Closes one 2026-04-24 audit finding (P2):
- cat-s6-efc7f6f6bd50: 30 strings.Contains(err.Error(), ...) sites
in internal/api/handler/ — brittle to repository-layer message
changes, untyped against the actual failure mode.
Approach (Option B from prompt design notes):
- New typed sentinels in internal/repository/errors.go:
ErrNotFound, ErrForeignKeyConstraint
IsForeignKeyError(err) helper (the only place substring
matching at the lib/pq boundary is allowed; isolates the
DB-driver string knowledge to one function).
- New typed sentinel in internal/domain/errors.go:
ErrValidation (reserved for future per-entity validation
wrappers; not yet used by all handlers).
- 49 sites in internal/repository/postgres/*.go updated to wrap
sql.ErrNoRows-derived errors via fmt.Errorf("...: %w",
repository.ErrNotFound).
- 18 not-found handler sites + 2 FK-constraint handler sites
refactored to errors.Is(err, repository.ErrNotFound) /
repository.IsForeignKeyError(err).
- 23 inline `fmt.Errorf("X not found")` test fixtures across
handler tests rewrapped to wrap repository.ErrNotFound.
- test_utils.go::ErrMockNotFound rewrapped to wrap
repository.ErrNotFound; renewal_policy.go closure docblock
updated to reflect the new convention.
- integration test mockJobRepository.Get wraps repository.ErrNotFound.
CI regression guardrail:
- .github/workflows/ci.yml::"Forbidden strings.Contains(err.Error())
regression guard (S-2)" greps for the three patterns ("not found",
"violates foreign key", "RESTRICT") under internal/api/handler/
and fails the build on regression.
Verification:
- go build ./... — clean
- go vet ./... — clean
- go test ./... -short -count=1 — all packages pass (handler +
repository + service + integration)
- golangci-lint v2.11.4 run ./... — 0 issues
- S-2 guardrail dry-run on post-fix tree → empty (good)
- All sibling guardrails (S-1, G-3, D-1+D-2, B-1, L-1, H-1, C-1, F-1, P-1) pass
Audit findings closed:
- cat-s6-efc7f6f6bd50 (P2)
Deferred follow-ups:
- 6 domain-specific substring patterns still inline in handlers
("cannot approve", "cannot reject", "cannot be parsed",
"no certificates found", "challenge password", "invalid"/
"required" validation chains in profiles + agent_groups). Each
needs its own typed sentinel, scoped per service. Documented
by the S-2 CI guardrail's allowlist for closure-comments only.
- Per-entity not-found sentinels (Option A — ErrCertificateNotFound,
ErrAgentNotFound, etc.) deferred. Generic ErrNotFound covers the
current dispatch needs; per-entity precision would let handlers
return entity-aware error bodies without a domain.Type field,
but not blocking.
shankar0123