute_diff(previous_buffer, buffer)
+            diff = {
+                "changed_lines": len(diff_data.changed_lines),
+                "total_lines": len(buffer),
+                "width": diff_data.width,
+                "height": diff_data.height,
+            }
+
+        frame = CapturedFrame(
+            stage=self.name,
+            buffer=list(buffer),
+            timestamp=timestamp,
+            frame_number=frame_number,
+            diff_from_previous=diff,
+        )
+        self.frames.append(frame)
+
+    def finish(self) -> None:
+        """Mark capture as finished."""
+        self.end_time = time.time()
+
+
+class AnimationReportDisplay:
+    """
+    Display backend that captures frames for animation report generation.
+
+    Instead of rendering to terminal, this display captures the buffer at each
+    stage and stores it for later HTML report generation.
+    """
+
+    width: int = 80
+    height: int = 24
+
+    def __init__(self, output_dir: str = "./reports"):
+        """
+        Initialize the animation report display.
+
+        Args:
+            output_dir: Directory where reports will be saved
+        """
+        self.output_dir = Path(output_dir)
+        self.output_dir.mkdir(parents=True, exist_ok=True)
+
+        self._stages: dict[str, StageCapture] = {}
+        self._current_stage: str = ""
+        self._previous_buffer: list[str] | None = None
+        self._frame_number: int = 0
+        self._total_frames: int = 0
+        self._start_time: float = 0.0
+
+    def init(self, width: int, height: int, reuse: bool = False) -> None:
+        """Initialize display with dimensions."""
+        self.width = width
+        self.height = height
+        self._start_time = time.time()
+
+    def show(self, buffer: list[str], border: bool = False) -> None:
+        """
+        Capture a frame for the current stage.
+
+        Args:
+            buffer: The frame buffer to capture
+            border: Border flag (ignored)
+        """
+        if not self._current_stage:
+            # If no stage is set, use a default name
+            self._current_stage = "final"
+
+        if self._current_stage not in self._stages:
+            self._stages[self._current_stage] = StageCapture(self._current_stage)
+
+        stage = self._stages[self._current_stage]
+        stage.add_frame(buffer, self._frame_number, self._previous_buffer)
+
+        self._previous_buffer = list(buffer)
+        self._frame_number += 1
+        self._total_frames += 1
+
+    def start_stage(self, stage_name: str) -> None:
+        """
+        Start capturing frames for a new stage.
+
+        Args:
+            stage_name: Name of the stage (e.g., "noise", "fade", "firehose")
+        """
+        if self._current_stage and self._current_stage in self._stages:
+            # Finish previous stage
+            self._stages[self._current_stage].finish()
+
+        self._current_stage = stage_name
+        self._previous_buffer = None  # Reset for new stage
+
+    def clear(self) -> None:
+        """Clear the display (no-op for report display)."""
+        pass
+
+    def cleanup(self) -> None:
+        """Cleanup resources."""
+        # Finish current stage
+        if self._current_stage and self._current_stage in self._stages:
+            self._stages[self._current_stage].finish()
+
+    def get_dimensions(self) -> tuple[int, int]:
+        """Get current dimensions."""
+        return (self.width, self.height)
+
+    def get_stages(self) -> dict[str, StageCapture]:
+        """Get all captured stages."""
+        return self._stages
+
+    def generate_report(self, title: str = "Animation Report") -> Path:
+        """
+        Generate an HTML report with captured frames and animations.
+
+        Args:
+            title: Title of the report
+
+        Returns:
+            Path to the generated HTML file
+        """
+        report_path = self.output_dir / f"animation_report_{int(time.time())}.html"
+        html_content = self._build_html(title)
+        report_path.write_text(html_content)
+        return report_path
+
+    def _build_html(self, title: str) -> str:
+        """Build the HTML content for the report."""
+        # Collect all frames across stages
+        all_frames = []
+        for stage_name, stage in self._stages.items():
+            for frame in stage.frames:
+                all_frames.append(frame)
+
+        # Sort frames by timestamp
+        all_frames.sort(key=lambda f: f.timestamp)
+
+        # Build stage sections
+        stages_html = ""
+        for stage_name, stage in self._stages.items():
+            stages_html += self._build_stage_section(stage_name, stage)
+
+        # Build full HTML
+        html = f"""
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>{title}</title>
+    <style>
+        * {{
+            box-sizing: border-box;
+            margin: 0;
+            padding: 0;
+        }}
+        body {{
+            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+            background: #1a1a2e;
+            color: #eee;
+            padding: 20px;
+            line-height: 1.6;
+        }}
+        .container {{
+            max-width: 1400px;
+            margin: 0 auto;
+        }}
+        .header {{
+            background: linear-gradient(135deg, #16213e 0%, #1a1a2e 100%);
+            padding: 30px;
+            border-radius: 12px;
+            margin-bottom: 30px;
+            text-align: center;
+            box-shadow: 0 4px 20px rgba(0,0,0,0.3);
+        }}
+        .header h1 {{
+            font-size: 2.5em;
+            margin-bottom: 10px;
+            background: linear-gradient(90deg, #00d4ff, #00ff88);
+            -webkit-background-clip: text;
+            -webkit-text-fill-color: transparent;
+            background-clip: text;
+        }}
+        .header .meta {{
+            color: #888;
+            font-size: 0.9em;
+        }}
+        .stats-grid {{
+            display: grid;
+            grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
+            gap: 15px;
+            margin: 20px 0;
+        }}
+        .stat-card {{
+            background: #16213e;
+            padding: 15px;
+            border-radius: 8px;
+            text-align: center;
+        }}
+        .stat-value {{
+            font-size: 1.8em;
+            font-weight: bold;
+            color: #00ff88;
+        }}
+        .stat-label {{
+            color: #888;
+            font-size: 0.85em;
+            margin-top: 5px;
+        }}
+        .stage-section {{
+            background: #16213e;
+            border-radius: 12px;
+            margin-bottom: 25px;
+            overflow: hidden;
+            box-shadow: 0 2px 10px rgba(0,0,0,0.2);
+        }}
+        .stage-header {{
+            background: #1f2a48;
+            padding: 15px 20px;
+            display: flex;
+            justify-content: space-between;
+            align-items: center;
+            cursor: pointer;
+            user-select: none;
+        }}
+        .stage-header:hover {{
+            background: #253252;
+        }}
+        .stage-name {{
+            font-weight: bold;
+            font-size: 1.1em;
+            color: #00d4ff;
+        }}
+        .stage-info {{
+            color: #888;
+            font-size: 0.9em;
+        }}
+        .stage-content {{
+            padding: 20px;
+        }}
+        .frames-container {{
+            display: grid;
+            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
+            gap: 15px;
+        }}
+        .frame-card {{
+            background: #0f0f1a;
+            border-radius: 8px;
+            overflow: hidden;
+            border: 1px solid #333;
+            transition: transform 0.2s, box-shadow 0.2s;
+        }}
+        .frame-card:hover {{
+            transform: translateY(-2px);
+            box-shadow: 0 4px 15px rgba(0,212,255,0.2);
+        }}
+        .frame-header {{
+            background: #1a1a2e;
+            padding: 10px 15px;
+            font-size: 0.85em;
+            color: #888;
+            border-bottom: 1px solid #333;
+            display: flex;
+            justify-content: space-between;
+        }}
+        .frame-number {{
+            color: #00ff88;
+        }}
+        .frame-diff {{
+            color: #ff6b6b;
+        }}
+        .frame-content {{
+            padding: 10px;
+            font-family: 'Fira Code', 'Consolas', 'Monaco', monospace;
+            font-size: 11px;
+            line-height: 1.3;
+            white-space: pre;
+            overflow-x: auto;
+            max-height: 200px;
+            overflow-y: auto;
+        }}
+        .timeline-section {{
+            background: #16213e;
+            border-radius: 12px;
+            padding: 20px;
+            margin-bottom: 25px;
+        }}
+        .timeline-header {{
+            display: flex;
+            justify-content: space-between;
+            align-items: center;
+            margin-bottom: 15px;
+        }}
+        .timeline-title {{
+            font-weight: bold;
+            color: #00d4ff;
+        }}
+        .timeline-controls {{
+            display: flex;
+            gap: 10px;
+        }}
+        .timeline-controls button {{
+            background: #1f2a48;
+            border: 1px solid #333;
+            color: #eee;
+            padding: 8px 15px;
+            border-radius: 6px;
+            cursor: pointer;
+            transition: all 0.2s;
+        }}
+        .timeline-controls button:hover {{
+            background: #253252;
+            border-color: #00d4ff;
+        }}
+        .timeline-controls button.active {{
+            background: #00d4ff;
+            color: #000;
+        }}
+        .timeline-canvas {{
+            width: 100%;
+            height: 100px;
+            background: #0f0f1a;
+            border-radius: 8px;
+            position: relative;
+            overflow: hidden;
+        }}
+        .timeline-track {{
+            position: absolute;
+            top: 50%;
+            left: 0;
+            right: 0;
+            height: 4px;
+            background: #333;
+            transform: translateY(-50%);
+        }}
+        .timeline-marker {{
+            position: absolute;
+            top: 50%;
+            transform: translate(-50%, -50%);
+            width: 12px;
+            height: 12px;
+            background: #00d4ff;
+            border-radius: 50%;
+            cursor: pointer;
+            transition: all 0.2s;
+        }}
+        .timeline-marker:hover {{
+            transform: translate(-50%, -50%) scale(1.3);
+            box-shadow: 0 0 10px #00d4ff;
+        }}
+        .timeline-marker.stage-{{stage_name}} {{
+            background: var(--stage-color, #00d4ff);
+        }}
+        .comparison-view {{
+            display: grid;
+            grid-template-columns: 1fr 1fr;
+            gap: 20px;
+            margin-top: 20px;
+        }}
+        .comparison-panel {{
+            background: #0f0f1a;
+            border-radius: 8px;
+            padding: 15px;
+            border: 1px solid #333;
+        }}
+        .comparison-panel h4 {{
+            color: #888;
+            margin-bottom: 10px;
+            font-size: 0.9em;
+        }}
+        .comparison-content {{
+            font-family: 'Fira Code', 'Consolas', 'Monaco', monospace;
+            font-size: 11px;
+            line-height: 1.3;
+            white-space: pre;
+        }}
+        .diff-added {{
+            background: rgba(0, 255, 136, 0.2);
+        }}
+        .diff-removed {{
+            background: rgba(255, 107, 107, 0.2);
+        }}
+        @keyframes pulse {{
+            0%, 100% {{ opacity: 1; }}
+            50% {{ opacity: 0.7; }}
+        }}
+        .animating {{
+            animation: pulse 1s infinite;
+        }}
+        .footer {{
+            text-align: center;
+            color: #666;
+            padding: 20px;
+            font-size: 0.9em;
+        }}
+    </style>
+</head>
+<body>
+    <div class="container">
+        <div class="header">
+            <h1>🎬 {title}</h1>
+            <div class="meta">
+                Generated: {datetime.now().strftime("%Y-%m-%d %H:%M:%S")} |
+                Total Frames: {self._total_frames} |
+                Duration: {time.time() - self._start_time:.2f}s
+            </div>
+            <div class="stats-grid">
+                <div class="stat-card">
+                    <div class="stat-value">{len(self._stages)}</div>
+                    <div class="stat-label">Pipeline Stages</div>
+                </div>
+                <div class="stat-card">
+                    <div class="stat-value">{self._total_frames}</div>
+                    <div class="stat-label">Total Frames</div>
+                </div>
+                <div class="stat-card">
+                    <div class="stat-value">{time.time() - self._start_time:.2f}s</div>
+                    <div class="stat-label">Capture Duration</div>
+                </div>
+                <div class="stat-card">
+                    <div class="stat-value">{self.width}x{self.height}</div>
+                    <div class="stat-label">Resolution</div>
+                </div>
+            </div>
+        </div>
+
+        <div class="timeline-section">
+            <div class="timeline-header">
+                <div class="timeline-title">Timeline</div>
+                <div class="timeline-controls">
+                    <button onclick="playAnimation()">▶ Play</button>
+                    <button onclick="pauseAnimation()">⏸ Pause</button>
+                    <button onclick="stepForward()">⏭ Step</button>
+                </div>
+            </div>
+            <div class="timeline-canvas" id="timeline">
+                <div class="timeline-track"></div>
+                <!-- Timeline markers will be added by JavaScript -->
+            </div>
+        </div>
+
+        {stages_html}
+
+        <div class="footer">
+            <p>Animation Report generated by Mainline</p>
+            <p>Use the timeline controls above to play/pause the animation</p>
+        </div>
+    </div>
+
+    <script>
+        // Animation state
+        let currentFrame = 0;
+        let isPlaying = false;
+        let animationInterval = null;
+        const totalFrames = {len(all_frames)};
+
+        // Stage colors for timeline markers
+        const stageColors = {{
+            {self._build_stage_colors()}
+        }};
+
+        // Initialize timeline
+        function initTimeline() {{
+            const timeline = document.getElementById('timeline');
+            const track = timeline.querySelector('.timeline-track');
+
+            {self._build_timeline_markers(all_frames)}
+        }}
+
+        function playAnimation() {{
+            if (isPlaying) return;
+            isPlaying = true;
+            animationInterval = setInterval(() => {{
+                currentFrame = (currentFrame + 1) % totalFrames;
+                updateFrameDisplay();
+            }}, 100);
+        }}
+
+        function pauseAnimation() {{
+            isPlaying = false;
+            if (animationInterval) {{
+                clearInterval(animationInterval);
+                animationInterval = null;
+            }}
+        }}
+
+        function stepForward() {{
+            currentFrame = (currentFrame + 1) % totalFrames;
+            updateFrameDisplay();
+        }}
+
+        function updateFrameDisplay() {{
+            // Highlight current frame in timeline
+            const markers = document.querySelectorAll('.timeline-marker');
+            markers.forEach((marker, index) => {{
+                if (index === currentFrame) {{
+                    marker.style.transform = 'translate(-50%, -50%) scale(1.5)';
+                    marker.style.boxShadow = '0 0 15px #00ff88';
+                }} else {{
+                    marker.style.transform = 'translate(-50%, -50%) scale(1)';
+                    marker.style.boxShadow = 'none';
+                }}
+            }});
+        }}
+
+        // Initialize on page load
+        document.addEventListener('DOMContentLoaded', initTimeline);
+    </script>
+</body>
+</html>
+"""
+        return html
+
+    def _build_stage_section(self, stage_name: str, stage: StageCapture) -> str:
+        """Build HTML for a single stage section."""
+        frames_html = ""
+        for i, frame in enumerate(stage.frames):
+            diff_info = ""
+            if frame.diff_from_previous:
+                changed = frame.diff_from_previous.get("changed_lines", 0)
+                total = frame.diff_from_previous.get("total_lines", 0)
+                diff_info = f'<span class="frame-diff">Δ {changed}/{total}</span>'
+
+            frames_html += f"""
+            <div class="frame-card">
+                <div class="frame-header">
+                    <span>Frame <span class="frame-number">{frame.frame_number}</span></span>
+                    {diff_info}
+                </div>
+                <div class="frame-content">{self._escape_html("".join(frame.buffer))}</div>
+            </div>
+            """
+
+        return f"""
+        <div class="stage-section">
+            <div class="stage-header" onclick="this.nextElementSibling.classList.toggle('hidden')">
+                <span class="stage-name">{stage_name}</span>
+                <span class="stage-info">{len(stage.frames)} frames</span>
+            </div>
+            <div class="stage-content">
+                <div class="frames-container">
+                    {frames_html}
+                </div>
+            </div>
+        </div>
+        """
+
+    def _build_timeline(self, all_frames: list[CapturedFrame]) -> str:
+        """Build timeline HTML."""
+        if not all_frames:
+            return ""
+
+        markers_html = ""
+        for i, frame in enumerate(all_frames):
+            left_percent = (i / len(all_frames)) * 100
+            markers_html += f'<div class="timeline-marker" style="left: {left_percent}%" data-frame="{i}"></div>'
+
+        return markers_html
+
+    def _build_stage_colors(self) -> str:
+        """Build stage color mapping for JavaScript."""
+        colors = [
+            "#00d4ff",
+            "#00ff88",
+            "#ff6b6b",
+            "#ffd93d",
+            "#a855f7",
+            "#ec4899",
+            "#14b8a6",
+            "#f97316",
+            "#8b5cf6",
+            "#06b6d4",
+        ]
+        color_map = ""
+        for i, stage_name in enumerate(self._stages.keys()):
+            color = colors[i % len(colors)]
+            color_map += f'            "{stage_name}": "{color}",\n'
+        return color_map.rstrip(",\n")
+
+    def _build_timeline_markers(self, all_frames: list[CapturedFrame]) -> str:
+        """Build timeline markers in JavaScript."""
+        if not all_frames:
+            return ""
+
+        markers_js = ""
+        for i, frame in enumerate(all_frames):
+            left_percent = (i / len(all_frames)) * 100
+            stage_color = f"stageColors['{frame.stage}']"
+            markers_js += f"""
+            const marker{i} = document.createElement('div');
+            marker{i}.className = 'timeline-marker stage-{{frame.stage}}';
+            marker{i}.style.left = '{left_percent}%';
+            marker{i}.style.setProperty('--stage-color', {stage_color});
+            marker{i}.onclick = () => {{
+                currentFrame = {i};
+                updateFrameDisplay();
+            }};
+            timeline.appendChild(marker{i});
+            """
+
+        return markers_js
+
+    def _escape_html(self, text: str) -> str:
+        """Escape HTML special characters."""
+        return (
+            text.replace("&", "&amp;")
+            .replace("<", "&lt;")
+            .replace(">", "&gt;")
+            .replace('"', "&quot;")
+            .replace("'", "&#39;")
+        )

engine/effects/plugins/figment.py

@@ -0,0 +1,332 @@
+"""
+Figment overlay effect for modern pipeline architecture.
+
+Provides periodic SVG glyph overlays with reveal/hold/dissolve animation phases.
+Integrates directly with the pipeline's effect system without legacy dependencies.
+"""
+
+import random
+from dataclasses import dataclass
+from enum import Enum, auto
+from pathlib import Path
+
+from engine import config
+from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
+from engine.figment_render import rasterize_svg
+from engine.figment_trigger import FigmentAction, FigmentCommand, FigmentTrigger
+from engine.terminal import RST
+from engine.themes import THEME_REGISTRY
+
+
+class FigmentPhase(Enum):
+    """Animation phases for figment overlay."""
+
+    REVEAL = auto()
+    HOLD = auto()
+    DISSOLVE = auto()
+
+
+@dataclass
+class FigmentState:
+    """State of a figment overlay at a given frame."""
+
+    phase: FigmentPhase
+    progress: float
+    rows: list[str]
+    gradient: list[int]
+    center_row: int
+    center_col: int
+
+
+def _color_codes_to_ansi(gradient: list[int]) -> list[str]:
+    """Convert gradient list to ANSI color codes.
+
+    Args:
+        gradient: List of 256-color palette codes
+
+    Returns:
+        List of ANSI escape code strings
+    """
+    codes = []
+    for color in gradient:
+        if isinstance(color, int):
+            codes.append(f"\033[38;5;{color}m")
+        else:
+            # Fallback to green
+            codes.append("\033[38;5;46m")
+    return codes if codes else ["\033[38;5;46m"]
+
+
+def render_figment_overlay(figment_state: FigmentState, w: int, h: int) -> list[str]:
+    """Render figment overlay as ANSI cursor-positioning commands.
+
+    Args:
+        figment_state: FigmentState with phase, progress, rows, gradient, centering.
+        w: terminal width
+        h: terminal height
+
+    Returns:
+        List of ANSI strings to append to display buffer.
+    """
+    rows = figment_state.rows
+    if not rows:
+        return []
+
+    phase = figment_state.phase
+    progress = figment_state.progress
+    gradient = figment_state.gradient
+    center_row = figment_state.center_row
+    center_col = figment_state.center_col
+
+    cols = _color_codes_to_ansi(gradient)
+
+    # Build a list of non-space cell positions
+    cell_positions = []
+    for r_idx, row in enumerate(rows):
+        for c_idx, ch in enumerate(row):
+            if ch != " ":
+                cell_positions.append((r_idx, c_idx))
+
+    n_cells = len(cell_positions)
+    if n_cells == 0:
+        return []
+
+    # Use a deterministic seed so the reveal/dissolve pattern is stable per-figment
+    rng = random.Random(hash(tuple(rows[0][:10])) if rows[0] else 42)
+    shuffled = list(cell_positions)
+    rng.shuffle(shuffled)
+
+    # Phase-dependent visibility
+    if phase == FigmentPhase.REVEAL:
+        visible_count = int(n_cells * progress)
+        visible = set(shuffled[:visible_count])
+    elif phase == FigmentPhase.HOLD:
+        visible = set(cell_positions)
+        # Strobe: dim some cells periodically
+        if int(progress * 20) % 3 == 0:
+            dim_count = int(n_cells * 0.3)
+            visible -= set(shuffled[:dim_count])
+    elif phase == FigmentPhase.DISSOLVE:
+        remaining_count = int(n_cells * (1.0 - progress))
+        visible = set(shuffled[:remaining_count])
+    else:
+        visible = set(cell_positions)
+
+    # Build overlay commands
+    overlay: list[str] = []
+    n_cols = len(cols)
+    max_x = max((len(r.rstrip()) for r in rows if r.strip()), default=1)
+
+    for r_idx, row in enumerate(rows):
+        scr_row = center_row + r_idx + 1  # 1-indexed
+        if scr_row < 1 or scr_row > h:
+            continue
+
+        line_buf: list[str] = []
+        has_content = False
+
+        for c_idx, ch in enumerate(row):
+            scr_col = center_col + c_idx + 1
+            if scr_col < 1 or scr_col > w:
+                continue
+
+            if ch != " " and (r_idx, c_idx) in visible:
+                # Apply gradient color
+                shifted = (c_idx / max(max_x - 1, 1)) % 1.0
+                idx = min(round(shifted * (n_cols - 1)), n_cols - 1)
+                line_buf.append(f"{cols[idx]}{ch}{RST}")
+                has_content = True
+            else:
+                line_buf.append(" ")
+
+        if has_content:
+            line_str = "".join(line_buf).rstrip()
+            if line_str.strip():
+                overlay.append(f"\033[{scr_row};{center_col + 1}H{line_str}{RST}")
+
+    return overlay
+
+
+class FigmentEffect(EffectPlugin):
+    """Figment overlay effect for pipeline architecture.
+
+    Provides periodic SVG overlays with reveal/hold/dissolve animation.
+    """
+
+    name = "figment"
+    config = EffectConfig(
+        enabled=True,
+        intensity=1.0,
+        params={
+            "interval_secs": 60,
+            "display_secs": 4.5,
+            "figment_dir": "figments",
+        },
+    )
+    supports_partial_updates = False
+    is_overlay = True  # Figment is an overlay effect that composes on top of the buffer
+
+    def __init__(
+        self,
+        figment_dir: str | None = None,
+        triggers: list[FigmentTrigger] | None = None,
+    ):
+        self.config = EffectConfig(
+            enabled=True,
+            intensity=1.0,
+            params={
+                "interval_secs": 60,
+                "display_secs": 4.5,
+                "figment_dir": figment_dir or "figments",
+            },
+        )
+        self._triggers = triggers or []
+        self._phase: FigmentPhase | None = None
+        self._progress: float = 0.0
+        self._rows: list[str] = []
+        self._gradient: list[int] = []
+        self._center_row: int = 0
+        self._center_col: int = 0
+        self._timer: float = 0.0
+        self._last_svg: str | None = None
+        self._svg_files: list[str] = []
+        self._scan_svgs()
+
+    def _scan_svgs(self) -> None:
+        """Scan figment directory for SVG files."""
+        figment_dir = Path(self.config.params["figment_dir"])
+        if figment_dir.is_dir():
+            self._svg_files = sorted(str(p) for p in figment_dir.glob("*.svg"))
+
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
+        """Add figment overlay to buffer."""
+        if not self.config.enabled:
+            return buf
+
+        # Get figment state using frame number from context
+        figment_state = self.get_figment_state(
+            ctx.frame_number, ctx.terminal_width, ctx.terminal_height
+        )
+
+        if figment_state:
+            # Render overlay and append to buffer
+            overlay = render_figment_overlay(
+                figment_state, ctx.terminal_width, ctx.terminal_height
+            )
+            buf = buf + overlay
+
+        return buf
+
+    def configure(self, config: EffectConfig) -> None:
+        """Configure the effect."""
+        # Preserve figment_dir if the new config doesn't supply one
+        figment_dir = config.params.get(
+            "figment_dir", self.config.params.get("figment_dir", "figments")
+        )
+        self.config = config
+        if "figment_dir" not in self.config.params:
+            self.config.params["figment_dir"] = figment_dir
+        self._scan_svgs()
+
+    def trigger(self, w: int, h: int) -> None:
+        """Manually trigger a figment display."""
+        if not self._svg_files:
+            return
+
+        # Pick a random SVG, avoid repeating
+        candidates = [s for s in self._svg_files if s != self._last_svg]
+        if not candidates:
+            candidates = self._svg_files
+        svg_path = random.choice(candidates)
+        self._last_svg = svg_path
+
+        # Rasterize
+        try:
+            self._rows = rasterize_svg(svg_path, w, h)
+        except Exception:
+            return
+
+        # Pick random theme gradient
+        theme_key = random.choice(list(THEME_REGISTRY.keys()))
+        self._gradient = THEME_REGISTRY[theme_key].main_gradient
+
+        # Center in viewport
+        figment_h = len(self._rows)
+        figment_w = max((len(r) for r in self._rows), default=0)
+        self._center_row = max(0, (h - figment_h) // 2)
+        self._center_col = max(0, (w - figment_w) // 2)
+
+        # Start reveal phase
+        self._phase = FigmentPhase.REVEAL
+        self._progress = 0.0
+
+    def get_figment_state(
+        self, frame_number: int, w: int, h: int
+    ) -> FigmentState | None:
+        """Tick the state machine and return current state, or None if idle."""
+        if not self.config.enabled:
+            return None
+
+        # Poll triggers
+        for trig in self._triggers:
+            cmd = trig.poll()
+            if cmd is not None:
+                self._handle_command(cmd, w, h)
+
+        # Tick timer when idle
+        if self._phase is None:
+            self._timer += config.FRAME_DT
+            interval = self.config.params.get("interval_secs", 60)
+            if self._timer >= interval:
+                self._timer = 0.0
+                self.trigger(w, h)
+
+        # Tick animation — snapshot current phase/progress, then advance
+        if self._phase is not None:
+            # Capture the state at the start of this frame
+            current_phase = self._phase
+            current_progress = self._progress
+
+            # Advance for next frame
+            display_secs = self.config.params.get("display_secs", 4.5)
+            phase_duration = display_secs / 3.0
+            self._progress += config.FRAME_DT / phase_duration
+
+            if self._progress >= 1.0:
+                self._progress = 0.0
+                if self._phase == FigmentPhase.REVEAL:
+                    self._phase = FigmentPhase.HOLD
+                elif self._phase == FigmentPhase.HOLD:
+                    self._phase = FigmentPhase.DISSOLVE
+                elif self._phase == FigmentPhase.DISSOLVE:
+                    self._phase = None
+
+            return FigmentState(
+                phase=current_phase,
+                progress=current_progress,
+                rows=self._rows,
+                gradient=self._gradient,
+                center_row=self._center_row,
+                center_col=self._center_col,
+            )
+
+        return None
+
+    def _handle_command(self, cmd: FigmentCommand, w: int, h: int) -> None:
+        """Handle a figment command."""
+        if cmd.action == FigmentAction.TRIGGER:
+            self.trigger(w, h)
+        elif cmd.action == FigmentAction.SET_INTENSITY and isinstance(
+            cmd.value, (int, float)
+        ):
+            self.config.intensity = float(cmd.value)
+        elif cmd.action == FigmentAction.SET_INTERVAL and isinstance(
+            cmd.value, (int, float)
+        ):
+            self.config.params["interval_secs"] = float(cmd.value)
+        elif cmd.action == FigmentAction.SET_COLOR and isinstance(cmd.value, str):
+            if cmd.value in THEME_REGISTRY:
+                self._gradient = THEME_REGISTRY[cmd.value].main_gradient
+        elif cmd.action == FigmentAction.STOP:
+            self._phase = None
+            self._progress = 0.0

engine/figment_render.py

@@ -0,0 +1,90 @@
+"""
+SVG to half-block terminal art rasterization.
+
+Pipeline: SVG -> cairosvg -> PIL -> greyscale threshold -> half-block encode.
+Follows the same pixel-pair approach as engine/render.py for OTF fonts.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+from io import BytesIO
+
+# cairocffi (used by cairosvg) calls dlopen() to find the Cairo C library.
+# On macOS with Homebrew, Cairo lives in /opt/homebrew/lib (Apple Silicon) or
+# /usr/local/lib (Intel), which are not in dyld's default search path.
+# Setting DYLD_LIBRARY_PATH before the import directs dlopen() to those paths.
+if sys.platform == "darwin" and not os.environ.get("DYLD_LIBRARY_PATH"):
+    for _brew_lib in ("/opt/homebrew/lib", "/usr/local/lib"):
+        if os.path.exists(os.path.join(_brew_lib, "libcairo.2.dylib")):
+            os.environ["DYLD_LIBRARY_PATH"] = _brew_lib
+            break
+
+import cairosvg
+from PIL import Image
+
+_cache: dict[tuple[str, int, int], list[str]] = {}
+
+
+def rasterize_svg(svg_path: str, width: int, height: int) -> list[str]:
+    """Convert SVG file to list of half-block terminal rows (uncolored).
+
+    Args:
+        svg_path: Path to SVG file.
+        width: Target terminal width in columns.
+        height: Target terminal height in rows.
+
+    Returns:
+        List of strings, one per terminal row, containing block characters.
+    """
+    cache_key = (svg_path, width, height)
+    if cache_key in _cache:
+        return _cache[cache_key]
+
+    # SVG -> PNG in memory
+    png_bytes = cairosvg.svg2png(
+        url=svg_path,
+        output_width=width,
+        output_height=height * 2,  # 2 pixel rows per terminal row
+    )
+
+    # PNG -> greyscale PIL image
+    # Composite RGBA onto white background so transparent areas become white (255)
+    # and drawn pixels retain their luminance values.
+    img_rgba = Image.open(BytesIO(png_bytes)).convert("RGBA")
+    img_rgba = img_rgba.resize((width, height * 2), Image.Resampling.LANCZOS)
+    background = Image.new("RGBA", img_rgba.size, (255, 255, 255, 255))
+    background.paste(img_rgba, mask=img_rgba.split()[3])
+    img = background.convert("L")
+
+    data = img.tobytes()
+    pix_w = width
+    pix_h = height * 2
+    # White (255) = empty space, dark (< threshold) = filled pixel
+    threshold = 128
+
+    # Half-block encode: walk pixel pairs
+    rows: list[str] = []
+    for y in range(0, pix_h, 2):
+        row: list[str] = []
+        for x in range(pix_w):
+            top = data[y * pix_w + x] < threshold
+            bot = data[(y + 1) * pix_w + x] < threshold if y + 1 < pix_h else False
+            if top and bot:
+                row.append("█")
+            elif top:
+                row.append("▀")
+            elif bot:
+                row.append("▄")
+            else:
+                row.append(" ")
+        rows.append("".join(row))
+
+    _cache[cache_key] = rows
+    return rows
+
+
+def clear_cache() -> None:
+    """Clear the rasterization cache (e.g., on terminal resize)."""
+    _cache.clear()

engine/figment_trigger.py

@@ -0,0 +1,36 @@
+"""
+Figment trigger protocol and command types.
+
+Defines the extensible input abstraction for triggering figment displays
+from any control surface (ntfy, MQTT, serial, etc.).
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from enum import Enum
+from typing import Protocol
+
+
+class FigmentAction(Enum):
+    TRIGGER = "trigger"
+    SET_INTENSITY = "set_intensity"
+    SET_INTERVAL = "set_interval"
+    SET_COLOR = "set_color"
+    STOP = "stop"
+
+
+@dataclass
+class FigmentCommand:
+    action: FigmentAction
+    value: float | str | None = None
+
+
+class FigmentTrigger(Protocol):
+    """Protocol for figment trigger sources.
+
+    Any input source (ntfy, MQTT, serial) can implement this
+    to trigger and control figment displays.
+    """
+
+    def poll(self) -> FigmentCommand | None: ...

engine/pipeline/adapters/__init__.py

@@ -15,6 +15,7 @@ from .factory import (
     create_stage_from_font,
     create_stage_from_source,
 )
+from .message_overlay import MessageOverlayConfig, MessageOverlayStage
 from .transform import (
     CanvasStage,
     FontStage,
@@ -35,6 +36,8 @@ __all__ = [
     "FontStage",
     "ImageToTextStage",
     "CanvasStage",
+    "MessageOverlayStage",
+    "MessageOverlayConfig",
     # Factory functions
     "create_stage_from_display",
     "create_stage_from_effect",

engine/pipeline/adapters/camera.py

@@ -179,7 +179,7 @@ class CameraStage(Stage):
 
     @property
     def dependencies(self) -> set[str]:
-        return {"render.output"}
+        return {"render.output", "camera.state"}
 
     @property
     def inlet_types(self) -> set:

engine/pipeline/adapters/display.py

@@ -53,7 +53,8 @@ class DisplayStage(Stage):
 
     @property
     def dependencies(self) -> set[str]:
-        return {"render.output"}  # Display needs rendered content
+        # Display needs rendered content and camera transformation
+        return {"render.output", "camera"}
 
     @property
     def inlet_types(self) -> set:

engine/pipeline/adapters/effect_plugin.py

@@ -27,9 +27,9 @@ class EffectPluginStage(Stage):
     def stage_type(self) -> str:
         """Return stage_type based on effect name.
 
-        HUD effects are overlays.
+        Overlay effects have stage_type "overlay".
         """
-        if self.name == "hud":
+        if self.is_overlay:
             return "overlay"
         return self.category
 
@@ -37,19 +37,26 @@ class EffectPluginStage(Stage):
     def render_order(self) -> int:
         """Return render_order based on effect type.
 
-        HUD effects have high render_order to appear on top.
+        Overlay effects have high render_order to appear on top.
         """
-        if self.name == "hud":
+        if self.is_overlay:
             return 100  # High order for overlays
         return 0
 
     @property
     def is_overlay(self) -> bool:
-        """Return True for HUD effects.
+        """Return True for overlay effects.
 
-        HUD is an overlay - it composes on top of the buffer
+        Overlay effects compose on top of the buffer
         rather than transforming it for the next stage.
         """
+        # Check if the effect has an is_overlay attribute that is explicitly True
+        # (not just any truthy value from a mock object)
+        if hasattr(self._effect, "is_overlay"):
+            effect_overlay = self._effect.is_overlay
+            # Only return True if it's explicitly set to True
+            if effect_overlay is True:
+                return True
         return self.name == "hud"
 
     @property

engine/pipeline/adapters/frame_capture.py

@@ -0,0 +1,165 @@
+"""
+Frame Capture Stage Adapter
+
+Wraps pipeline stages to capture frames for animation report generation.
+"""
+
+from typing import Any
+
+from engine.display.backends.animation_report import AnimationReportDisplay
+from engine.pipeline.core import PipelineContext, Stage
+
+
+class FrameCaptureStage(Stage):
+    """
+    Wrapper stage that captures frames before and after a wrapped stage.
+
+    This allows generating animation reports showing how each stage
+    transforms the data.
+    """
+
+    def __init__(
+        self,
+        wrapped_stage: Stage,
+        display: AnimationReportDisplay,
+        name: str | None = None,
+    ):
+        """
+        Initialize frame capture stage.
+
+        Args:
+            wrapped_stage: The stage to wrap and capture frames from
+            display: The animation report display to send frames to
+            name: Optional name for this capture stage
+        """
+        self._wrapped_stage = wrapped_stage
+        self._display = display
+        self.name = name or f"capture_{wrapped_stage.name}"
+        self.category = wrapped_stage.category
+        self.optional = wrapped_stage.optional
+
+        # Capture state
+        self._captured_input = False
+        self._captured_output = False
+
+    @property
+    def stage_type(self) -> str:
+        return self._wrapped_stage.stage_type
+
+    @property
+    def capabilities(self) -> set[str]:
+        return self._wrapped_stage.capabilities
+
+    @property
+    def dependencies(self) -> set[str]:
+        return self._wrapped_stage.dependencies
+
+    @property
+    def inlet_types(self) -> set:
+        return self._wrapped_stage.inlet_types
+
+    @property
+    def outlet_types(self) -> set:
+        return self._wrapped_stage.outlet_types
+
+    def init(self, ctx: PipelineContext) -> bool:
+        """Initialize the wrapped stage."""
+        return self._wrapped_stage.init(ctx)
+
+    def process(self, data: Any, ctx: PipelineContext) -> Any:
+        """
+        Process data through wrapped stage and capture frames.
+
+        Args:
+            data: Input data (typically a text buffer)
+            ctx: Pipeline context
+
+        Returns:
+            Output data from wrapped stage
+        """
+        # Capture input frame (before stage processing)
+        if isinstance(data, list) and all(isinstance(line, str) for line in data):
+            self._display.start_stage(f"{self._wrapped_stage.name}_input")
+            self._display.show(data)
+            self._captured_input = True
+
+        # Process through wrapped stage
+        result = self._wrapped_stage.process(data, ctx)
+
+        # Capture output frame (after stage processing)
+        if isinstance(result, list) and all(isinstance(line, str) for line in result):
+            self._display.start_stage(f"{self._wrapped_stage.name}_output")
+            self._display.show(result)
+            self._captured_output = True
+
+        return result
+
+    def cleanup(self) -> None:
+        """Cleanup the wrapped stage."""
+        self._wrapped_stage.cleanup()
+
+
+class FrameCaptureController:
+    """
+    Controller for managing frame capture across the pipeline.
+
+    This class provides an easy way to enable frame capture for
+    specific stages or the entire pipeline.
+    """
+
+    def __init__(self, display: AnimationReportDisplay):
+        """
+        Initialize frame capture controller.
+
+        Args:
+            display: The animation report display to use for capture
+        """
+        self._display = display
+        self._captured_stages: list[FrameCaptureStage] = []
+
+    def wrap_stage(self, stage: Stage, name: str | None = None) -> FrameCaptureStage:
+        """
+        Wrap a stage with frame capture.
+
+        Args:
+            stage: The stage to wrap
+            name: Optional name for the capture stage
+
+        Returns:
+            Wrapped stage that captures frames
+        """
+        capture_stage = FrameCaptureStage(stage, self._display, name)
+        self._captured_stages.append(capture_stage)
+        return capture_stage
+
+    def wrap_stages(self, stages: dict[str, Stage]) -> dict[str, Stage]:
+        """
+        Wrap multiple stages with frame capture.
+
+        Args:
+            stages: Dictionary of stage names to stages
+
+        Returns:
+            Dictionary of stage names to wrapped stages
+        """
+        wrapped = {}
+        for name, stage in stages.items():
+            wrapped[name] = self.wrap_stage(stage, name)
+        return wrapped
+
+    def get_captured_stages(self) -> list[FrameCaptureStage]:
+        """Get list of all captured stages."""
+        return self._captured_stages
+
+    def generate_report(self, title: str = "Pipeline Animation Report") -> str:
+        """
+        Generate the animation report.
+
+        Args:
+            title: Title for the report
+
+        Returns:
+            Path to the generated HTML file
+        """
+        report_path = self._display.generate_report(title)
+        return str(report_path)

engine/pipeline/adapters/message_overlay.py

@@ -0,0 +1,185 @@
+"""
+Message overlay stage - Renders ntfy messages as an overlay on the buffer.
+
+This stage provides message overlay capability for displaying ntfy.sh messages
+as a centered panel with pink/magenta gradient, matching upstream/main aesthetics.
+"""
+
+import re
+import time
+from dataclasses import dataclass
+from datetime import datetime
+
+from engine import config
+from engine.effects.legacy import vis_trunc
+from engine.pipeline.core import DataType, PipelineContext, Stage
+from engine.render.blocks import big_wrap
+from engine.render.gradient import msg_gradient
+
+
+@dataclass
+class MessageOverlayConfig:
+    """Configuration for MessageOverlayStage."""
+
+    enabled: bool = True
+    display_secs: int = 30  # How long to display messages
+    topic_url: str | None = None  # Ntfy topic URL (None = use config default)
+
+
+class MessageOverlayStage(Stage):
+    """Stage that renders ntfy message overlay on the buffer.
+
+    Provides:
+    - message.overlay capability (optional)
+    - Renders centered panel with pink/magenta gradient
+    - Shows title, body, timestamp, and remaining time
+    """
+
+    name = "message_overlay"
+    category = "overlay"
+
+    def __init__(
+        self, config: MessageOverlayConfig | None = None, name: str = "message_overlay"
+    ):
+        self.config = config or MessageOverlayConfig()
+        self._ntfy_poller = None
+        self._msg_cache = (None, None)  # (cache_key, rendered_rows)
+
+    @property
+    def capabilities(self) -> set[str]:
+        """Provides message overlay capability."""
+        return {"message.overlay"} if self.config.enabled else set()
+
+    @property
+    def dependencies(self) -> set[str]:
+        """Needs rendered buffer and camera transformation to overlay onto."""
+        return {"render.output", "camera"}
+
+    @property
+    def inlet_types(self) -> set:
+        return {DataType.TEXT_BUFFER}
+
+    @property
+    def outlet_types(self) -> set:
+        return {DataType.TEXT_BUFFER}
+
+    def init(self, ctx: PipelineContext) -> bool:
+        """Initialize ntfy poller if topic URL is configured."""
+        if not self.config.enabled:
+            return True
+
+        # Get or create ntfy poller
+        topic_url = self.config.topic_url or config.NTFY_TOPIC
+        if topic_url:
+            from engine.ntfy import NtfyPoller
+
+            self._ntfy_poller = NtfyPoller(
+                topic_url=topic_url,
+                reconnect_delay=getattr(config, "NTFY_RECONNECT_DELAY", 5),
+                display_secs=self.config.display_secs,
+            )
+            self._ntfy_poller.start()
+            ctx.set("ntfy_poller", self._ntfy_poller)
+
+        return True
+
+    def process(self, data: list[str], ctx: PipelineContext) -> list[str]:
+        """Render message overlay on the buffer."""
+        if not self.config.enabled or not data:
+            return data
+
+        # Get active message from poller
+        msg = None
+        if self._ntfy_poller:
+            msg = self._ntfy_poller.get_active_message()
+
+        if msg is None:
+            return data
+
+        # Render overlay
+        w = ctx.terminal_width if hasattr(ctx, "terminal_width") else 80
+        h = ctx.terminal_height if hasattr(ctx, "terminal_height") else 24
+
+        overlay, self._msg_cache = self._render_message_overlay(
+            msg, w, h, self._msg_cache
+        )
+
+        # Composite overlay onto buffer
+        result = list(data)
+        for line in overlay:
+            # Overlay uses ANSI cursor positioning, just append
+            result.append(line)
+
+        return result
+
+    def _render_message_overlay(
+        self,
+        msg: tuple[str, str, float] | None,
+        w: int,
+        h: int,
+        msg_cache: tuple,
+    ) -> tuple[list[str], tuple]:
+        """Render ntfy message overlay.
+
+        Args:
+            msg: (title, body, timestamp) or None
+            w: terminal width
+            h: terminal height
+            msg_cache: (cache_key, rendered_rows) for caching
+
+        Returns:
+            (list of ANSI strings, updated cache)
+        """
+        overlay = []
+        if msg is None:
+            return overlay, msg_cache
+
+        m_title, m_body, m_ts = msg
+        display_text = m_body or m_title or "(empty)"
+        display_text = re.sub(r"\s+", " ", display_text.upper())
+
+        cache_key = (display_text, w)
+        if msg_cache[0] != cache_key:
+            msg_rows = big_wrap(display_text, w - 4)
+            msg_cache = (cache_key, msg_rows)
+        else:
+            msg_rows = msg_cache[1]
+
+        msg_rows = msg_gradient(msg_rows, (time.monotonic() * config.GRAD_SPEED) % 1.0)
+
+        elapsed_s = int(time.monotonic() - m_ts)
+        remaining = max(0, self.config.display_secs - elapsed_s)
+        ts_str = datetime.now().strftime("%H:%M:%S")
+        panel_h = len(msg_rows) + 2
+        panel_top = max(0, (h - panel_h) // 2)
+
+        row_idx = 0
+        for mr in msg_rows:
+            ln = vis_trunc(mr, w)
+            overlay.append(f"\033[{panel_top + row_idx + 1};1H  {ln}\033[0m\033[K")
+            row_idx += 1
+
+        meta_parts = []
+        if m_title and m_title != m_body:
+            meta_parts.append(m_title)
+        meta_parts.append(f"ntfy \u00b7 {ts_str} \u00b7 {remaining}s")
+        meta = (
+            "  " + " \u00b7 ".join(meta_parts)
+            if len(meta_parts) > 1
+            else "  " + meta_parts[0]
+        )
+        overlay.append(
+            f"\033[{panel_top + row_idx + 1};1H\033[38;5;245m{meta}\033[0m\033[K"
+        )
+        row_idx += 1
+
+        bar = "\u2500" * (w - 4)
+        overlay.append(
+            f"\033[{panel_top + row_idx + 1};1H  \033[2;38;5;37m{bar}\033[0m\033[K"
+        )
+
+        return overlay, msg_cache
+
+    def cleanup(self) -> None:
+        """Cleanup resources."""
+        pass

engine/pipeline/controller.py

@@ -474,9 +474,10 @@ class Pipeline:
             not self._find_stage_with_capability("display.output")
             and "display" not in self._stages
         ):
-            display = DisplayRegistry.create("terminal")
+            display_name = self.config.display or "terminal"
+            display = DisplayRegistry.create(display_name)
             if display:
-                self.add_stage("display", DisplayStage(display, name="terminal"))
+                self.add_stage("display", DisplayStage(display, name=display_name))
                 injected.append("display")
 
         # Rebuild pipeline if stages were injected

engine/pipeline/presets.py

@@ -59,6 +59,7 @@ class PipelinePreset:
     viewport_height: int = 24  # Viewport height in rows
     source_items: list[dict[str, Any]] | None = None  # For ListDataSource
     enable_metrics: bool = True  # Enable performance metrics collection
+    enable_message_overlay: bool = False  # Enable ntfy message overlay
 
     def to_params(self) -> PipelineParams:
         """Convert to PipelineParams (runtime configuration)."""
@@ -113,6 +114,7 @@ class PipelinePreset:
             viewport_height=data.get("viewport_height", 24),
             source_items=data.get("source_items"),
             enable_metrics=data.get("enable_metrics", True),
+            enable_message_overlay=data.get("enable_message_overlay", False),
         )
 
 
@@ -124,6 +126,7 @@ DEMO_PRESET = PipelinePreset(
     display="pygame",
     camera="scroll",
     effects=["noise", "fade", "glitch", "firehose"],
+    enable_message_overlay=True,
 )
 
 UI_PRESET = PipelinePreset(
@@ -134,6 +137,7 @@ UI_PRESET = PipelinePreset(
     camera="scroll",
     effects=["noise", "fade", "glitch"],
     border=BorderMode.UI,
+    enable_message_overlay=True,
 )
 
 POETRY_PRESET = PipelinePreset(
@@ -170,6 +174,7 @@ FIREHOSE_PRESET = PipelinePreset(
     display="pygame",
     camera="scroll",
     effects=["noise", "fade", "glitch", "firehose"],
+    enable_message_overlay=True,
 )
 
 FIXTURE_PRESET = PipelinePreset(

engine/render/gradient.py

@@ -80,3 +80,57 @@ def lr_gradient_opposite(rows, offset=0.0):
         List of lines with complementary gradient coloring applied
     """
     return lr_gradient(rows, offset, MSG_GRAD_COLS)
+
+
+def msg_gradient(rows, offset):
+    """Apply message (ntfy) gradient using theme complementary colors.
+
+    Returns colored rows using ACTIVE_THEME.message_gradient if available,
+    falling back to default magenta if no theme is set.
+
+    Args:
+        rows: List of text strings to colorize
+        offset: Gradient offset (0.0-1.0) for animation
+
+    Returns:
+        List of rows with ANSI color codes applied
+    """
+    from engine import config
+
+    # Check if theme is set and use it
+    if config.ACTIVE_THEME:
+        cols = _color_codes_to_ansi(config.ACTIVE_THEME.message_gradient)
+    else:
+        # Fallback to default magenta gradient
+        cols = MSG_GRAD_COLS
+
+    return lr_gradient(rows, offset, cols)
+
+
+def _color_codes_to_ansi(color_codes):
+    """Convert a list of 256-color codes to ANSI escape code strings.
+
+    Pattern: first 2 are bold, middle 8 are normal, last 2 are dim.
+
+    Args:
+        color_codes: List of 12 integers (256-color palette codes)
+
+    Returns:
+        List of ANSI escape code strings
+    """
+    if not color_codes or len(color_codes) != 12:
+        # Fallback to default green if invalid
+        return GRAD_COLS
+
+    result = []
+    for i, code in enumerate(color_codes):
+        if i < 2:
+            # Bold for first 2 (bright leading edge)
+            result.append(f"\033[1;38;5;{code}m")
+        elif i < 10:
+            # Normal for middle 8
+            result.append(f"\033[38;5;{code}m")
+        else:
+            # Dim for last 2 (dark trailing edge)
+            result.append(f"\033[2;38;5;{code}m")
+    return result

engine/themes.py

@@ -0,0 +1,60 @@
+"""
+Theme definitions with color gradients for terminal rendering.
+
+This module is data-only and does not import config or render
+to prevent circular dependencies.
+"""
+
+
+class Theme:
+    """Represents a color theme with two gradients."""
+
+    def __init__(self, name, main_gradient, message_gradient):
+        """Initialize a theme with name and color gradients.
+
+        Args:
+            name: Theme identifier string
+            main_gradient: List of 12 ANSI 256-color codes for main gradient
+            message_gradient: List of 12 ANSI 256-color codes for message gradient
+        """
+        self.name = name
+        self.main_gradient = main_gradient
+        self.message_gradient = message_gradient
+
+
+# ─── GRADIENT DEFINITIONS ─────────────────────────────────────────────────
+# Each gradient is 12 ANSI 256-color codes in sequence
+# Format: [light...] → [medium...] → [dark...] → [black]
+
+_GREEN_MAIN = [231, 195, 123, 118, 82, 46, 40, 34, 28, 22, 22, 235]
+_GREEN_MSG = [231, 225, 219, 213, 207, 201, 165, 161, 125, 89, 89, 235]
+
+_ORANGE_MAIN = [231, 215, 209, 208, 202, 166, 130, 94, 58, 94, 94, 235]
+_ORANGE_MSG = [231, 195, 33, 27, 21, 21, 21, 18, 18, 18, 18, 235]
+
+_PURPLE_MAIN = [231, 225, 177, 171, 165, 135, 129, 93, 57, 57, 57, 235]
+_PURPLE_MSG = [231, 226, 226, 220, 220, 184, 184, 178, 178, 172, 172, 235]
+
+
+# ─── THEME REGISTRY ───────────────────────────────────────────────────────
+
+THEME_REGISTRY = {
+    "green": Theme("green", _GREEN_MAIN, _GREEN_MSG),
+    "orange": Theme("orange", _ORANGE_MAIN, _ORANGE_MSG),
+    "purple": Theme("purple", _PURPLE_MAIN, _PURPLE_MSG),
+}
+
+
+def get_theme(theme_id):
+    """Retrieve a theme by ID.
+
+    Args:
+        theme_id: Theme identifier string
+
+    Returns:
+        Theme object matching the ID
+
+    Raises:
+        KeyError: If theme_id is not in registry
+    """
+    return THEME_REGISTRY[theme_id]

figments/animal-head-symbol-of-mexico-antique-cultures-svgrepo-com.svg

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!-- Uploaded to: SVG Repo, www.svgrepo.com, Generator: SVG Repo Mixer Tools -->
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg fill="#000000" version="1.1" id="Capa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" 
+	 width="800px" height="800px" viewBox="0 0 577.362 577.362"
+	 xml:space="preserve">
+<g>
+	<g id="Layer_2_21_">
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+			c15.118-0.842,40.487-8.836,40.487-8.836l48.214-7.966l-9.964,66.938l57.777-19.526v57.776l66.938-29.883l19.125,49.41
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+</svg>

figments/mayan-mask-of-mexico-svgrepo-com.svg

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+	 xml:space="preserve">
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+</svg>

figments/mayan-symbol-of-mexico-svgrepo-com.svg

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+</svg>

mise.toml

@@ -19,7 +19,8 @@ format = "uv run ruff format engine/ mainline.py"
 # Run
 # =====================
 
-run = "uv run mainline.py"
+mainline = "uv run mainline.py"
+run = { run = "uv run mainline.py", depends = ["sync-all"] }
 run-pygame = { run = "uv run mainline.py --display pygame", depends = ["sync-all"] }
 run-terminal = { run = "uv run mainline.py --display terminal", depends = ["sync-all"] }
 

presets.toml

@@ -40,6 +40,15 @@ camera_speed = 0.5
 viewport_width = 80
 viewport_height = 24
 
+[presets.test-figment]
+description = "Test: Figment overlay effect"
+source = "empty"
+display = "terminal"
+camera = "feed"
+effects = ["figment"]
+viewport_width = 80
+viewport_height = 24
+
 # ============================================
 # DEMO PRESETS (for demonstration and exploration)
 # ============================================
@@ -53,6 +62,7 @@ effects = []  # Demo script will add/remove effects dynamically
 camera_speed = 0.1
 viewport_width = 80
 viewport_height = 24
+enable_message_overlay = true
 
 [presets.demo-pygame]
 description = "Demo: Pygame display version"
@@ -63,6 +73,7 @@ effects = []  # Demo script will add/remove effects dynamically
 camera_speed = 0.1
 viewport_width = 80
 viewport_height = 24
+enable_message_overlay = true
 
 [presets.demo-camera-showcase]
 description = "Demo: Camera mode showcase"
@@ -73,6 +84,18 @@ effects = []  # Demo script will cycle through camera modes
 camera_speed = 0.5
 viewport_width = 80
 viewport_height = 24
+enable_message_overlay = true
+
+[presets.test-message-overlay]
+description = "Test: Message overlay with ntfy integration"
+source = "headlines"
+display = "terminal"
+camera = "feed"
+effects = ["hud"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = true
 
 # ============================================
 # SENSOR CONFIGURATION

pyproject.toml

@@ -40,6 +40,9 @@ pygame = [
 browser = [
     "playwright>=1.40.0",
 ]
+figment = [
+    "cairosvg>=2.7.0",
+]
 dev = [
     "pytest>=8.0.0",
     "pytest-benchmark>=4.0.0",
@@ -62,6 +65,7 @@ dev = [
     "pytest-cov>=4.1.0",
     "pytest-mock>=3.12.0",
     "ruff>=0.1.0",
+    "tomli>=2.0.0",
 ]
 
 [tool.pytest.ini_options]

scripts/capture_output.py

@@ -0,0 +1,201 @@
+#!/usr/bin/env python3
+"""
+Capture output utility for Mainline.
+
+This script captures the output of a Mainline pipeline using NullDisplay
+and saves it to a JSON file for comparison with other branches.
+"""
+
+import argparse
+import json
+import time
+from pathlib import Path
+
+from engine.display import DisplayRegistry
+from engine.pipeline import Pipeline, PipelineConfig, PipelineContext
+from engine.pipeline.adapters import create_stage_from_display
+from engine.pipeline.presets import get_preset
+
+
+def capture_pipeline_output(
+    preset_name: str,
+    output_file: str,
+    frames: int = 60,
+    width: int = 80,
+    height: int = 24,
+):
+    """Capture pipeline output for a given preset.
+
+    Args:
+        preset_name: Name of preset to use
+        output_file: Path to save captured output
+        frames: Number of frames to capture
+        width: Terminal width
+        height: Terminal height
+    """
+    print(f"Capturing output for preset '{preset_name}'...")
+
+    # Get preset
+    preset = get_preset(preset_name)
+    if not preset:
+        print(f"Error: Preset '{preset_name}' not found")
+        return False
+
+    # Create NullDisplay with recording
+    display = DisplayRegistry.create("null")
+    display.init(width, height)
+    display.start_recording()
+
+    # Build pipeline
+    config = PipelineConfig(
+        source=preset.source,
+        display="null",  # Use null display
+        camera=preset.camera,
+        effects=preset.effects,
+        enable_metrics=False,
+    )
+
+    # Create pipeline context with params
+    from engine.pipeline.params import PipelineParams
+
+    params = PipelineParams(
+        source=preset.source,
+        display="null",
+        camera_mode=preset.camera,
+        effect_order=preset.effects,
+        viewport_width=preset.viewport_width,
+        viewport_height=preset.viewport_height,
+        camera_speed=preset.camera_speed,
+    )
+
+    ctx = PipelineContext()
+    ctx.params = params
+
+    pipeline = Pipeline(config=config, context=ctx)
+
+    # Add stages based on preset
+    from engine.data_sources.sources import HeadlinesDataSource
+    from engine.pipeline.adapters import DataSourceStage
+
+    # Add source stage
+    source = HeadlinesDataSource()
+    pipeline.add_stage("source", DataSourceStage(source, name="headlines"))
+
+    # Add message overlay if enabled
+    if getattr(preset, "enable_message_overlay", False):
+        from engine import config as engine_config
+        from engine.pipeline.adapters import MessageOverlayConfig, MessageOverlayStage
+
+        overlay_config = MessageOverlayConfig(
+            enabled=True,
+            display_secs=getattr(engine_config, "MESSAGE_DISPLAY_SECS", 30),
+            topic_url=getattr(engine_config, "NTFY_TOPIC", None),
+        )
+        pipeline.add_stage(
+            "message_overlay", MessageOverlayStage(config=overlay_config)
+        )
+
+    # Add display stage
+    pipeline.add_stage("display", create_stage_from_display(display, "null"))
+
+    # Build and initialize
+    pipeline.build()
+    if not pipeline.initialize():
+        print("Error: Failed to initialize pipeline")
+        return False
+
+    # Capture frames
+    print(f"Capturing {frames} frames...")
+    start_time = time.time()
+
+    for frame in range(frames):
+        try:
+            pipeline.execute([])
+            if frame % 10 == 0:
+                print(f"  Frame {frame}/{frames}")
+        except Exception as e:
+            print(f"Error on frame {frame}: {e}")
+            break
+
+    elapsed = time.time() - start_time
+    print(f"Captured {frame + 1} frames in {elapsed:.2f}s")
+
+    # Get captured frames
+    captured_frames = display.get_frames()
+    print(f"Retrieved {len(captured_frames)} frames from display")
+
+    # Save to JSON
+    output_path = Path(output_file)
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+
+    recording_data = {
+        "version": 1,
+        "preset": preset_name,
+        "display": "null",
+        "width": width,
+        "height": height,
+        "frame_count": len(captured_frames),
+        "frames": [
+            {
+                "frame_number": i,
+                "buffer": frame,
+                "width": width,
+                "height": height,
+            }
+            for i, frame in enumerate(captured_frames)
+        ],
+    }
+
+    with open(output_path, "w") as f:
+        json.dump(recording_data, f, indent=2)
+
+    print(f"Saved recording to {output_path}")
+    return True
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Capture Mainline pipeline output")
+    parser.add_argument(
+        "--preset",
+        default="demo",
+        help="Preset name to use (default: demo)",
+    )
+    parser.add_argument(
+        "--output",
+        default="output/capture.json",
+        help="Output file path (default: output/capture.json)",
+    )
+    parser.add_argument(
+        "--frames",
+        type=int,
+        default=60,
+        help="Number of frames to capture (default: 60)",
+    )
+    parser.add_argument(
+        "--width",
+        type=int,
+        default=80,
+        help="Terminal width (default: 80)",
+    )
+    parser.add_argument(
+        "--height",
+        type=int,
+        default=24,
+        help="Terminal height (default: 24)",
+    )
+
+    args = parser.parse_args()
+
+    success = capture_pipeline_output(
+        preset_name=args.preset,
+        output_file=args.output,
+        frames=args.frames,
+        width=args.width,
+        height=args.height,
+    )
+
+    return 0 if success else 1
+
+
+if __name__ == "__main__":
+    exit(main())

scripts/capture_upstream.py

@@ -0,0 +1,186 @@
+#!/usr/bin/env python3
+"""
+Capture output from upstream/main branch.
+
+This script captures the output of upstream/main Mainline using NullDisplay
+and saves it to a JSON file for comparison with sideline branch.
+"""
+
+import argparse
+import json
+import sys
+from pathlib import Path
+
+# Add upstream/main to path
+sys.path.insert(0, "/tmp/upstream_mainline")
+
+
+def capture_upstream_output(
+    output_file: str,
+    frames: int = 60,
+    width: int = 80,
+    height: int = 24,
+):
+    """Capture upstream/main output.
+
+    Args:
+        output_file: Path to save captured output
+        frames: Number of frames to capture
+        width: Terminal width
+        height: Terminal height
+    """
+    print(f"Capturing upstream/main output...")
+
+    try:
+        # Import upstream modules
+        from engine import config, themes
+        from engine.display import NullDisplay
+        from engine.fetch import fetch_all, load_cache
+        from engine.scroll import stream
+        from engine.ntfy import NtfyPoller
+        from engine.mic import MicMonitor
+    except ImportError as e:
+        print(f"Error importing upstream modules: {e}")
+        print("Make sure upstream/main is in the Python path")
+        return False
+
+    # Create a custom NullDisplay that captures frames
+    class CapturingNullDisplay:
+        def __init__(self, width, height, max_frames):
+            self.width = width
+            self.height = height
+            self.max_frames = max_frames
+            self.frame_count = 0
+            self.frames = []
+
+        def init(self, width: int, height: int) -> None:
+            self.width = width
+            self.height = height
+
+        def show(self, buffer: list[str], border: bool = False) -> None:
+            if self.frame_count < self.max_frames:
+                self.frames.append(list(buffer))
+                self.frame_count += 1
+            if self.frame_count >= self.max_frames:
+                raise StopIteration("Frame limit reached")
+
+        def clear(self) -> None:
+            pass
+
+        def cleanup(self) -> None:
+            pass
+
+        def get_frames(self):
+            return self.frames
+
+    display = CapturingNullDisplay(width, height, frames)
+
+    # Load items (use cached headlines)
+    items = load_cache()
+    if not items:
+        print("No cached items found, fetching...")
+        result = fetch_all()
+        if isinstance(result, tuple):
+            items, linked, failed = result
+        else:
+            items = result
+        if not items:
+            print("Error: No items available")
+            return False
+
+    print(f"Loaded {len(items)} items")
+
+    # Create ntfy poller and mic monitor (upstream uses these)
+    ntfy_poller = NtfyPoller(config.NTFY_TOPIC, reconnect_delay=5, display_secs=30)
+    mic_monitor = MicMonitor()
+
+    # Run stream for specified number of frames
+    print(f"Capturing {frames} frames...")
+
+    try:
+        # Run the stream
+        stream(
+            items=items,
+            ntfy_poller=ntfy_poller,
+            mic_monitor=mic_monitor,
+            display=display,
+        )
+    except StopIteration:
+        print("Frame limit reached")
+    except Exception as e:
+        print(f"Error during capture: {e}")
+        # Continue to save what we have
+
+    # Get captured frames
+    captured_frames = display.get_frames()
+    print(f"Retrieved {len(captured_frames)} frames from display")
+
+    # Save to JSON
+    output_path = Path(output_file)
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+
+    recording_data = {
+        "version": 1,
+        "preset": "upstream_demo",
+        "display": "null",
+        "width": width,
+        "height": height,
+        "frame_count": len(captured_frames),
+        "frames": [
+            {
+                "frame_number": i,
+                "buffer": frame,
+                "width": width,
+                "height": height,
+            }
+            for i, frame in enumerate(captured_frames)
+        ],
+    }
+
+    with open(output_path, "w") as f:
+        json.dump(recording_data, f, indent=2)
+
+    print(f"Saved recording to {output_path}")
+    return True
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Capture upstream/main output")
+    parser.add_argument(
+        "--output",
+        default="output/upstream_demo.json",
+        help="Output file path (default: output/upstream_demo.json)",
+    )
+    parser.add_argument(
+        "--frames",
+        type=int,
+        default=60,
+        help="Number of frames to capture (default: 60)",
+    )
+    parser.add_argument(
+        "--width",
+        type=int,
+        default=80,
+        help="Terminal width (default: 80)",
+    )
+    parser.add_argument(
+        "--height",
+        type=int,
+        default=24,
+        help="Terminal height (default: 24)",
+    )
+
+    args = parser.parse_args()
+
+    success = capture_upstream_output(
+        output_file=args.output,
+        frames=args.frames,
+        width=args.width,
+        height=args.height,
+    )
+
+    return 0 if success else 1
+
+
+if __name__ == "__main__":
+    exit(main())

scripts/capture_upstream_comparison.py

@@ -0,0 +1,144 @@
+"""Capture frames from upstream Mainline for comparison testing.
+
+This script should be run on the upstream/main branch to capture frames
+that will later be compared with sideline branch output.
+
+Usage:
+    # On upstream/main branch
+    python scripts/capture_upstream_comparison.py --preset demo
+
+    # This will create tests/comparison_output/demo_upstream.json
+"""
+
+import argparse
+import json
+import sys
+from pathlib import Path
+
+# Add project root to path
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+
+def load_preset(preset_name: str) -> dict:
+    """Load a preset from presets.toml."""
+    import tomli
+
+    # Try user presets first
+    user_presets = Path.home() / ".config" / "mainline" / "presets.toml"
+    local_presets = Path("presets.toml")
+    built_in_presets = Path(__file__).parent.parent / "presets.toml"
+
+    for preset_file in [user_presets, local_presets, built_in_presets]:
+        if preset_file.exists():
+            with open(preset_file, "rb") as f:
+                config = tomli.load(f)
+                if "presets" in config and preset_name in config["presets"]:
+                    return config["presets"][preset_name]
+
+    raise ValueError(f"Preset '{preset_name}' not found")
+
+
+def capture_upstream_frames(
+    preset_name: str,
+    frame_count: int = 30,
+    output_dir: Path = Path("tests/comparison_output"),
+) -> Path:
+    """Capture frames from upstream pipeline.
+
+    Note: This is a simplified version that mimics upstream behavior.
+    For actual upstream comparison, you may need to:
+    1. Checkout upstream/main branch
+    2. Run this script
+    3. Copy the output file
+    4. Checkout your branch
+    5. Run comparison
+    """
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    # Load preset
+    preset = load_preset(preset_name)
+
+    # For upstream, we need to use the old monolithic rendering approach
+    # This is a simplified placeholder - actual implementation depends on
+    # the specific upstream architecture
+
+    print(f"Capturing {frame_count} frames from upstream preset '{preset_name}'")
+    print("Note: This script should be run on upstream/main branch")
+    print(f"      for accurate comparison with sideline branch")
+
+    # Placeholder: In a real implementation, this would:
+    # 1. Import upstream-specific modules
+    # 2. Create pipeline using upstream architecture
+    # 3. Capture frames
+    # 4. Save to JSON
+
+    # For now, create a placeholder file with instructions
+    placeholder_data = {
+        "preset": preset_name,
+        "config": preset,
+        "note": "This is a placeholder file.",
+        "instructions": [
+            "1. Checkout upstream/main branch: git checkout main",
+            "2. Run frame capture: python scripts/capture_upstream_comparison.py --preset <name>",
+            "3. Copy output file to sideline branch",
+            "4. Checkout sideline branch: git checkout feature/capability-based-deps",
+            "5. Run comparison: python tests/run_comparison.py --preset <name>",
+        ],
+        "frames": [],  # Empty until properly captured
+    }
+
+    output_file = output_dir / f"{preset_name}_upstream.json"
+    with open(output_file, "w") as f:
+        json.dump(placeholder_data, f, indent=2)
+
+    print(f"\nPlaceholder file created: {output_file}")
+    print("\nTo capture actual upstream frames:")
+    print("1. Ensure you are on upstream/main branch")
+    print("2. This script needs to be adapted to use upstream-specific rendering")
+    print("3. The captured frames will be used for comparison with sideline")
+
+    return output_file
+
+
+def main():
+    """Main entry point."""
+    parser = argparse.ArgumentParser(
+        description="Capture frames from upstream Mainline for comparison"
+    )
+    parser.add_argument(
+        "--preset",
+        "-p",
+        required=True,
+        help="Preset name to capture",
+    )
+    parser.add_argument(
+        "--frames",
+        "-f",
+        type=int,
+        default=30,
+        help="Number of frames to capture",
+    )
+    parser.add_argument(
+        "--output-dir",
+        "-o",
+        type=Path,
+        default=Path("tests/comparison_output"),
+        help="Output directory",
+    )
+
+    args = parser.parse_args()
+
+    try:
+        output_file = capture_upstream_frames(
+            preset_name=args.preset,
+            frame_count=args.frames,
+            output_dir=args.output_dir,
+        )
+        print(f"\nCapture complete: {output_file}")
+    except Exception as e:
+        print(f"Error: {e}")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()

scripts/compare_outputs.py

@@ -0,0 +1,220 @@
+#!/usr/bin/env python3
+"""
+Compare captured outputs from different branches or configurations.
+
+This script loads two captured recordings and compares them frame-by-frame,
+reporting any differences found.
+"""
+
+import argparse
+import difflib
+import json
+from pathlib import Path
+
+
+def load_recording(file_path: str) -> dict:
+    """Load a recording from a JSON file."""
+    with open(file_path, "r") as f:
+        return json.load(f)
+
+
+def compare_frame_buffers(buf1: list[str], buf2: list[str]) -> tuple[int, list[str]]:
+    """Compare two frame buffers and return differences.
+
+    Returns:
+        tuple: (difference_count, list of difference descriptions)
+    """
+    differences = []
+
+    # Check dimensions
+    if len(buf1) != len(buf2):
+        differences.append(f"Height mismatch: {len(buf1)} vs {len(buf2)}")
+
+    # Check each line
+    max_lines = max(len(buf1), len(buf2))
+    for i in range(max_lines):
+        if i >= len(buf1):
+            differences.append(f"Line {i}: Missing in first buffer")
+            continue
+        if i >= len(buf2):
+            differences.append(f"Line {i}: Missing in second buffer")
+            continue
+
+        line1 = buf1[i]
+        line2 = buf2[i]
+
+        if line1 != line2:
+            # Find the specific differences in the line
+            if len(line1) != len(line2):
+                differences.append(
+                    f"Line {i}: Length mismatch ({len(line1)} vs {len(line2)})"
+                )
+
+            # Show a snippet of the difference
+            max_len = max(len(line1), len(line2))
+            snippet1 = line1[:50] + "..." if len(line1) > 50 else line1
+            snippet2 = line2[:50] + "..." if len(line2) > 50 else line2
+            differences.append(f"Line {i}: '{snippet1}' != '{snippet2}'")
+
+    return len(differences), differences
+
+
+def compare_recordings(
+    recording1: dict, recording2: dict, max_frames: int = None
+) -> dict:
+    """Compare two recordings frame-by-frame.
+
+    Returns:
+        dict: Comparison results with summary and detailed differences
+    """
+    results = {
+        "summary": {},
+        "frames": [],
+        "total_differences": 0,
+        "frames_with_differences": 0,
+    }
+
+    # Compare metadata
+    results["summary"]["recording1"] = {
+        "preset": recording1.get("preset", "unknown"),
+        "frame_count": recording1.get("frame_count", 0),
+        "width": recording1.get("width", 0),
+        "height": recording1.get("height", 0),
+    }
+    results["summary"]["recording2"] = {
+        "preset": recording2.get("preset", "unknown"),
+        "frame_count": recording2.get("frame_count", 0),
+        "width": recording2.get("width", 0),
+        "height": recording2.get("height", 0),
+    }
+
+    # Compare frames
+    frames1 = recording1.get("frames", [])
+    frames2 = recording2.get("frames", [])
+
+    num_frames = min(len(frames1), len(frames2))
+    if max_frames:
+        num_frames = min(num_frames, max_frames)
+
+    print(f"Comparing {num_frames} frames...")
+
+    for frame_idx in range(num_frames):
+        frame1 = frames1[frame_idx]
+        frame2 = frames2[frame_idx]
+
+        buf1 = frame1.get("buffer", [])
+        buf2 = frame2.get("buffer", [])
+
+        diff_count, differences = compare_frame_buffers(buf1, buf2)
+
+        if diff_count > 0:
+            results["total_differences"] += diff_count
+            results["frames_with_differences"] += 1
+            results["frames"].append(
+                {
+                    "frame_number": frame_idx,
+                    "differences": differences,
+                    "diff_count": diff_count,
+                }
+            )
+
+            if frame_idx < 5:  # Only print first 5 frames with differences
+                print(f"\nFrame {frame_idx} ({diff_count} differences):")
+                for diff in differences[:5]:  # Limit to 5 differences per frame
+                    print(f"  - {diff}")
+
+    # Summary
+    results["summary"]["total_frames_compared"] = num_frames
+    results["summary"]["frames_with_differences"] = results["frames_with_differences"]
+    results["summary"]["total_differences"] = results["total_differences"]
+    results["summary"]["match_percentage"] = (
+        (1 - results["frames_with_differences"] / num_frames) * 100
+        if num_frames > 0
+        else 0
+    )
+
+    return results
+
+
+def print_comparison_summary(results: dict):
+    """Print a summary of the comparison results."""
+    print("\n" + "=" * 80)
+    print("COMPARISON SUMMARY")
+    print("=" * 80)
+
+    r1 = results["summary"]["recording1"]
+    r2 = results["summary"]["recording2"]
+
+    print(f"\nRecording 1: {r1['preset']}")
+    print(
+        f"  Frames: {r1['frame_count']}, Width: {r1['width']}, Height: {r1['height']}"
+    )
+
+    print(f"\nRecording 2: {r2['preset']}")
+    print(
+        f"  Frames: {r2['frame_count']}, Width: {r2['width']}, Height: {r2['height']}"
+    )
+
+    print(f"\nComparison:")
+    print(f"  Frames compared: {results['summary']['total_frames_compared']}")
+    print(f"  Frames with differences: {results['summary']['frames_with_differences']}")
+    print(f"  Total differences: {results['summary']['total_differences']}")
+    print(f"  Match percentage: {results['summary']['match_percentage']:.2f}%")
+
+    if results["summary"]["match_percentage"] == 100:
+        print("\n✓ Recordings match perfectly!")
+    else:
+        print("\n⚠ Recordings have differences.")
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Compare captured outputs from different branches"
+    )
+    parser.add_argument(
+        "recording1",
+        help="First recording file (JSON)",
+    )
+    parser.add_argument(
+        "recording2",
+        help="Second recording file (JSON)",
+    )
+    parser.add_argument(
+        "--max-frames",
+        type=int,
+        help="Maximum number of frames to compare",
+    )
+    parser.add_argument(
+        "--output",
+        "-o",
+        help="Output file for detailed comparison results (JSON)",
+    )
+
+    args = parser.parse_args()
+
+    # Load recordings
+    print(f"Loading {args.recording1}...")
+    recording1 = load_recording(args.recording1)
+
+    print(f"Loading {args.recording2}...")
+    recording2 = load_recording(args.recording2)
+
+    # Compare
+    results = compare_recordings(recording1, recording2, args.max_frames)
+
+    # Print summary
+    print_comparison_summary(results)
+
+    # Save detailed results if requested
+    if args.output:
+        output_path = Path(args.output)
+        output_path.parent.mkdir(parents=True, exist_ok=True)
+        with open(output_path, "w") as f:
+            json.dump(results, f, indent=2)
+        print(f"\nDetailed results saved to {args.output}")
+
+    return 0
+
+
+if __name__ == "__main__":
+    exit(main())

tests/comparison_capture.py

@@ -0,0 +1,489 @@
+"""Frame capture utilities for upstream vs sideline comparison.
+
+This module provides functions to capture frames from both upstream and sideline
+implementations for visual comparison and performance analysis.
+"""
+
+import json
+import time
+from pathlib import Path
+from typing import Any, Dict, List, Tuple
+
+import tomli
+
+from engine.pipeline import Pipeline, PipelineConfig, PipelineContext
+from engine.pipeline.params import PipelineParams
+
+
+def load_comparison_preset(preset_name: str) -> Any:
+    """Load a comparison preset from comparison_presets.toml.
+
+    Args:
+        preset_name: Name of the preset to load
+
+    Returns:
+        Preset configuration dictionary
+    """
+    presets_file = Path("tests/comparison_presets.toml")
+    if not presets_file.exists():
+        raise FileNotFoundError(f"Comparison presets file not found: {presets_file}")
+
+    with open(presets_file, "rb") as f:
+        config = tomli.load(f)
+
+    presets = config.get("presets", {})
+    full_name = (
+        f"presets.{preset_name}"
+        if not preset_name.startswith("presets.")
+        else preset_name
+    )
+    simple_name = (
+        preset_name.replace("presets.", "")
+        if preset_name.startswith("presets.")
+        else preset_name
+    )
+
+    if full_name in presets:
+        return presets[full_name]
+    elif simple_name in presets:
+        return presets[simple_name]
+    else:
+        raise ValueError(
+            f"Preset '{preset_name}' not found in {presets_file}. Available: {list(presets.keys())}"
+        )
+
+
+def capture_frames(
+    preset_name: str,
+    frame_count: int = 30,
+    output_dir: Path = Path("tests/comparison_output"),
+) -> Dict[str, Any]:
+    """Capture frames from sideline pipeline using a preset.
+
+    Args:
+        preset_name: Name of preset to use
+        frame_count: Number of frames to capture
+        output_dir: Directory to save captured frames
+
+    Returns:
+        Dictionary with captured frames and metadata
+    """
+    from engine.pipeline.presets import get_preset
+
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    # Load preset - try comparison presets first, then built-in presets
+    try:
+        preset = load_comparison_preset(preset_name)
+        # Convert dict to object-like access
+        from types import SimpleNamespace
+
+        preset = SimpleNamespace(**preset)
+    except (FileNotFoundError, ValueError):
+        # Fall back to built-in presets
+        preset = get_preset(preset_name)
+        if not preset:
+            raise ValueError(
+                f"Preset '{preset_name}' not found in comparison or built-in presets"
+            )
+
+    # Create pipeline config from preset
+    config = PipelineConfig(
+        source=preset.source,
+        display="null",  # Always use null display for capture
+        camera=preset.camera,
+        effects=preset.effects,
+    )
+
+    # Create pipeline
+    ctx = PipelineContext()
+    ctx.terminal_width = preset.viewport_width
+    ctx.terminal_height = preset.viewport_height
+    pipeline = Pipeline(config=config, context=ctx)
+
+    # Create params
+    params = PipelineParams(
+        viewport_width=preset.viewport_width,
+        viewport_height=preset.viewport_height,
+    )
+    ctx.params = params
+
+    # Add stages based on source type (similar to pipeline_runner)
+    from engine.display import DisplayRegistry
+    from engine.pipeline.adapters import create_stage_from_display
+    from engine.data_sources.sources import EmptyDataSource
+    from engine.pipeline.adapters import DataSourceStage
+
+    # Add source stage
+    if preset.source == "empty":
+        source_stage = DataSourceStage(
+            EmptyDataSource(width=preset.viewport_width, height=preset.viewport_height),
+            name="empty",
+        )
+    else:
+        # For headlines/poetry, use the actual source
+        from engine.data_sources.sources import HeadlinesDataSource, PoetryDataSource
+
+        if preset.source == "headlines":
+            source_stage = DataSourceStage(HeadlinesDataSource(), name="headlines")
+        elif preset.source == "poetry":
+            source_stage = DataSourceStage(PoetryDataSource(), name="poetry")
+        else:
+            # Fallback to empty
+            source_stage = DataSourceStage(
+                EmptyDataSource(
+                    width=preset.viewport_width, height=preset.viewport_height
+                ),
+                name="empty",
+            )
+    pipeline.add_stage("source", source_stage)
+
+    # Add font stage for headlines/poetry (with viewport filter)
+    if preset.source in ["headlines", "poetry"]:
+        from engine.pipeline.adapters import FontStage, ViewportFilterStage
+
+        # Add viewport filter to prevent rendering all items
+        pipeline.add_stage(
+            "viewport_filter", ViewportFilterStage(name="viewport-filter")
+        )
+        # Add font stage for block character rendering
+        pipeline.add_stage("font", FontStage(name="font"))
+    else:
+        # Fallback to simple conversion for empty/other sources
+        from engine.pipeline.adapters import SourceItemsToBufferStage
+
+        pipeline.add_stage("render", SourceItemsToBufferStage(name="items-to-buffer"))
+
+    # Add camera stage
+    from engine.camera import Camera
+    from engine.pipeline.adapters import CameraStage, CameraClockStage
+
+    # Create camera based on preset
+    if preset.camera == "feed":
+        camera = Camera.feed()
+    elif preset.camera == "scroll":
+        camera = Camera.scroll(speed=0.1)
+    elif preset.camera == "horizontal":
+        camera = Camera.horizontal(speed=0.1)
+    else:
+        camera = Camera.feed()
+
+    camera.set_canvas_size(preset.viewport_width, preset.viewport_height * 2)
+
+    # Add camera update (for animation)
+    pipeline.add_stage("camera_update", CameraClockStage(camera, name="camera-clock"))
+    # Add camera stage
+    pipeline.add_stage("camera", CameraStage(camera, name=preset.camera))
+
+    # Add effects
+    if preset.effects:
+        from engine.effects.registry import EffectRegistry
+        from engine.pipeline.adapters import create_stage_from_effect
+
+        effect_registry = EffectRegistry()
+        for effect_name in preset.effects:
+            effect = effect_registry.get(effect_name)
+            if effect:
+                pipeline.add_stage(
+                    f"effect_{effect_name}",
+                    create_stage_from_effect(effect, effect_name),
+                )
+
+    # Add message overlay stage if enabled (BEFORE display)
+    if getattr(preset, "enable_message_overlay", False):
+        from engine.pipeline.adapters import MessageOverlayConfig, MessageOverlayStage
+
+        overlay_config = MessageOverlayConfig(
+            enabled=True,
+            display_secs=30,
+        )
+        pipeline.add_stage(
+            "message_overlay", MessageOverlayStage(config=overlay_config)
+        )
+
+    # Add null display stage (LAST)
+    null_display = DisplayRegistry.create("null")
+    if null_display:
+        pipeline.add_stage("display", create_stage_from_display(null_display, "null"))
+
+    # Build pipeline
+    pipeline.build()
+
+    # Enable recording on null display if available
+    display_stage = pipeline._stages.get("display")
+    if display_stage and hasattr(display_stage, "_display"):
+        backend = display_stage._display
+        if hasattr(backend, "start_recording"):
+            backend.start_recording()
+
+    # Capture frames
+    frames = []
+    start_time = time.time()
+
+    for i in range(frame_count):
+        frame_start = time.time()
+        stage_result = pipeline.execute()
+        frame_time = time.time() - frame_start
+
+    # Get frames from display recording
+    display_stage = pipeline._stages.get("display")
+    if display_stage and hasattr(display_stage, "_display"):
+        backend = display_stage._display
+        if hasattr(backend, "get_recorded_data"):
+            recorded_frames = backend.get_recorded_data()
+            # Add render_time_ms to each frame
+            for frame in recorded_frames:
+                frame["render_time_ms"] = frame_time * 1000
+            frames = recorded_frames
+
+    # Fallback: create empty frames if no recording
+    if not frames:
+        for i in range(frame_count):
+            frames.append(
+                {
+                    "frame_number": i,
+                    "buffer": [],
+                    "width": preset.viewport_width,
+                    "height": preset.viewport_height,
+                    "render_time_ms": frame_time * 1000,
+                }
+            )
+
+    # Stop recording on null display
+    display_stage = pipeline._stages.get("display")
+    if display_stage and hasattr(display_stage, "_display"):
+        backend = display_stage._display
+        if hasattr(backend, "stop_recording"):
+            backend.stop_recording()
+
+    total_time = time.time() - start_time
+
+    # Save captured data
+    output_file = output_dir / f"{preset_name}_sideline.json"
+    captured_data = {
+        "preset": preset_name,
+        "config": {
+            "source": preset.source,
+            "camera": preset.camera,
+            "effects": preset.effects,
+            "viewport_width": preset.viewport_width,
+            "viewport_height": preset.viewport_height,
+            "enable_message_overlay": getattr(preset, "enable_message_overlay", False),
+        },
+        "capture_stats": {
+            "frame_count": frame_count,
+            "total_time_ms": total_time * 1000,
+            "avg_frame_time_ms": (total_time * 1000) / frame_count,
+            "fps": frame_count / total_time if total_time > 0 else 0,
+        },
+        "frames": frames,
+    }
+
+    with open(output_file, "w") as f:
+        json.dump(captured_data, f, indent=2)
+
+    return captured_data
+
+
+def compare_captured_outputs(
+    sideline_file: Path,
+    upstream_file: Path,
+    output_dir: Path = Path("tests/comparison_output"),
+) -> Dict[str, Any]:
+    """Compare captured outputs from sideline and upstream.
+
+    Args:
+        sideline_file: Path to sideline captured output
+        upstream_file: Path to upstream captured output
+        output_dir: Directory to save comparison results
+
+    Returns:
+        Dictionary with comparison results
+    """
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    # Load captured data
+    with open(sideline_file) as f:
+        sideline_data = json.load(f)
+
+    with open(upstream_file) as f:
+        upstream_data = json.load(f)
+
+    # Compare configurations
+    config_diff = {}
+    for key in [
+        "source",
+        "camera",
+        "effects",
+        "viewport_width",
+        "viewport_height",
+        "enable_message_overlay",
+    ]:
+        sideline_val = sideline_data["config"].get(key)
+        upstream_val = upstream_data["config"].get(key)
+        if sideline_val != upstream_val:
+            config_diff[key] = {"sideline": sideline_val, "upstream": upstream_val}
+
+    # Compare frame counts
+    sideline_frames = len(sideline_data["frames"])
+    upstream_frames = len(upstream_data["frames"])
+    frame_count_match = sideline_frames == upstream_frames
+
+    # Compare individual frames
+    frame_comparisons = []
+    total_diff = 0
+    max_diff = 0
+    identical_frames = 0
+
+    min_frames = min(sideline_frames, upstream_frames)
+    for i in range(min_frames):
+        sideline_frame = sideline_data["frames"][i]
+        upstream_frame = upstream_data["frames"][i]
+
+        sideline_buffer = sideline_frame["buffer"]
+        upstream_buffer = upstream_frame["buffer"]
+
+        # Compare buffers line by line
+        line_diffs = []
+        frame_diff = 0
+        max_lines = max(len(sideline_buffer), len(upstream_buffer))
+
+        for line_idx in range(max_lines):
+            sideline_line = (
+                sideline_buffer[line_idx] if line_idx < len(sideline_buffer) else ""
+            )
+            upstream_line = (
+                upstream_buffer[line_idx] if line_idx < len(upstream_buffer) else ""
+            )
+
+            if sideline_line != upstream_line:
+                line_diffs.append(
+                    {
+                        "line": line_idx,
+                        "sideline": sideline_line,
+                        "upstream": upstream_line,
+                    }
+                )
+                frame_diff += 1
+
+        if frame_diff == 0:
+            identical_frames += 1
+
+        total_diff += frame_diff
+        max_diff = max(max_diff, frame_diff)
+
+        frame_comparisons.append(
+            {
+                "frame_number": i,
+                "differences": frame_diff,
+                "line_diffs": line_diffs[
+                    :5
+                ],  # Only store first 5 differences per frame
+                "render_time_diff_ms": sideline_frame.get("render_time_ms", 0)
+                - upstream_frame.get("render_time_ms", 0),
+            }
+        )
+
+    # Calculate statistics
+    stats = {
+        "total_frames_compared": min_frames,
+        "identical_frames": identical_frames,
+        "frames_with_differences": min_frames - identical_frames,
+        "total_differences": total_diff,
+        "max_differences_per_frame": max_diff,
+        "avg_differences_per_frame": total_diff / min_frames if min_frames > 0 else 0,
+        "match_percentage": (identical_frames / min_frames * 100)
+        if min_frames > 0
+        else 0,
+    }
+
+    # Compare performance stats
+    sideline_stats = sideline_data.get("capture_stats", {})
+    upstream_stats = upstream_data.get("capture_stats", {})
+    performance_comparison = {
+        "sideline": {
+            "total_time_ms": sideline_stats.get("total_time_ms", 0),
+            "avg_frame_time_ms": sideline_stats.get("avg_frame_time_ms", 0),
+            "fps": sideline_stats.get("fps", 0),
+        },
+        "upstream": {
+            "total_time_ms": upstream_stats.get("total_time_ms", 0),
+            "avg_frame_time_ms": upstream_stats.get("avg_frame_time_ms", 0),
+            "fps": upstream_stats.get("fps", 0),
+        },
+        "diff": {
+            "total_time_ms": sideline_stats.get("total_time_ms", 0)
+            - upstream_stats.get("total_time_ms", 0),
+            "avg_frame_time_ms": sideline_stats.get("avg_frame_time_ms", 0)
+            - upstream_stats.get("avg_frame_time_ms", 0),
+            "fps": sideline_stats.get("fps", 0) - upstream_stats.get("fps", 0),
+        },
+    }
+
+    # Build comparison result
+    result = {
+        "preset": sideline_data["preset"],
+        "config_diff": config_diff,
+        "frame_count_match": frame_count_match,
+        "stats": stats,
+        "performance_comparison": performance_comparison,
+        "frame_comparisons": frame_comparisons,
+        "sideline_file": str(sideline_file),
+        "upstream_file": str(upstream_file),
+    }
+
+    # Save comparison result
+    output_file = output_dir / f"{sideline_data['preset']}_comparison.json"
+    with open(output_file, "w") as f:
+        json.dump(result, f, indent=2)
+
+    return result
+
+
+def generate_html_report(
+    comparison_results: List[Dict[str, Any]],
+    output_dir: Path = Path("tests/comparison_output"),
+) -> Path:
+    """Generate HTML report from comparison results using acceptance_report.py.
+
+    Args:
+        comparison_results: List of comparison results
+        output_dir: Directory to save HTML report
+
+    Returns:
+        Path to generated HTML report
+    """
+    from tests.acceptance_report import save_index_report
+
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    # Generate index report with links to all comparison results
+    reports = []
+    for result in comparison_results:
+        reports.append(
+            {
+                "test_name": f"comparison-{result['preset']}",
+                "status": "PASS" if result.get("status") == "success" else "FAIL",
+                "frame_count": result["stats"]["total_frames_compared"],
+                "duration_ms": result["performance_comparison"]["sideline"][
+                    "total_time_ms"
+                ],
+            }
+        )
+
+    # Save index report
+    index_file = save_index_report(reports, str(output_dir))
+
+    # Also save a summary JSON file for programmatic access
+    summary_file = output_dir / "comparison_summary.json"
+    with open(summary_file, "w") as f:
+        json.dump(
+            {
+                "timestamp": __import__("datetime").datetime.now().isoformat(),
+                "results": comparison_results,
+            },
+            f,
+            indent=2,
+        )
+
+    return Path(index_file)

tests/comparison_presets.toml

@@ -0,0 +1,253 @@
+# Comparison Presets for Upstream vs Sideline Testing
+# These presets are designed to test various pipeline configurations
+# to ensure visual equivalence and performance parity
+
+# ============================================
+# CORE PIPELINE TESTS (Basic functionality)
+# ============================================
+
+[presets.comparison-basic]
+description = "Comparison: Basic pipeline, no effects"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-with-message-overlay]
+description = "Comparison: Basic pipeline with message overlay"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = true
+frame_count = 30
+
+# ============================================
+# EFFECT TESTS (Various effect combinations)
+# ============================================
+
+[presets.comparison-single-effect]
+description = "Comparison: Single effect (border)"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = ["border"]
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-multiple-effects]
+description = "Comparison: Multiple effects chain"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = ["border", "tint", "hud"]
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-all-effects]
+description = "Comparison: All available effects"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = ["border", "tint", "hud", "fade", "noise", "glitch"]
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+# ============================================
+# CAMERA MODE TESTS (Different viewport behaviors)
+# ============================================
+
+[presets.comparison-camera-feed]
+description = "Comparison: Feed camera mode"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-camera-scroll]
+description = "Comparison: Scroll camera mode"
+source = "headlines"
+display = "null"
+camera = "scroll"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+camera_speed = 0.5
+
+[presets.comparison-camera-horizontal]
+description = "Comparison: Horizontal camera mode"
+source = "headlines"
+display = "null"
+camera = "horizontal"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+# ============================================
+# SOURCE TESTS (Different data sources)
+# ============================================
+
+[presets.comparison-source-headlines]
+description = "Comparison: Headlines source"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-source-poetry]
+description = "Comparison: Poetry source"
+source = "poetry"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-source-empty]
+description = "Comparison: Empty source (blank canvas)"
+source = "empty"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+# ============================================
+# DIMENSION TESTS (Different viewport sizes)
+# ============================================
+
+[presets.comparison-small-viewport]
+description = "Comparison: Small viewport"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 60
+viewport_height = 20
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-large-viewport]
+description = "Comparison: Large viewport"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 120
+viewport_height = 40
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-wide-viewport]
+description = "Comparison: Wide viewport"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 160
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+# ============================================
+# COMPREHENSIVE TESTS (Combined scenarios)
+# ============================================
+
+[presets.comparison-comprehensive-1]
+description = "Comparison: Headlines + Effects + Message Overlay"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = ["border", "tint"]
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = true
+frame_count = 30
+
+[presets.comparison-comprehensive-2]
+description = "Comparison: Poetry + Camera Scroll + Effects"
+source = "poetry"
+display = "null"
+camera = "scroll"
+effects = ["fade", "noise"]
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+camera_speed = 0.3
+
+[presets.comparison-comprehensive-3]
+description = "Comparison: Headlines + Horizontal Camera + All Effects"
+source = "headlines"
+display = "null"
+camera = "horizontal"
+effects = ["border", "tint", "hud", "fade"]
+viewport_width = 100
+viewport_height = 30
+enable_message_overlay = true
+frame_count = 30
+
+# ============================================
+# REGRESSION TESTS (Specific edge cases)
+# ============================================
+
+[presets.comparison-regression-empty-message]
+description = "Regression: Empty message overlay"
+source = "empty"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 24
+enable_message_overlay = true
+frame_count = 30
+
+[presets.comparison-regression-narrow-viewport]
+description = "Regression: Very narrow viewport with long text"
+source = "headlines"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 40
+viewport_height = 24
+enable_message_overlay = false
+frame_count = 30
+
+[presets.comparison-regression-tall-viewport]
+description = "Regression: Tall viewport with few items"
+source = "empty"
+display = "null"
+camera = "feed"
+effects = []
+viewport_width = 80
+viewport_height = 60
+enable_message_overlay = false
+frame_count = 30

tests/run_comparison.py

@@ -0,0 +1,243 @@
+"""Main comparison runner for upstream vs sideline testing.
+
+This script runs comparisons between upstream and sideline implementations
+using multiple presets and generates HTML reports.
+"""
+
+import argparse
+import json
+import sys
+from pathlib import Path
+
+from tests.comparison_capture import (
+    capture_frames,
+    compare_captured_outputs,
+    generate_html_report,
+)
+
+
+def load_comparison_presets() -> list[str]:
+    """Load list of comparison presets from config file.
+
+    Returns:
+        List of preset names
+    """
+    import tomli
+
+    config_file = Path("tests/comparison_presets.toml")
+    if not config_file.exists():
+        raise FileNotFoundError(f"Comparison presets not found: {config_file}")
+
+    with open(config_file, "rb") as f:
+        config = tomli.load(f)
+
+    presets = list(config.get("presets", {}).keys())
+    # Strip "presets." prefix if present
+    return [p.replace("presets.", "") for p in presets]
+
+
+def run_comparison_for_preset(
+    preset_name: str,
+    sideline_only: bool = False,
+    upstream_file: Path | None = None,
+) -> dict:
+    """Run comparison for a single preset.
+
+    Args:
+        preset_name: Name of preset to test
+        sideline_only: If True, only capture sideline frames
+        upstream_file: Path to upstream captured output (if not None, use this instead of capturing)
+
+    Returns:
+        Comparison result dict
+    """
+    print(f"  Running preset: {preset_name}")
+
+    # Capture sideline frames
+    sideline_data = capture_frames(preset_name, frame_count=30)
+    sideline_file = Path(f"tests/comparison_output/{preset_name}_sideline.json")
+
+    if sideline_only:
+        return {
+            "preset": preset_name,
+            "status": "sideline_only",
+            "sideline_file": str(sideline_file),
+        }
+
+    # Use provided upstream file or look for it
+    if upstream_file:
+        upstream_path = upstream_file
+    else:
+        upstream_path = Path(f"tests/comparison_output/{preset_name}_upstream.json")
+
+    if not upstream_path.exists():
+        print(f"    Warning: Upstream file not found: {upstream_path}")
+        return {
+            "preset": preset_name,
+            "status": "missing_upstream",
+            "sideline_file": str(sideline_file),
+            "upstream_file": str(upstream_path),
+        }
+
+    # Compare outputs
+    try:
+        comparison_result = compare_captured_outputs(
+            sideline_file=sideline_file,
+            upstream_file=upstream_path,
+        )
+        comparison_result["status"] = "success"
+        return comparison_result
+    except Exception as e:
+        print(f"    Error comparing outputs: {e}")
+        return {
+            "preset": preset_name,
+            "status": "error",
+            "error": str(e),
+            "sideline_file": str(sideline_file),
+            "upstream_file": str(upstream_path),
+        }
+
+
+def main():
+    """Main entry point for comparison runner."""
+    parser = argparse.ArgumentParser(
+        description="Run comparison tests between upstream and sideline implementations"
+    )
+    parser.add_argument(
+        "--preset",
+        "-p",
+        help="Run specific preset (can be specified multiple times)",
+        action="append",
+        dest="presets",
+    )
+    parser.add_argument(
+        "--all",
+        "-a",
+        help="Run all comparison presets",
+        action="store_true",
+    )
+    parser.add_argument(
+        "--sideline-only",
+        "-s",
+        help="Only capture sideline frames (no comparison)",
+        action="store_true",
+    )
+    parser.add_argument(
+        "--upstream-file",
+        "-u",
+        help="Path to upstream captured output file",
+        type=Path,
+    )
+    parser.add_argument(
+        "--output-dir",
+        "-o",
+        help="Output directory for captured frames and reports",
+        type=Path,
+        default=Path("tests/comparison_output"),
+    )
+    parser.add_argument(
+        "--no-report",
+        help="Skip HTML report generation",
+        action="store_true",
+    )
+
+    args = parser.parse_args()
+
+    # Determine which presets to run
+    if args.presets:
+        presets_to_run = args.presets
+    elif args.all:
+        presets_to_run = load_comparison_presets()
+    else:
+        print("Error: Either --preset or --all must be specified")
+        print(f"Available presets: {', '.join(load_comparison_presets())}")
+        sys.exit(1)
+
+    print(f"Running comparison for {len(presets_to_run)} preset(s)")
+    print(f"Output directory: {args.output_dir}")
+    print()
+
+    # Run comparisons
+    results = []
+    for preset_name in presets_to_run:
+        try:
+            result = run_comparison_for_preset(
+                preset_name,
+                sideline_only=args.sideline_only,
+                upstream_file=args.upstream_file,
+            )
+            results.append(result)
+
+            if result["status"] == "success":
+                match_pct = result["stats"]["match_percentage"]
+                print(f"    ✓ Match: {match_pct:.1f}%")
+            elif result["status"] == "missing_upstream":
+                print(f"    ⚠ Missing upstream file")
+            elif result["status"] == "error":
+                print(f"    ✗ Error: {result['error']}")
+            else:
+                print(f"    ✓ Captured sideline only")
+
+        except Exception as e:
+            print(f"    ✗ Failed: {e}")
+            results.append(
+                {
+                    "preset": preset_name,
+                    "status": "failed",
+                    "error": str(e),
+                }
+            )
+
+    # Generate HTML report
+    if not args.no_report and not args.sideline_only:
+        successful_results = [r for r in results if r.get("status") == "success"]
+        if successful_results:
+            print(f"\nGenerating HTML report...")
+            report_file = generate_html_report(successful_results, args.output_dir)
+            print(f"  Report saved to: {report_file}")
+
+            # Also save summary JSON
+            summary_file = args.output_dir / "comparison_summary.json"
+            with open(summary_file, "w") as f:
+                json.dump(
+                    {
+                        "timestamp": __import__("datetime").datetime.now().isoformat(),
+                        "presets_tested": [r["preset"] for r in results],
+                        "results": results,
+                    },
+                    f,
+                    indent=2,
+                )
+            print(f"  Summary saved to: {summary_file}")
+        else:
+            print(f"\nNote: No successful comparisons to report.")
+            print(f"      Capture files saved in {args.output_dir}")
+            print(f"      Run comparison when upstream files are available.")
+
+    # Print summary
+    print("\n" + "=" * 60)
+    print("SUMMARY")
+    print("=" * 60)
+
+    status_counts = {}
+    for result in results:
+        status = result.get("status", "unknown")
+        status_counts[status] = status_counts.get(status, 0) + 1
+
+    for status, count in sorted(status_counts.items()):
+        print(f"  {status}: {count}")
+
+    if "success" in status_counts:
+        successful_results = [r for r in results if r.get("status") == "success"]
+        avg_match = sum(
+            r["stats"]["match_percentage"] for r in successful_results
+        ) / len(successful_results)
+        print(f"\n  Average match rate: {avg_match:.1f}%")
+
+    # Exit with error code if any failures
+    if any(r.get("status") in ["error", "failed"] for r in results):
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()

tests/test_adapters.py

@@ -1,17 +1,16 @@
 """
 Tests for engine/pipeline/adapters.py - Stage adapters for the pipeline.
 
-Tests Stage adapters that bridge existing components to the Stage interface:
-- DataSourceStage: Wraps DataSource objects
-- DisplayStage: Wraps Display backends
-- PassthroughStage: Simple pass-through stage for pre-rendered data
-- SourceItemsToBufferStage: Converts SourceItem objects to text buffers
-- EffectPluginStage: Wraps effect plugins
+Tests Stage adapters that bridge existing components to the Stage interface.
+Focuses on behavior testing rather than mock interactions.
 """
 
 from unittest.mock import MagicMock
 
 from engine.data_sources.sources import SourceItem
+from engine.display.backends.null import NullDisplay
+from engine.effects.plugins import discover_plugins
+from engine.effects.registry import get_registry
 from engine.pipeline.adapters import (
     DataSourceStage,
     DisplayStage,
@@ -25,28 +24,14 @@ from engine.pipeline.core import PipelineContext
 class TestDataSourceStage:
     """Test DataSourceStage adapter."""
 
-    def test_datasource_stage_name(self):
-        """DataSourceStage stores name correctly."""
+    def test_datasource_stage_properties(self):
+        """DataSourceStage has correct name, category, and capabilities."""
         mock_source = MagicMock()
         stage = DataSourceStage(mock_source, name="headlines")
+
         assert stage.name == "headlines"
-
-    def test_datasource_stage_category(self):
-        """DataSourceStage has 'source' category."""
-        mock_source = MagicMock()
-        stage = DataSourceStage(mock_source, name="headlines")
         assert stage.category == "source"
-
-    def test_datasource_stage_capabilities(self):
-        """DataSourceStage advertises source capability."""
-        mock_source = MagicMock()
-        stage = DataSourceStage(mock_source, name="headlines")
         assert "source.headlines" in stage.capabilities
-
-    def test_datasource_stage_dependencies(self):
-        """DataSourceStage has no dependencies."""
-        mock_source = MagicMock()
-        stage = DataSourceStage(mock_source, name="headlines")
         assert stage.dependencies == set()
 
     def test_datasource_stage_process_calls_get_items(self):
@@ -64,7 +49,7 @@ class TestDataSourceStage:
         assert result == mock_items
         mock_source.get_items.assert_called_once()
 
-    def test_datasource_stage_process_fallback_returns_data(self):
+    def test_datasource_stage_process_fallback(self):
         """DataSourceStage.process() returns data if no get_items method."""
         mock_source = MagicMock(spec=[])  # No get_items method
         stage = DataSourceStage(mock_source, name="headlines")
@@ -76,124 +61,68 @@ class TestDataSourceStage:
 
 
 class TestDisplayStage:
-    """Test DisplayStage adapter."""
+    """Test DisplayStage adapter using NullDisplay for real behavior."""
+
+    def test_display_stage_properties(self):
+        """DisplayStage has correct name, category, and capabilities."""
+        display = NullDisplay()
+        stage = DisplayStage(display, name="terminal")
 
-    def test_display_stage_name(self):
-        """DisplayStage stores name correctly."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
         assert stage.name == "terminal"
-
-    def test_display_stage_category(self):
-        """DisplayStage has 'display' category."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
         assert stage.category == "display"
-
-    def test_display_stage_capabilities(self):
-        """DisplayStage advertises display capability."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
         assert "display.output" in stage.capabilities
-
-    def test_display_stage_dependencies(self):
-        """DisplayStage depends on render.output."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
         assert "render.output" in stage.dependencies
 
-    def test_display_stage_init(self):
-        """DisplayStage.init() calls display.init() with dimensions."""
-        mock_display = MagicMock()
-        mock_display.init.return_value = True
-        stage = DisplayStage(mock_display, name="terminal")
+    def test_display_stage_init_and_process(self):
+        """DisplayStage initializes display and processes buffer."""
+        from engine.pipeline.params import PipelineParams
+
+        display = NullDisplay()
+        stage = DisplayStage(display, name="terminal")
 
         ctx = PipelineContext()
-        ctx.params = MagicMock()
-        ctx.params.viewport_width = 100
-        ctx.params.viewport_height = 30
+        ctx.params = PipelineParams()
+        ctx.params.viewport_width = 80
+        ctx.params.viewport_height = 24
 
+        # Initialize
         result = stage.init(ctx)
-
         assert result is True
-        mock_display.init.assert_called_once_with(100, 30, reuse=False)
 
-    def test_display_stage_init_uses_defaults(self):
-        """DisplayStage.init() uses defaults when params missing."""
-        mock_display = MagicMock()
-        mock_display.init.return_value = True
-        stage = DisplayStage(mock_display, name="terminal")
+        # Process buffer
+        buffer = ["Line 1", "Line 2", "Line 3"]
+        output = stage.process(buffer, ctx)
+        assert output == buffer
 
-        ctx = PipelineContext()
-        ctx.params = None
+        # Verify display captured the buffer
+        assert display._last_buffer == buffer
 
-        result = stage.init(ctx)
-
-        assert result is True
-        mock_display.init.assert_called_once_with(80, 24, reuse=False)
-
-    def test_display_stage_process_calls_show(self):
-        """DisplayStage.process() calls display.show() with data."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
-
-        test_buffer = [[["A", "red"] for _ in range(80)] for _ in range(24)]
-        ctx = PipelineContext()
-        result = stage.process(test_buffer, ctx)
-
-        assert result == test_buffer
-        mock_display.show.assert_called_once_with(test_buffer)
-
-    def test_display_stage_process_skips_none_data(self):
+    def test_display_stage_skips_none_data(self):
         """DisplayStage.process() skips show() if data is None."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
+        display = NullDisplay()
+        stage = DisplayStage(display, name="terminal")
 
         ctx = PipelineContext()
         result = stage.process(None, ctx)
 
         assert result is None
-        mock_display.show.assert_not_called()
-
-    def test_display_stage_cleanup(self):
-        """DisplayStage.cleanup() calls display.cleanup()."""
-        mock_display = MagicMock()
-        stage = DisplayStage(mock_display, name="terminal")
-
-        stage.cleanup()
-
-        mock_display.cleanup.assert_called_once()
+        assert display._last_buffer is None
 
 
 class TestPassthroughStage:
     """Test PassthroughStage adapter."""
 
-    def test_passthrough_stage_name(self):
-        """PassthroughStage stores name correctly."""
+    def test_passthrough_stage_properties(self):
+        """PassthroughStage has correct properties."""
         stage = PassthroughStage(name="test")
+
         assert stage.name == "test"
-
-    def test_passthrough_stage_category(self):
-        """PassthroughStage has 'render' category."""
-        stage = PassthroughStage()
         assert stage.category == "render"
-
-    def test_passthrough_stage_is_optional(self):
-        """PassthroughStage is optional."""
-        stage = PassthroughStage()
         assert stage.optional is True
-
-    def test_passthrough_stage_capabilities(self):
-        """PassthroughStage advertises render output capability."""
-        stage = PassthroughStage()
         assert "render.output" in stage.capabilities
-
-    def test_passthrough_stage_dependencies(self):
-        """PassthroughStage depends on source."""
-        stage = PassthroughStage()
         assert "source" in stage.dependencies
 
-    def test_passthrough_stage_process_returns_data_unchanged(self):
+    def test_passthrough_stage_process_unchanged(self):
         """PassthroughStage.process() returns data unchanged."""
         stage = PassthroughStage()
         ctx = PipelineContext()
@@ -210,32 +139,17 @@ class TestPassthroughStage:
 class TestSourceItemsToBufferStage:
     """Test SourceItemsToBufferStage adapter."""
 
-    def test_source_items_to_buffer_stage_name(self):
-        """SourceItemsToBufferStage stores name correctly."""
+    def test_source_items_to_buffer_stage_properties(self):
+        """SourceItemsToBufferStage has correct properties."""
         stage = SourceItemsToBufferStage(name="custom-name")
+
         assert stage.name == "custom-name"
-
-    def test_source_items_to_buffer_stage_category(self):
-        """SourceItemsToBufferStage has 'render' category."""
-        stage = SourceItemsToBufferStage()
         assert stage.category == "render"
-
-    def test_source_items_to_buffer_stage_is_optional(self):
-        """SourceItemsToBufferStage is optional."""
-        stage = SourceItemsToBufferStage()
         assert stage.optional is True
-
-    def test_source_items_to_buffer_stage_capabilities(self):
-        """SourceItemsToBufferStage advertises render output capability."""
-        stage = SourceItemsToBufferStage()
         assert "render.output" in stage.capabilities
-
-    def test_source_items_to_buffer_stage_dependencies(self):
-        """SourceItemsToBufferStage depends on source."""
-        stage = SourceItemsToBufferStage()
         assert "source" in stage.dependencies
 
-    def test_source_items_to_buffer_stage_process_single_line_item(self):
+    def test_source_items_to_buffer_stage_process_single_line(self):
         """SourceItemsToBufferStage converts single-line SourceItem."""
         stage = SourceItemsToBufferStage()
         ctx = PipelineContext()
@@ -247,10 +161,10 @@ class TestSourceItemsToBufferStage:
 
         assert isinstance(result, list)
         assert len(result) >= 1
-        # Result should be lines of text
         assert all(isinstance(line, str) for line in result)
+        assert "Single line content" in result[0]
 
-    def test_source_items_to_buffer_stage_process_multiline_item(self):
+    def test_source_items_to_buffer_stage_process_multiline(self):
         """SourceItemsToBufferStage splits multiline SourceItem content."""
         stage = SourceItemsToBufferStage()
         ctx = PipelineContext()
@@ -283,63 +197,76 @@ class TestSourceItemsToBufferStage:
 
 
 class TestEffectPluginStage:
-    """Test EffectPluginStage adapter."""
+    """Test EffectPluginStage adapter with real effect plugins."""
 
-    def test_effect_plugin_stage_name(self):
-        """EffectPluginStage stores name correctly."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="blur")
-        assert stage.name == "blur"
+    def test_effect_plugin_stage_properties(self):
+        """EffectPluginStage has correct properties for real effects."""
+        discover_plugins()
+        registry = get_registry()
+        effect = registry.get("noise")
 
-    def test_effect_plugin_stage_category(self):
-        """EffectPluginStage has 'effect' category."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="blur")
+        stage = EffectPluginStage(effect, name="noise")
+
+        assert stage.name == "noise"
         assert stage.category == "effect"
-
-    def test_effect_plugin_stage_is_not_optional(self):
-        """EffectPluginStage is required when configured."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="blur")
         assert stage.optional is False
-
-    def test_effect_plugin_stage_capabilities(self):
-        """EffectPluginStage advertises effect capability with name."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="blur")
-        assert "effect.blur" in stage.capabilities
-
-    def test_effect_plugin_stage_dependencies(self):
-        """EffectPluginStage has no static dependencies."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="blur")
-        # EffectPluginStage has empty dependencies - they are resolved dynamically
-        assert stage.dependencies == set()
-
-    def test_effect_plugin_stage_stage_type(self):
-        """EffectPluginStage.stage_type returns effect for non-HUD."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="blur")
-        assert stage.stage_type == "effect"
+        assert "effect.noise" in stage.capabilities
 
     def test_effect_plugin_stage_hud_special_handling(self):
         """EffectPluginStage has special handling for HUD effect."""
-        mock_effect = MagicMock()
-        stage = EffectPluginStage(mock_effect, name="hud")
+        discover_plugins()
+        registry = get_registry()
+        hud_effect = registry.get("hud")
+
+        stage = EffectPluginStage(hud_effect, name="hud")
+
         assert stage.stage_type == "overlay"
         assert stage.is_overlay is True
         assert stage.render_order == 100
 
-    def test_effect_plugin_stage_process(self):
-        """EffectPluginStage.process() calls effect.process()."""
-        mock_effect = MagicMock()
-        mock_effect.process.return_value = "processed_data"
+    def test_effect_plugin_stage_process_real_effect(self):
+        """EffectPluginStage.process() calls real effect.process()."""
+        from engine.pipeline.params import PipelineParams
 
-        stage = EffectPluginStage(mock_effect, name="blur")
+        discover_plugins()
+        registry = get_registry()
+        effect = registry.get("noise")
+
+        stage = EffectPluginStage(effect, name="noise")
         ctx = PipelineContext()
-        test_buffer = "test_buffer"
+        ctx.params = PipelineParams()
+        ctx.params.viewport_width = 80
+        ctx.params.viewport_height = 24
+        ctx.params.frame_number = 0
 
+        test_buffer = ["Line 1", "Line 2", "Line 3"]
         result = stage.process(test_buffer, ctx)
 
-        assert result == "processed_data"
-        mock_effect.process.assert_called_once()
+        # Should return a list (possibly modified buffer)
+        assert isinstance(result, list)
+        # Noise effect should preserve line count
+        assert len(result) == len(test_buffer)
+
+    def test_effect_plugin_stage_process_with_real_figment(self):
+        """EffectPluginStage processes figment effect correctly."""
+        from engine.pipeline.params import PipelineParams
+
+        discover_plugins()
+        registry = get_registry()
+        figment = registry.get("figment")
+
+        stage = EffectPluginStage(figment, name="figment")
+        ctx = PipelineContext()
+        ctx.params = PipelineParams()
+        ctx.params.viewport_width = 80
+        ctx.params.viewport_height = 24
+        ctx.params.frame_number = 0
+
+        test_buffer = ["Line 1", "Line 2", "Line 3"]
+        result = stage.process(test_buffer, ctx)
+
+        # Figment is an overlay effect
+        assert stage.is_overlay is True
+        assert stage.stage_type == "overlay"
+        # Result should be a list
+        assert isinstance(result, list)

tests/test_canvas.py

@@ -0,0 +1,285 @@
+"""
+Unit tests for engine.canvas.Canvas.
+
+Tests the core 2D rendering surface without any display dependencies.
+"""
+
+from engine.canvas import Canvas, CanvasRegion
+
+
+class TestCanvasRegion:
+    """Tests for CanvasRegion dataclass."""
+
+    def test_is_valid_positive_dimensions(self):
+        """Positive width and height returns True."""
+        region = CanvasRegion(0, 0, 10, 5)
+        assert region.is_valid() is True
+
+    def test_is_valid_zero_width(self):
+        """Zero width returns False."""
+        region = CanvasRegion(0, 0, 0, 5)
+        assert region.is_valid() is False
+
+    def test_is_valid_zero_height(self):
+        """Zero height returns False."""
+        region = CanvasRegion(0, 0, 10, 0)
+        assert region.is_valid() is False
+
+    def test_is_valid_negative_dimensions(self):
+        """Negative dimensions return False."""
+        region = CanvasRegion(0, 0, -1, 5)
+        assert region.is_valid() is False
+
+    def test_rows_computes_correct_set(self):
+        """rows() returns set of row indices in region."""
+        region = CanvasRegion(2, 3, 4, 2)
+        assert region.rows() == {3, 4}
+
+
+class TestCanvas:
+    """Tests for Canvas class."""
+
+    def test_init_default_dimensions(self):
+        """Default width=80, height=24."""
+        canvas = Canvas()
+        assert canvas.width == 80
+        assert canvas.height == 24
+        assert len(canvas._grid) == 24
+        assert len(canvas._grid[0]) == 80
+
+    def test_init_custom_dimensions(self):
+        """Custom dimensions are set correctly."""
+        canvas = Canvas(100, 50)
+        assert canvas.width == 100
+        assert canvas.height == 50
+
+    def test_clear_empties_grid(self):
+        """clear() resets all cells to spaces."""
+        canvas = Canvas(5, 3)
+        canvas.put_text(0, 0, "Hello")
+        canvas.clear()
+        region = canvas.get_region(0, 0, 5, 3)
+        assert all(all(cell == " " for cell in row) for row in region)
+
+    def test_clear_marks_entire_canvas_dirty(self):
+        """clear() marks entire canvas as dirty."""
+        canvas = Canvas(10, 5)
+        canvas.clear()
+        dirty = canvas.get_dirty_regions()
+        assert len(dirty) == 1
+        assert dirty[0].x == 0 and dirty[0].y == 0
+        assert dirty[0].width == 10 and dirty[0].height == 5
+
+    def test_put_text_single_char(self):
+        """put_text writes a single character at position."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(3, 2, "X")
+        assert canvas._grid[2][3] == "X"
+
+    def test_put_text_multiple_chars(self):
+        """put_text writes multiple characters in a row."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(2, 1, "ABC")
+        assert canvas._grid[1][2] == "A"
+        assert canvas._grid[1][3] == "B"
+        assert canvas._grid[1][4] == "C"
+
+    def test_put_text_ignores_overflow_right(self):
+        """Characters beyond width are ignored."""
+        canvas = Canvas(5, 5)
+        canvas.put_text(3, 0, "XYZ")
+        assert canvas._grid[0][3] == "X"
+        assert canvas._grid[0][4] == "Y"
+        # Z would be at index 5, which is out of bounds
+
+    def test_put_text_ignores_overflow_bottom(self):
+        """Rows beyond height are ignored."""
+        canvas = Canvas(5, 3)
+        canvas.put_text(0, 5, "test")
+        # Row 5 doesn't exist, nothing should be written
+        assert all(cell == " " for row in canvas._grid for cell in row)
+
+    def test_put_text_marks_dirty_region(self):
+        """put_text marks the written area as dirty."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(2, 1, "Hello")
+        dirty = canvas.get_dirty_regions()
+        assert len(dirty) == 1
+        assert dirty[0].x == 2 and dirty[0].y == 1
+        assert dirty[0].width == 5 and dirty[0].height == 1
+
+    def test_put_text_empty_string_no_dirty(self):
+        """Empty string does not create dirty region."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(0, 0, "")
+        assert not canvas.is_dirty()
+
+    def test_put_region_single_cell(self):
+        """put_region writes a single cell correctly."""
+        canvas = Canvas(5, 5)
+        content = [["X"]]
+        canvas.put_region(2, 2, content)
+        assert canvas._grid[2][2] == "X"
+
+    def test_put_region_multiple_rows(self):
+        """put_region writes multiple rows correctly."""
+        canvas = Canvas(10, 10)
+        content = [["A", "B"], ["C", "D"]]
+        canvas.put_region(1, 1, content)
+        assert canvas._grid[1][1] == "A"
+        assert canvas._grid[1][2] == "B"
+        assert canvas._grid[2][1] == "C"
+        assert canvas._grid[2][2] == "D"
+
+    def test_put_region_partial_out_of_bounds(self):
+        """put_region clips content that extends beyond canvas bounds."""
+        canvas = Canvas(5, 5)
+        content = [["A", "B", "C"], ["D", "E", "F"]]
+        canvas.put_region(4, 4, content)
+        # Only cell (4,4) should be within bounds
+        assert canvas._grid[4][4] == "A"
+        # Others are out of bounds
+        assert canvas._grid[4][5] == " " if 5 < 5 else True  # index 5 doesn't exist
+        assert canvas._grid[5][4] == " " if 5 < 5 else True  # row 5 doesn't exist
+
+    def test_put_region_marks_dirty(self):
+        """put_region marks dirty region covering written area (clipped)."""
+        canvas = Canvas(10, 10)
+        content = [["A", "B", "C"], ["D", "E", "F"]]
+        canvas.put_region(2, 2, content)
+        dirty = canvas.get_dirty_regions()
+        assert len(dirty) == 1
+        assert dirty[0].x == 2 and dirty[0].y == 2
+        assert dirty[0].width == 3 and dirty[0].height == 2
+
+    def test_fill_rectangle(self):
+        """fill() fills a rectangular region with character."""
+        canvas = Canvas(10, 10)
+        canvas.fill(2, 2, 3, 2, "*")
+        for y in range(2, 4):
+            for x in range(2, 5):
+                assert canvas._grid[y][x] == "*"
+
+    def test_fill_entire_canvas(self):
+        """fill() can fill entire canvas."""
+        canvas = Canvas(5, 3)
+        canvas.fill(0, 0, 5, 3, "#")
+        for row in canvas._grid:
+            assert all(cell == "#" for cell in row)
+
+    def test_fill_empty_region_no_dirty(self):
+        """fill with zero dimensions does not mark dirty."""
+        canvas = Canvas(10, 10)
+        canvas.fill(0, 0, 0, 5, "X")
+        assert not canvas.is_dirty()
+
+    def test_fill_clips_to_bounds(self):
+        """fill clips to canvas boundaries."""
+        canvas = Canvas(5, 5)
+        canvas.fill(3, 3, 5, 5, "X")
+        # Should only fill within bounds: (3,3) to (4,4)
+        assert canvas._grid[3][3] == "X"
+        assert canvas._grid[3][4] == "X"
+        assert canvas._grid[4][3] == "X"
+        assert canvas._grid[4][4] == "X"
+        # Out of bounds should remain spaces
+        assert canvas._grid[5] if 5 < 5 else True  # row 5 doesn't exist
+
+    def test_get_region_extracts_subgrid(self):
+        """get_region returns correct rectangular subgrid."""
+        canvas = Canvas(10, 10)
+        for y in range(10):
+            for x in range(10):
+                canvas._grid[y][x] = chr(ord("A") + (x % 26))
+        region = canvas.get_region(2, 3, 4, 2)
+        assert len(region) == 2
+        assert len(region[0]) == 4
+        assert region[0][0] == "C"  # (2,3) = 'C'
+        assert region[1][2] == "E"  # (4,4) = 'E'
+
+    def test_get_region_out_of_bounds_returns_spaces(self):
+        """get_region pads out-of-bounds areas with spaces."""
+        canvas = Canvas(5, 5)
+        canvas.put_text(0, 0, "HELLO")
+        # Region overlapping right edge: cols 3-4 inside, col5+ outside
+        region = canvas.get_region(3, 0, 5, 2)
+        assert region[0][0] == "L"
+        assert region[0][1] == "O"
+        assert region[0][2] == " "  # col5 out of bounds
+        assert all(cell == " " for cell in region[1])
+
+    def test_get_region_flat_returns_lines(self):
+        """get_region_flat returns list of joined strings."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(0, 0, "FIRST")
+        canvas.put_text(0, 1, "SECOND")
+        flat = canvas.get_region_flat(0, 0, 6, 2)
+        assert flat == ["FIRST ", "SECOND"]
+
+    def test_mark_dirty_manual(self):
+        """mark_dirty() can be called manually to mark arbitrary region."""
+        canvas = Canvas(10, 10)
+        canvas.mark_dirty(5, 5, 3, 2)
+        dirty = canvas.get_dirty_regions()
+        assert len(dirty) == 1
+        assert dirty[0] == CanvasRegion(5, 5, 3, 2)
+
+    def test_get_dirty_rows_union(self):
+        """get_dirty_rows() returns union of all dirty row indices."""
+        canvas = Canvas(10, 10)
+        canvas.put_text(0, 0, "A")  # row 0
+        canvas.put_text(0, 2, "B")  # row 2
+        canvas.mark_dirty(0, 1, 1, 1)  # row 1
+        rows = canvas.get_dirty_rows()
+        assert rows == {0, 1, 2}
+
+    def test_is_dirty_after_operations(self):
+        """is_dirty() returns True after any modifying operation."""
+        canvas = Canvas(10, 10)
+        assert not canvas.is_dirty()
+        canvas.put_text(0, 0, "X")
+        assert canvas.is_dirty()
+        _ = canvas.get_dirty_regions()  # resets
+        assert not canvas.is_dirty()
+
+    def test_resize_same_size_no_change(self):
+        """resize with same dimensions does nothing."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(0, 0, "TEST")
+        canvas.resize(10, 5)
+        assert canvas._grid[0][0] == "T"
+
+    def test_resize_larger_preserves_content(self):
+        """resize to larger canvas preserves existing content."""
+        canvas = Canvas(5, 3)
+        canvas.put_text(1, 1, "AB")
+        canvas.resize(10, 6)
+        assert canvas.width == 10
+        assert canvas.height == 6
+        assert canvas._grid[1][1] == "A"
+        assert canvas._grid[1][2] == "B"
+        # New area should be spaces
+        assert canvas._grid[0][0] == " "
+
+    def test_resize_smaller_truncates(self):
+        """resize to smaller canvas drops content outside new bounds."""
+        canvas = Canvas(10, 5)
+        canvas.put_text(8, 4, "XYZ")
+        canvas.resize(5, 3)
+        assert canvas.width == 5
+        assert canvas.height == 3
+        # Content at (8,4) should be lost
+        # But content within new bounds should remain
+        canvas2 = Canvas(10, 5)
+        canvas2.put_text(2, 2, "HI")
+        canvas2.resize(5, 3)
+        assert canvas2._grid[2][2] == "H"
+
+    def test_resize_does_not_auto_mark_dirty(self):
+        """resize() does not automatically mark dirty (caller responsibility)."""
+        canvas = Canvas(10, 10)
+        canvas.put_text(0, 0, "A")
+        _ = canvas.get_dirty_regions()  # reset
+        canvas.resize(5, 5)
+        # Resize doesn't mark dirty - this is current implementation
+        assert not canvas.is_dirty()

tests/test_comparison_framework.py

@@ -0,0 +1,341 @@
+"""Comparison framework tests for upstream vs sideline pipeline.
+
+These tests verify that the comparison framework works correctly
+and can be used for regression testing.
+"""
+
+import json
+import tempfile
+from pathlib import Path
+
+import pytest
+
+from tests.comparison_capture import capture_frames, compare_captured_outputs
+
+
+class TestComparisonCapture:
+    """Tests for frame capture functionality."""
+
+    def test_capture_basic_preset(self):
+        """Test capturing frames from a basic preset."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            output_dir = Path(tmpdir)
+
+            # Capture frames
+            result = capture_frames(
+                preset_name="comparison-basic",
+                frame_count=10,
+                output_dir=output_dir,
+            )
+
+            # Verify result structure
+            assert "preset" in result
+            assert "config" in result
+            assert "frames" in result
+            assert "capture_stats" in result
+
+            # Verify frame count
+            assert len(result["frames"]) == 10
+
+            # Verify frame structure
+            frame = result["frames"][0]
+            assert "frame_number" in frame
+            assert "buffer" in frame
+            assert "width" in frame
+            assert "height" in frame
+
+    def test_capture_with_message_overlay(self):
+        """Test capturing frames with message overlay enabled."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            output_dir = Path(tmpdir)
+
+            result = capture_frames(
+                preset_name="comparison-with-message-overlay",
+                frame_count=5,
+                output_dir=output_dir,
+            )
+
+            # Verify message overlay is enabled in config
+            assert result["config"]["enable_message_overlay"] is True
+
+    def test_capture_multiple_presets(self):
+        """Test capturing frames from multiple presets."""
+        presets = ["comparison-basic", "comparison-single-effect"]
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            output_dir = Path(tmpdir)
+
+            for preset in presets:
+                result = capture_frames(
+                    preset_name=preset,
+                    frame_count=5,
+                    output_dir=output_dir,
+                )
+                assert result["preset"] == preset
+
+
+class TestComparisonAnalysis:
+    """Tests for comparison analysis functionality."""
+
+    def test_compare_identical_outputs(self):
+        """Test comparing identical outputs shows 100% match."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            output_dir = Path(tmpdir)
+
+            # Create two identical captured outputs
+            sideline_file = output_dir / "test_sideline.json"
+            upstream_file = output_dir / "test_upstream.json"
+
+            test_data = {
+                "preset": "test",
+                "config": {"viewport_width": 80, "viewport_height": 24},
+                "frames": [
+                    {
+                        "frame_number": 0,
+                        "buffer": ["Line 1", "Line 2", "Line 3"],
+                        "width": 80,
+                        "height": 24,
+                        "render_time_ms": 10.0,
+                    }
+                ],
+                "capture_stats": {
+                    "frame_count": 1,
+                    "total_time_ms": 10.0,
+                    "avg_frame_time_ms": 10.0,
+                    "fps": 100.0,
+                },
+            }
+
+            with open(sideline_file, "w") as f:
+                json.dump(test_data, f)
+
+            with open(upstream_file, "w") as f:
+                json.dump(test_data, f)
+
+            # Compare
+            result = compare_captured_outputs(
+                sideline_file=sideline_file,
+                upstream_file=upstream_file,
+            )
+
+            # Should have 100% match
+            assert result["stats"]["match_percentage"] == 100.0
+            assert result["stats"]["identical_frames"] == 1
+            assert result["stats"]["total_differences"] == 0
+
+    def test_compare_different_outputs(self):
+        """Test comparing different outputs detects differences."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            output_dir = Path(tmpdir)
+
+            sideline_file = output_dir / "test_sideline.json"
+            upstream_file = output_dir / "test_upstream.json"
+
+            # Create different outputs
+            sideline_data = {
+                "preset": "test",
+                "config": {"viewport_width": 80, "viewport_height": 24},
+                "frames": [
+                    {
+                        "frame_number": 0,
+                        "buffer": ["Sideline Line 1", "Line 2"],
+                        "width": 80,
+                        "height": 24,
+                        "render_time_ms": 10.0,
+                    }
+                ],
+                "capture_stats": {
+                    "frame_count": 1,
+                    "total_time_ms": 10.0,
+                    "avg_frame_time_ms": 10.0,
+                    "fps": 100.0,
+                },
+            }
+
+            upstream_data = {
+                "preset": "test",
+                "config": {"viewport_width": 80, "viewport_height": 24},
+                "frames": [
+                    {
+                        "frame_number": 0,
+                        "buffer": ["Upstream Line 1", "Line 2"],
+                        "width": 80,
+                        "height": 24,
+                        "render_time_ms": 12.0,
+                    }
+                ],
+                "capture_stats": {
+                    "frame_count": 1,
+                    "total_time_ms": 12.0,
+                    "avg_frame_time_ms": 12.0,
+                    "fps": 83.33,
+                },
+            }
+
+            with open(sideline_file, "w") as f:
+                json.dump(sideline_data, f)
+
+            with open(upstream_file, "w") as f:
+                json.dump(upstream_data, f)
+
+            # Compare
+            result = compare_captured_outputs(
+                sideline_file=sideline_file,
+                upstream_file=upstream_file,
+            )
+
+            # Should detect differences
+            assert result["stats"]["match_percentage"] < 100.0
+            assert result["stats"]["total_differences"] > 0
+            assert len(result["frame_comparisons"][0]["line_diffs"]) > 0
+
+    def test_performance_comparison(self):
+        """Test that performance metrics are compared correctly."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            output_dir = Path(tmpdir)
+
+            sideline_file = output_dir / "test_sideline.json"
+            upstream_file = output_dir / "test_upstream.json"
+
+            sideline_data = {
+                "preset": "test",
+                "config": {"viewport_width": 80, "viewport_height": 24},
+                "frames": [
+                    {
+                        "frame_number": 0,
+                        "buffer": [],
+                        "width": 80,
+                        "height": 24,
+                        "render_time_ms": 10.0,
+                    }
+                ],
+                "capture_stats": {
+                    "frame_count": 1,
+                    "total_time_ms": 10.0,
+                    "avg_frame_time_ms": 10.0,
+                    "fps": 100.0,
+                },
+            }
+
+            upstream_data = {
+                "preset": "test",
+                "config": {"viewport_width": 80, "viewport_height": 24},
+                "frames": [
+                    {
+                        "frame_number": 0,
+                        "buffer": [],
+                        "width": 80,
+                        "height": 24,
+                        "render_time_ms": 12.0,
+                    }
+                ],
+                "capture_stats": {
+                    "frame_count": 1,
+                    "total_time_ms": 12.0,
+                    "avg_frame_time_ms": 12.0,
+                    "fps": 83.33,
+                },
+            }
+
+            with open(sideline_file, "w") as f:
+                json.dump(sideline_data, f)
+
+            with open(upstream_file, "w") as f:
+                json.dump(upstream_data, f)
+
+            result = compare_captured_outputs(
+                sideline_file=sideline_file,
+                upstream_file=upstream_file,
+            )
+
+            # Verify performance comparison
+            perf = result["performance_comparison"]
+            assert "sideline" in perf
+            assert "upstream" in perf
+            assert "diff" in perf
+            assert (
+                perf["sideline"]["fps"] > perf["upstream"]["fps"]
+            )  # Sideline is faster in this example
+
+
+class TestComparisonPresets:
+    """Tests for comparison preset configuration."""
+
+    def test_comparison_presets_exist(self):
+        """Test that comparison presets file exists and is valid."""
+        presets_file = Path("tests/comparison_presets.toml")
+        assert presets_file.exists(), "Comparison presets file should exist"
+
+    def test_preset_structure(self):
+        """Test that presets have required fields."""
+        import tomli
+
+        with open("tests/comparison_presets.toml", "rb") as f:
+            config = tomli.load(f)
+
+        presets = config.get("presets", {})
+        assert len(presets) > 0, "Should have at least one preset"
+
+        for preset_name, preset_config in presets.items():
+            # Each preset should have required fields
+            assert "source" in preset_config, f"{preset_name} should have 'source'"
+            assert "display" in preset_config, f"{preset_name} should have 'display'"
+            assert "camera" in preset_config, f"{preset_name} should have 'camera'"
+            assert "viewport_width" in preset_config, (
+                f"{preset_name} should have 'viewport_width'"
+            )
+            assert "viewport_height" in preset_config, (
+                f"{preset_name} should have 'viewport_height'"
+            )
+            assert "frame_count" in preset_config, (
+                f"{preset_name} should have 'frame_count'"
+            )
+
+    def test_preset_variety(self):
+        """Test that presets cover different scenarios."""
+        import tomli
+
+        with open("tests/comparison_presets.toml", "rb") as f:
+            config = tomli.load(f)
+
+        presets = config.get("presets", {})
+
+        # Should have presets for different categories
+        categories = {
+            "basic": 0,
+            "effect": 0,
+            "camera": 0,
+            "source": 0,
+            "viewport": 0,
+            "comprehensive": 0,
+            "regression": 0,
+        }
+
+        for preset_name in presets.keys():
+            name_lower = preset_name.lower()
+            if "basic" in name_lower:
+                categories["basic"] += 1
+            elif (
+                "effect" in name_lower or "border" in name_lower or "tint" in name_lower
+            ):
+                categories["effect"] += 1
+            elif "camera" in name_lower:
+                categories["camera"] += 1
+            elif "source" in name_lower:
+                categories["source"] += 1
+            elif (
+                "viewport" in name_lower
+                or "small" in name_lower
+                or "large" in name_lower
+            ):
+                categories["viewport"] += 1
+            elif "comprehensive" in name_lower:
+                categories["comprehensive"] += 1
+            elif "regression" in name_lower:
+                categories["regression"] += 1
+
+        # Verify we have variety
+        assert categories["basic"] > 0, "Should have at least one basic preset"
+        assert categories["effect"] > 0, "Should have at least one effect preset"
+        assert categories["camera"] > 0, "Should have at least one camera preset"
+        assert categories["source"] > 0, "Should have at least one source preset"

tests/test_figment_effect.py

@@ -0,0 +1,103 @@
+"""
+Tests for the FigmentOverlayEffect plugin.
+"""
+
+import pytest
+
+from engine.effects.plugins import discover_plugins
+from engine.effects.registry import get_registry
+from engine.effects.types import EffectConfig, create_effect_context
+from engine.pipeline.adapters import EffectPluginStage
+
+
+class TestFigmentEffect:
+    """Tests for FigmentOverlayEffect."""
+
+    def setup_method(self):
+        """Discover plugins before each test."""
+        discover_plugins()
+
+    def test_figment_plugin_discovered(self):
+        """Figment plugin is discovered and registered."""
+        registry = get_registry()
+        figment = registry.get("figment")
+        assert figment is not None
+        assert figment.name == "figment"
+
+    def test_figment_plugin_enabled_by_default(self):
+        """Figment plugin is enabled by default."""
+        registry = get_registry()
+        figment = registry.get("figment")
+        assert figment.config.enabled is True
+
+    def test_figment_renders_overlay(self):
+        """Figment renders SVG overlay after interval."""
+        registry = get_registry()
+        figment = registry.get("figment")
+
+        # Configure with short interval for testing
+        config = EffectConfig(
+            enabled=True,
+            intensity=1.0,
+            params={
+                "interval_secs": 0.1,  # 100ms
+                "display_secs": 1.0,
+                "figment_dir": "figments",
+            },
+        )
+        figment.configure(config)
+
+        # Create test buffer
+        buf = [" " * 80 for _ in range(24)]
+
+        # Create context
+        ctx = create_effect_context(
+            terminal_width=80,
+            terminal_height=24,
+            frame_number=0,
+        )
+
+        # Process frames until figment renders
+        for i in range(20):
+            result = figment.process(buf, ctx)
+            if len(result) > len(buf):
+                # Figment rendered overlay
+                assert len(result) > len(buf)
+                # Check that overlay lines contain ANSI escape codes
+                overlay_lines = result[len(buf) :]
+                assert len(overlay_lines) > 0
+                # First overlay line should contain cursor positioning
+                assert "\x1b[" in overlay_lines[0]
+                assert "H" in overlay_lines[0]
+                return
+            ctx.frame_number += 1
+
+        pytest.fail("Figment did not render in 20 frames")
+
+    def test_figment_stage_capabilities(self):
+        """EffectPluginStage wraps figment correctly."""
+        registry = get_registry()
+        figment = registry.get("figment")
+
+        stage = EffectPluginStage(figment, name="figment")
+        assert "effect.figment" in stage.capabilities
+
+    def test_figment_configure_preserves_params(self):
+        """Figment configuration preserves figment_dir."""
+        registry = get_registry()
+        figment = registry.get("figment")
+
+        # Configure without figment_dir
+        config = EffectConfig(
+            enabled=True,
+            intensity=1.0,
+            params={
+                "interval_secs": 30.0,
+                "display_secs": 3.0,
+            },
+        )
+        figment.configure(config)
+
+        # figment_dir should be preserved
+        assert "figment_dir" in figment.config.params
+        assert figment.config.params["figment_dir"] == "figments"

tests/test_figment_pipeline.py

@@ -0,0 +1,79 @@
+"""
+Integration tests for figment effect in the pipeline.
+"""
+
+from engine.effects.plugins import discover_plugins
+from engine.effects.registry import get_registry
+from engine.pipeline import Pipeline, PipelineConfig, get_preset
+from engine.pipeline.adapters import (
+    EffectPluginStage,
+    SourceItemsToBufferStage,
+    create_stage_from_display,
+)
+from engine.pipeline.controller import PipelineRunner
+
+
+class TestFigmentPipeline:
+    """Tests for figment effect in pipeline integration."""
+
+    def setup_method(self):
+        """Discover plugins before each test."""
+        discover_plugins()
+
+    def test_figment_in_pipeline(self):
+        """Figment effect can be added to pipeline."""
+        registry = get_registry()
+        figment = registry.get("figment")
+
+        pipeline = Pipeline(
+            config=PipelineConfig(
+                source="empty",
+                display="null",
+                camera="feed",
+                effects=["figment"],
+            )
+        )
+
+        # Add source stage
+        from engine.data_sources.sources import EmptyDataSource
+        from engine.pipeline.adapters import DataSourceStage
+
+        empty_source = EmptyDataSource(width=80, height=24)
+        pipeline.add_stage("source", DataSourceStage(empty_source, name="empty"))
+
+        # Add render stage
+        pipeline.add_stage("render", SourceItemsToBufferStage(name="items-to-buffer"))
+
+        # Add figment effect stage
+        pipeline.add_stage("effect_figment", EffectPluginStage(figment, name="figment"))
+
+        # Add display stage
+        from engine.display import DisplayRegistry
+
+        display = DisplayRegistry.create("null")
+        display.init(0, 0)
+        pipeline.add_stage("display", create_stage_from_display(display, "null"))
+
+        # Build and initialize pipeline
+        pipeline.build()
+        assert pipeline.initialize()
+
+        # Use PipelineRunner to step through frames
+        runner = PipelineRunner(pipeline)
+        runner.start()
+
+        # Run pipeline for a few frames
+        for i in range(10):
+            runner.step()
+            # Result might be None for null display, but that's okay
+
+        # Verify pipeline ran without errors
+        assert pipeline.context.params.frame_number == 10
+
+    def test_figment_preset(self):
+        """Figment preset is properly configured."""
+        preset = get_preset("test-figment")
+        assert preset is not None
+        assert preset.source == "empty"
+        assert preset.display == "terminal"
+        assert "figment" in preset.effects

tests/test_figment_render.py

@@ -0,0 +1,104 @@
+"""
+Tests to verify figment rendering in the pipeline.
+"""
+
+from engine.effects.plugins import discover_plugins
+from engine.effects.registry import get_registry
+from engine.effects.types import EffectConfig
+from engine.pipeline import Pipeline, PipelineConfig
+from engine.pipeline.adapters import (
+    EffectPluginStage,
+    SourceItemsToBufferStage,
+    create_stage_from_display,
+)
+from engine.pipeline.controller import PipelineRunner
+
+
+def test_figment_renders_in_pipeline():
+    """Verify figment renders overlay in pipeline."""
+    # Discover plugins
+    discover_plugins()
+
+    # Get figment plugin
+    registry = get_registry()
+    figment = registry.get("figment")
+
+    # Configure with short interval for testing
+    config = EffectConfig(
+        enabled=True,
+        intensity=1.0,
+        params={
+            "interval_secs": 0.1,  # 100ms
+            "display_secs": 1.0,
+            "figment_dir": "figments",
+        },
+    )
+    figment.configure(config)
+
+    # Create pipeline
+    pipeline = Pipeline(
+        config=PipelineConfig(
+            source="empty",
+            display="null",
+            camera="feed",
+            effects=["figment"],
+        )
+    )
+
+    # Add source stage
+    from engine.data_sources.sources import EmptyDataSource
+    from engine.pipeline.adapters import DataSourceStage
+
+    empty_source = EmptyDataSource(width=80, height=24)
+    pipeline.add_stage("source", DataSourceStage(empty_source, name="empty"))
+
+    # Add render stage
+    pipeline.add_stage("render", SourceItemsToBufferStage(name="items-to-buffer"))
+
+    # Add figment effect stage
+    pipeline.add_stage("effect_figment", EffectPluginStage(figment, name="figment"))
+
+    # Add display stage
+    from engine.display import DisplayRegistry
+
+    display = DisplayRegistry.create("null")
+    display.init(0, 0)
+    pipeline.add_stage("display", create_stage_from_display(display, "null"))
+
+    # Build and initialize pipeline
+    pipeline.build()
+    assert pipeline.initialize()
+
+    # Use PipelineRunner to step through frames
+    runner = PipelineRunner(pipeline)
+    runner.start()
+
+    # Run pipeline until figment renders (or timeout)
+    figment_rendered = False
+    for i in range(30):
+        runner.step()
+
+        # Check if figment rendered by inspecting the display's internal buffer
+        # The null display stores the last rendered buffer
+        if hasattr(display, "_last_buffer") and display._last_buffer:
+            buffer = display._last_buffer
+            # Check if buffer contains ANSI escape codes (indicating figment overlay)
+            # Figment adds overlay lines at the end of the buffer
+            for line in buffer:
+                if "\x1b[" in line:
+                    figment_rendered = True
+                    print(f"Figment rendered at frame {i}")
+                    # Print first few lines containing escape codes
+                    for j, line in enumerate(buffer[:10]):
+                        if "\x1b[" in line:
+                            print(f"Line {j}: {repr(line[:80])}")
+                    break
+            if figment_rendered:
+                break
+
+    assert figment_rendered, "Figment did not render in 30 frames"
+
+
+if __name__ == "__main__":
+    test_figment_renders_in_pipeline()
+    print("Test passed!")

tests/test_firehose.py

@@ -0,0 +1,125 @@
+"""Tests for FirehoseEffect plugin."""
+
+import pytest
+
+from engine.effects.plugins.firehose import FirehoseEffect
+from engine.effects.types import EffectContext
+
+
+@pytest.fixture(autouse=True)
+def patch_config(monkeypatch):
+    """Patch config globals for firehose tests."""
+    import engine.config as config
+
+    monkeypatch.setattr(config, "FIREHOSE", False)
+    monkeypatch.setattr(config, "FIREHOSE_H", 12)
+    monkeypatch.setattr(config, "MODE", "news")
+    monkeypatch.setattr(config, "GLITCH", "░▒▓█▌▐╌╍╎╏┃┆┇┊┋")
+    monkeypatch.setattr(config, "KATA", "ﾊﾐﾋｰｳｼﾅﾓﾆｻﾜﾂｵﾘｱﾎﾃﾏｹﾒｴｶｷﾑﾕﾗｾﾈｽﾀﾇﾍ")
+
+
+def test_firehose_disabled_returns_input():
+    """Firehose disabled returns input buffer unchanged."""
+    effect = FirehoseEffect()
+    effect.configure(effect.config)
+    buf = ["line1", "line2"]
+    ctx = EffectContext(
+        terminal_width=80,
+        terminal_height=24,
+        scroll_cam=0,
+        ticker_height=0,
+        items=[("Title", "Source", "2025-01-01T00:00:00")],
+    )
+    import engine.config as config
+
+    config.FIREHOSE = False
+    result = effect.process(buf, ctx)
+    assert result == buf
+
+
+def test_firehose_enabled_adds_lines():
+    """Firehose enabled adds FIREHOSE_H lines to output."""
+    effect = FirehoseEffect()
+    effect.configure(effect.config)
+    buf = ["line1"]
+    ctx = EffectContext(
+        terminal_width=80,
+        terminal_height=24,
+        scroll_cam=0,
+        ticker_height=0,
+        items=[("Title", "Source", "2025-01-01T00:00:00")] * 10,
+    )
+    import engine.config as config
+
+    config.FIREHOSE = True
+    config.FIREHOSE_H = 3
+    result = effect.process(buf, ctx)
+    assert len(result) == 4
+    assert any("\033[" in line for line in result[1:])
+
+
+def test_firehose_respects_terminal_width():
+    """Firehose lines are truncated to terminal width."""
+    effect = FirehoseEffect()
+    effect.configure(effect.config)
+    ctx = EffectContext(
+        terminal_width=40,
+        terminal_height=24,
+        scroll_cam=0,
+        ticker_height=0,
+        items=[("A" * 100, "Source", "2025-01-01T00:00:00")],
+    )
+    import engine.config as config
+
+    config.FIREHOSE = True
+    config.FIREHOSE_H = 2
+    result = effect.process([], ctx)
+    firehose_lines = [line for line in result if "\033[" in line]
+    for line in firehose_lines:
+        # Strip all ANSI escape sequences (CSI sequences ending with letter)
+        import re
+
+        plain = re.sub(r"\x1b\[[^a-zA-Z]*[a-zA-Z]", "", line)
+        # Extract content after position code
+        content = plain.split("H", 1)[1] if "H" in plain else plain
+        assert len(content) <= 40
+
+
+def test_firehose_zero_height_noop():
+    """Firehose with zero height returns buffer unchanged."""
+    effect = FirehoseEffect()
+    effect.configure(effect.config)
+    buf = ["line1"]
+    ctx = EffectContext(
+        terminal_width=80,
+        terminal_height=24,
+        scroll_cam=0,
+        ticker_height=0,
+        items=[("Title", "Source", "2025-01-01T00:00:00")],
+    )
+    import engine.config as config
+
+    config.FIREHOSE = True
+    config.FIREHOSE_H = 0
+    result = effect.process(buf, ctx)
+    assert result == buf
+
+
+def test_firehose_with_no_items():
+    """Firehose with no content items returns buffer unchanged."""
+    effect = FirehoseEffect()
+    effect.configure(effect.config)
+    buf = ["line1"]
+    ctx = EffectContext(
+        terminal_width=80,
+        terminal_height=24,
+        scroll_cam=0,
+        ticker_height=0,
+        items=[],
+    )
+    import engine.config as config
+
+    config.FIREHOSE = True
+    config.FIREHOSE_H = 3
+    result = effect.process(buf, ctx)
+    assert result == buf

tests/test_pipeline_order.py

@@ -0,0 +1,118 @@
+"""Tests for pipeline execution order verification."""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+from engine.pipeline import Pipeline, Stage, discover_stages
+from engine.pipeline.core import DataType
+
+
+@pytest.fixture(autouse=True)
+def reset_registry():
+    """Reset stage registry before each test."""
+    from engine.pipeline.registry import StageRegistry
+
+    StageRegistry._discovered = False
+    StageRegistry._categories.clear()
+    StageRegistry._instances.clear()
+    discover_stages()
+    yield
+    StageRegistry._discovered = False
+    StageRegistry._categories.clear()
+    StageRegistry._instances.clear()
+
+
+def _create_mock_stage(name: str, category: str, capabilities: set, dependencies: set):
+    """Helper to create a mock stage."""
+    mock = MagicMock(spec=Stage)
+    mock.name = name
+    mock.category = category
+    mock.stage_type = category
+    mock.render_order = 0
+    mock.is_overlay = False
+    mock.inlet_types = {DataType.ANY}
+    mock.outlet_types = {DataType.TEXT_BUFFER}
+    mock.capabilities = capabilities
+    mock.dependencies = dependencies
+    mock.process = lambda data, ctx: data
+    mock.init = MagicMock(return_value=True)
+    mock.cleanup = MagicMock()
+    mock.is_enabled = MagicMock(return_value=True)
+    mock.set_enabled = MagicMock()
+    mock._enabled = True
+    return mock
+
+
+def test_pipeline_execution_order_linear():
+    """Verify stages execute in linear order based on dependencies."""
+    pipeline = Pipeline()
+    pipeline.build(auto_inject=False)
+
+    source = _create_mock_stage("source", "source", {"source"}, set())
+    render = _create_mock_stage("render", "render", {"render"}, {"source"})
+    effect = _create_mock_stage("effect", "effect", {"effect"}, {"render"})
+    display = _create_mock_stage("display", "display", {"display"}, {"effect"})
+
+    pipeline.add_stage("source", source, initialize=False)
+    pipeline.add_stage("render", render, initialize=False)
+    pipeline.add_stage("effect", effect, initialize=False)
+    pipeline.add_stage("display", display, initialize=False)
+
+    pipeline._rebuild()
+
+    assert pipeline.execution_order == [
+        "source",
+        "render",
+        "effect",
+        "display",
+    ]
+
+
+def test_pipeline_effects_chain_order():
+    """Verify effects execute in config order when chained."""
+    pipeline = Pipeline()
+    pipeline.build(auto_inject=False)
+
+    # Source and render
+    source = _create_mock_stage("source", "source", {"source"}, set())
+    render = _create_mock_stage("render", "render", {"render"}, {"source"})
+
+    # Effects chain: effect_a → effect_b → effect_c
+    effect_a = _create_mock_stage("effect_a", "effect", {"effect_a"}, {"render"})
+    effect_b = _create_mock_stage("effect_b", "effect", {"effect_b"}, {"effect_a"})
+    effect_c = _create_mock_stage("effect_c", "effect", {"effect_c"}, {"effect_b"})
+
+    # Display
+    display = _create_mock_stage("display", "display", {"display"}, {"effect_c"})
+
+    for stage in [source, render, effect_a, effect_b, effect_c, display]:
+        pipeline.add_stage(stage.name, stage, initialize=False)
+
+    pipeline._rebuild()
+
+    effect_names = [
+        name for name in pipeline.execution_order if name.startswith("effect_")
+    ]
+    assert effect_names == ["effect_a", "effect_b", "effect_c"]
+
+
+def test_pipeline_overlay_executes_after_regular_effects():
+    """Overlay stages should execute after all regular effects."""
+    pipeline = Pipeline()
+    pipeline.build(auto_inject=False)
+
+    effect = _create_mock_stage("effect1", "effect", {"effect1"}, {"render"})
+    overlay = _create_mock_stage("overlay_test", "overlay", {"overlay"}, {"effect1"})
+    display = _create_mock_stage("display", "display", {"display"}, {"overlay"})
+
+    for stage in [effect, overlay, display]:
+        pipeline.add_stage(stage.name, stage, initialize=False)
+
+    pipeline._rebuild()
+
+    names = pipeline.execution_order
+    idx_effect = names.index("effect1")
+    idx_overlay = names.index("overlay_test")
+    idx_display = names.index("display")
+    assert idx_effect < idx_overlay < idx_display

tests/test_renderer.py

@@ -0,0 +1,164 @@
+"""
+Unit tests for engine.display.renderer module.
+
+Tests ANSI parsing and PIL rendering utilities.
+"""
+
+import pytest
+
+try:
+    from PIL import Image
+
+    PIL_AVAILABLE = True
+except ImportError:
+    PIL_AVAILABLE = False
+
+from engine.display.renderer import ANSI_COLORS, parse_ansi, render_to_pil
+
+
+class TestParseANSI:
+    """Tests for parse_ansi function."""
+
+    def test_plain_text(self):
+        """Plain text without ANSI codes returns single token."""
+        tokens = parse_ansi("Hello World")
+        assert len(tokens) == 1
+        assert tokens[0][0] == "Hello World"
+        # Check default colors
+        assert tokens[0][1] == (204, 204, 204)  # fg
+        assert tokens[0][2] == (0, 0, 0)  # bg
+        assert tokens[0][3] is False  # bold
+
+    def test_empty_string(self):
+        """Empty string returns single empty token."""
+        tokens = parse_ansi("")
+        assert tokens == [("", (204, 204, 204), (0, 0, 0), False)]
+
+    def test_reset_code(self):
+        """Reset code (ESC[0m) restores defaults."""
+        tokens = parse_ansi("\x1b[31mRed\x1b[0mNormal")
+        assert len(tokens) == 2
+        assert tokens[0][0] == "Red"
+        # Red fg should be ANSI_COLORS[1]
+        assert tokens[0][1] == ANSI_COLORS[1]
+        assert tokens[1][0] == "Normal"
+        assert tokens[1][1] == (204, 204, 204)  # back to default
+
+    def test_bold_code(self):
+        """Bold code (ESC[1m) sets bold flag."""
+        tokens = parse_ansi("\x1b[1mBold")
+        assert tokens[0][3] is True
+
+    def test_bold_off_code(self):
+        """Bold off (ESC[22m) clears bold."""
+        tokens = parse_ansi("\x1b[1mBold\x1b[22mNormal")
+        assert tokens[0][3] is True
+        assert tokens[1][3] is False
+
+    def test_4bit_foreground_colors(self):
+        """4-bit foreground colors (30-37, 90-97) work."""
+        # Test normal red (31)
+        tokens = parse_ansi("\x1b[31mRed")
+        assert tokens[0][1] == ANSI_COLORS[1]  # color 1 = red
+
+        # Test bright cyan (96) - maps to index 14 (bright cyan)
+        tokens = parse_ansi("\x1b[96mCyan")
+        assert tokens[0][1] == ANSI_COLORS[14]  # bright cyan
+
+    def test_4bit_background_colors(self):
+        """4-bit background colors (40-47, 100-107) work."""
+        # Green bg = 42
+        tokens = parse_ansi("\x1b[42mText")
+        assert tokens[0][2] == ANSI_COLORS[2]  # color 2 = green
+
+        # Bright magenta bg = 105
+        tokens = parse_ansi("\x1b[105mText")
+        assert tokens[0][2] == ANSI_COLORS[13]  # bright magenta (13)
+
+    def test_multiple_ansi_codes_in_sequence(self):
+        """Multiple codes in one escape sequence are parsed."""
+        tokens = parse_ansi("\x1b[1;31;42mBold Red on Green")
+        assert tokens[0][0] == "Bold Red on Green"
+        assert tokens[0][3] is True  # bold
+        assert tokens[0][1] == ANSI_COLORS[1]  # red fg
+        assert tokens[0][2] == ANSI_COLORS[2]  # green bg
+
+    def test_nested_ansi_sequences(self):
+        """Multiple separate ANSI sequences are tokenized correctly."""
+        text = "\x1b[31mRed\x1b[32mGreen\x1b[0mNormal"
+        tokens = parse_ansi(text)
+        assert len(tokens) == 3
+        assert tokens[0][0] == "Red"
+        assert tokens[1][0] == "Green"
+        assert tokens[2][0] == "Normal"
+
+    def test_interleaved_text_and_ansi(self):
+        """Text before and after ANSI codes is tokenized."""
+        tokens = parse_ansi("Pre\x1b[31mRedPost")
+        assert len(tokens) == 2
+        assert tokens[0][0] == "Pre"
+        assert tokens[1][0] == "RedPost"
+        assert tokens[1][1] == ANSI_COLORS[1]
+
+    def test_all_standard_4bit_colors(self):
+        """All 4-bit color indices (0-15) map to valid RGB."""
+        for i in range(16):
+            tokens = parse_ansi(f"\x1b[{i}mX")
+            # Should be a defined color or default fg
+            fg = tokens[0][1]
+            valid = fg in ANSI_COLORS.values() or fg == (204, 204, 204)
+            assert valid, f"Color {i} produced invalid fg {fg}"
+
+    def test_unknown_code_ignored(self):
+        """Unknown numeric codes are ignored, keep current style."""
+        tokens = parse_ansi("\x1b[99mText")
+        # 99 is not recognized, should keep previous state (defaults)
+        assert tokens[0][1] == (204, 204, 204)
+
+
+@pytest.mark.skipif(not PIL_AVAILABLE, reason="PIL not available")
+class TestRenderToPIL:
+    """Tests for render_to_pil function (requires PIL)."""
+
+    def test_renders_plain_text(self):
+        """Plain buffer renders as image."""
+        buffer = ["Hello"]
+        img = render_to_pil(buffer, width=10, height=1)
+        assert isinstance(img, Image.Image)
+        assert img.mode == "RGBA"
+
+    def test_renders_with_ansi_colors(self):
+        """Buffer with ANSI colors renders correctly."""
+        buffer = ["\x1b[31mRed\x1b[0mNormal"]
+        img = render_to_pil(buffer, width=20, height=1)
+        assert isinstance(img, Image.Image)
+
+    def test_multi_line_buffer(self):
+        """Multiple lines render with correct height."""
+        buffer = ["Line1", "Line2", "Line3"]
+        img = render_to_pil(buffer, width=10, height=3)
+        # Height should be approximately 3 * cell_height (18-2 padding)
+        assert img.height > 0
+
+    def test_clipping_to_height(self):
+        """Buffer longer than height is clipped."""
+        buffer = ["Line1", "Line2", "Line3", "Line4"]
+        img = render_to_pil(buffer, width=10, height=2)
+        # Should only render 2 lines
+        assert img.height < img.width * 2  # roughly 2 lines tall
+
+    def test_cell_dimensions_respected(self):
+        """Custom cell_width and cell_height are used."""
+        buffer = ["Test"]
+        img = render_to_pil(buffer, width=5, height=1, cell_width=20, cell_height=25)
+        assert img.width == 5 * 20
+        assert img.height == 25
+
+    def test_font_fallback_on_invalid(self):
+        """Invalid font path falls back to default font."""
+        buffer = ["Test"]
+        # Should not crash with invalid font path
+        img = render_to_pil(
+            buffer, width=5, height=1, font_path="/nonexistent/font.ttf"
+        )
+        assert isinstance(img, Image.Image)

tests/test_streaming.py

@@ -2,6 +2,7 @@
 Tests for streaming protocol utilities.
 """
 
+
 from engine.display.streaming import (
     FrameDiff,
     MessageType,

tests/test_vis_offset.py

@@ -1,3 +1,4 @@
+
 from engine.effects.legacy import vis_offset, vis_trunc
 
 

tests/test_visual_verification.py

@@ -0,0 +1,234 @@
+"""
+Visual verification tests for message overlay and effect rendering.
+
+These tests verify that the sideline pipeline produces visual output
+that matches the expected behavior of upstream/main, even if the
+buffer format differs due to architectural differences.
+"""
+
+import json
+from pathlib import Path
+
+import pytest
+
+from engine.display import DisplayRegistry
+from engine.pipeline import Pipeline, PipelineConfig, PipelineContext
+from engine.pipeline.adapters import create_stage_from_display
+from engine.pipeline.params import PipelineParams
+from engine.pipeline.presets import get_preset
+
+
+class TestMessageOverlayVisuals:
+    """Test message overlay visual rendering."""
+
+    def test_message_overlay_produces_output(self):
+        """Verify message overlay stage produces output when ntfy message is present."""
+        # This test verifies the message overlay stage is working
+        # It doesn't compare with upstream, just verifies functionality
+
+        from engine.pipeline.adapters.message_overlay import MessageOverlayStage
+        from engine.pipeline.adapters import MessageOverlayConfig
+
+        # Test the rendering function directly
+        stage = MessageOverlayStage(
+            config=MessageOverlayConfig(enabled=True, display_secs=30)
+        )
+
+        # Test with a mock message
+        msg = ("Test Title", "Test Message Body", 0.0)
+        w, h = 80, 24
+
+        # Render overlay
+        overlay, _ = stage._render_message_overlay(msg, w, h, (None, None))
+
+        # Verify overlay has content
+        assert len(overlay) > 0, "Overlay should have content when message is present"
+
+        # Verify overlay contains expected content
+        overlay_text = "".join(overlay)
+        # Note: Message body is rendered as block characters, not text
+        # The title appears in the metadata line
+        assert "Test Title" in overlay_text, "Overlay should contain message title"
+        assert "ntfy" in overlay_text, "Overlay should contain ntfy metadata"
+        assert "\033[" in overlay_text, "Overlay should contain ANSI codes"
+
+    def test_message_overlay_appears_in_correct_position(self):
+        """Verify message overlay appears in centered position."""
+        # This test verifies the message overlay positioning logic
+        # It checks that the overlay coordinates are calculated correctly
+
+        from engine.pipeline.adapters.message_overlay import MessageOverlayStage
+        from engine.pipeline.adapters import MessageOverlayConfig
+
+        stage = MessageOverlayStage(config=MessageOverlayConfig())
+
+        # Test positioning calculation
+        msg = ("Test Title", "Test Body", 0.0)
+        w, h = 80, 24
+
+        # Render overlay
+        overlay, _ = stage._render_message_overlay(msg, w, h, (None, None))
+
+        # Verify overlay has content
+        assert len(overlay) > 0, "Overlay should have content"
+
+        # Verify overlay contains cursor positioning codes
+        overlay_text = "".join(overlay)
+        assert "\033[" in overlay_text, "Overlay should contain ANSI codes"
+        assert "H" in overlay_text, "Overlay should contain cursor positioning"
+
+        # Verify panel is centered (check first line's position)
+        # Panel height is len(msg_rows) + 2 (content + meta + border)
+        # panel_top = max(0, (h - panel_h) // 2)
+        # First content line should be at panel_top + 1
+        first_line = overlay[0]
+        assert "\033[" in first_line, "First line should have cursor positioning"
+        assert ";1H" in first_line, "First line should position at column 1"
+
+    def test_theme_system_integration(self):
+        """Verify theme system is integrated with message overlay."""
+        from engine import config as engine_config
+        from engine.themes import THEME_REGISTRY
+
+        # Verify theme registry has expected themes
+        assert "green" in THEME_REGISTRY, "Green theme should exist"
+        assert "orange" in THEME_REGISTRY, "Orange theme should exist"
+        assert "purple" in THEME_REGISTRY, "Purple theme should exist"
+
+        # Verify active theme is set
+        assert engine_config.ACTIVE_THEME is not None, "Active theme should be set"
+        assert engine_config.ACTIVE_THEME.name in THEME_REGISTRY, (
+            "Active theme should be in registry"
+        )
+
+        # Verify theme has gradient colors
+        assert len(engine_config.ACTIVE_THEME.main_gradient) == 12, (
+            "Main gradient should have 12 colors"
+        )
+        assert len(engine_config.ACTIVE_THEME.message_gradient) == 12, (
+            "Message gradient should have 12 colors"
+        )
+
+
+class TestPipelineExecutionOrder:
+    """Test pipeline execution order for visual consistency."""
+
+    def test_message_overlay_after_camera(self):
+        """Verify message overlay is applied after camera transformation."""
+        from engine.pipeline import Pipeline, PipelineConfig, PipelineContext
+        from engine.pipeline.adapters import (
+            create_stage_from_display,
+            MessageOverlayStage,
+            MessageOverlayConfig,
+        )
+        from engine.display import DisplayRegistry
+
+        # Create pipeline
+        config = PipelineConfig(
+            source="empty",
+            display="null",
+            camera="feed",
+            effects=[],
+        )
+
+        ctx = PipelineContext()
+        pipeline = Pipeline(config=config, context=ctx)
+
+        # Add stages
+        from engine.data_sources.sources import EmptyDataSource
+        from engine.pipeline.adapters import DataSourceStage
+
+        pipeline.add_stage(
+            "source",
+            DataSourceStage(EmptyDataSource(width=80, height=24), name="empty"),
+        )
+        pipeline.add_stage(
+            "message_overlay", MessageOverlayStage(config=MessageOverlayConfig())
+        )
+        pipeline.add_stage(
+            "display", create_stage_from_display(DisplayRegistry.create("null"), "null")
+        )
+
+        # Build and check order
+        pipeline.build()
+        execution_order = pipeline.execution_order
+
+        # Verify message_overlay comes after camera stages
+        camera_idx = next(
+            (i for i, name in enumerate(execution_order) if "camera" in name), -1
+        )
+        msg_idx = next(
+            (i for i, name in enumerate(execution_order) if "message_overlay" in name),
+            -1,
+        )
+
+        if camera_idx >= 0 and msg_idx >= 0:
+            assert msg_idx > camera_idx, "Message overlay should be after camera stage"
+
+
+class TestCapturedOutputAnalysis:
+    """Test analysis of captured output files."""
+
+    def test_captured_files_exist(self):
+        """Verify captured output files exist."""
+        sideline_path = Path("output/sideline_demo.json")
+        upstream_path = Path("output/upstream_demo.json")
+
+        assert sideline_path.exists(), "Sideline capture file should exist"
+        assert upstream_path.exists(), "Upstream capture file should exist"
+
+    def test_captured_files_valid(self):
+        """Verify captured output files are valid JSON."""
+        sideline_path = Path("output/sideline_demo.json")
+        upstream_path = Path("output/upstream_demo.json")
+
+        with open(sideline_path) as f:
+            sideline = json.load(f)
+        with open(upstream_path) as f:
+            upstream = json.load(f)
+
+        # Verify structure
+        assert "frames" in sideline, "Sideline should have frames"
+        assert "frames" in upstream, "Upstream should have frames"
+        assert len(sideline["frames"]) > 0, "Sideline should have at least one frame"
+        assert len(upstream["frames"]) > 0, "Upstream should have at least one frame"
+
+    def test_sideline_buffer_format(self):
+        """Verify sideline buffer format is plain text."""
+        sideline_path = Path("output/sideline_demo.json")
+
+        with open(sideline_path) as f:
+            sideline = json.load(f)
+
+        # Check first frame
+        frame0 = sideline["frames"][0]["buffer"]
+
+        # Sideline should have plain text lines (no cursor positioning)
+        # Check first few lines
+        for i, line in enumerate(frame0[:5]):
+            # Should not start with cursor positioning
+            if line.strip():
+                assert not line.startswith("\033["), (
+                    f"Line {i} should not start with cursor positioning"
+                )
+                # Should have actual content
+                assert len(line.strip()) > 0, f"Line {i} should have content"
+
+    def test_upstream_buffer_format(self):
+        """Verify upstream buffer format includes cursor positioning."""
+        upstream_path = Path("output/upstream_demo.json")
+
+        with open(upstream_path) as f:
+            upstream = json.load(f)
+
+        # Check first frame
+        frame0 = upstream["frames"][0]["buffer"]
+
+        # Upstream should have cursor positioning codes
+        overlay_text = "".join(frame0[:10])
+        assert "\033[" in overlay_text, "Upstream buffer should contain ANSI codes"
+        assert "H" in overlay_text, "Upstream buffer should contain cursor positioning"
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])