glm-5.1
bde1cc4e70
The 751-line architecture.md violated the SDD process modular documentation target (~500 lines). It also had duplicate TaskGraph class definitions (one monolith, one decomposed) that directly contradicted each other, and embedded consumer-specific tool dispatch mappings that belong in downstream projects. Changes: - Split into 8 focused documents + 7 ADR records + redirect page - Removed the monolithic TaskGraph class (kept only decomposed version) - Moved CLI→plugin dispatch mapping out (belongs in plugin architecture) - Extracted implementation code (frontmatter splitter, findCycles, DAG propagation) into WHAT/WHY descriptions per architect role spec - Added proper ADR format for all resolved design decisions - Fixed review issues: C_fail mapping, DuplicateNodeError/DuplicateEdgeError types, ValidationError/GraphValidationError definitions, mutation error handling contract, enum naming convention, validation timing clarification
28 lines
1.6 KiB
Markdown
28 lines
1.6 KiB
Markdown
# ADR-004: DAG-propagation as default workflow cost model
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**Status**: Accepted
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## Context
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The Rust CLI computes expected value per-task independently — no upstream quality degradation. The Python research model implements DAG-propagation where each parent's failure degrades the child's effective probability. The independent model is dangerously optimistic for non-trivial workflows: poor planning (p=0.65) shows a 213% cost increase vs good planning (p=0.92) with the propagation model, but barely any difference with the independent model.
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## Decision
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**DAG-propagation is the default mode.** The independent model is a degenerate case accessible via `propagationMode: 'independent'` or `defaultQualityDegradation: 0`.
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## Consequences
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### Positive
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- More accurate cost estimates — captures the structural reality that upstream failures multiply downstream damage
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- Per-task output includes both `pIntrinsic` and `pEffective` so consumers can see the degradation effect
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- The independent model is still available as an opt-in degenerate case
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- Per-edge `qualityDegradation` allows fine-grained modeling of how much each dependency bleeds failure
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### Negative
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- More complex implementation than simple sum
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- Results differ from the Rust CLI — consumers migrating from CLI to library will see different numbers
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- Requires `qualityDegradation` per edge (default 0.9) which adds a concept the Rust CLI didn't have
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### Mitigation
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The `propagationMode` option allows consumers to start with the independent model and migrate to DAG-propagation when ready. The per-task `pIntrinsic`/`pEffective` split makes the propagation effect transparent. |