test(phase0): expand test coverage, security audit, and benchmarks
Add 29 new tests across auth/, crypt/, and trust/ packages:
- auth: concurrent sessions, token uniqueness, challenge expiry boundary,
empty password, long/unicode usernames, air-gapped round-trip, expired refresh
- crypt: wrong passphrase, empty/large plaintext, KDF determinism, HKDF info
separation, checksum edge cases
- trust: concurrent registry operations, tier validation, token expiry boundary,
empty ScopedRepos behaviour, unknown capabilities
Add benchmark suites:
- crypt: Argon2, ChaCha20, AES-GCM, HMAC (1KB/1MB payloads)
- trust: PolicyEvaluate (100 agents), RegistryGet, RegistryRegister
Security audit documented in FINDINGS.md:
- F1: LTHN hash used for password verification (medium)
- F2: PGP private keys not zeroed after use (low, upstream limitation)
- F3: Empty ScopedRepos bypasses repo scope check (medium)
- F4: go vet clean, no math/rand, no secrets in error messages
All tests pass with -race. go vet clean.
Co-Authored-By: Virgil <virgil@lethean.io>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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