fix(continuous-learning-v2): add lazy-start observer logic (#508)

* feat(continuous-learning-v2): add lazy-start observer logic

Auto-starts observer when observer.enabled: true in config and no .observer.pid exists.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(continuous-learning-v2): address PR review concerns

- Use flock for atomic check-then-act to prevent race conditions
- Check both project-scoped AND global PID files before starting
- Support CLV2_CONFIG override for config file path
- Check disabled file in lazy-start logic
- Use double-check pattern after acquiring lock

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(observe.sh): address PR review comments

- Add stale PID cleanup via _CHECK_OBSERVER_RUNNING function
- Add macOS fallback using lockfile when flock unavailable
- Fix CLV2_CONFIG override: use EFFECTIVE_CONFIG for both check and read
- Use proper Python context manager (with open() as f)
- Deduplicate signaled PIDs to avoid duplicate USR1 signals

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(observe.sh): wrap macOS lockfile fallback in subshell with trap

- Wrap lockfile block in subshell so exit 0 only terminates that block
- Add trap for EXIT to clean up lock file on script interruption
- Add -l 30 (30 second expiry) to prevent permanent lock file stuck

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(observe.sh): address remaining PR review comments

- Validate PID is a positive integer before kill calls to prevent
  signaling invalid targets (e.g. -1 could signal all processes)
- Pass config path via env var instead of interpolating shell variable
  into Python -c string to prevent injection/breakage on special paths
- Check CLV2_CONFIG-derived directory for disabled file so disable
  guard respects the same config source as lazy-start

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

skills/continuous-learning-v2/hooks/observe.sh

@@ -83,10 +83,13 @@ fi
 
 CONFIG_DIR="${HOME}/.claude/homunculus"
 
-# Skip if disabled
+# Skip if disabled (check both default and CLV2_CONFIG-derived locations)
 if [ -f "$CONFIG_DIR/disabled" ]; then
   exit 0
 fi
+if [ -n "${CLV2_CONFIG:-}" ] && [ -f "$(dirname "$CLV2_CONFIG")/disabled" ]; then
+  exit 0
+fi
 
 # Prevent observe.sh from firing on non-human sessions to avoid:
 #   - ECC observing its own Haiku observer sessions (self-loop)
@@ -275,12 +278,109 @@ if parsed["output"] is not None:
 print(json.dumps(observation))
 ' >> "$OBSERVATIONS_FILE"
 
-# Signal observer if running (check both project-scoped and global observer)
+# Lazy-start observer if enabled but not running (first-time setup)
+# Use flock for atomic check-then-act to prevent race conditions
+# Fallback for macOS (no flock): use lockfile or skip
+LAZY_START_LOCK="${PROJECT_DIR}/.observer-start.lock"
+_CHECK_OBSERVER_RUNNING() {
+  local pid_file="$1"
+  if [ -f "$pid_file" ]; then
+    local pid
+    pid=$(cat "$pid_file" 2>/dev/null)
+    # Validate PID is a positive integer (>1) to prevent signaling invalid targets
+    case "$pid" in
+      ''|*[!0-9]*|0|1)
+        rm -f "$pid_file" 2>/dev/null || true
+        return 1
+        ;;
+    esac
+    if kill -0 "$pid" 2>/dev/null; then
+      return 0  # Process is alive
+    fi
+    # Stale PID file - remove it
+    rm -f "$pid_file" 2>/dev/null || true
+  fi
+  return 1  # No PID file or process dead
+}
+
+if [ -f "${CONFIG_DIR}/disabled" ]; then
+  OBSERVER_ENABLED=false
+else
+  OBSERVER_ENABLED=false
+  CONFIG_FILE="${SKILL_ROOT}/config.json"
+  # Allow CLV2_CONFIG override
+  if [ -n "${CLV2_CONFIG:-}" ]; then
+    CONFIG_FILE="$CLV2_CONFIG"
+  fi
+  # Use effective config path for both existence check and reading
+  EFFECTIVE_CONFIG="$CONFIG_FILE"
+  if [ -f "$EFFECTIVE_CONFIG" ] && [ -n "$PYTHON_CMD" ]; then
+    _enabled=$(CLV2_CONFIG_PATH="$EFFECTIVE_CONFIG" "$PYTHON_CMD" -c "
+import json, os
+with open(os.environ['CLV2_CONFIG_PATH']) as f:
+    cfg = json.load(f)
+print(str(cfg.get('observer', {}).get('enabled', False)).lower())
+" 2>/dev/null || echo "false")
+    if [ "$_enabled" = "true" ]; then
+      OBSERVER_ENABLED=true
+    fi
+  fi
+fi
+
+# Check both project-scoped AND global PID files (with stale PID recovery)
+if [ "$OBSERVER_ENABLED" = "true" ]; then
+  # Clean up stale PID files first
+  _CHECK_OBSERVER_RUNNING "${PROJECT_DIR}/.observer.pid" || true
+  _CHECK_OBSERVER_RUNNING "${CONFIG_DIR}/.observer.pid" || true
+
+  # Check if observer is now running after cleanup
+  if [ ! -f "${PROJECT_DIR}/.observer.pid" ] && [ ! -f "${CONFIG_DIR}/.observer.pid" ]; then
+    # Use flock if available (Linux), fallback for macOS
+    if command -v flock >/dev/null 2>&1; then
+      (
+        flock -n 9 || exit 0
+        # Double-check PID files after acquiring lock
+        _CHECK_OBSERVER_RUNNING "${PROJECT_DIR}/.observer.pid" || true
+        _CHECK_OBSERVER_RUNNING "${CONFIG_DIR}/.observer.pid" || true
+        if [ ! -f "${PROJECT_DIR}/.observer.pid" ] && [ ! -f "${CONFIG_DIR}/.observer.pid" ]; then
+          nohup "${SKILL_ROOT}/agents/start-observer.sh" start >/dev/null 2>&1 &
+        fi
+      ) 9>"$LAZY_START_LOCK"
+    else
+      # macOS fallback: use lockfile if available, otherwise skip
+      if command -v lockfile >/dev/null 2>&1; then
+        # Use subshell to isolate exit and add trap for cleanup
+        (
+          trap 'rm -f "$LAZY_START_LOCK" 2>/dev/null || true' EXIT
+          lockfile -r 1 -l 30 "$LAZY_START_LOCK" 2>/dev/null || exit 0
+          _CHECK_OBSERVER_RUNNING "${PROJECT_DIR}/.observer.pid" || true
+          _CHECK_OBSERVER_RUNNING "${CONFIG_DIR}/.observer.pid" || true
+          if [ ! -f "${PROJECT_DIR}/.observer.pid" ] && [ ! -f "${CONFIG_DIR}/.observer.pid" ]; then
+            nohup "${SKILL_ROOT}/agents/start-observer.sh" start >/dev/null 2>&1 &
+          fi
+          rm -f "$LAZY_START_LOCK" 2>/dev/null || true
+        )
+      fi
+    fi
+  fi
+fi
+
+# Signal observer if running (check both project-scoped and global observer, deduplicate)
+signaled_pids=" "
 for pid_file in "${PROJECT_DIR}/.observer.pid" "${CONFIG_DIR}/.observer.pid"; do
   if [ -f "$pid_file" ]; then
-    observer_pid=$(cat "$pid_file")
+    observer_pid=$(cat "$pid_file" 2>/dev/null || true)
+    # Validate PID is a positive integer (>1)
+    case "$observer_pid" in
+      ''|*[!0-9]*|0|1) rm -f "$pid_file" 2>/dev/null || true; continue ;;
+    esac
+    # Deduplicate: skip if already signaled this pass
+    case "$signaled_pids" in
+      *" $observer_pid "*) continue ;;
+    esac
     if kill -0 "$observer_pid" 2>/dev/null; then
       kill -USR1 "$observer_pid" 2>/dev/null || true
+      signaled_pids="${signaled_pids}${observer_pid} "
     fi
   fi
 done