Previously: jwt_secret defaulted to dev-secret-CHANGE-ME so a missing
env var in production would silently boot with a known-public dev HMAC
key — an instant auth bypass for any service verifying JWTs.
Now:
- Field(...) with no default → missing env raises ValidationError at boot
- min_length=32 enforces minimum entropy (rejects dev placeholder too)
- field_validator rejects the literal dev-secret-CHANGE-ME in ENVIRONMENT=prod
as belt-and-suspenders in case min_length is loosened later
Verified behavior:
- no env, no .env -> ValidationError: Field required
- ENVIRONMENT=prod, no JWT_SECRET -> ValidationError: Field required
- prod, JWT_SECRET=dev-secret-... -> ValidationError: string_too_short
- prod, JWT_SECRET=short -> ValidationError: string_too_short
- prod, JWT_SECRET=<64 hex> -> OK, len=64
.env.example updated to show the placeholder + generation hint.
Refs AUDIT-2026-Q3.md P1.5.
