test(admin_test_token): pin ADMIN_TOKEN IDOR-fix (#112) gate behavior

The admin test-token endpoint has a critical security check at
admin_test_token.go:64-72 — the IDOR fix from #112 that requires an
explicit ADMIN_TOKEN bearer when the env var is set. Pre-fix, the
route accepted ANY bearer that matched a live org token, allowing
cross-org test-token minting (and therefore cross-org workspace
authentication). The current code uses subtle.ConstantTimeCompare
against ADMIN_TOKEN.

Test coverage was zero. The existing tests exercised the
ADMIN_TOKEN-unset path (local dev / CI) but never set ADMIN_TOKEN.
A regression that:

  - removed the os.Getenv("ADMIN_TOKEN") check
  - inverted the comparison
  - replaced ConstantTimeCompare with bytes.Equal (timing leak)
  - re-introduced the AdminAuth fallback that allows org tokens

would not fail any test, and the breakage would re-open the IDOR
that #112 closed.

Adds four tests covering the gate matrix:

  - ADMIN_TOKEN set + no Authorization header → 401
  - ADMIN_TOKEN set + wrong Authorization → 401
  - ADMIN_TOKEN set + correct Authorization → 200
  - ADMIN_TOKEN unset + no Authorization → 200 (gate bypassed safely)

The 4-row matrix pins the gate's full truth table: any regression in
either dimension (gate enabled/disabled, header correct/wrong) trips
exactly one test.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

workspace-server/internal/handlers/admin_test_token_test.go

@@ -129,3 +129,97 @@ func TestAdminTestToken_HappyPath_TokenValidates(t *testing.T) {
 }
 
 func sqlErrNoRows() error { return sql.ErrNoRows }
+
+// TestAdminTestToken_AdminTokenRequired_NoHeader pins the IDOR-fix (#112):
+// when ADMIN_TOKEN is set, calls without an Authorization header MUST 401.
+// Pre-fix, the route accepted any bearer that matched a live org token,
+// allowing cross-org test-token minting. The current code uses
+// subtle.ConstantTimeCompare against ADMIN_TOKEN explicitly. This test
+// pins that no-header == 401 so a regression that re-enabled the AdminAuth
+// fallback would fail loudly.
+func TestAdminTestToken_AdminTokenRequired_NoHeader(t *testing.T) {
+	setupTestDB(t)
+	t.Setenv("MOLECULE_ENV", "development")
+	t.Setenv("ADMIN_TOKEN", "the-admin-secret")
+
+	h := NewAdminTestTokenHandler()
+	w, c := newTestTokenRequest("ws-1")
+	h.GetTestToken(c)
+
+	if w.Code != http.StatusUnauthorized {
+		t.Fatalf("expected 401 with ADMIN_TOKEN set + no Authorization, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// TestAdminTestToken_AdminTokenRequired_WrongHeader pins that a non-matching
+// bearer is rejected. Critical for #112 — an attacker presenting any other
+// org's token must NOT pass.
+func TestAdminTestToken_AdminTokenRequired_WrongHeader(t *testing.T) {
+	setupTestDB(t)
+	t.Setenv("MOLECULE_ENV", "development")
+	t.Setenv("ADMIN_TOKEN", "the-admin-secret")
+
+	h := NewAdminTestTokenHandler()
+	w, c := newTestTokenRequest("ws-1")
+	c.Request.Header.Set("Authorization", "Bearer wrong-token")
+	h.GetTestToken(c)
+
+	if w.Code != http.StatusUnauthorized {
+		t.Fatalf("expected 401 with wrong Authorization, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// TestAdminTestToken_AdminTokenRequired_CorrectHeader pins the success
+// path through the ADMIN_TOKEN gate. Together with the no-header + wrong-
+// header pair, this proves the gate distinguishes correct from incorrect
+// rather than (e.g.) erroring on every request.
+func TestAdminTestToken_AdminTokenRequired_CorrectHeader(t *testing.T) {
+	mock := setupTestDB(t)
+	t.Setenv("MOLECULE_ENV", "development")
+	t.Setenv("ADMIN_TOKEN", "the-admin-secret")
+
+	mock.ExpectQuery("SELECT id FROM workspaces WHERE id =").
+		WithArgs("ws-1").
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow("ws-1"))
+	mock.ExpectExec("INSERT INTO workspace_auth_tokens").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	h := NewAdminTestTokenHandler()
+	w, c := newTestTokenRequest("ws-1")
+	c.Request.Header.Set("Authorization", "Bearer the-admin-secret")
+	h.GetTestToken(c)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200 with correct ADMIN_TOKEN, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("sqlmock expectations not met — INSERT into workspace_auth_tokens did not run, suggesting the gate short-circuited the success path: %v", err)
+	}
+}
+
+// TestAdminTestToken_AdminTokenEmpty_GateBypassedSafely pins that when
+// ADMIN_TOKEN is unset (typical local-dev setup), the explicit gate is
+// bypassed and the route works without an Authorization header. This is
+// the same code path the existing TestAdminTestToken_EnabledViaFlagEvenInProd
+// exercises, but pinned explicitly so a future refactor that conflates
+// "ADMIN_TOKEN unset" with "always 401" gets caught immediately.
+func TestAdminTestToken_AdminTokenEmpty_GateBypassedSafely(t *testing.T) {
+	mock := setupTestDB(t)
+	t.Setenv("MOLECULE_ENV", "development")
+	t.Setenv("ADMIN_TOKEN", "")
+
+	mock.ExpectQuery("SELECT id FROM workspaces WHERE id =").
+		WithArgs("ws-1").
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow("ws-1"))
+	mock.ExpectExec("INSERT INTO workspace_auth_tokens").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	h := NewAdminTestTokenHandler()
+	w, c := newTestTokenRequest("ws-1")
+	// Note: NO Authorization header — the gate is unset, so this MUST work.
+	h.GetTestToken(c)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200 with ADMIN_TOKEN empty + no Authorization, got %d: %s", w.Code, w.Body.String())
+	}
+}