v0.78.0: DELETE /escrow/stage-secret — idempotent staged-secret wipe

The staged offsite repo password was wiped only by the escrow-create
ceremony; a confirm without a fresh ceremony (password already escrowed)
left the 0600 staged file behind. The controller calls this on every
EscrowState flip to escrowed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

internal/localapi/escrow_stage.go

@@ -55,3 +55,23 @@ func (s *Server) handleStageEscrowSecret(w http.ResponseWriter, r *http.Request,
 	s.logger.Info("local-api: staged offsite restic repo password for escrow (field name only)", "vmid", vmid)
 	writeOK(w, map[string]any{"staged": true})
 }
+
+// handleWipeStagedEscrowSecret removes the staged offsite secret once its escrow is confirmed (or on
+// operator cleanup). Idempotent: an absent file is a clean 200 {removed:false}. Closes the fork-4 hygiene
+// gap where a confirm WITHOUT a fresh ceremony (the password was already escrowed) left the staged 0600
+// file behind indefinitely.
+func (s *Server) handleWipeStagedEscrowSecret(w http.ResponseWriter, r *http.Request, vmid int) {
+	path := s.escrowStagePath
+	_ = os.Remove(path + ".tmp") // a stale partial from an interrupted stage, if any
+	err := os.Remove(path)
+	switch {
+	case err == nil:
+		s.logger.Info("local-api: wiped staged escrow secret", "vmid", vmid)
+		writeOK(w, map[string]any{"removed": true})
+	case os.IsNotExist(err):
+		writeOK(w, map[string]any{"removed": false})
+	default:
+		s.logger.Error("local-api: wipe staged escrow secret", "vmid", vmid, "err", err)
+		writeErr(w, http.StatusInternalServerError, "could not remove the staged secret")
+	}
+}

internal/localapi/escrow_stage_test.go

@@ -66,6 +66,43 @@ func TestStageEscrowSecret_StagesScopesAndHidesValue(t *testing.T) {
 	}
 }
 
+// TestWipeStagedEscrowSecret: DELETE removes the staged file (EFFECT: file gone), is idempotent when
+// absent, and requires auth.
+func TestWipeStagedEscrowSecret(t *testing.T) {
+	srv := newTestServerS(t, &fakeGuests{}, &fakeBackups{}, &fakeStore{}, nil)
+	stagePath := filepath.Join(t.TempDir(), "escrow-stage", "restic_repo_password")
+	srv.escrowStagePath = stagePath
+	h := srv.Handler()
+
+	// stage something first
+	if w := do(t, h, "POST", "/escrow/stage-secret", "A", `{"vmid":8200,"restic_repo_password":"deadbeef"}`); w.Code != 200 {
+		t.Fatalf("stage: got %d", w.Code)
+	}
+	if _, err := os.Stat(stagePath); err != nil {
+		t.Fatalf("staged file must exist before the wipe: %v", err)
+	}
+
+	// wipe → removed:true, file gone
+	w := do(t, h, "DELETE", "/escrow/stage-secret", "A", "")
+	if w.Code != 200 || !strings.Contains(w.Body.String(), `"removed":true`) {
+		t.Fatalf("wipe: got %d body=%s", w.Code, w.Body.String())
+	}
+	if _, err := os.Stat(stagePath); !os.IsNotExist(err) {
+		t.Fatal("staged file must be GONE after the wipe")
+	}
+
+	// idempotent: wipe again → 200 removed:false
+	w2 := do(t, h, "DELETE", "/escrow/stage-secret", "A", "")
+	if w2.Code != 200 || !strings.Contains(w2.Body.String(), `"removed":false`) {
+		t.Fatalf("re-wipe must be a clean idempotent 200 removed:false, got %d body=%s", w2.Code, w2.Body.String())
+	}
+
+	// auth required
+	if w3 := do(t, h, "DELETE", "/escrow/stage-secret", "NOPE", ""); w3.Code != 401 {
+		t.Fatalf("unauthenticated wipe must be 401, got %d", w3.Code)
+	}
+}
+
 // TestStageEscrowSecret_NoSecretInLog: the staged value never appears in a log line (hygiene is load-bearing).
 func TestStageEscrowSecret_NoSecretInLog(t *testing.T) {
 	var logbuf bytes.Buffer

internal/localapi/server.go

@@ -314,6 +314,8 @@ func (s *Server) Handler() http.Handler {
 
 	// fork-4: stage the controller-pushed offsite restic repo password for the escrow-create ceremony.
 	mux.HandleFunc("POST /escrow/stage-secret", s.withGuest(s.handleStageEscrowSecret))
+	// fork-4 hygiene: wipe the staged secret once escrowed (controller calls this on confirm). Idempotent.
+	mux.HandleFunc("DELETE /escrow/stage-secret", s.withGuest(s.handleWipeStagedEscrowSecret))
 	return mux
 }