pi-hooks

A Claude Code-compatible hooks runner for pi. Reads .pi/hooks.json from your project and maps SessionStart, PreToolUse, and Stop events to pi lifecycle events — matching Claude Code's hooks protocol including stdin JSON and stdout additionalContext capture.

Install

Requires the pi CLI.

From npm (recommended)

# Global (user) install — available in every project
pi install npm:@fyeeme/pi-hooks

# Project-local — written to .pi/settings.json, shareable with your team
pi install -l npm:@fyeeme/pi-hooks

# Pinned version — skipped by `pi update`
pi install npm:@fyeeme/pi-hooks@1.0.0

# Try it once without saving (current run only)
pi -e npm:@fyeeme/pi-hooks

From GitHub

Source: fyeeme/pi-packages.

# HTTPS shorthand
pi install git:github.com/fyeeme/pi-packages
# Pin to a tag or commit (skipped by `pi update`)
pi install git:github.com/fyeeme/pi-packages@v1.0.0
# Raw URL form
pi install https://github.com/fyeeme/pi-packages

See the Pi Packages guide on pi.dev for the full list of source types, scopes, and pi update behavior.

Configuration

Create .pi/hooks.json in your project root:

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "",
        "hooks": [
          {
            "type": "command",
            "command": "serena-hooks activate --client=claude-code"
          }
        ]
      }
    ],
    "PreToolUse": [
      {
        "matcher": "",
        "hooks": [
          {
            "type": "command",
            "command": "serena-hooks remind --client=claude-code"
          }
        ]
      },
      {
        "matcher": "plugin_serena_serena_.*",
        "hooks": [
          {
            "type": "command",
            "command": "serena-hooks auto-approve --client=claude-code"
          }
        ]
      }
    ],
    "Stop": [
      {
        "matcher": "",
        "hooks": [
          {
            "type": "command",
            "command": "serena-hooks cleanup --client=claude-code"
          }
        ]
      }
    ]
  }
}

Event Mapping

hooks.json event	pi event	Notes
SessionStart	session_start	Runs on session start/reload/switch. matcher matches the source (startup/resume/clear/...); empty matcher matches all. additionalContext is injected into the first user message via the context event.
PreToolUse	tool_call	Runs before each tool. matcher is a regex against the pi tool name. additionalContext is injected before the next LLM call. permissionDecision: "deny" or exit code 2 blocks the tool (terminate: true; in a single-tool / all-terminating batch this also skips the follow-up LLM call — requires pi >= 0.84.1).
Stop	session_shutdown	Runs on exit/reload/session switch. Cleanup only — decision: "block" is not honored (pi cannot prevent exit). Stop hooks are awaited, so a slow hook delays exit up to its timeout (default 60s); keep them fast.

Matcher semantics

matcher is a regex (Claude Code compatible), tested against the full tool name (PreToolUse) or session source (SessionStart):

• "" or "*" — match all
• "Edit|Write" — match either
• "Notebook.*" — prefix match
• "plugin_serena_serena_.*" — all serena tools

Breaking change from 1.0.x: matchers were previously interpreted as globs (*/?). If you upgraded, convert patterns like plugin_serena_serena_* → plugin_serena_serena_.*. Invalid regex matches nothing and warns once at first use (never throws).

Protocol

Commands receive Claude Code-compatible JSON on stdin (session_id is the pi session UUID; transcript_path is the conversation JSONL path):

{ "hook_event_name": "SessionStart", "session_id": "<uuid>", "transcript_path": "/path/to/session.jsonl", "cwd": "/proj", "permission_mode": "default", "source": "startup" }
{ "hook_event_name": "PreToolUse", "session_id": "<uuid>", "transcript_path": "...", "cwd": "/proj", "permission_mode": "default", "tool_name": "bash", "tool_input": {} }
{ "hook_event_name": "Stop", "session_id": "<uuid>", "transcript_path": "...", "cwd": "/proj", "permission_mode": "default" }

Commands may return JSON on stdout, or control flow via exit codes:

{ "hookSpecificOutput": { "additionalContext": "context injected into the conversation" } }
{ "hookSpecificOutput": { "hookEventName": "PreToolUse", "permissionDecision": "deny", "permissionDecisionReason": "blocked" } }

• exit code 0 with additionalContext → context injected.
• exit code 2 (PreToolUse) → tool call blocked (terminate: true); reason fed to the model. terminate skips the follow-up LLM call only when the denied call is in an all-terminating batch (pi >= 0.84.1, #7715); in a multi-tool batch the block always applies but the agent may continue.
• exit code 2 (Stop) → ignored (pi cannot block exit).
• other non-zero → logged, execution continues.
• non-JSON stdout → logged as a warning, ignored.
• each hook may set "timeout" (seconds, default 60); matching hooks run in parallel.

The additionalContext is injected into the pi conversation (appended to the last user message, never as a new turn).

MCP Tool Names

Pi names MCP tools as <serverName>_<toolName> (not mcp__server__tool like Claude Code), so target them with regex like plugin_serena_serena_.*. Check your actual tool names with /mcp in pi to set the correct matcher.

Config Override

Set PI_HOOKS_CONFIG env var to point to a custom config path.