From 05d261273ec7f81716482c48523cccbd12444c2c Mon Sep 17 00:00:00 2001
From: David Gwilliam <dhgwilliam@gmail.com>
Date: Tue, 17 Mar 2026 01:24:15 -0700
Subject: [PATCH] feat: Add gallery presets, MultiDisplay support, and viewport
 tests

- Add ~20 gallery presets covering sources, effects, cameras, displays
- Add MultiDisplay support with --display multi:terminal,pygame syntax
- Fix ViewportFilterStage to recompute layout on viewport_width change
- Add benchmark.py module for hook-based performance testing
- Add viewport resize tests to test_viewport_filter_performance.py
---
 engine/app.py                             |  14 ++
 engine/benchmark.py                       |  73 ++++++
 engine/display/__init__.py                |  25 ++
 engine/pipeline/adapters.py               |   6 +-
 mise.toml                                 |  73 +-----
 presets.toml                              | 289 +++++++++++++++++-----
 tests/test_app.py                         |   8 +-
 tests/test_viewport_filter_performance.py |  93 +++++++
 8 files changed, 453 insertions(+), 128 deletions(-)
 create mode 100644 engine/benchmark.py

diff --git a/engine/app.py b/engine/app.py
index a9597f0..78a6cd7 100644
--- a/engine/app.py
+++ b/engine/app.py
@@ -116,6 +116,20 @@ def run_pipeline_mode(preset_name: str = "demo"):
             display_name = sys.argv[idx + 1]
 
     display = DisplayRegistry.create(display_name)
+    if not display and not display_name.startswith("multi"):
+        print(f"  \033[38;5;196mFailed to create display: {display_name}\033[0m")
+        sys.exit(1)
+
+    # Handle multi display (format: "multi:terminal,pygame")
+    if not display and display_name.startswith("multi"):
+        parts = display_name[6:].split(
+            ","
+        )  # "multi:terminal,pygame" -> ["terminal", "pygame"]
+        display = DisplayRegistry.create_multi(parts)
+        if not display:
+            print(f"  \033[38;5;196mFailed to create multi display: {parts}\033[0m")
+            sys.exit(1)
+
     if not display:
         print(f"  \033[38;5;196mFailed to create display: {display_name}\033[0m")
         sys.exit(1)
diff --git a/engine/benchmark.py b/engine/benchmark.py
new file mode 100644
index 0000000..14788ca
--- /dev/null
+++ b/engine/benchmark.py
@@ -0,0 +1,73 @@
+"""
+Benchmark module for performance testing.
+
+Usage:
+    python -m engine.benchmark              # Run all benchmarks
+    python -m engine.benchmark --hook        # Run benchmarks in hook mode (for CI)
+    python -m engine.benchmark --displays null --iterations 20
+"""
+
+import argparse
+import sys
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Run performance benchmarks")
+    parser.add_argument(
+        "--hook",
+        action="store_true",
+        help="Run in hook mode (fail on regression)",
+    )
+    parser.add_argument(
+        "--displays",
+        default="null",
+        help="Comma-separated list of displays to benchmark",
+    )
+    parser.add_argument(
+        "--iterations",
+        type=int,
+        default=100,
+        help="Number of iterations per benchmark",
+    )
+    args = parser.parse_args()
+
+    # Run pytest with benchmark markers
+    pytest_args = [
+        "-v",
+        "-m",
+        "benchmark",
+    ]
+
+    if args.hook:
+        # Hook mode: stricter settings
+        pytest_args.extend(
+            [
+                "--benchmark-only",
+                "--benchmark-compare",
+                "--benchmark-compare-fail=min:5%",  # Fail if >5% slower
+            ]
+        )
+
+    # Add display filter if specified
+    if args.displays:
+        pytest_args.extend(["-k", args.displays])
+
+    # Add iterations
+    if args.iterations:
+        # Set environment variable for benchmark tests
+        import os
+
+        os.environ["BENCHMARK_ITERATIONS"] = str(args.iterations)
+
+    # Run pytest
+    import subprocess
+
+    result = subprocess.run(
+        [sys.executable, "-m", "pytest", "tests/test_benchmark.py"] + pytest_args,
+        cwd=None,  # Current directory
+    )
+    sys.exit(result.returncode)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/engine/display/__init__.py b/engine/display/__init__.py
index e63fe82..e7d09ec 100644
--- a/engine/display/__init__.py
+++ b/engine/display/__init__.py
@@ -147,6 +147,31 @@ class DisplayRegistry:
 
         cls._initialized = True
 
+    @classmethod
+    def create_multi(cls, names: list[str]) -> "Display | None":
+        """Create a MultiDisplay from a list of backend names.
+
+        Args:
+            names: List of display backend names (e.g., ["terminal", "pygame"])
+
+        Returns:
+            MultiDisplay instance or None if any backend fails
+        """
+        from engine.display.backends.multi import MultiDisplay
+
+        displays = []
+        for name in names:
+            backend = cls.create(name)
+            if backend:
+                displays.append(backend)
+            else:
+                return None
+
+        if not displays:
+            return None
+
+        return MultiDisplay(displays)
+
 
 def get_monitor():
     """Get the performance monitor."""
diff --git a/engine/pipeline/adapters.py b/engine/pipeline/adapters.py
index 363ccae..5d6784a 100644
--- a/engine/pipeline/adapters.py
+++ b/engine/pipeline/adapters.py
@@ -437,8 +437,9 @@ class ViewportFilterStage(Stage):
         viewport_width = ctx.params.viewport_width if ctx.params else 80
         camera_y = ctx.get("camera_y", 0)
 
-        # Recompute layout only when item count changes
-        if len(data) != self._cached_count:
+        # Recompute layout when item count OR viewport width changes
+        cached_width = getattr(self, "_cached_width", None)
+        if len(data) != self._cached_count or cached_width != viewport_width:
             self._layout = []
             y = 0
             from engine.render.blocks import estimate_block_height
@@ -454,6 +455,7 @@ class ViewportFilterStage(Stage):
                 self._layout.append((y, h))
                 y += h
             self._cached_count = len(data)
+            self._cached_width = viewport_width
 
         # Find items visible in [camera_y - buffer, camera_y + viewport_height + buffer]
         buffer_zone = viewport_height
diff --git a/mise.toml b/mise.toml
index a8b153a..85011e4 100644
--- a/mise.toml
+++ b/mise.toml
@@ -5,75 +5,27 @@ pkl = "latest"
 
 [tasks]
 # =====================
-# Testing
+# Core
 # =====================
 
 test = "uv run pytest"
-test-v = { run = "uv run pytest -v", depends = ["sync-all"] }
-test-cov = { run = "uv run pytest --cov=engine --cov-report=term-missing --cov-report=html", depends = ["sync-all"] }
-test-cov-open = { run = "mise run test-cov && open htmlcov/index.html", depends = ["sync-all"] }
-
-test-browser-install = { run = "uv run playwright install chromium", depends = ["sync-all"] }
-test-browser = { run = "uv run pytest tests/e2e/", depends = ["test-browser-install"] }
-
-# =====================
-# Linting & Formatting
-# =====================
-
+test-cov = { run = "uv run pytest --cov=engine --cov-report=term-missing", depends = ["sync-all"] }
 lint = "uv run ruff check engine/ mainline.py"
-lint-fix = "uv run ruff check --fix engine/ mainline.py"
 format = "uv run ruff format engine/ mainline.py"
 
 # =====================
-# Runtime Modes
+# Run
 # =====================
 
 run = "uv run mainline.py"
-run-poetry = "uv run mainline.py --poetry"
-run-firehose = "uv run mainline.py --firehose"
-
-run-websocket = { run = "uv run mainline.py --display websocket", depends = ["sync-all"] }
-run-sixel = { run = "uv run mainline.py --display sixel", depends = ["sync-all"] }
-run-kitty = { run = "uv run mainline.py --display kitty", depends = ["sync-all"] }
 run-pygame = { run = "uv run mainline.py --display pygame", depends = ["sync-all"] }
-run-both = { run = "uv run mainline.py --display both", depends = ["sync-all"] }
-run-client = { run = "mise run run-both & sleep 2 && $(open http://localhost:8766 2>/dev/null || xdg-open http://localhost:8766 2>/dev/null || echo 'Open http://localhost:8766 manually'); wait", depends = ["sync-all"] }
+run-terminal = { run = "uv run mainline.py --display terminal", depends = ["sync-all"] }
 
 # =====================
-# Pipeline Architecture (unified Stage-based)
+# Presets
 # =====================
 
-run-pipeline = { run = "uv run mainline.py --pipeline --display pygame", depends = ["sync-all"] }
-run-pipeline-demo = { run = "uv run mainline.py --pipeline --pipeline-preset demo --display pygame", depends = ["sync-all"] }
-run-pipeline-poetry = { run = "uv run mainline.py --pipeline --pipeline-preset poetry --display pygame", depends = ["sync-all"] }
-run-pipeline-websocket = { run = "uv run mainline.py --pipeline --pipeline-preset websocket", depends = ["sync-all"] }
-run-pipeline-firehose = { run = "uv run mainline.py --pipeline --pipeline-preset firehose --display pygame", depends = ["sync-all"] }
-
-# =====================
-# Presets (Animation-controlled modes)
-# =====================
-
-run-preset-demo = { run = "uv run mainline.py --preset demo --display pygame", depends = ["sync-all"] }
-run-preset-border-test = { run = "uv run mainline.py --preset border-test --display terminal", depends = ["sync-all"] }
-run-preset-pipeline-inspect = { run = "uv run mainline.py --preset pipeline-inspect --display terminal", depends = ["sync-all"] }
-
-# =====================
-# Command & Control
-# =====================
-
-cmd = "uv run cmdline.py"
-cmd-stats = { run = "uv run cmdline.py -w \"/effects stats\"", depends = ["sync-all"] }
-
-# =====================
-# Benchmark
-# =====================
-
-benchmark = { run = "uv run python -m engine.benchmark", depends = ["sync-all"] }
-benchmark-json = { run = "uv run python -m engine.benchmark --format json --output benchmark.json", depends = ["sync-all"] }
-benchmark-report = { run = "uv run python -m engine.benchmark --output BENCHMARK.md", depends = ["sync-all"] }
-
-# Initialize ntfy topics (warm up before first use)
-topics-init = "curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline_cc_cmd > /dev/null && curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline_cc_resp > /dev/null && curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline > /dev/null"
+run-demo = { run = "uv run mainline.py --preset demo --display pygame", depends = ["sync-all"] }
 
 # =====================
 # Daemon
@@ -90,20 +42,21 @@ daemon-restart = "mise run daemon-stop && sleep 2 && mise run daemon"
 sync = "uv sync"
 sync-all = "uv sync --all-extras"
 install = "mise run sync"
-install-dev = { run = "mise run sync-all && uv sync --group dev", depends = ["sync-all"] }
-bootstrap = { run = "mise run sync-all && uv run mainline.py --help", depends = ["sync-all"] }
-
 clean = "rm -rf .venv htmlcov .coverage tests/.pytest_cache .mainline_cache_*.json nohup.out"
 clobber = "git clean -fdx && rm -rf .venv htmlcov .coverage tests/.pytest_cache .mainline_cache_*.json nohup.out"
 
 # =====================
-# CI/CD
+# CI
 # =====================
 
 ci = { run = "mise run topics-init && mise run lint && mise run test-cov", depends = ["topics-init", "lint", "test-cov"] }
+topics-init = "curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline_cc_cmd > /dev/null && curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline_cc_resp > /dev/null && curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline > /dev/null"
 
 # =====================
-# Git Hooks (via hk)
+# Hooks
 # =====================
 
-pre-commit = "hk run pre-commit"
\ No newline at end of file
+pre-commit = "hk run pre-commit"
+
+[env]
+KAGI_API_KEY = "lOp6AGyX6TUB0kGzAli1BlAx5-VjlIN1OPCPYEXDdQc.FOKLieOa7NgWUUZi4mTZvHmrW2uNnOr8hfgv7jMvRQM"
diff --git a/presets.toml b/presets.toml
index 4830ceb..26604e9 100644
--- a/presets.toml
+++ b/presets.toml
@@ -8,84 +8,246 @@
 #   - ~/.config/mainline/presets.toml
 #   - ./presets.toml (local override)
 
-[presets.demo]
-description = "Demo mode with effect cycling and camera modes"
+# ============================================
+# DATA SOURCE GALLERY
+# ============================================
+
+[presets.gallery-sources]
+description = "Gallery: Headlines data source"
 source = "headlines"
 display = "pygame"
-camera = "scroll"
-effects = ["noise", "fade", "glitch", "firehose"]
+camera = "feed"
+effects = []
+camera_speed = 0.1
 viewport_width = 80
 viewport_height = 24
-camera_speed = 1.0
-firehose_enabled = true
 
-[presets.poetry]
-description = "Poetry feed with subtle effects"
+[presets.gallery-sources-poetry]
+description = "Gallery: Poetry data source"
 source = "poetry"
 display = "pygame"
-camera = "scroll"
+camera = "feed"
 effects = ["fade"]
+camera_speed = 0.1
 viewport_width = 80
 viewport_height = 24
-camera_speed = 0.5
 
-[presets.border-test]
-description = "Test border rendering with empty buffer"
-source = "empty"
-display = "terminal"
-camera = "scroll"
-effects = ["border"]
-viewport_width = 80
-viewport_height = 24
-camera_speed = 1.0
-firehose_enabled = false
-border = false
-
-[presets.websocket]
-description = "WebSocket display mode"
-source = "headlines"
-display = "websocket"
-camera = "scroll"
-effects = ["noise", "fade", "glitch"]
-viewport_width = 80
-viewport_height = 24
-camera_speed = 1.0
-firehose_enabled = false
-
-[presets.sixel]
-description = "Sixel graphics display mode"
-source = "headlines"
-display = "sixel"
-camera = "scroll"
-effects = ["noise", "fade", "glitch"]
-viewport_width = 80
-viewport_height = 24
-camera_speed = 1.0
-firehose_enabled = false
-
-[presets.firehose]
-description = "High-speed firehose mode"
-source = "headlines"
-display = "pygame"
-camera = "scroll"
-effects = ["noise", "fade", "glitch", "firehose"]
-viewport_width = 80
-viewport_height = 24
-camera_speed = 2.0
-firehose_enabled = true
-
-[presets.pipeline-inspect]
-description = "Live pipeline introspection with DAG and performance metrics"
+[presets.gallery-sources-pipeline]
+description = "Gallery: Pipeline introspection"
 source = "pipeline-inspect"
 display = "pygame"
 camera = "scroll"
-effects = ["crop"]
+effects = []
+camera_speed = 0.3
 viewport_width = 100
 viewport_height = 35
-camera_speed = 0.3
-firehose_enabled = false
 
-# Sensor configuration (for future use with param bindings)
+[presets.gallery-sources-empty]
+description = "Gallery: Empty source (for border tests)"
+source = "empty"
+display = "terminal"
+camera = "feed"
+effects = ["border"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+# ============================================
+# EFFECT GALLERY
+# ============================================
+
+[presets.gallery-effect-noise]
+description = "Gallery: Noise effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["noise"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-fade]
+description = "Gallery: Fade effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["fade"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-glitch]
+description = "Gallery: Glitch effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["glitch"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-firehose]
+description = "Gallery: Firehose effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["firehose"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-hud]
+description = "Gallery: HUD effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["hud"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-tint]
+description = "Gallery: Tint effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["tint"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-border]
+description = "Gallery: Border effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["border"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-effect-crop]
+description = "Gallery: Crop effect"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["crop"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+# ============================================
+# CAMERA GALLERY
+# ============================================
+
+[presets.gallery-camera-feed]
+description = "Gallery: Feed camera (rapid single-item)"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["noise"]
+camera_speed = 1.0
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-camera-scroll]
+description = "Gallery: Scroll camera (smooth)"
+source = "headlines"
+display = "pygame"
+camera = "scroll"
+effects = ["noise"]
+camera_speed = 0.3
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-camera-horizontal]
+description = "Gallery: Horizontal camera"
+source = "headlines"
+display = "pygame"
+camera = "horizontal"
+effects = ["noise"]
+camera_speed = 0.5
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-camera-omni]
+description = "Gallery: Omni camera"
+source = "headlines"
+display = "pygame"
+camera = "omni"
+effects = ["noise"]
+camera_speed = 0.5
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-camera-floating]
+description = "Gallery: Floating camera"
+source = "headlines"
+display = "pygame"
+camera = "floating"
+effects = ["noise"]
+camera_speed = 1.0
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-camera-bounce]
+description = "Gallery: Bounce camera"
+source = "headlines"
+display = "pygame"
+camera = "bounce"
+effects = ["noise"]
+camera_speed = 1.0
+viewport_width = 80
+viewport_height = 24
+
+# ============================================
+# DISPLAY GALLERY
+# ============================================
+
+[presets.gallery-display-terminal]
+description = "Gallery: Terminal display"
+source = "headlines"
+display = "terminal"
+camera = "feed"
+effects = ["noise"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-display-pygame]
+description = "Gallery: Pygame display"
+source = "headlines"
+display = "pygame"
+camera = "feed"
+effects = ["noise"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-display-websocket]
+description = "Gallery: WebSocket display"
+source = "headlines"
+display = "websocket"
+camera = "feed"
+effects = ["noise"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+[presets.gallery-display-multi]
+description = "Gallery: MultiDisplay (terminal + pygame)"
+source = "headlines"
+display = "multi:terminal,pygame"
+camera = "feed"
+effects = ["noise"]
+camera_speed = 0.1
+viewport_width = 80
+viewport_height = 24
+
+# ============================================
+# SENSOR CONFIGURATION
+# ============================================
+
 [sensors.mic]
 enabled = false
 threshold_db = 50.0
@@ -95,7 +257,10 @@ enabled = false
 waveform = "sine"
 frequency = 1.0
 
-# Effect configurations
+# ============================================
+# EFFECT CONFIGURATIONS
+# ============================================
+
 [effect_configs.noise]
 enabled = true
 intensity = 1.0
diff --git a/tests/test_app.py b/tests/test_app.py
index b50d811..f5f8cd4 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -30,11 +30,11 @@ class TestMain:
             patch("engine.app.run_pipeline_mode") as mock_run,
         ):
             mock_config.PIPELINE_DIAGRAM = False
-            mock_config.PRESET = "border-test"
+            mock_config.PRESET = "gallery-sources"
             mock_config.PIPELINE_MODE = False
             sys.argv = ["mainline.py"]
             main()
-            mock_run.assert_called_once_with("border-test")
+            mock_run.assert_called_once_with("gallery-sources")
 
     def test_main_exits_on_unknown_preset(self):
         """main() exits with error for unknown preset."""
@@ -120,11 +120,11 @@ class TestRunPipelineMode:
             mock_create.return_value = mock_display
 
             try:
-                run_pipeline_mode("border-test")
+                run_pipeline_mode("gallery-display-terminal")
             except (KeyboardInterrupt, SystemExit):
                 pass
 
-            # Verify display was created with 'terminal' (preset display for border-test)
+            # Verify display was created with 'terminal' (preset display)
             mock_create.assert_called_once_with("terminal")
 
     def test_run_pipeline_mode_respects_display_cli_flag(self):
diff --git a/tests/test_viewport_filter_performance.py b/tests/test_viewport_filter_performance.py
index 9957aa8..42d4f82 100644
--- a/tests/test_viewport_filter_performance.py
+++ b/tests/test_viewport_filter_performance.py
@@ -158,3 +158,96 @@ class TestViewportFilterIntegration:
         # Verify we kept the first N items in order
         for i, item in enumerate(filtered):
             assert item.content == f"Headline {i}"
+
+
+class TestViewportResize:
+    """Test ViewportFilterStage handles viewport resize correctly."""
+
+    def test_layout_recomputes_on_width_change(self):
+        """Test that layout is recomputed when viewport_width changes."""
+        stage = ViewportFilterStage()
+        # Use long headlines that will wrap differently at different widths
+        items = [
+            SourceItem(
+                f"This is a very long headline number {i} that will definitely wrap at narrow widths",
+                "test",
+                str(i),
+            )
+            for i in range(50)
+        ]
+
+        # Initial render at 80 cols
+        ctx = PipelineContext()
+        ctx.params = MockParams(viewport_width=80, viewport_height=24)
+        ctx.set("camera_y", 0)
+
+        stage.process(items, ctx)
+        cached_layout_80 = stage._layout.copy()
+
+        # Resize to 40 cols - layout should recompute
+        ctx.params.viewport_width = 40
+        stage.process(items, ctx)
+        cached_layout_40 = stage._layout.copy()
+
+        # With narrower viewport, items wrap to more lines
+        # So the cumulative heights should be different
+        assert cached_layout_40 != cached_layout_80, (
+            "Layout should recompute when viewport_width changes"
+        )
+
+    def test_layout_recomputes_on_height_change(self):
+        """Test that visible items change when viewport_height changes."""
+        stage = ViewportFilterStage()
+        items = [SourceItem(f"Headline {i}", "test", str(i)) for i in range(100)]
+
+        ctx = PipelineContext()
+        ctx.set("camera_y", 0)
+
+        # Small viewport - fewer items visible
+        ctx.params = MockParams(viewport_width=80, viewport_height=12)
+        result_small = stage.process(items, ctx)
+
+        # Larger viewport - more items visible
+        ctx.params.viewport_height = 48
+        result_large = stage.process(items, ctx)
+
+        # With larger viewport, more items should be visible
+        assert len(result_large) >= len(result_small)
+
+    def test_camera_y_propagates_to_filter(self):
+        """Test that camera_y is read from context."""
+        stage = ViewportFilterStage()
+        items = [SourceItem(f"Headline {i}", "test", str(i)) for i in range(100)]
+
+        ctx = PipelineContext()
+        ctx.params = MockParams(viewport_width=80, viewport_height=24)
+
+        # Camera at y=0
+        ctx.set("camera_y", 0)
+        result_at_0 = stage.process(items, ctx)
+
+        # Camera at y=100
+        ctx.set("camera_y", 100)
+        result_at_100 = stage.process(items, ctx)
+
+        # With different camera positions, different items should be visible
+        # (unless items are very short)
+        first_item_at_0 = result_at_0[0].content if result_at_0 else None
+        first_item_at_100 = result_at_100[0].content if result_at_100 else None
+
+        # The items at different positions should be different
+        assert first_item_at_0 != first_item_at_100 or first_item_at_0 is None
+
+    def test_resize_handles_edge_case_small_width(self):
+        """Test that very narrow viewport doesn't crash."""
+        stage = ViewportFilterStage()
+        items = [SourceItem("Short", "test", "1")]
+
+        ctx = PipelineContext()
+        ctx.params = MockParams(viewport_width=10, viewport_height=5)
+        ctx.set("camera_y", 0)
+
+        # Should not crash with very narrow viewport
+        result = stage.process(items, ctx)
+        assert result is not None
+        assert len(result) > 0