refactor: decompose BuildContractCoverageFunc + dedup utilities

[yvonnedevlinrh]

Summary

Phase 2a of CRAPload fragility reduction (#166). Decomposes BuildContractCoverageFunc — the single worst CRAPload offender (CRAP 506, complexity 22) — into 3 independently testable helpers. Eliminates 2 duplicated utility functions across goprovider and aireport, fixing a latent pkg.Errors validation bug in the process.

Changes

Decomposition

Extracted 3 helpers from BuildContractCoverageFunc (complexity 22 → 7):

Helper	Purpose	Testability
computeCoverageReason	Pure function: report → ContractCoverageInfo with reason/confidence	Direct struct-literal tests
buildEffectsSet	Side effect analysis per package → map[string]bool	DI via loadAndAnalyzeFn parameter
buildCoverageMap	Quality pipeline per package → coverage map + degraded list	DI via contractCoverageDeps

Deduplication

Duplicate	Consolidated to	Bug fixed
loadTestPackageForQuality (aireport)	goprovider.LoadTestPackage (exported)	Missing pkg.Errors validation in aireport copy
loadGazeConfigBestEffort (goprovider + aireport)	config.LoadFromDir (new)	N/A — identical copies

Files changed (6 source + 5 spec + 3 learnings)

internal/config/config.go              (+15)  — Added LoadFromDir
internal/config/config_test.go         (+68)  — 3 new tests
internal/provider/goprovider/contract.go           (+207/-174) — 3 helpers, export, dedup
internal/provider/goprovider/contract_internal_test.go (+293) — 13 new tests
internal/aireport/runner_steps.go      (-47)  — Removed duplicates, wired imports
internal/aireport/runner_steps_test.go (-40)  — Removed 4 duplicate tests

Metrics

Metric	Before	After
BuildContractCoverageFunc complexity	22	7
BuildContractCoverageFunc CRAP	506	< 30
Net new tests	—	+12 (16 added, 4 removed)
Duplicate functions eliminated	—	2

Verification

go build ./...                              # PASS
go test -race -count=1 -short ./...         # 16/16 packages PASS
golangci-lint run                           # 0 issues
gocyclo contract.go | grep BuildContract    # 7 (target ≤ 8)

Spec artifacts

Full OpenSpec change at openspec/changes/crapload-decompose-pr2a/:

• proposal.md — motivation + constitution alignment
• design.md — 5 design decisions with alternatives rejected
• specs/decompose-dedup.md — 5 ADDED, 3 MODIFIED, 2 REMOVED requirements with 17 Given/When/Then scenarios
• tasks.md — 9 tasks in 4 groups, all checked off

Review council

• Spec review: 5/5 APPROVE (Adversary, Architect, Guard, Testing, SRE)
• Code review: 4/4 APPROVE (Architect, Testing, Guard, Adversary)

[jflowers]

Clean refactoring PR that achieves its stated goal: decomposing the worst CRAPload offender (BuildContractCoverageFunc, CRAP 506 → <30) into three independently testable helpers, while consolidating two duplicated utility functions. The pkg.Errors validation bug fix in the aireport copy of loadTestPackage is a legitimate side-effect improvement.

• All 5 CI checks pass (MegaLinter, unit/integration on Go 1.24+1.25, E2E on Go 1.24+1.25)
• Spec artifacts comprehensive (proposal, design, specs with 17 Given/When/Then scenarios, 9 tasks all checked)
• Constitution compliance verified (Accuracy, Testability improved; Minimal Assumptions, Actionable Output N/A)
• No security concerns — no new inputs, no path construction changes, no dependency additions
• Net +12 tests (16 added, 4 removed), all new helper tests run without testing.Short() guard

This review was generated by /review-pr (AI-assisted).