taskgraph_ts/tasks/implementation/cost-benefit/workflow-cost.md

id, name, status, depends_on, scope, risk, impact, level

id	name	status	depends_on	scope	risk	impact	level
cost-benefit/workflow-cost	Implement workflowCost orchestration function	completed	cost-benefit/dag-propagation graph/queries	moderate	medium	component	implementation

Description

Implement workflowCost(graph: TaskGraph, options?: WorkflowCostOptions): WorkflowCostResult in src/analysis/cost-benefit.ts. This orchestrates the per-task EV calculations, handles DAG propagation, and enriches results with taskId and name from the graph.

Acceptance Criteria

• workflowCost accepts WorkflowCostOptions with optional: includeCompleted, limit, propagationMode, defaultQualityRetention
• Default propagation mode: "dag-propagate" per ADR-004
• Default defaultQualityRetention: 0.9
• Each task in result includes: taskId, name, ev, pIntrinsic, pEffective, probability (= pEffective), scopeCost, impactWeight
• totalEv: sum of all task EVs (excluding completed tasks from output when includeCompleted: false)
• averageEv: totalEv / tasks.length
• propagationMode: reflected in result
• When includeCompleted: false: completed tasks excluded from tasks array but remain in propagation chain with p=1.0
• When includeCompleted: false: only "completed" status triggers exclusion; "failed" and "blocked" are always included
• When limit is set: returns at most limit tasks (sorted by EV descending? or topological order? spec says "limits the number of tasks in the result" — use topological order with limit)
• Throws CircularDependencyError if graph is cyclic
• Unit tests: full workflow cost calculation, independent vs dag-propagate comparison, excludeCompleted scenarios, limit behavior

References

• docs/architecture/cost-benefit.md — workflow cost, skip-completed semantics
• docs/architecture/api-surface.md — workflowCost signature, WorkflowCostOptions
• docs/architecture/decisions/004-workflow-cost-dag-propagation.md — ADR-004

Notes

Fixed includeCompleted default from true to false to match the api-surface.md specification. The implementation was mostly complete from prior dependency tasks (dag-propagation), but the default was incorrect. Updated the test suite to verify the correct default behavior and explicitly test the includeCompleted: true opt-in case.

Summary

Implemented workflowCost orchestration function and fixed includeCompleted default to false per api-surface.md.

• Modified: src/analysis/cost-benefit.ts — fixed includeCompleted default from true to false
• Modified: test/cost-benefit.test.ts — updated default-behavior test and added explicit includeCompleted: true test
• Tests: 64 cost-benefit tests, all passing; 562 total tests across 12 test files, all passing