v0.77.0: fork-4 — escrow the offsite restic repo password under R

IdentityBundle gains ResticRepoPassword (rides existing age-under-R
WrapIdentityBundle; custody spike febdc56 proved a recovered value opens the
real repo). POST /escrow/stage-secret (withGuest, scopedFromBody) transiently
stages the controller-pushed password (0600, atomic, NEVER logged), which the
escrow-create ceremony auto-injects then wipes. Adds AttachResticPassword +
StagedResticPasswordPath + WipeStagedResticPassword; EscrowStagePath injectable
for tests. Tests: bundle carries pw byte-exact + not-in-blob + wrong-R fails
closed; stage 0600 + non-secret ack + cross-guest 403 + value-not-in-log.
Additive; PBS-K escrow untouched. NOT yet live-validated (supervised ceremony).

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

internal/escrow/identity_test.go

@@ -3,7 +3,9 @@ package escrow
 import (
 	"bytes"
 	"context"
+	"os"
 	"os/exec"
+	"path/filepath"
 	"runtime"
 	"testing"
 )
@@ -65,6 +67,61 @@ func TestIdentity_RoundTrip(t *testing.T) {
 	}
 }
 
+// fork-4: the IdentityBundle carries the offsite restic repo password under R, byte-exact and encrypted;
+// a wrong R fails closed. (The spike proved a recovered value opens the real repo; this guards the field.)
+func TestIdentity_RoundTrip_CarriesResticPassword(t *testing.T) {
+	ensureAge(t)
+	ctx := context.Background()
+	const R = "throwaway-correct-horse-battery-staple-fork4"
+	const pw = "deadbeefcafef00d0123456789abcdef0123456789abcdef0123456789abcdef" // 64 hex, synthetic
+	bundle := IdentityBundle{TunnelToken: "tt", PBSToken: "pt", ResticRepoPassword: pw}
+	blob, err := WrapIdentityBundle(ctx, bundle, R)
+	if err != nil {
+		t.Fatalf("WrapIdentityBundle: %v", err)
+	}
+	if bytes.Contains(blob, []byte(pw)) {
+		t.Fatal("the blob leaks the restic password plaintext — not encrypted")
+	}
+	got, err := UnwrapIdentityBundle(ctx, blob, R)
+	if err != nil {
+		t.Fatalf("UnwrapIdentityBundle: %v", err)
+	}
+	if got.ResticRepoPassword != pw {
+		t.Fatalf("recovered restic password not byte-exact: got %q", got.ResticRepoPassword)
+	}
+	if got != bundle {
+		t.Fatalf("recovered bundle = %+v, want %+v", got, bundle)
+	}
+	if _, err := UnwrapIdentityBundle(ctx, blob, R+"-WRONG"); err == nil {
+		t.Fatal("a wrong recovery code must fail closed (no bundle, no restic password)")
+	}
+}
+
+// AttachResticPassword: missing file → clean no-attach; staged file → trimmed value attached; empty → error.
+func TestAttachResticPassword(t *testing.T) {
+	b := &IdentityBundle{}
+	if ok, err := AttachResticPassword(b, filepath.Join(t.TempDir(), "absent")); ok || err != nil {
+		t.Fatalf("missing staged file must be a clean no-attach, got ok=%v err=%v", ok, err)
+	}
+	f := filepath.Join(t.TempDir(), "pw")
+	if err := os.WriteFile(f, []byte("  abc123def  \n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	ok, err := AttachResticPassword(b, f)
+	if err != nil || !ok {
+		t.Fatalf("attach from staged file: ok=%v err=%v", ok, err)
+	}
+	if b.ResticRepoPassword != "abc123def" {
+		t.Fatalf("want trimmed value, got %q", b.ResticRepoPassword)
+	}
+	if err := os.WriteFile(f, []byte("   \n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := AttachResticPassword(&IdentityBundle{}, f); err == nil {
+		t.Fatal("an empty staged file must error (an operator would want to know)")
+	}
+}
+
 // Wrong R fails CLOSED — no bundle emitted.
 func TestIdentity_WrongRFailsClosed(t *testing.T) {
 	ensureAge(t)