forked from genewildish/Mainline
David Gwilliam
7eaa441574
- Add for quick startup using first N feeds - Add background thread for full fetch and caching - Update to use fast fetch - Update docs and skills
98 lines
3.1 KiB
Markdown
98 lines
3.1 KiB
Markdown
---
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name: mainline-architecture
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description: Pipeline stages, capability resolution, and core architecture patterns
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compatibility: opencode
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metadata:
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audience: developers
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source_type: codebase
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---
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## What This Skill Covers
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This skill covers Mainline's pipeline architecture - the Stage-based system for dependency resolution, data flow, and component composition.
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## Key Concepts
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### Stage Class (engine/pipeline/core.py)
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The `Stage` ABC is the foundation. All pipeline components inherit from it:
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```python
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class Stage(ABC):
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name: str
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category: str # "source", "effect", "overlay", "display", "camera"
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optional: bool = False
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@property
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def capabilities(self) -> set[str]:
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"""What this stage provides (e.g., 'source.headlines')"""
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return set()
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@property
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def dependencies(self) -> set[str]:
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"""What this stage needs (e.g., {'source'})"""
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return set()
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```
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### Capability-Based Dependencies
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The Pipeline resolves dependencies using **prefix matching**:
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- `"source"` matches `"source.headlines"`, `"source.poetry"`, etc.
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- `"camera.state"` matches the camera state capability
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- This allows flexible composition without hardcoding specific stage names
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### Minimum Capabilities
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The pipeline requires these minimum capabilities to function:
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- `"source"` - Data source capability
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- `"render.output"` - Rendered content capability
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- `"display.output"` - Display output capability
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- `"camera.state"` - Camera state for viewport filtering
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These are automatically injected if missing (auto-injection).
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### DataType Enum
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PureData-style data types for inlet/outlet validation:
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- `SOURCE_ITEMS`: List[SourceItem] - raw items from sources
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- `ITEM_TUPLES`: List[tuple] - (title, source, timestamp) tuples
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- `TEXT_BUFFER`: List[str] - rendered ANSI buffer
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- `RAW_TEXT`: str - raw text strings
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- `PIL_IMAGE`: PIL Image object
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### Pipeline Execution
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The Pipeline (engine/pipeline/controller.py):
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1. Collects all stages from StageRegistry
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2. Resolves dependencies using prefix matching
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3. Executes stages in dependency order
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4. Handles errors for non-optional stages
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### Canvas & Camera
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- **Canvas** (`engine/canvas.py`): 2D rendering surface with dirty region tracking
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- **Camera** (`engine/camera.py`): Viewport controller for scrolling content
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Canvas tracks dirty regions automatically when content is written via `put_region`, `put_text`, `fill`, enabling partial buffer updates.
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## Adding New Stages
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1. Create a class inheriting from `Stage`
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2. Define `capabilities` and `dependencies` properties
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3. Implement required abstract methods
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4. Register in StageRegistry or use as adapter
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## Common Patterns
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- Use adapters (engine/pipeline/adapters.py) to wrap existing components as stages
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- Set `optional=True` for stages that can fail gracefully
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- Use `stage_type` and `render_order` for execution ordering
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- Clock stages update state independently of data flow
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## Sources
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- engine/pipeline/core.py - Stage base class
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- engine/pipeline/controller.py - Pipeline implementation
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- engine/pipeline/adapters/ - Stage adapters
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- docs/PIPELINE.md - Pipeline documentation
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