Closes CRIT-5 of the 2026-05-10 audit — the LAST Critical blocker for
v2.1.0. The OIDCProvider.AllowedEmailDomains field shipped persisted
(internal/auth/oidc/domain/types.go:47), API-surfaced
(internal/api/handler/auth_session_oidc.go), MCP-surfaced
(internal/mcp/tools_auth_bundle2.go), and GUI-editable, but the
verifier in internal/auth/oidc/service.go::HandleCallback NEVER read
it. Operators filling allowed_email_domains: ["acme.com"] expected
"users outside acme.com cannot log in" — the field had zero effect.
Textbook lying-field shape per CLAUDE.md's "complete path" rule.
This commit:
- Adds Step 7.5 to HandleCallback (between profile-claim resolve and
group-claim resolve): when the provider's AllowedEmailDomains slice
is non-empty, the user's email-domain MUST match a list entry (case-
insensitive exact match; subdomains NOT auto-accepted — operators
who want dev.acme.com authorized must list it explicitly).
- Two new sentinel errors at the package level:
- ErrEmailDomainNotAllowed — email is set but domain not in list
- ErrEmailMissingButRequired — allowlist set + ID token has no email
- New extractEmailDomain helper: case-folds + trims whitespace + uses
LastIndex for the @ split + rejects empty input / no-@ / empty
local-part / empty domain-part. Returns the lowercase domain or
an error.
- 21 regression tests in internal/auth/oidc/email_domain_test.go:
- 10 extractEmailDomain shape cases (plain, mixed-case input,
leading/trailing whitespace, subdomain preserved, empty, no @,
empty local-part, empty domain-part, multiple @ via LastIndex).
- 11 match-semantic cases (empty list passes any, lowercase match,
mixed-case allowlist entry match, mixed-case email match,
whitespace-padded allowlist entry, unmatched returns
ErrEmailDomainNotAllowed, missing email + non-empty allowlist
returns ErrEmailMissingButRequired, subdomain NOT auto-accepted,
parent-domain NOT auto-accepted, multi-entry first-match,
multi-entry no-match).
Subdomain matching (alice@dev.acme.com against allowlist=[acme.com])
is intentionally NOT auto-accepted. The audit's MED-line tracks the
wildcard / suffix support story for v3; v2.1 ships strict.
Verification gate green:
- gofmt clean
- go vet clean
- go test -short -count=1 ./internal/auth/oidc/... ./internal/api/...
./internal/domain/auth/ — all pass (incl. existing OIDC service
test suite, the 4 BCL tests, the auditor pin, and the AST
RBAC-gate coverage guard).
Branch dev/auth-bundle-2 status post-commit: CRIT-1 (68ca42f),
CRIT-2 (ca1e135), CRIT-3 (00eace8), CRIT-4 (f1d9771), CRIT-5 (this)
— all five Criticals from the 2026-05-10 audit closed. v2.1.0 is
unblocked. HIGH-1..HIGH-12 + MEDs + LOWs are independently mergeable
follow-ups (spec at cowork/auth-bundles-fixes-2026-05-10/).
Refs: cowork/auth-bundles-audit-2026-05-10.md CRIT-5
shankar0123