diff --git a/action/action-agent.sh b/action/action-agent.sh
index d9daea5..87a3c5b 100755
--- a/action/action-agent.sh
+++ b/action/action-agent.sh
@@ -100,6 +100,7 @@ fi
 echo $$ > "$LOCKFILE"
 
 cleanup() {
+  local exit_code=$?
   # Kill lifetime watchdog if running
   if [ -n "${LIFETIME_WATCHDOG_PID:-}" ] && kill -0 "$LIFETIME_WATCHDOG_PID" 2>/dev/null; then
     kill "$LIFETIME_WATCHDOG_PID" 2>/dev/null || true
@@ -118,8 +119,14 @@ cleanup() {
   fi
   # Best-effort docker cleanup for containers started during this action
   (cd "${WORKTREE}" 2>/dev/null && docker compose down 2>/dev/null) || true
-  # Destroy the worktree — the runtime owns the lifecycle
-  cleanup_worktree
+  # Preserve worktree on crash for debugging; clean up on success
+  local final_phase=""
+  [ -f "$PHASE_FILE" ] && final_phase=$(head -1 "$PHASE_FILE" 2>/dev/null || true)
+  if [ "${final_phase:-}" = "PHASE:crashed" ] || [ "${_MONITOR_LOOP_EXIT:-}" = "crashed" ] || [ "$exit_code" -ne 0 ]; then
+    log "PRESERVED crashed worktree for debugging: $WORKTREE"
+  else
+    cleanup_worktree
+  fi
   rm -f "$PHASE_FILE" "${PHASE_FILE%.phase}.context" "$IMPL_SUMMARY_FILE" "$PREFLIGHT_RESULT"
 }
 trap cleanup EXIT
diff --git a/dev/phase-handler.sh b/dev/phase-handler.sh
index d2f3ce8..e1b06d6 100644
--- a/dev/phase-handler.sh
+++ b/dev/phase-handler.sh
@@ -817,8 +817,7 @@ $(printf '%s' "$REFUSAL_JSON" | head -c 2000)
       "session crashed unexpectedly — marking blocked" \
       "session crashed unexpectedly — marking blocked${PR_NUMBER:+ | PR <a href='${FORGE_WEB}/pulls/${PR_NUMBER}'>#${PR_NUMBER}</a>}"
     post_blocked_diagnostic "crashed"
-    [ -z "${PR_NUMBER:-}" ] && cleanup_worktree
-    [ -n "${PR_NUMBER:-}" ] && log "keeping worktree (PR #${PR_NUMBER} still open)"
+    log "PRESERVED crashed worktree for debugging: $WORKTREE"
     rm -f "$PHASE_FILE" "$IMPL_SUMMARY_FILE" "$THREAD_FILE" "${SCRATCH_FILE:-}" \
       "/tmp/ci-result-${PROJECT_NAME}-${ISSUE}.txt"
     [ -n "${PR_NUMBER:-}" ] && rm -f "/tmp/review-injected-${PROJECT_NAME}-${PR_NUMBER}"
diff --git a/lib/formula-session.sh b/lib/formula-session.sh
index b75ae80..37c3274 100644
--- a/lib/formula-session.sh
+++ b/lib/formula-session.sh
@@ -174,6 +174,53 @@ formula_phase_callback() {
   esac
 }
 
+# ── Stale crashed worktree cleanup ─────────────────────────────────────────
+
+# cleanup_stale_crashed_worktrees [MAX_AGE_HOURS]
+# Removes preserved crashed worktrees older than MAX_AGE_HOURS (default 24).
+# Scans /tmp for orphaned worktrees matching agent naming patterns.
+# Safe to call from any agent; intended for supervisor/gardener housekeeping.
+# Requires globals: PROJECT_REPO_ROOT.
+cleanup_stale_crashed_worktrees() {
+  local max_age_hours="${1:-24}"
+  local max_age_seconds=$((max_age_hours * 3600))
+  local now
+  now=$(date +%s)
+  local cleaned=0
+
+  # Collect active tmux pane working directories for safety check
+  local active_dirs=""
+  active_dirs=$(tmux list-panes -a -F '#{pane_current_path}' 2>/dev/null || true)
+
+  local wt_dir
+  for wt_dir in /tmp/*-worktree-* /tmp/action-*-[0-9]* /tmp/disinto-*; do
+    [ -d "$wt_dir" ] || continue
+    # Must be a git worktree (has .git file or directory)
+    [ -f "$wt_dir/.git" ] || [ -d "$wt_dir/.git" ] || continue
+
+    # Check age (use directory mtime)
+    local dir_mtime
+    dir_mtime=$(stat -c %Y "$wt_dir" 2>/dev/null || echo "$now")
+    local age=$((now - dir_mtime))
+    [ "$age" -lt "$max_age_seconds" ] && continue
+
+    # Skip if an active tmux pane is using this worktree
+    if [ -n "$active_dirs" ] && echo "$active_dirs" | grep -qF "$wt_dir"; then
+      continue
+    fi
+
+    # Remove the worktree
+    git -C "${PROJECT_REPO_ROOT}" worktree remove "$wt_dir" --force 2>/dev/null || rm -rf "$wt_dir"
+    log "cleaned stale crashed worktree: ${wt_dir} (age: $((age / 3600))h)"
+    cleaned=$((cleaned + 1))
+  done
+
+  # Prune any dangling worktree references
+  git -C "${PROJECT_REPO_ROOT}" worktree prune 2>/dev/null || true
+
+  [ "$cleaned" -gt 0 ] && log "cleaned ${cleaned} stale crashed worktree(s)"
+}
+
 # ── Scratch file helpers (compaction survival) ────────────────────────────
 
 # build_scratch_instruction SCRATCH_FILE
@@ -306,8 +353,12 @@ run_formula_and_monitor() {
 
   matrix_send "$agent_name" "${agent_name^} session finished (${FINAL_PHASE:-no phase})" 2>/dev/null || true
 
-  # Clean up per-agent worktree — "the runtime creates and destroys"
-  remove_formula_worktree
+  # Preserve worktree on crash for debugging; clean up on success
+  if [ "${_MONITOR_LOOP_EXIT:-}" = "crashed" ]; then
+    log "PRESERVED crashed worktree for debugging: ${_FORMULA_SESSION_WORKDIR:-}"
+  else
+    remove_formula_worktree
+  fi
 
   log "--- ${agent_name^} run done ---"
 }
diff --git a/supervisor/supervisor-run.sh b/supervisor/supervisor-run.sh
index 5b5c223..b4ac052 100755
--- a/supervisor/supervisor-run.sh
+++ b/supervisor/supervisor-run.sh
@@ -50,6 +50,9 @@ check_memory 2000
 
 log "--- Supervisor run start ---"
 
+# ── Housekeeping: clean up stale crashed worktrees (>24h) ────────────────
+cleanup_stale_crashed_worktrees 24
+
 # ── Collect pre-flight metrics ────────────────────────────────────────────
 log "Running preflight.sh"
 PREFLIGHT_OUTPUT=""