taskgraph_ts/tasks/implementation/cost-benefit/risk-analysis.md

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

id	name	status	depends_on	scope	risk	impact	level
cost-benefit/risk-analysis	Implement riskPath, riskDistribution, and shouldDecomposeTask functions	completed	cost-benefit/ev-calculation analysis/critical-path schema/numeric-methods-and-defaults	moderate	low	component	implementation

Description

Implement the three risk analysis functions: riskPath, riskDistribution, and shouldDecomposeTask. These are standalone composable functions that serve different analysis use cases.

Acceptance Criteria

• riskPath(graph: TaskGraph): RiskPathResult:
  • Calls weightedCriticalPath with weight function riskWeight * impactWeight
  • Returns { path: string[], totalRisk: number }
  • totalRisk is the sum of weight values along the path
• riskDistribution(graph: TaskGraph): RiskDistributionResult:
  • Groups all tasks by their risk attribute
  • Returns { trivial: string[], low: string[], medium: string[], high: string[], critical: string[], unspecified: string[] }
  • Tasks with risk: undefined (not assessed) go in unspecified
  • No duplicate task IDs in any bucket
• shouldDecomposeTask(attrs: TaskGraphNodeAttributes): DecomposeResult:
  • Pure function — takes node attributes (not a graph)
  • Internally calls resolveDefaults for risk and scope (nullable fields)
  • Flags decomposition when: risk >= "high" OR scope >= "broad"
  • Returns { shouldDecompose: boolean, reasons: string[] }
  • Unassessed tasks (null/undefined risk or scope) are never flagged — default values are below threshold
  • Provides specific reasons: e.g., "risk: high — failure probability 0.35", "scope: broad — cost estimate 4.0"
• Unit tests for all three functions with known inputs/outputs

References

• docs/architecture/api-surface.md — risk analysis functions
• docs/architecture/cost-benefit.md — riskPath, riskDistribution, shouldDecomposeTask, decomposition threshold

Notes

All three functions implemented following architecture docs. riskPath delegates to weightedCriticalPath with riskWeight*impactWeight weight function and sums weights for totalRisk. riskDistribution iterates all nodes and groups by risk attribute (undefined/null → unspecified). shouldDecomposeTask is a pure function using resolveDefaults to fill nullable fields before checking thresholds (risk >= high, scope >= broad), with specific reason strings including numeric values.

Summary

Implemented riskPath, riskDistribution, and shouldDecomposeTask functions.

• Modified: src/analysis/risk.ts (riskPath + riskDistribution)
• Modified: src/analysis/decompose.ts (shouldDecomposeTask)
• Created: test/risk-analysis.test.ts
• Tests: 29, all passing (590 total suite)