glm-5.1
131e3e929b
Break the @alkdev/taskgraph architecture specs into dependency-ordered implementation tasks across 8 component directories: setup, schema, error, graph, analysis, cost-benefit, frontmatter, api, and review. Each task has clear acceptance criteria referencing specific architecture docs. Three review tasks serve as quality gates at critical junction points (schemas-and-errors, graph-complete, complete-library). The dependency graph is validated acyclic with 9 topological levels enabling significant parallelism across independent work streams.
48 lines
1.8 KiB
Markdown
48 lines
1.8 KiB
Markdown
---
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id: cost-benefit/ev-calculation
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name: Implement calculateTaskEv pure function
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status: pending
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depends_on:
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- schema/numeric-methods-and-defaults
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- schema/result-types
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scope: narrow
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risk: low
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impact: component
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level: implementation
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---
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## Description
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Implement `calculateTaskEv(p, scopeCost, impactWeight, config?): EvResult` in `src/analysis/cost-benefit.ts`. This is the pure math function — takes numeric inputs, returns EV result. No graph dependency.
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Per [cost-benefit.md](../../../docs/architecture/cost-benefit.md):
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```
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EV = P_success × C_success + (1 - P_success) × C_fail
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```
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Where `C_fail = scopeCost + fallbackCost + timeLost × expectedRetries`.
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## Acceptance Criteria
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- [ ] `calculateTaskEv(p: number, scopeCost: number, impactWeight: number, config?: EvConfig): EvResult`
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- [ ] Returns `EvResult`: `{ ev, pSuccess, expectedRetries }`
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- [ ] `expectedRetries` = `(1 - p) / p` when `p > 0`, else 0 (geometric series)
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- [ ] `C_fail = scopeCost * impactWeight + fallbackCost + timeLost * expectedRetries` (impactWeight scales the cost)
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- [ ] `EV = p * scopeCost * impactWeight + (1-p) * C_fail`
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- [ ] When `config.retries` is provided and > 0, caps `expectedRetries` at `retries`
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- [ ] When `config.valueRate` is non-zero, multiplies the final EV
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- [ ] Edge cases: `p = 0` (guaranteed failure), `p = 1` (guaranteed success), default config (all zeros)
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- [ ] Unit tests: known calculations from the Python research model, boundary values, config variations
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## References
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- docs/architecture/cost-benefit.md — EV formula, EvConfig parameters, EvResult
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- docs/architecture/api-surface.md — calculateTaskEv signature
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- docs/architecture/schemas.md — EvConfig, EvResult schemas
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## Notes
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> To be filled by implementation agent
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## Summary
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> To be filled on completion |