Hooks reference changedhooks
Nearest release: v2.1.295, published 4 hours before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Upstream edited this page at 8 Oct 2026 22:59 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 8 Oct 2026 23:07 UTC.
Upstream edited
Recorded here
Lines+16added
Lines−8removed
From line
1,159
where the diff opens
First seen
14 Aug 2026
this site's first read of the page
Recorded edits92to this page, all time
#### Reload skills that a hook installs
The whole hunk
from line 1159, old and new numbered
/
from line 1159
11591159
11601160#### SessionStart decision control
11611161
1162Claude Code adds stdout it [treats as plain text](#exit-code-0) to Claude's context. In addition to the [JSON output fields](#json-output) available to all hooks, you can return these event-specific fields:
1162A SessionStart hook can add context for Claude, supply the first user message, set the session title, watch files, and reload skills. Return the field for each one, in addition to the [JSON output fields](#json-output) available to all hooks:
11631163
11641164| Field | Description |
11651165| :- | :- |
11661166| `additionalContext` | String added to Claude's context at the start of the conversation, before the first prompt. See [Add context for Claude](#add-context-for-claude) for how the text is delivered and what to put in it |
1167| `initialUserMessage` | String used as the first user message of the session. Applies in [non-interactive mode](/docs/en/headless) with the `-p` flag, where it becomes the first turn even if no prompt is provided. If a prompt is provided, it follows as the next turn. Unlike `additionalContext`, which attaches to an existing turn, this creates the turn |
1168| `sessionTitle` | Sets the session title, with the same effect as `/rename`. Use to name sessions automatically from the launch folder, git branch, or worktree name. Applies when `source` is `"startup"`, `"resume"`, or `"fork"`; ignored on `"clear"` and `"compact"` |
1167| `initialUserMessage` | String used as the first user message of the session, in [non-interactive mode](/docs/en/headless) with the `-p` flag. It becomes the first turn even if you pass no prompt. A prompt you do pass follows as the next turn |
1168| `sessionTitle` | Sets the session title, with the same effect as `/rename`. Applies when `source` is `"startup"`, `"resume"`, or `"fork"` |
11691169| `watchPaths` | Array of absolute paths to watch for [FileChanged](#filechanged) events during this session |
1170| `reloadSkills` | Boolean. When `true`, Claude Code re-scans the [skill](/docs/en/skills) and command directories after the SessionStart hooks complete, so skills the hook installed are available in the same session, starting with the first prompt |
1170| `reloadSkills` | Boolean. When `true`, Claude Code re-scans the [skill](/docs/en/skills) and command directories after the SessionStart hooks complete. See [Reload skills that a hook installs](#reload-skills-that-a-hook-installs) |
11711171
1172This output adds context and names the session:
1173
11721174```json theme={null}
11731175{
11741176 "hookSpecificOutput": {
from line 1181
11791181}
11801182```
11811183
1182Since plain stdout already reaches Claude for this event, a hook that only loads context can print to stdout directly without building JSON. Use the JSON form when you need to combine context with other fields such as `sessionTitle`.
1184A hook that only adds context can print it without building JSON, because Claude Code adds a SessionStart hook's [plain-text stdout](#exit-code-0) to Claude's context.
11831185
1184Use `reloadSkills` when a SessionStart hook installs or updates skills. Skill discovery normally runs before SessionStart hooks finish, so files the hook writes into `~/.claude/skills/` or `.claude/skills/` would otherwise only appear in the next session. This example syncs a shared skills repository and requests the re-scan:
1186If your plugin's SessionStart hook supplies `initialUserMessage` or `sessionTitle`, install the plugin before the session starts. Claude Code ignores both fields from a plugin that finishes installing after the SessionStart hooks have run.
11851187
1188#### Reload skills that a hook installs
1189
1190To make skills that a SessionStart hook installs available in the same session, return `reloadSkills`. Skill discovery normally runs before SessionStart hooks finish, so without it, files a hook writes into `~/.claude/skills/` or `.claude/skills/` can be missing when the first prompt runs.
1191
1192This example syncs a shared skills repository and requests the re-scan:
1193
11861194```bash theme={null}
11871195#!/bin/bash
11881196
from line 1200
11921200echo '{"hookSpecificOutput": {"hookEventName": "SessionStart", "reloadSkills": true}}'
11931201```
11941202
1195The repository URL is a placeholder; replace it with your own skills repository. With the placeholder, the clone fails and prints a `fatal:` message to stderr. Stderr from a SessionStart hook that exits 0 is informational only, so the `reloadSkills` request still applies.
1203The repository URL is a placeholder. Replace it with your own skills repository.
11961204
11971205#### Persist environment variables
11981206
No line in this hunk matches that.