fix: resolve terminal display wobble and effect dimension stability

- Fix TerminalDisplay: add screen clear each frame (cursor home + erase down)
- Fix CameraStage: use set_canvas_size instead of read-only viewport properties
- Fix Glitch effect: preserve visible line lengths, remove cursor positioning
- Fix Fade effect: return original line when fade=0 instead of empty string
- Fix Noise effect: use input line length instead of terminal_width
- Remove HUD effect from all presets (redundant with border FPS display)
- Add regression tests for effect dimension stability
- Add docs/ARCHITECTURE.md with Mermaid diagrams
- Add mise tasks: diagram-ascii, diagram-validate, diagram-check
- Move markdown docs to docs/ (ARCHITECTURE, Refactor, hardware specs)
- Remove redundant requirements files (use pyproject.toml)
- Add *.dot and *.png to .gitignore

Closes #25

engine/pipeline/adapters.py

@@ -347,9 +347,12 @@ class CameraStage(Stage):
             )
 
             # 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 size to achieve desired viewport (viewport = canvas / zoom)
+            if hasattr(self._camera, "set_canvas_size"):
+                self._camera.set_canvas_size(
+                    width=int(viewport_width * self._camera.zoom),
+                    height=int(viewport_height * self._camera.zoom),
+                )
 
             # 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)

engine/pipeline/params.py

@@ -32,7 +32,7 @@ class PipelineParams:
 
     # Effect config
     effect_order: list[str] = field(
-        default_factory=lambda: ["noise", "fade", "glitch", "firehose", "hud"]
+        default_factory=lambda: ["noise", "fade", "glitch", "firehose"]
     )
     effect_enabled: dict[str, bool] = field(default_factory=dict)
     effect_intensity: dict[str, float] = field(default_factory=dict)
@@ -127,19 +127,19 @@ DEFAULT_HEADLINE_PARAMS = PipelineParams(
     source="headlines",
     display="terminal",
     camera_mode="vertical",
-    effect_order=["noise", "fade", "glitch", "firehose", "hud"],
+    effect_order=["noise", "fade", "glitch", "firehose"],
 )
 
 DEFAULT_PYGAME_PARAMS = PipelineParams(
     source="headlines",
     display="pygame",
     camera_mode="vertical",
-    effect_order=["noise", "fade", "glitch", "firehose", "hud"],
+    effect_order=["noise", "fade", "glitch", "firehose"],
 )
 
 DEFAULT_PIPELINE_PARAMS = PipelineParams(
     source="pipeline",
     display="pygame",
     camera_mode="trace",
-    effect_order=["hud"],  # Just HUD for pipeline viz
+    effect_order=[],  # No effects for pipeline viz
 )

engine/pipeline/preset_loader.py

@@ -19,7 +19,7 @@ DEFAULT_PRESET: dict[str, Any] = {
     "source": "headlines",
     "display": "terminal",
     "camera": "vertical",
-    "effects": ["hud"],
+    "effects": [],
     "viewport": {"width": 80, "height": 24},
     "camera_speed": 1.0,
     "firehose_enabled": False,
@@ -263,7 +263,7 @@ def generate_preset_toml(
     """
 
     if effects is None:
-        effects = ["fade", "hud"]
+        effects = ["fade"]
 
     output = []
     output.append(f"[presets.{name}]")

engine/pipeline/presets.py

@@ -80,7 +80,7 @@ DEMO_PRESET = PipelinePreset(
     source="headlines",
     display="pygame",
     camera="scroll",
-    effects=["noise", "fade", "glitch", "firehose", "hud"],
+    effects=["noise", "fade", "glitch", "firehose"],
 )
 
 POETRY_PRESET = PipelinePreset(
@@ -89,7 +89,7 @@ POETRY_PRESET = PipelinePreset(
     source="poetry",
     display="pygame",
     camera="scroll",
-    effects=["fade", "hud"],
+    effects=["fade"],
 )
 
 PIPELINE_VIZ_PRESET = PipelinePreset(
@@ -98,7 +98,7 @@ PIPELINE_VIZ_PRESET = PipelinePreset(
     source="pipeline",
     display="terminal",
     camera="trace",
-    effects=["hud"],
+    effects=[],
 )
 
 WEBSOCKET_PRESET = PipelinePreset(
@@ -107,7 +107,7 @@ WEBSOCKET_PRESET = PipelinePreset(
     source="headlines",
     display="websocket",
     camera="scroll",
-    effects=["noise", "fade", "glitch", "hud"],
+    effects=["noise", "fade", "glitch"],
 )
 
 SIXEL_PRESET = PipelinePreset(
@@ -116,7 +116,7 @@ SIXEL_PRESET = PipelinePreset(
     source="headlines",
     display="sixel",
     camera="scroll",
-    effects=["noise", "fade", "glitch", "hud"],
+    effects=["noise", "fade", "glitch"],
 )
 
 FIREHOSE_PRESET = PipelinePreset(
@@ -125,7 +125,7 @@ FIREHOSE_PRESET = PipelinePreset(
     source="headlines",
     display="pygame",
     camera="scroll",
-    effects=["noise", "fade", "glitch", "firehose", "hud"],
+    effects=["noise", "fade", "glitch", "firehose"],
 )