Verification matrix

Every public feature maps to automated tests. The matrix is enforced by test/verification-matrix.test.ts, which verifies that:

1. Each feature references at least one test file
2. Those files exist on disk
3. Those files contain keywords proving the feature is exercised

Feature	Test files
createLastcall()	test/unit/create-lastcall.test.ts
getDefaultLastcall()	create-lastcall.test.ts, singleton.test.ts
register() / unregister()	handler-registry.test.ts, create-lastcall.test.ts
Shutdown idempotency	create-lastcall.test.ts
Phases (pre/drain/cleanup/post)	shutdown-runner.test.ts, create-lastcall.test.ts
Priority ordering	handler-registry.test.ts
Dependency graph	topological-sort.test.ts, handler-registry.test.ts
Per-handler timeout	create-lastcall.test.ts
Global shutdown timeout	shutdown-runner.test.ts
Critical vs non-critical exit codes	shutdown-runner.test.ts, create-lastcall.test.ts
Signal handling	signal-listener.test.ts, create-lastcall.test.ts
simulateSignal()	create-lastcall.test.ts
withHttpServer()	shutdown-runner.test.ts, integration/integration.test.ts
Lifecycle events	events.test.ts, create-lastcall.test.ts
Metrics hooks	shutdown-runner.test.ts
Exception capture	create-lastcall.test.ts
autoExit / custom exit()	create-lastcall.test.ts
Default logger	logger.test.ts, create-lastcall.test.ts
Handler context + abortSignal	create-lastcall.test.ts, shutdown-runner.test.ts
Child process integration (IPC)	integration/integration.test.ts
Package exports	index.test.ts
Cross-phase dependency validation	handler-registry.test.ts
Register blocked during shutdown	create-lastcall.test.ts
TopologicalSortError export	index.test.ts
Process listener cleanup	create-lastcall.test.ts
Async handler failures	shutdown-runner.test.ts, create-lastcall.test.ts
Handler overwrite semantics	create-lastcall.test.ts

Integration tests trigger shutdown via child-process IPC, not OS signals — reliable on Windows and Linux alike.