diff --git a/.woodpecker/agent-smoke.sh b/.woodpecker/agent-smoke.sh
index fe322ec..712fae0 100644
--- a/.woodpecker/agent-smoke.sh
+++ b/.woodpecker/agent-smoke.sh
@@ -60,9 +60,9 @@ get_candidates() {
         if (match(p, /^[a-z][a-zA-Z0-9_]*_[a-zA-Z0-9_]+/)) {
           word = substr(p, RSTART, RLENGTH)
           rest = substr(p, RSTART + RLENGTH, 1)
-          # Skip: case labels (word)), Python/jq patterns (word:),
+          # Skip: case labels (word) or word|), Python/jq patterns (word:),
           #        object method calls (word.method), assignments (word=)
-          if (rest == ")" || rest == ":" || rest == "." || rest == "=") continue
+          if (rest == ")" || rest == "|" || rest == ":" || rest == "." || rest == "=") continue
           print word
         }
       }
diff --git a/AGENTS.md b/AGENTS.md
index ca7096e..e0d9e12 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -232,7 +232,7 @@ sourced as needed.
 | `lib/load-project.sh` | Parses a `projects/*.toml` file into env vars (`PROJECT_NAME`, `CODEBERG_REPO`, `WOODPECKER_REPO_ID`, monitoring toggles, Matrix config, etc.). | env.sh (when `PROJECT_TOML` is set), supervisor-poll (per-project iteration) |
 | `lib/parse-deps.sh` | Extracts dependency issue numbers from an issue body (stdin → stdout, one number per line). Matches `## Dependencies` / `## Depends on` / `## Blocked by` sections and inline `depends on #N` patterns. Not sourced — executed via `bash lib/parse-deps.sh`. | dev-poll, supervisor-poll |
 | `lib/matrix_listener.sh` | Long-poll Matrix sync daemon. Dispatches thread replies to the correct agent via well-known files (`/tmp/{agent}-escalation-reply`). Handles supervisor, gardener, dev, review, vault, and action reply routing. Run as systemd service. | Standalone daemon |
-| `lib/agent-session.sh` | Shared tmux + Claude session helpers: `create_agent_session()`, `inject_formula()`, `agent_wait_for_claude_ready()`, `agent_inject_into_session()`, `agent_kill_session()`, `monitor_phase_loop()`, `read_phase()`. | dev-agent.sh, gardener-agent.sh |
+| `lib/agent-session.sh` | Shared tmux + Claude session helpers: `create_agent_session()`, `inject_formula()`, `agent_wait_for_claude_ready()`, `agent_inject_into_session()`, `agent_kill_session()`, `monitor_phase_loop()`, `read_phase()`. `monitor_phase_loop` sets `_MONITOR_LOOP_EXIT` to one of: `done`, `idle_timeout`, `idle_prompt` (Claude returned to `❯` for 3 consecutive polls without writing any phase — callback invoked with `PHASE:failed`, session already dead), `crashed`, or a `PHASE:*` string. Agents must handle `idle_prompt` in both their callback and their post-loop exit handler. | dev-agent.sh, gardener-agent.sh |
 
 ---
 
diff --git a/dev/dev-agent.sh b/dev/dev-agent.sh
index 6a5a2ea..aee14ee 100755
--- a/dev/dev-agent.sh
+++ b/dev/dev-agent.sh
@@ -714,12 +714,18 @@ monitor_phase_loop "$PHASE_FILE" "$IDLE_TIMEOUT" _on_phase_change
 
 # Handle exit reason from monitor_phase_loop
 case "${_MONITOR_LOOP_EXIT:-}" in
-  idle_timeout)
-    notify_ctx \
-      "session idle for 2h — killed. Escalating to gardener." \
-      "session idle for 2h — killed. Escalating to gardener.${PR_NUMBER:+ PR <a href='${CODEBERG_WEB}/pulls/${PR_NUMBER}'>#${PR_NUMBER}</a>}"
+  idle_timeout|idle_prompt)
+    if [ "${_MONITOR_LOOP_EXIT:-}" = "idle_prompt" ]; then
+      notify_ctx \
+        "session finished without phase signal — killed. Escalating to gardener." \
+        "session finished without phase signal — killed. Escalating to gardener.${PR_NUMBER:+ PR <a href='${CODEBERG_WEB}/pulls/${PR_NUMBER}'>#${PR_NUMBER}</a>}"
+    else
+      notify_ctx \
+        "session idle for 2h — killed. Escalating to gardener." \
+        "session idle for 2h — killed. Escalating to gardener.${PR_NUMBER:+ PR <a href='${CODEBERG_WEB}/pulls/${PR_NUMBER}'>#${PR_NUMBER}</a>}"
+    fi
     # Escalate: write to project-suffixed escalation file so gardener picks it up
-    echo "{\"issue\":${ISSUE},\"pr\":${PR_NUMBER:-0},\"reason\":\"idle_timeout\",\"ts\":\"$(date -u +%Y-%m-%dT%H:%M:%SZ)\"}" \
+    echo "{\"issue\":${ISSUE},\"pr\":${PR_NUMBER:-0},\"reason\":\"${_MONITOR_LOOP_EXIT:-idle_timeout}\",\"ts\":\"$(date -u +%Y-%m-%dT%H:%M:%SZ)\"}" \
       >> "${FACTORY_ROOT}/supervisor/escalations-${PROJECT_NAME}.jsonl"
     # Restore labels: remove in-progress, add backlog
     cleanup_labels
diff --git a/gardener/gardener-agent.sh b/gardener/gardener-agent.sh
index 7591cba..33ad66b 100644
--- a/gardener/gardener-agent.sh
+++ b/gardener/gardener-agent.sh
@@ -222,7 +222,7 @@ fi
 # ── Build prompt from formula + dynamic context ────────────────────────────
 log "Building gardener prompt from formula"
 
-PROMPT="You are the issue gardener for ${CODEBERG_REPO}. Work through the formula below — there is no time limit, run until PHASE:done.
+PROMPT="You are the issue gardener for ${CODEBERG_REPO}. Work through the formula below. You MUST write PHASE:done to '${PHASE_FILE}' when finished — the orchestrator will time you out if you return to the prompt without signalling.
 
 ${CONTEXT_SECTION}
 ## Formula
@@ -303,14 +303,23 @@ gardener_phase_callback() {
   esac
 }
 
-# No idle timeout — gardener runs until PHASE:done or PHASE:failed
-monitor_phase_loop "$PHASE_FILE" 999999 "gardener_phase_callback"
+monitor_phase_loop "$PHASE_FILE" 7200 "gardener_phase_callback"
 
 FINAL_PHASE=$(read_phase)
 log "Final phase: ${FINAL_PHASE:-none}"
 
 if [ "$FINAL_PHASE" != "PHASE:done" ]; then
-  log "gardener-agent finished without PHASE:done (phase: ${FINAL_PHASE:-none})"
+  case "${_MONITOR_LOOP_EXIT:-}" in
+    idle_prompt)
+      log "gardener-agent: Claude returned to prompt without writing phase signal — no phase file written"
+      ;;
+    idle_timeout)
+      log "gardener-agent: timed out after 2h with no phase signal"
+      ;;
+    *)
+      log "gardener-agent finished without PHASE:done (phase: ${FINAL_PHASE:-none}, exit: ${_MONITOR_LOOP_EXIT:-})"
+      ;;
+  esac
   exit 0
 fi
 
diff --git a/lib/agent-session.sh b/lib/agent-session.sh
index 11d819b..0292680 100644
--- a/lib/agent-session.sh
+++ b/lib/agent-session.sh
@@ -60,11 +60,16 @@ inject_formula() {
 }
 
 # Monitor a phase file, calling a callback on changes and handling idle timeout.
-# Sets _MONITOR_LOOP_EXIT to the exit reason (idle_timeout, done, failed, break).
+# Sets _MONITOR_LOOP_EXIT to the exit reason (idle_timeout, idle_prompt, done, failed, break).
 # Sets _MONITOR_SESSION to the resolved session name (arg 4 or $SESSION_NAME).
 #   Callbacks should reference _MONITOR_SESSION instead of $SESSION_NAME directly.
 # Args: phase_file idle_timeout_secs callback_fn [session_name]
 #   session_name — tmux session to health-check; falls back to $SESSION_NAME global
+#
+# Idle prompt detection: if Claude returns to the ❯ prompt for 3 consecutive polls
+# WITHOUT having written any phase signal, the session is killed and the callback is
+# invoked with "PHASE:failed".  This handles the case where Claude completes its work
+# but skips the phase protocol entirely.
 monitor_phase_loop() {
   local phase_file="$1"
   local idle_timeout="$2"
@@ -76,6 +81,7 @@ monitor_phase_loop() {
   local poll_interval="${PHASE_POLL_INTERVAL:-10}"
   local last_mtime=0
   local idle_elapsed=0
+  local idle_pane_count=0
 
   while true; do
     sleep "$poll_interval"
@@ -99,6 +105,7 @@ monitor_phase_loop() {
             return 1
           fi
           idle_elapsed=0
+          idle_pane_count=0
           continue
           ;;
       esac
@@ -117,6 +124,29 @@ monitor_phase_loop() {
         agent_kill_session "${_session}"
         return 0
       fi
+      # Idle prompt detection: Claude finished without writing a phase signal.
+      # Only fires when current_phase is empty (no phase ever written).
+      # Note: tmux capture-pane captures the full visible pane area, not just the
+      # last line.  Prior tool output containing ❯ (e.g. a zsh subshell prompt in
+      # Claude's output) could trigger a false positive — the same risk exists in
+      # agent_wait_for_claude_ready().  Requiring 3 consecutive polls (≥2 poll
+      # intervals of sustained idle) reduces but does not eliminate this risk.
+      if [ -z "$current_phase" ] && tmux has-session -t "${_session}" 2>/dev/null && \
+         tmux capture-pane -t "${_session}" -p 2>/dev/null | grep -q '❯'; then
+        idle_pane_count=$(( idle_pane_count + 1 ))
+        if [ "$idle_pane_count" -ge 3 ]; then
+          _MONITOR_LOOP_EXIT="idle_prompt"
+          # Session is already killed before the callback is invoked.
+          # Callbacks that handle PHASE:failed must not assume the session is alive.
+          agent_kill_session "${_session}"
+          if type "${callback}" &>/dev/null; then
+            "$callback" "PHASE:failed"
+          fi
+          return 0
+        fi
+      else
+        idle_pane_count=0
+      fi
       continue
     fi