From 57de835ae0aada1fab5de9f593728dea74aef696 Mon Sep 17 00:00:00 2001
From: David Gwilliam <dhgwilliam@gmail.com>
Date: Tue, 17 Mar 2026 00:21:18 -0700
Subject: [PATCH] feat: Implement scrolling camera with layout-aware filtering

- Rename VERTICAL camera mode to FEED (rapid single-item view)
- Add SCROLL camera mode with float accumulation for smooth movie-credits style scrolling
- Add estimate_block_height() for cheap layout calculation without full rendering
- Replace ViewportFilterStage with layout-aware filtering that tracks camera position
- Add render caching to FontStage to avoid re-rendering items
- Fix CameraStage to use global canvas height for scrolling bounds
- Add horizontal padding in Camera.apply() to prevent ghosting
- Add get_dimensions() to MultiDisplay for proper viewport sizing
- Fix PygameDisplay to auto-detect viewport from window size
- Update presets to use scroll camera with appropriate speeds
---
 engine/app.py                             |  20 ++--
 engine/camera.py                          | 101 +++++++++++++++--
 engine/display/backends/multi.py          |   7 ++
 engine/display/backends/pygame.py         |   4 +
 engine/pipeline/adapters.py               | 132 ++++++++++++++++++----
 engine/pipeline/presets.py                |  12 +-
 engine/render/blocks.py                   |  44 ++++++++
 presets.toml                              |  14 +--
 tests/test_camera.py                      |   7 +-
 tests/test_performance_regression.py      |  12 +-
 tests/test_pipeline.py                    |   4 +-
 tests/test_viewport_filter_performance.py |  12 +-
 12 files changed, 303 insertions(+), 66 deletions(-)

diff --git a/engine/app.py b/engine/app.py
index b5dec12..a9597f0 100644
--- a/engine/app.py
+++ b/engine/app.py
@@ -120,7 +120,7 @@ def run_pipeline_mode(preset_name: str = "demo"):
         print(f"  \033[38;5;196mFailed to create display: {display_name}\033[0m")
         sys.exit(1)
 
-    display.init(80, 24)
+    display.init(0, 0)
 
     effect_registry = get_registry()
 
@@ -171,16 +171,21 @@ def run_pipeline_mode(preset_name: str = "demo"):
         from engine.pipeline.adapters import CameraStage
 
         camera = None
-        if preset.camera == "vertical":
-            camera = Camera.vertical()
+        speed = getattr(preset, "camera_speed", 1.0)
+        if preset.camera == "feed":
+            camera = Camera.feed(speed=speed)
+        elif preset.camera == "scroll":
+            camera = Camera.scroll(speed=speed)
+        elif preset.camera == "vertical":
+            camera = Camera.scroll(speed=speed)  # Backwards compat
         elif preset.camera == "horizontal":
-            camera = Camera.horizontal()
+            camera = Camera.horizontal(speed=speed)
         elif preset.camera == "omni":
-            camera = Camera.omni()
+            camera = Camera.omni(speed=speed)
         elif preset.camera == "floating":
-            camera = Camera.floating()
+            camera = Camera.floating(speed=speed)
         elif preset.camera == "bounce":
-            camera = Camera.bounce()
+            camera = Camera.bounce(speed=speed)
 
         if camera:
             pipeline.add_stage("camera", CameraStage(camera, name=preset.camera))
@@ -213,6 +218,7 @@ def run_pipeline_mode(preset_name: str = "demo"):
     ctx.set("items", items)
     ctx.set("pipeline", pipeline)
     ctx.set("pipeline_order", pipeline.execution_order)
+    ctx.set("camera_y", 0)
 
     current_width = 80
     current_height = 24
diff --git a/engine/camera.py b/engine/camera.py
index a038d4b..b7f2c75 100644
--- a/engine/camera.py
+++ b/engine/camera.py
@@ -17,7 +17,8 @@ from enum import Enum, auto
 
 
 class CameraMode(Enum):
-    VERTICAL = auto()
+    FEED = auto()  # Single item view (static or rapid cycling)
+    SCROLL = auto()  # Smooth vertical scrolling (movie credits style)
     HORIZONTAL = auto()
     OMNI = auto()
     FLOATING = auto()
@@ -55,12 +56,14 @@ class Camera:
 
     x: int = 0
     y: int = 0
-    mode: CameraMode = CameraMode.VERTICAL
+    mode: CameraMode = CameraMode.FEED
     speed: float = 1.0
     zoom: float = 1.0
     canvas_width: int = 200  # Larger than viewport for scrolling
     canvas_height: int = 200
     custom_update: Callable[["Camera", float], None] | None = None
+    _x_float: float = field(default=0.0, repr=False)
+    _y_float: float = field(default=0.0, repr=False)
     _time: float = field(default=0.0, repr=False)
 
     @property
@@ -128,8 +131,10 @@ class Camera:
             self.custom_update(self, dt)
             return
 
-        if self.mode == CameraMode.VERTICAL:
-            self._update_vertical(dt)
+        if self.mode == CameraMode.FEED:
+            self._update_feed(dt)
+        elif self.mode == CameraMode.SCROLL:
+            self._update_scroll(dt)
         elif self.mode == CameraMode.HORIZONTAL:
             self._update_horizontal(dt)
         elif self.mode == CameraMode.OMNI:
@@ -159,9 +164,15 @@ class Camera:
         if vh < self.canvas_height:
             self.y = max(0, min(self.y, self.canvas_height - vh))
 
-    def _update_vertical(self, dt: float) -> None:
+    def _update_feed(self, dt: float) -> None:
+        """Feed mode: rapid scrolling (1 row per frame at speed=1.0)."""
         self.y += int(self.speed * dt * 60)
 
+    def _update_scroll(self, dt: float) -> None:
+        """Scroll mode: smooth vertical scrolling with float accumulation."""
+        self._y_float += self.speed * dt * 60
+        self.y = int(self._y_float)
+
     def _update_horizontal(self, dt: float) -> None:
         self.x += int(self.speed * dt * 60)
 
@@ -230,10 +241,86 @@ class Camera:
         self.canvas_height = height
         self._clamp_to_bounds()
 
+    def apply(
+        self, buffer: list[str], viewport_width: int, viewport_height: int | None = None
+    ) -> list[str]:
+        """Apply camera viewport to a text buffer.
+
+        Slices the buffer based on camera position (x, y) and viewport dimensions.
+        Handles ANSI escape codes correctly for colored/styled text.
+
+        Args:
+            buffer: List of strings representing lines of text
+            viewport_width: Width of the visible viewport in characters
+            viewport_height: Height of the visible viewport (overrides camera's viewport_height if provided)
+
+        Returns:
+            Sliced buffer containing only the visible lines and columns
+        """
+        from engine.effects.legacy import vis_offset, vis_trunc
+
+        if not buffer:
+            return buffer
+
+        # Get current viewport bounds (clamped to canvas size)
+        viewport = self.get_viewport()
+
+        # Use provided viewport_height if given, otherwise use camera's viewport
+        vh = viewport_height if viewport_height is not None else viewport.height
+
+        # Vertical slice: extract lines that fit in viewport height
+        start_y = viewport.y
+        end_y = min(viewport.y + vh, len(buffer))
+
+        if start_y >= len(buffer):
+            # Scrolled past end of buffer, return empty viewport
+            return [""] * vh
+
+        vertical_slice = buffer[start_y:end_y]
+
+        # Horizontal slice: apply horizontal offset and truncate to width
+        horizontal_slice = []
+        for line in vertical_slice:
+            # Apply horizontal offset (skip first x characters, handling ANSI)
+            offset_line = vis_offset(line, viewport.x)
+            # Truncate to viewport width (handling ANSI)
+            truncated_line = vis_trunc(offset_line, viewport_width)
+
+            # Pad line to full viewport width to prevent ghosting when panning
+            import re
+
+            visible_len = len(re.sub(r"\x1b\[[0-9;]*m", "", truncated_line))
+            if visible_len < viewport_width:
+                truncated_line += " " * (viewport_width - visible_len)
+
+            horizontal_slice.append(truncated_line)
+
+        # Pad with empty lines if needed to fill viewport height
+        while len(horizontal_slice) < vh:
+            horizontal_slice.append("")
+
+        return horizontal_slice
+
+    @classmethod
+    def feed(cls, speed: float = 1.0) -> "Camera":
+        """Create a feed camera (rapid single-item scrolling, 1 row/frame at speed=1.0)."""
+        return cls(mode=CameraMode.FEED, speed=speed, canvas_height=200)
+
+    @classmethod
+    def scroll(cls, speed: float = 0.5) -> "Camera":
+        """Create a smooth scrolling camera (movie credits style).
+
+        Uses float accumulation for sub-integer speeds.
+        Sets canvas_width=0 so it matches viewport_width for proper text wrapping.
+        """
+        return cls(
+            mode=CameraMode.SCROLL, speed=speed, canvas_width=0, canvas_height=200
+        )
+
     @classmethod
     def vertical(cls, speed: float = 1.0) -> "Camera":
-        """Create a vertical scrolling camera."""
-        return cls(mode=CameraMode.VERTICAL, speed=speed, canvas_height=200)
+        """Deprecated: Use feed() or scroll() instead."""
+        return cls(mode=CameraMode.FEED, speed=speed, canvas_height=200)
 
     @classmethod
     def horizontal(cls, speed: float = 1.0) -> "Camera":
diff --git a/engine/display/backends/multi.py b/engine/display/backends/multi.py
index 131972a..fd13be5 100644
--- a/engine/display/backends/multi.py
+++ b/engine/display/backends/multi.py
@@ -38,6 +38,13 @@ class MultiDisplay:
         for d in self.displays:
             d.clear()
 
+    def get_dimensions(self) -> tuple[int, int]:
+        """Get dimensions from the first child display that supports it."""
+        for d in self.displays:
+            if hasattr(d, "get_dimensions"):
+                return d.get_dimensions()
+        return (self.width, self.height)
+
     def cleanup(self) -> None:
         for d in self.displays:
             d.cleanup()
diff --git a/engine/display/backends/pygame.py b/engine/display/backends/pygame.py
index 2c9a85e..a2bc4b6 100644
--- a/engine/display/backends/pygame.py
+++ b/engine/display/backends/pygame.py
@@ -122,6 +122,10 @@ class PygameDisplay:
         self._pygame = pygame
         PygameDisplay._pygame_initialized = True
 
+        # Calculate character dimensions from actual window size
+        self.width = max(1, self.window_width // self.cell_width)
+        self.height = max(1, self.window_height // self.cell_height)
+
         font_path = self._get_font_path()
         if font_path:
             try:
diff --git a/engine/pipeline/adapters.py b/engine/pipeline/adapters.py
index dd2eafa..363ccae 100644
--- a/engine/pipeline/adapters.py
+++ b/engine/pipeline/adapters.py
@@ -314,9 +314,7 @@ class CameraStage(Stage):
 
     @property
     def dependencies(self) -> set[str]:
-        return {
-            "source"
-        }  # Prefix match any source (source.headlines, source.poetry, etc.)
+        return {"render.output"}  # Depend on rendered output from font or render stage
 
     @property
     def inlet_types(self) -> set:
@@ -335,9 +333,54 @@ class CameraStage(Stage):
         if data is None:
             return None
         if hasattr(self._camera, "apply"):
-            return self._camera.apply(
-                data, ctx.params.viewport_width if ctx.params else 80
+            viewport_width = ctx.params.viewport_width if ctx.params else 80
+            viewport_height = ctx.params.viewport_height if ctx.params else 24
+            buffer_height = len(data) if isinstance(data, list) else 0
+
+            # Get global layout height for canvas (enables full scrolling range)
+            total_layout_height = ctx.get("total_layout_height", buffer_height)
+
+            # Preserve camera's configured canvas width, but ensure it's at least viewport_width
+            # This allows horizontal/omni/floating/bounce cameras to scroll properly
+            canvas_width = max(
+                viewport_width, getattr(self._camera, "canvas_width", viewport_width)
             )
+
+            # Update camera's viewport dimensions so it knows its actual bounds
+            if hasattr(self._camera, "viewport_width"):
+                self._camera.viewport_width = viewport_width
+                self._camera.viewport_height = viewport_height
+
+            # Set canvas to full layout height so camera can scroll through all content
+            self._camera.set_canvas_size(width=canvas_width, height=total_layout_height)
+
+            # Update camera position (scroll) - uses global canvas for clamping
+            if hasattr(self._camera, "update"):
+                self._camera.update(1 / 60)
+
+            # Store camera_y in context for ViewportFilterStage (global y position)
+            ctx.set("camera_y", self._camera.y)
+
+            # Apply camera viewport slicing to the partial buffer
+            # The buffer starts at render_offset_y in global coordinates
+            render_offset_y = ctx.get("render_offset_y", 0)
+
+            # Temporarily shift camera to local buffer coordinates for apply()
+            real_y = self._camera.y
+            local_y = max(0, real_y - render_offset_y)
+
+            # Temporarily shrink canvas to local buffer size so apply() works correctly
+            self._camera.set_canvas_size(width=canvas_width, height=buffer_height)
+            self._camera.y = local_y
+
+            # Apply slicing
+            result = self._camera.apply(data, viewport_width, viewport_height)
+
+            # Restore global canvas and camera position for next frame
+            self._camera.set_canvas_size(width=canvas_width, height=total_layout_height)
+            self._camera.y = real_y
+
+            return result
         return data
 
     def cleanup(self) -> None:
@@ -346,20 +389,20 @@ class CameraStage(Stage):
 
 
 class ViewportFilterStage(Stage):
-    """Stage that limits items to fit in viewport.
+    """Stage that limits items based on layout calculation.
 
-    Filters the input list of items to only include as many as can fit
-    in the visible viewport. This prevents FontStage from rendering
-    thousands of items when only a few are visible, reducing processing time.
-
-    Estimate: each rendered item typically takes 5-8 terminal lines.
-    For a 24-line viewport, we limit to ~4 items (conservative estimate).
+    Computes cumulative y-offsets for all items using cheap height estimation,
+    then returns only items that overlap the camera's viewport window.
+    This prevents FontStage from rendering thousands of items when only a few
+    are visible, while still allowing camera scrolling through all content.
     """
 
     def __init__(self, name: str = "viewport-filter"):
         self.name = name
         self.category = "filter"
         self.optional = False
+        self._cached_count = 0
+        self._layout: list[tuple[int, int]] = []
 
     @property
     def stage_type(self) -> str:
@@ -386,21 +429,60 @@ class ViewportFilterStage(Stage):
         return {DataType.SOURCE_ITEMS}
 
     def process(self, data: Any, ctx: PipelineContext) -> Any:
-        """Filter items to viewport-fitting count."""
+        """Filter items based on layout and camera position."""
         if data is None or not isinstance(data, list):
             return data
 
-        # Estimate: each rendered headline takes 5-8 lines
-        # Use a conservative factor to ensure we don't run out of space
-        lines_per_item = 6
         viewport_height = ctx.params.viewport_height if ctx.params else 24
+        viewport_width = ctx.params.viewport_width if ctx.params else 80
+        camera_y = ctx.get("camera_y", 0)
 
-        # Calculate how many items we need to fill the viewport
-        # Add 1 extra to account for padding/spacing
-        max_items = max(1, viewport_height // lines_per_item + 1)
+        # Recompute layout only when item count changes
+        if len(data) != self._cached_count:
+            self._layout = []
+            y = 0
+            from engine.render.blocks import estimate_block_height
 
-        # Return only the items that fit in the viewport
-        return data[:max_items]
+            for item in data:
+                if hasattr(item, "content"):
+                    title = item.content
+                elif isinstance(item, tuple):
+                    title = str(item[0]) if item else ""
+                else:
+                    title = str(item)
+                h = estimate_block_height(title, viewport_width)
+                self._layout.append((y, h))
+                y += h
+            self._cached_count = len(data)
+
+        # Find items visible in [camera_y - buffer, camera_y + viewport_height + buffer]
+        buffer_zone = viewport_height
+        vis_start = max(0, camera_y - buffer_zone)
+        vis_end = camera_y + viewport_height + buffer_zone
+
+        visible_items = []
+        render_offset_y = 0
+        first_visible_found = False
+        for i, (start_y, height) in enumerate(self._layout):
+            item_end = start_y + height
+            if item_end > vis_start and start_y < vis_end:
+                if not first_visible_found:
+                    render_offset_y = start_y
+                    first_visible_found = True
+                visible_items.append(data[i])
+
+        # Compute total layout height for the canvas
+        total_layout_height = 0
+        if self._layout:
+            last_start, last_height = self._layout[-1]
+            total_layout_height = last_start + last_height
+
+        # Store metadata for CameraStage
+        ctx.set("render_offset_y", render_offset_y)
+        ctx.set("total_layout_height", total_layout_height)
+
+        # Always return at least one item to avoid empty buffer errors
+        return visible_items if visible_items else data[:1]
 
 
 class FontStage(Stage):
@@ -434,6 +516,7 @@ class FontStage(Stage):
         self._font_size = font_size
         self._font_ref = font_ref
         self._font = None
+        self._render_cache: dict[tuple[str, str, int], list[str]] = {}
 
     @property
     def stage_type(self) -> str:
@@ -504,8 +587,15 @@ class FontStage(Stage):
                     src = "unknown"
                     ts = "0"
 
+                # Check cache first
+                cache_key = (title, src, ts, w)
+                if cache_key in self._render_cache:
+                    result.extend(self._render_cache[cache_key])
+                    continue
+
                 try:
                     block_lines, color_code, meta_idx = make_block(title, src, ts, w)
+                    self._render_cache[cache_key] = block_lines
                     result.extend(block_lines)
                 except Exception:
                     result.append(title)
diff --git a/engine/pipeline/presets.py b/engine/pipeline/presets.py
index 970146f..26e94a2 100644
--- a/engine/pipeline/presets.py
+++ b/engine/pipeline/presets.py
@@ -45,7 +45,7 @@ class PipelinePreset:
     description: str = ""
     source: str = "headlines"
     display: str = "terminal"
-    camera: str = "vertical"
+    camera: str = "scroll"
     effects: list[str] = field(default_factory=list)
     border: bool = False
 
@@ -79,7 +79,7 @@ DEMO_PRESET = PipelinePreset(
     description="Demo mode with effect cycling and camera modes",
     source="headlines",
     display="pygame",
-    camera="vertical",
+    camera="scroll",
     effects=["noise", "fade", "glitch", "firehose", "hud"],
 )
 
@@ -88,7 +88,7 @@ POETRY_PRESET = PipelinePreset(
     description="Poetry feed with subtle effects",
     source="poetry",
     display="pygame",
-    camera="vertical",
+    camera="scroll",
     effects=["fade", "hud"],
 )
 
@@ -106,7 +106,7 @@ WEBSOCKET_PRESET = PipelinePreset(
     description="WebSocket display mode",
     source="headlines",
     display="websocket",
-    camera="vertical",
+    camera="scroll",
     effects=["noise", "fade", "glitch", "hud"],
 )
 
@@ -115,7 +115,7 @@ SIXEL_PRESET = PipelinePreset(
     description="Sixel graphics display mode",
     source="headlines",
     display="sixel",
-    camera="vertical",
+    camera="scroll",
     effects=["noise", "fade", "glitch", "hud"],
 )
 
@@ -124,7 +124,7 @@ FIREHOSE_PRESET = PipelinePreset(
     description="High-speed firehose mode",
     source="headlines",
     display="pygame",
-    camera="vertical",
+    camera="scroll",
     effects=["noise", "fade", "glitch", "firehose", "hud"],
 )
 
diff --git a/engine/render/blocks.py b/engine/render/blocks.py
index 02cefc4..3492317 100644
--- a/engine/render/blocks.py
+++ b/engine/render/blocks.py
@@ -13,6 +13,50 @@ from engine import config
 from engine.sources import NO_UPPER, SCRIPT_FONTS, SOURCE_LANGS
 from engine.translate import detect_location_language, translate_headline
 
+
+def estimate_block_height(title: str, width: int, fnt=None) -> int:
+    """Estimate rendered block height without full PIL rendering.
+
+    Uses font bbox measurement to count wrapped lines, then computes:
+    height = num_lines * RENDER_H + (num_lines - 1) + 2
+
+    Args:
+        title: Headline text to measure
+        width: Terminal width in characters
+        fnt: Optional PIL font (uses default if None)
+
+    Returns:
+        Estimated height in terminal rows
+    """
+    if fnt is None:
+        fnt = font()
+    text = re.sub(r"\s+", " ", title.upper())
+    words = text.split()
+    lines = 0
+    cur = ""
+    for word in words:
+        test = f"{cur} {word}".strip() if cur else word
+        bbox = fnt.getbbox(test)
+        if bbox:
+            img_h = bbox[3] - bbox[1] + 8
+            pix_h = config.RENDER_H * 2
+            scale = pix_h / max(img_h, 1)
+            term_w = int((bbox[2] - bbox[0] + 8) * scale)
+        else:
+            term_w = 0
+        max_term_w = width - 4 - 4
+        if term_w > max_term_w and cur:
+            lines += 1
+            cur = word
+        else:
+            cur = test
+    if cur:
+        lines += 1
+    if lines == 0:
+        lines = 1
+    return lines * config.RENDER_H + max(0, lines - 1) + 2
+
+
 # ─── FONT LOADING ─────────────────────────────────────────
 _FONT_OBJ = None
 _FONT_OBJ_KEY = None
diff --git a/presets.toml b/presets.toml
index 4f3a3ec..4830ceb 100644
--- a/presets.toml
+++ b/presets.toml
@@ -12,7 +12,7 @@
 description = "Demo mode with effect cycling and camera modes"
 source = "headlines"
 display = "pygame"
-camera = "vertical"
+camera = "scroll"
 effects = ["noise", "fade", "glitch", "firehose"]
 viewport_width = 80
 viewport_height = 24
@@ -23,7 +23,7 @@ firehose_enabled = true
 description = "Poetry feed with subtle effects"
 source = "poetry"
 display = "pygame"
-camera = "vertical"
+camera = "scroll"
 effects = ["fade"]
 viewport_width = 80
 viewport_height = 24
@@ -33,7 +33,7 @@ camera_speed = 0.5
 description = "Test border rendering with empty buffer"
 source = "empty"
 display = "terminal"
-camera = "vertical"
+camera = "scroll"
 effects = ["border"]
 viewport_width = 80
 viewport_height = 24
@@ -45,7 +45,7 @@ border = false
 description = "WebSocket display mode"
 source = "headlines"
 display = "websocket"
-camera = "vertical"
+camera = "scroll"
 effects = ["noise", "fade", "glitch"]
 viewport_width = 80
 viewport_height = 24
@@ -56,7 +56,7 @@ firehose_enabled = false
 description = "Sixel graphics display mode"
 source = "headlines"
 display = "sixel"
-camera = "vertical"
+camera = "scroll"
 effects = ["noise", "fade", "glitch"]
 viewport_width = 80
 viewport_height = 24
@@ -67,7 +67,7 @@ firehose_enabled = false
 description = "High-speed firehose mode"
 source = "headlines"
 display = "pygame"
-camera = "vertical"
+camera = "scroll"
 effects = ["noise", "fade", "glitch", "firehose"]
 viewport_width = 80
 viewport_height = 24
@@ -78,7 +78,7 @@ firehose_enabled = true
 description = "Live pipeline introspection with DAG and performance metrics"
 source = "pipeline-inspect"
 display = "pygame"
-camera = "vertical"
+camera = "scroll"
 effects = ["crop"]
 viewport_width = 100
 viewport_height = 35
diff --git a/tests/test_camera.py b/tests/test_camera.py
index b55a968..60c5bb4 100644
--- a/tests/test_camera.py
+++ b/tests/test_camera.py
@@ -1,19 +1,18 @@
-
 from engine.camera import Camera, CameraMode
 
 
 def test_camera_vertical_default():
     """Test default vertical camera."""
     cam = Camera()
-    assert cam.mode == CameraMode.VERTICAL
+    assert cam.mode == CameraMode.FEED
     assert cam.x == 0
     assert cam.y == 0
 
 
 def test_camera_vertical_factory():
     """Test vertical factory method."""
-    cam = Camera.vertical(speed=2.0)
-    assert cam.mode == CameraMode.VERTICAL
+    cam = Camera.feed(speed=2.0)
+    assert cam.mode == CameraMode.FEED
     assert cam.speed == 2.0
 
 
diff --git a/tests/test_performance_regression.py b/tests/test_performance_regression.py
index 6ffe845..c89c959 100644
--- a/tests/test_performance_regression.py
+++ b/tests/test_performance_regression.py
@@ -75,8 +75,8 @@ class TestViewportFilterPerformance:
 
         With 1438 items and 24-line viewport:
         - Without filter: FontStage renders all 1438 items
-        - With filter: FontStage renders ~5 items
-        - Expected improvement: 1438 / 5 ≈ 288x
+        - With filter: FontStage renders ~3 items (layout-based)
+        - Expected improvement: 1438 / 3 ≈ 479x
         """
         test_items = [
             SourceItem(f"Headline {i}", "source", str(i)) for i in range(1438)
@@ -89,10 +89,10 @@ class TestViewportFilterPerformance:
         filtered = stage.process(test_items, ctx)
         improvement_factor = len(test_items) / len(filtered)
 
-        # Verify we get expected 288x improvement
-        assert 250 < improvement_factor < 300
-        # Verify filtered count is reasonable
-        assert 4 <= len(filtered) <= 6
+        # Verify we get expected ~479x improvement (better than old ~288x)
+        assert 400 < improvement_factor < 600
+        # Verify filtered count is reasonable (layout-based is more precise)
+        assert 2 <= len(filtered) <= 5
 
 
 class TestPipelinePerformanceWithRealData:
diff --git a/tests/test_pipeline.py b/tests/test_pipeline.py
index 6717462..ef6e16f 100644
--- a/tests/test_pipeline.py
+++ b/tests/test_pipeline.py
@@ -627,12 +627,12 @@ class TestStageAdapters:
         from engine.pipeline.adapters import CameraStage
         from engine.pipeline.core import PipelineContext
 
-        camera = Camera(mode=CameraMode.VERTICAL)
+        camera = Camera(mode=CameraMode.FEED)
         stage = CameraStage(camera, name="vertical")
         PipelineContext()
 
         assert "camera" in stage.capabilities
-        assert "source" in stage.dependencies  # Prefix matches any source
+        assert "render.output" in stage.dependencies  # Depends on rendered content
 
 
 class TestDataSourceStage:
diff --git a/tests/test_viewport_filter_performance.py b/tests/test_viewport_filter_performance.py
index 94f7ba7..9957aa8 100644
--- a/tests/test_viewport_filter_performance.py
+++ b/tests/test_viewport_filter_performance.py
@@ -5,7 +5,6 @@ of items processed by FontStage, preventing the 10+ second hangs observed with
 large headline sources.
 """
 
-
 from engine.data_sources.sources import SourceItem
 from engine.pipeline.adapters import ViewportFilterStage
 from engine.pipeline.core import PipelineContext
@@ -97,7 +96,8 @@ class TestViewportFilterStage:
         # With 1438 items and 24-line viewport:
         # - Without filter: FontStage renders all 1438 items
         # - With filter: FontStage renders only ~5 items
-        # - Improvement: 1438 / 5 = 287.6x fewer items to render
+        # - Improvement: 1438 / 3 = ~479x fewer items to render
+        #   (layout-based filtering is more precise than old estimate)
 
         test_items = [
             SourceItem(f"Headline {i}", "source", str(i)) for i in range(1438)
@@ -110,10 +110,10 @@ class TestViewportFilterStage:
         filtered = stage.process(test_items, ctx)
         improvement_factor = len(test_items) / len(filtered)
 
-        # Verify we get at least 200x improvement
-        assert improvement_factor > 200
-        # Verify we get the expected ~288x improvement
-        assert 250 < improvement_factor < 300
+        # Verify we get at least 400x improvement (better than old ~288x)
+        assert improvement_factor > 400
+        # Verify we get the expected ~479x improvement
+        assert 400 < improvement_factor < 600
 
 
 class TestViewportFilterIntegration: