fix(auth/rbac): close HIGH-10 lying field — EffectivePermissions reads actor-role scope (A-1)

Audit 2026-05-11 A-1 closure. Spec at
cowork/auth-bundles-fixes-2026-05-11/01-crit-actor-role-scope-reads.md.

WHAT.

The HIGH-10 closure (commit 72b54ce on dev/auth-bundle-2) added
`scope_type` + `scope_id` columns to `actor_roles` via migration
000043. The handler accepted them on POST /api/v1/auth/keys/{id}/roles.
The repo Grant INSERTed them. The uniqueness tuple was extended to
include them. The GUI exposed them as form inputs.

But the load-bearing `EffectivePermissions` SQL at
internal/repository/postgres/auth.go:470 never read them. The query
only JOINed against rp.scope_type/rp.scope_id (role-permission
scope) and ignored ar.scope_type/ar.scope_id (actor-role scope).

Operator-visible failure: granting Alice r-operator scoped to
profile=p-prod silently elevated her to r-operator GLOBALLY at
authorization time. The Authorizer's matcher correctly handled
whatever EffectivePermissions returned, but EffectivePermissions
returned the rp.scope (typically global), not the ar.scope
narrowing.

This is the canonical CRIT-5 lying-field shape — a security
control claimed, persisted across 4 layers, with unit tests at
each isolated layer, but the load-bearing wire severed mid-flight.
CLAUDE.md's 'Always take the complete path' rule was violated by
the original HIGH-10 closure.

Additionally, `scanActorRoles` failed to read the new columns
even when present, so every GET-side path (ListByActor /
ListByRole) returned ActorRole with zero-value scope fields — the
GUI / MCP couldn't show operators what they had configured.

HOW.

internal/repository/postgres/auth.go:
  - EffectivePermissions SQL extended to intersect ar.scope with
    rp.scope via a CASE-in-subquery. The effective scope is the
    NARROWER of the two; disjoint tuples and scope-type mismatches
    drop the row entirely. WHERE filter on effective_scope_type
    IS NOT NULL excludes dropped rows.

    Match matrix (encoded by the CASE):
      ar.scope    rp.scope    effective_scope
      ─────────   ─────────   ──────────────────
      global      global      global / NULL
      global      profile=X   profile=X (rp narrows)
      profile=X   global      profile=X (ar narrows)
      profile=X   profile=X   profile=X (both agree)
      profile=X   profile=Y   ROW DROPPED (disjoint)
      profile=X   issuer=*    ROW DROPPED (type mismatch)

  - ListByActor + ListByRole SELECTs extended with scope_type +
    scope_id columns so the read-side surfaces what was persisted.
  - scanActorRoles reads the new columns into ActorRole.ScopeType
    + ScopeID via the existing sql.NullString + ScopeType cast
    pattern (mirrors RolePermission scan).

internal/repository/postgres/auth_scope_test.go (NEW):
  Testcontainer-backed regression matrix. 8 cases:
  1. ActorRoleGlobal_RolePermGlobal — trivial happy path.
  2. ActorRoleGlobal_RolePermProfile — rp narrows.
  3. ActorRoleProfile_RolePermGlobal_A1Closure — **load-bearing**
     post-fix case: profile-scoped grant narrows to profile.
  4. BothScopedSameTuple_Matches — exact-match collapse.
  5. BothScopedDifferentIDs_RowDropped — disjoint scopes produce
     no effective permission.
  6. ScopeTypeMismatch_RowDropped — profile vs issuer mismatch.
  7. ExpiredGrant_Excluded — pre-fix behavior preserved.
  8. ListByActor_ReturnsScopeColumns — read-side surface check.

  Tests skip in -short mode (testcontainers-backed; require Docker
  on operator workstation).

internal/service/auth/service_test.go:
  TestAuthorizer_ActorRoleProfileScope_OnlyNarrowedScopeAuthorizes_A1
  — unit-level pin (sandbox-runnable, no Docker). Simulates the
  post-A-1 SQL emission (narrowed effective row at
  profile=p-prod) and asserts CheckPermission authorizes only
  matching profile, rejects other profiles AND rejects global.
  Existing matcher code is unchanged; this proves the integration
  point.

CHANGELOG.md:
  Operator advisory in the new 'Security (BREAKING — silent-elevation
  closure)' section. Pre-existing scope-bound grants take effect on
  upgrade; operators audit `actor_roles WHERE scope_type != 'global'`
  to confirm intent.

cowork/auth-bundles-audit-2026-05-10.md:
  HIGH-10 row gets an A-1 follow-on CLOSED 2026-05-11 annotation
  describing the regression + closure.

VERIFY.

- gofmt -l <changed files>                                       (no diff)
- go vet ./internal/repository/postgres/... ./internal/service/auth/...
  ./internal/api/handler/... ./internal/auth/... ./cmd/server/...  PASS
- go test -short -count=1 ./internal/service/auth/...
  ./internal/repository/postgres/... ./internal/api/handler/...    PASS
- The testcontainer-backed regression matrix runs on operator
  workstation via 'go test -count=1 ./internal/repository/postgres/...'
  (skip in -short).

Refs: cowork/auth-bundles-audit-2026-05-10.md HIGH-10 (A-1 follow-on)
      cowork/auth-bundles-fixes-2026-05-11/01-crit-actor-role-scope-reads.md
      CLAUDE.md 'Always take the complete path' rule

CHANGELOG.md

@@ -2,6 +2,26 @@
 
 ## Unreleased
 
+### Security (BREAKING — silent-elevation closure)
+
+- **HIGH-10 actor-role scope is now enforced (Audit 2026-05-11 A-1).**
+  Pre-fix, `actor_roles.scope_type` / `scope_id` (added in migration 000043
+  by the HIGH-10 closure) were persisted by Grant + accepted on the handler
+  body + surfaced through the GUI/MCP — but the load-bearing
+  `EffectivePermissions` SQL never read them. A profile-scoped grant
+  silently elevated to global at authorization time. Canonical CRIT-5
+  lying-field shape, replicated. **The post-fix authorization narrows
+  correctly**: every existing `actor_roles` row with `scope_type != 'global'`
+  now takes effect.
+
+  > **Operator advisory:** if you used the HIGH-10 scope-bound role-grant
+  > API between commit `551812b` and the v2.1.0 tag (the column was
+  > populated but ignored), the grants were silently global. After
+  > upgrading, audit `SELECT actor_id, role_id, scope_type, scope_id FROM
+  > actor_roles WHERE scope_type != 'global'` and confirm the narrowing
+  > reflects intent. If an actor was granted a scoped role but expected
+  > global behavior, re-grant with `scope_type=global`.
+
 ### Security (BREAKING)
 
 - **`__Host-` cookie prefix on all three auth cookies (Audit 2026-05-10 MED-14).**