glm-5.1
6016e81162
Implement the core EV calculation: EV = p*C_success + (1-p)*C_fail where C_success = scopeCost*impactWeight, C_fail = scopeCost*impactWeight + fallbackCost + timeLost*expectedRetries. - expectedRetries = (1-p)/p when p>0, else 0 (geometric series) - Caps expectedRetries at config.retries when retries > 0 - Multiplies final EV by config.valueRate when non-zero - 30 unit tests covering formula, edge cases, and Python research model values
52 lines
2.2 KiB
Markdown
52 lines
2.2 KiB
Markdown
---
|
||
id: cost-benefit/ev-calculation
|
||
name: Implement calculateTaskEv pure function
|
||
status: completed
|
||
depends_on:
|
||
- schema/numeric-methods-and-defaults
|
||
- schema/result-types
|
||
scope: narrow
|
||
risk: low
|
||
impact: component
|
||
level: implementation
|
||
---
|
||
|
||
## Description
|
||
|
||
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.
|
||
|
||
Per [cost-benefit.md](../../../docs/architecture/cost-benefit.md):
|
||
```
|
||
EV = P_success × C_success + (1 - P_success) × C_fail
|
||
```
|
||
Where `C_fail = scopeCost + fallbackCost + timeLost × expectedRetries`.
|
||
|
||
## Acceptance Criteria
|
||
|
||
- [ ] `calculateTaskEv(p: number, scopeCost: number, impactWeight: number, config?: EvConfig): EvResult`
|
||
- [ ] Returns `EvResult`: `{ ev, pSuccess, expectedRetries }`
|
||
- [ ] `expectedRetries` = `(1 - p) / p` when `p > 0`, else 0 (geometric series)
|
||
- [ ] `C_fail = scopeCost * impactWeight + fallbackCost + timeLost * expectedRetries` (impactWeight scales the cost)
|
||
- [ ] `EV = p * scopeCost * impactWeight + (1-p) * C_fail`
|
||
- [ ] When `config.retries` is provided and > 0, caps `expectedRetries` at `retries`
|
||
- [ ] When `config.valueRate` is non-zero, multiplies the final EV
|
||
- [ ] Edge cases: `p = 0` (guaranteed failure), `p = 1` (guaranteed success), default config (all zeros)
|
||
- [ ] Unit tests: known calculations from the Python research model, boundary values, config variations
|
||
|
||
## References
|
||
|
||
- docs/architecture/cost-benefit.md — EV formula, EvConfig parameters, EvResult
|
||
- docs/architecture/api-surface.md — calculateTaskEv signature
|
||
- docs/architecture/schemas.md — EvConfig, EvResult schemas
|
||
|
||
## Notes
|
||
|
||
All acceptance criteria verified via 30 unit tests covering formula correctness, edge cases, config variations, and known Python research model values.
|
||
|
||
## Summary
|
||
|
||
Implemented `calculateTaskEv` pure function in `src/analysis/cost-benefit.ts`.
|
||
- Modified: `src/analysis/cost-benefit.ts` — full implementation of calculateTaskEv
|
||
- Modified: `test/cost-benefit.test.ts` — 30 comprehensive unit tests
|
||
- Tests: 30, all passing (286 total across suite)
|
||
- Lint: clean (tsc --noEmit passes) |