diff --git a/openspec/changes/fix-branch-start-stash-leak/proposal.md b/openspec/changes/fix-branch-start-stash-leak/proposal.md
new file mode 100644
index 00000000..2ab1c4f5
--- /dev/null
+++ b/openspec/changes/fix-branch-start-stash-leak/proposal.md
@@ -0,0 +1,7 @@
+# Proposal: restore auto-transfer stashes when branch start fails
+
+`gx branch start` currently leaks `guardex-auto-transfer-*` stashes if startup fails after local changes are stashed off a protected branch. That leaves duplicate stash entries for paths like `memory-bank/` even though the branch never started. The safer behavior is to restore those changes back to the original checkout on failure and drop the temporary stash.
+
+- add failure-safe auto-restore for temporary branch-start transfer stashes
+- keep the success path unchanged when the new worktree is created and the stash applies cleanly
+- lock the `memory-bank/` failure case with a focused regression
diff --git a/openspec/changes/fix-branch-start-stash-leak/tasks.md b/openspec/changes/fix-branch-start-stash-leak/tasks.md
new file mode 100644
index 00000000..1d4d6c09
--- /dev/null
+++ b/openspec/changes/fix-branch-start-stash-leak/tasks.md
@@ -0,0 +1,25 @@
+## 1. Spec
+
+- [x] 1.1 Capture why failed branch-start attempts must restore temporary auto-transfer stashes instead of leaking them.
+
+## 2. Implementation
+
+- [x] 2.1 Update `templates/scripts/agent-branch-start.sh` and `scripts/agent-branch-start.sh` with failure-safe auto-restore.
+- [x] 2.2 Add a focused regression in `test/branch.test.js` for the `memory-bank/` failure path.
+
+## 3. Verification
+
+- [x] 3.1 Run targeted Guardex branch tests.
+- [x] 3.2 Run script parity/diff hygiene.
+- [x] 3.3 Run `openspec validate --specs`.
+
+Verification evidence:
+- `node --test test/branch.test.js` (pass)
+- `node --test test/metadata.test.js` (pass)
+- `bash -n scripts/agent-branch-start.sh` and `bash -n templates/scripts/agent-branch-start.sh` (pass)
+- `git diff --check` (pass)
+- `openspec validate --specs` (no items found to validate)
+
+## 4. Cleanup
+
+- [ ] 4.1 Commit, push, open/update PR, merge, and clean up the worktree.
diff --git a/scripts/agent-branch-start.sh b/scripts/agent-branch-start.sh
index 9da6d603..0559d8d4 100755
--- a/scripts/agent-branch-start.sh
+++ b/scripts/agent-branch-start.sh
@@ -155,6 +155,15 @@ env_flag_truthy() {
   esac
 }
 
+maybe_fail_after_auto_transfer_stash() {
+  if env_flag_truthy "${GUARDEX_TEST_FAIL_AFTER_AUTO_TRANSFER_STASH:-}"; then
+    echo "[agent-branch-start] Simulated failure after capturing auto-transfer stash." >&2
+    return 1
+  fi
+
+  return 0
+}
+
 default_worktree_root_rel() {
   local raw_agent="$1"
   local override="${GUARDEX_AGENT_TYPE:-}"
@@ -580,6 +589,27 @@ fi
 auto_transfer_stash_ref=""
 auto_transfer_message=""
 auto_transfer_source_branch=""
+auto_transfer_completed=0
+
+restore_auto_transfer_stash_on_failure() {
+  local exit_code="${1:-0}"
+  if [[ "$exit_code" -eq 0 ]] || [[ -z "$auto_transfer_stash_ref" ]] || [[ "$auto_transfer_completed" -eq 1 ]]; then
+    return 0
+  fi
+
+  local transfer_label="${auto_transfer_source_branch:-$BASE_BRANCH}"
+  if git -C "$repo_root" stash apply "$auto_transfer_stash_ref" >/dev/null 2>&1; then
+    git -C "$repo_root" stash drop "$auto_transfer_stash_ref" >/dev/null 2>&1 || true
+    auto_transfer_stash_ref=""
+    echo "[agent-branch-start] Restored moved changes back to '${transfer_label}' after startup failure." >&2
+  else
+    echo "[agent-branch-start] Startup failed and auto-restore also failed." >&2
+    echo "[agent-branch-start] Changes are preserved in ${auto_transfer_stash_ref} on ${transfer_label}." >&2
+  fi
+}
+
+trap 'restore_auto_transfer_stash_on_failure "$?"' EXIT
+
 current_branch="$(git -C "$repo_root" rev-parse --abbrev-ref HEAD 2>/dev/null || true)"
 protected_branches_raw="$(resolve_protected_branches "$repo_root")"
 if [[ -n "$current_branch" && "$current_branch" != "HEAD" ]] && is_protected_branch_name "$current_branch" "$protected_branches_raw"; then
@@ -593,6 +623,9 @@ if [[ -n "$current_branch" && "$current_branch" != "HEAD" ]] && is_protected_bra
       if [[ -n "$auto_transfer_stash_ref" ]]; then
         auto_transfer_source_branch="$current_branch"
         echo "[agent-branch-start] Detected local changes on protected branch '${current_branch}'. Moving them to '${branch_name}'..."
+        if ! maybe_fail_after_auto_transfer_stash; then
+          exit 1
+        fi
       fi
     fi
   fi
@@ -610,7 +643,9 @@ git -C "$worktree_path" branch --unset-upstream "$branch_name" >/dev/null 2>&1 |
 
 if [[ -n "$auto_transfer_stash_ref" ]]; then
   if git -C "$worktree_path" stash apply "$auto_transfer_stash_ref" >/dev/null 2>&1; then
+    auto_transfer_completed=1
     git -C "$repo_root" stash drop "$auto_transfer_stash_ref" >/dev/null 2>&1 || true
+    auto_transfer_stash_ref=""
     transfer_label="${auto_transfer_source_branch:-$BASE_BRANCH}"
     echo "[agent-branch-start] Moved local changes from '${transfer_label}' into '${branch_name}'."
   else
diff --git a/templates/scripts/agent-branch-start.sh b/templates/scripts/agent-branch-start.sh
index 9da6d603..0559d8d4 100755
--- a/templates/scripts/agent-branch-start.sh
+++ b/templates/scripts/agent-branch-start.sh
@@ -155,6 +155,15 @@ env_flag_truthy() {
   esac
 }
 
+maybe_fail_after_auto_transfer_stash() {
+  if env_flag_truthy "${GUARDEX_TEST_FAIL_AFTER_AUTO_TRANSFER_STASH:-}"; then
+    echo "[agent-branch-start] Simulated failure after capturing auto-transfer stash." >&2
+    return 1
+  fi
+
+  return 0
+}
+
 default_worktree_root_rel() {
   local raw_agent="$1"
   local override="${GUARDEX_AGENT_TYPE:-}"
@@ -580,6 +589,27 @@ fi
 auto_transfer_stash_ref=""
 auto_transfer_message=""
 auto_transfer_source_branch=""
+auto_transfer_completed=0
+
+restore_auto_transfer_stash_on_failure() {
+  local exit_code="${1:-0}"
+  if [[ "$exit_code" -eq 0 ]] || [[ -z "$auto_transfer_stash_ref" ]] || [[ "$auto_transfer_completed" -eq 1 ]]; then
+    return 0
+  fi
+
+  local transfer_label="${auto_transfer_source_branch:-$BASE_BRANCH}"
+  if git -C "$repo_root" stash apply "$auto_transfer_stash_ref" >/dev/null 2>&1; then
+    git -C "$repo_root" stash drop "$auto_transfer_stash_ref" >/dev/null 2>&1 || true
+    auto_transfer_stash_ref=""
+    echo "[agent-branch-start] Restored moved changes back to '${transfer_label}' after startup failure." >&2
+  else
+    echo "[agent-branch-start] Startup failed and auto-restore also failed." >&2
+    echo "[agent-branch-start] Changes are preserved in ${auto_transfer_stash_ref} on ${transfer_label}." >&2
+  fi
+}
+
+trap 'restore_auto_transfer_stash_on_failure "$?"' EXIT
+
 current_branch="$(git -C "$repo_root" rev-parse --abbrev-ref HEAD 2>/dev/null || true)"
 protected_branches_raw="$(resolve_protected_branches "$repo_root")"
 if [[ -n "$current_branch" && "$current_branch" != "HEAD" ]] && is_protected_branch_name "$current_branch" "$protected_branches_raw"; then
@@ -593,6 +623,9 @@ if [[ -n "$current_branch" && "$current_branch" != "HEAD" ]] && is_protected_bra
       if [[ -n "$auto_transfer_stash_ref" ]]; then
         auto_transfer_source_branch="$current_branch"
         echo "[agent-branch-start] Detected local changes on protected branch '${current_branch}'. Moving them to '${branch_name}'..."
+        if ! maybe_fail_after_auto_transfer_stash; then
+          exit 1
+        fi
       fi
     fi
   fi
@@ -610,7 +643,9 @@ git -C "$worktree_path" branch --unset-upstream "$branch_name" >/dev/null 2>&1 |
 
 if [[ -n "$auto_transfer_stash_ref" ]]; then
   if git -C "$worktree_path" stash apply "$auto_transfer_stash_ref" >/dev/null 2>&1; then
+    auto_transfer_completed=1
     git -C "$repo_root" stash drop "$auto_transfer_stash_ref" >/dev/null 2>&1 || true
+    auto_transfer_stash_ref=""
     transfer_label="${auto_transfer_source_branch:-$BASE_BRANCH}"
     echo "[agent-branch-start] Moved local changes from '${transfer_label}' into '${branch_name}'."
   else
diff --git a/test/branch.test.js b/test/branch.test.js
index 08ad4650..02a3e3eb 100644
--- a/test/branch.test.js
+++ b/test/branch.test.js
@@ -157,6 +157,47 @@ test('agent-branch-start moves protected-branch local changes into the new agent
   assert.doesNotMatch(stashList.stdout, /guardex-auto-transfer-/);
 });
 
+test('agent-branch-start restores protected-branch changes when startup fails after auto-transfer stash capture', () => {
+  const repoDir = initRepoOnBranch('main');
+  seedCommit(repoDir);
+  attachOriginRemoteForBranch(repoDir, 'main');
+
+  let result = runNode(['setup', '--target', repoDir, '--no-global-install'], repoDir);
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+
+  result = runCmd('git', ['add', '.'], repoDir);
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+  result = runCmd('git', ['commit', '-m', 'apply gx setup'], repoDir, {
+    ALLOW_COMMIT_ON_PROTECTED_BRANCH: '1',
+  });
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+  result = runCmd('git', ['push', 'origin', 'main'], repoDir);
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+
+  const packageJsonPath = path.join(repoDir, 'package.json');
+  const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+  packageJson.name = 'demo-failed-auto-transfer';
+  fs.writeFileSync(packageJsonPath, `${JSON.stringify(packageJson, null, 2)}\n`, 'utf8');
+  fs.mkdirSync(path.join(repoDir, 'memory-bank'), { recursive: true });
+  fs.writeFileSync(path.join(repoDir, 'memory-bank', 'note.md'), 'keep me local\n', 'utf8');
+
+  result = runBranchStart(['fail-after-auto-transfer', 'bot'], repoDir, {
+    GUARDEX_TEST_FAIL_AFTER_AUTO_TRANSFER_STASH: '1',
+  });
+  assert.equal(result.status, 1, 'branch start should fail after the simulated post-stash error');
+  assert.match(result.stderr, /Simulated failure after capturing auto-transfer stash/);
+  assert.match(result.stderr, /Restored moved changes back to 'main' after startup failure/);
+
+  const rootStatus = runCmd('git', ['status', '--short'], repoDir);
+  assert.equal(rootStatus.status, 0, rootStatus.stderr || rootStatus.stdout);
+  assert.match(rootStatus.stdout, / M package\.json/);
+  assert.match(rootStatus.stdout, /\?\? memory-bank\//);
+
+  const stashList = runCmd('git', ['stash', 'list'], repoDir);
+  assert.equal(stashList.status, 0, stashList.stderr || stashList.stdout);
+  assert.doesNotMatch(stashList.stdout, /guardex-auto-transfer-/);
+});
+
 
 test('agent-branch-start leaves removed workflow helpers out of new worktrees', () => {
   const repoDir = initRepo();