feat: adopt Ralph pattern — pipe to claude (no --print), working Stop hook

lib/hooks.sh

@@ -1,19 +1,50 @@
 #!/bin/bash
-# Stop hook management for Claude Code loop continuation.
+# Stop hook management for the agent loop.
 #
-# NOTE: Hooks are currently no-ops. The loop uses `claude --print` (non-interactive),
-# which runs to completion and exits naturally — no Stop hook is needed to signal
-# iteration boundaries. The install/remove interface is preserved so that a future
-# interactive mode can be added without changing loop.sh's call sites.
+# The Stop hook sends SIGINT to the loop's parent process when a claude session
+# finishes. This is how claude signals "I'm done" back to the bash loop —
+# the Ralph pattern (ghuntley.com/ralph).
 #
-# If interactive mode is added, the hook mechanism will need redesign: `kill -INT $PPID`
-# targets the hook runner's parent (Claude Code), not loop.sh. A sentinel-file or
-# named-pipe approach would be more reliable.
+# Without this hook, claude would exit to an interactive prompt instead of
+# returning control to the loop script.
+
+SETTINGS_FILE="${PROJECT_ROOT}/.claude/settings.local.json"
 
 install_hooks() {
-    :  # no-op — see note above
+    if [ ! -f "$SETTINGS_FILE" ]; then
+        mkdir -p "$(dirname "$SETTINGS_FILE")"
+        echo '{}' > "$SETTINGS_FILE"
+    fi
+
+    if command -v jq &>/dev/null; then
+        jq '.hooks.Stop = [{"matcher": "", "hooks": [{"type": "command", "command": "kill -INT $PPID || true"}]}]' \
+            "$SETTINGS_FILE" > "${SETTINGS_FILE}.tmp" && mv "${SETTINGS_FILE}.tmp" "$SETTINGS_FILE"
+    else
+        python3 -c "
+import json, os
+p = '$SETTINGS_FILE'
+s = json.load(open(p)) if os.path.exists(p) else {}
+s.setdefault('hooks', {})['Stop'] = [{'matcher': '', 'hooks': [{'type': 'command', 'command': 'kill -INT \$PPID || true'}]}]
+json.dump(s, open(p, 'w'), indent=2)
+"
+    fi
+    log "Stop hook installed"
 }
 
 remove_hooks() {
-    :  # no-op — see note above
+    if [ -f "$SETTINGS_FILE" ]; then
+        if command -v jq &>/dev/null; then
+            jq 'del(.hooks.Stop)' "$SETTINGS_FILE" > "${SETTINGS_FILE}.tmp" && mv "${SETTINGS_FILE}.tmp" "$SETTINGS_FILE"
+            jq 'if .hooks == {} then del(.hooks) else . end' "$SETTINGS_FILE" > "${SETTINGS_FILE}.tmp" && mv "${SETTINGS_FILE}.tmp" "$SETTINGS_FILE"
+        else
+            python3 -c "
+import json
+s = json.load(open('$SETTINGS_FILE'))
+s.get('hooks', {}).pop('Stop', None)
+if not s.get('hooks'): s.pop('hooks', None)
+json.dump(s, open('$SETTINGS_FILE', 'w'), indent=2)
+"
+        fi
+        log "Stop hook removed"
+    fi
 }