Test Coverage Plan

Last updated: 2026-06-28

Status measured on 2026-05-13: lines 82.58%, statements 82.58%, functions 84.23%, branches 75.22%. Phases 1-5 are complete. Current focus is Phase 6 (>=85%) and Phase 7 (>=90%).

Baseline

There are multiple coverage numbers depending on how the report is computed. For planning, only one of them is useful.

Metric	Scope	Statements / Lines	Branches	Functions	Notes
Legacy	Old npm run test:coverage	79.42%	75.15%	67.94%	Inflated: counts test files and excludes open-sse
Diagnostic	Source-only, excluding tests and excluding open-sse	68.16%	63.55%	64.06%	Useful only to isolate src/**
Recommended baseline	Source-only, excluding tests and including open-sse	82.58%	75.22%	84.23%	This is the project-wide baseline to improve

The recommended baseline is the number to optimize against.

Rules

• Coverage targets apply to source files, not to tests/**.
• open-sse/** is part of the product and must remain in scope.
• New code should not reduce coverage in touched areas.
• Prefer testing behavior and branch outcomes over implementation details.
• Prefer temp SQLite databases and small fixtures over broad mocks for src/lib/db/**.

Current command set

• npm run test:coverage
  • Main source coverage gate for the unit test suite
  • Generates text-summary, html, json-summary, and lcov
• npm run coverage:report
  • Detailed file-by-file report from the latest run
• npm run test:coverage:legacy
  • Historical comparison only

Milestones

Phase	Target	Focus	Status
Phase 1	60% statements / lines	Quick wins and low-risk utility coverage	✅ Done
Phase 2	65% statements / lines	DB and route foundations	✅ Done
Phase 3	70% statements / lines	Provider validation and usage analytics	✅ Done
Phase 4	75% statements / lines	open-sse translators and helpers	✅ Done
Phase 5	80% statements / lines	open-sse handlers and executor branches	✅ Done
Phase 6	85% statements / lines	Harder edge cases, branch debt, regression suites	In progress
Phase 7	90% statements / lines	Final sweep, gap closure, strict ratchet	Pending

Branches and functions should ratchet upward with each phase, but the primary hard target is statements / lines.

Priority hotspots

These files have the lowest line coverage today (< 60%) and offer the best return for Phases 6-7. Generated from coverage/coverage-summary.json on 2026-05-13:

#	File	Lines %
1	open-sse/services/compression/validation.ts	7.87%
2	src/app/api/v1/batches/route.ts	9.67%
3	src/app/docs/components/FeedbackWidget.tsx	9.80%
4	open-sse/services/compression/toolResultCompressor.ts	10.00%
5	src/app/docs/components/DocCodeBlocks.tsx	10.63%
6	open-sse/services/compression/engines/rtk/lineFilter.ts	10.96%
7	open-sse/services/specificityRules.ts	11.28%
8	src/mitm/systemCommands.ts	12.19%
9	open-sse/services/compression/aggressive.ts	12.77%
10	src/app/api/v1/batches/[id]/cancel/route.ts	12.98%
11	open-sse/services/compression/progressiveAging.ts	13.26%
12	open-sse/services/compression/engines/rtk/smartTruncate.ts	13.43%
13	open-sse/services/compression/engines/rtk/deduplicator.ts	13.51%
14	src/lib/cloudAgent/agents/jules.ts	13.52%
15	open-sse/services/compression/lite.ts	14.46%
16	src/app/api/v1/rerank/route.ts	14.94%
17	open-sse/services/compression/preservation.ts	15.07%
18	src/lib/cloudAgent/agents/codex.ts	15.54%
19	open-sse/services/tierResolver.ts	16.66%
20	src/app/docs/components/DocsLazyWrapper.tsx	16.66%

Themes for Phases 6-7:

• open-sse/services/compression/** is the densest cluster of low coverage and dominates the remaining gap.
• Batch and rerank API routes (src/app/api/v1/batches/**, src/app/api/v1/rerank/route.ts) need handler-level tests.
• Cloud agent adapters (src/lib/cloudAgent/agents/jules.ts, codex.ts) and tierResolver.ts need scenario tests.
• Docs UI components and src/mitm/systemCommands.ts are lower priority but cheap branch wins.

Execution checklist

Phase 1: 56.95% -> 60%

• Fix coverage metric so it reflects source code instead of test files
• Keep a legacy coverage script for comparison
• Record the baseline and hotspots in-repo
• Add focused tests for low-risk utilities:
  • src/shared/utils/upstreamError.ts
  • src/shared/utils/fetchTimeout.ts
  • src/lib/api/errorResponse.ts
  • src/shared/utils/apiAuth.ts
  • src/lib/display/names.ts
• Add route tests for:
  • src/app/api/settings/require-login/route.ts
  • src/app/api/providers/[id]/models/route.ts

Phase 2: 60% -> 65%

• Add DB-backed tests for:
  • src/lib/db/modelComboMappings.ts
  • src/lib/db/settings.ts
  • src/lib/db/registeredKeys.ts
• Cover branch behavior in:
  • src/lib/providers/validation.ts
  • src/app/api/v1/embeddings/route.ts
  • src/app/api/v1/moderations/route.ts

Phase 3: 65% -> 70%

• Add usage analytics tests for:
  • src/lib/usage/usageHistory.ts
  • src/lib/usage/usageStats.ts
  • src/lib/usage/costCalculator.ts
• Expand route coverage for proxy management and settings branches

Phase 4: 70% -> 75%

• Cover translator helpers and central translation paths:
  • open-sse/translator/index.ts
  • open-sse/translator/helpers/*
  • open-sse/translator/request/*
  • open-sse/translator/response/*

Phase 5: 75% -> 80%

• Add handler-level tests for:
  • open-sse/handlers/chatCore.ts
  • open-sse/handlers/responsesHandler.js
  • open-sse/handlers/imageGeneration.js
  • open-sse/handlers/embeddings.js
• Add executor branch coverage for provider-specific auth, retries, and endpoint overrides

Phase 6: 80% -> 85%

• Merge more edge-case suites into the main coverage path
• Increase function coverage for DB modules with weak constructor/helper coverage
• Close branch gaps in settings.ts, registeredKeys.ts, validation.ts, and translator helpers

Phase 7: 85% -> 90%

• Treat the remaining low-coverage files as blockers
• Add regression tests for every uncovered production bug fixed during the push to 90%
• Raise the coverage gate in CI only after the local baseline is stable for at least two consecutive runs

Ratchet policy

Update npm run test:coverage thresholds only after the project actually exceeds the next milestone with a comfortable buffer.

Current gate: npm run test:coverage enforces 60 statements / 60 lines / 60 functions / 60 branches (the metric was rebased in Quality-Gates Fase 6A.1 — the earlier 82.58% baseline was inflated because it counted test files and excluded open-sse). The test:coverage:legacy command preserves the old 50/50/50 metric for historical comparison.

For ad-hoc threshold checks against the latest report use:

node scripts/check/test-report-summary.mjs --threshold 75

Recommended ratchet sequence (order is statements-lines / branches / functions):

1. 55/60/55
2. 60/62/58
3. 65/64/62
4. 70/66/66
5. 75/70/72 <– current gate (75/70/75)
6. 80/75/78
7. 85/80/84
8. 90/85/88

Next ratchet target is 80/75/78 once branch coverage holds above 78% for two consecutive runs.

Known gap

The current coverage command measures the main Node unit suite and includes source reached from it, including open-sse. It does not yet merge Vitest coverage into a single unified report. That merge is worth doing later, but it is not a blocker for starting the 60% -> 80% climb.

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