- New src/config/paths.test.ts: 11 tests covering resolveGatewayPort
profile-aware precedence (env > config > profile > global default)
- Extend bootstrap-external.test.ts: 15 new tests for
readExistingGatewayPort (config reading, fallback, edge cases) and
isPersistedPortAcceptable (18789 rejection guard, end-to-end composition)
- Extend web-runtime-command.test.ts: 2 new tests verifying the fallback
returns 19001 when manifest has no lastGatewayPort or is null
- Update test fixtures across all test files to expect port 19001
All 5 critical mutations verified: removing profile check, removing
18789 guard, reverting fallback, changing constant, breaking config
reader -- each caught by at least 2 tests.