Extract pemToBase64Der and buildClientAuthentication from caddy.ts into
a new caddy-mtls.ts module, adding groupMtlsDomainsByCaSet to group mTLS
domains by their CA fingerprint before building TLS connection policies.
Previously all mTLS domains sharing a cert type (auto-managed, imported,
or managed) were grouped into a single policy, causing CA union: a client
cert from CA_B could authenticate against a host that only trusted CA_A.
The fix creates one policy per unique CA set, ensuring strict per-host
CA isolation across all three TLS policy code paths.
Also adds:
- tests/unit/caddy-mtls.test.ts (26 tests) covering pemToBase64Der,
buildClientAuthentication, groupMtlsDomainsByCaSet, and cross-CA
isolation regression tests
- tests/unit/instance-sync-env.test.ts (33 tests) for the five pure
env-reading functions in instance-sync.ts
- tests/integration/instance-sync.test.ts (16 tests) for
buildSyncPayload and applySyncPayload using an in-memory SQLite db
- Fix tests/helpers/db.ts to use a relative import for db/schema so it
works inside vi.mock factory dynamic imports
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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