Mods reference

Look up any event a mod can handle, mods API method it can call, or render site it can draw in. Entries cover the Claude Code CLI and the Desktop app as of v2.1.290, and the VS Code extension as of v2.1.299. Each entry gives the name and a one-line description, and links to the guide section that explains it where there is one.

The complete reference is Claude Code’s TypeScript declarations for mods, which describe every event, method, and element, with examples. The copy on GitHub can be older than the Claude Code version you have installed. When the two disagree, trust the copy Claude Code writes for your version.

Files

A mod is a plugin directory with these files:

File	Required	Contents
`.claude-plugin/plugin.json`	Yes	The plugin manifest. Mods add no required fields.
`hooks/hooks.json`	Yes	`modules`: an array with one path, relative to this file, to the hooks module, as in `"modules": ["./register.js"]`. Can also hold settings hooks under `hooks`.
The hooks module, such as `hooks/register.js`	Yes	The mod’s entry point. Exports `register(on, options)`. Named `.js`, `.mjs`, `.cjs`, `.jsx`, `.ts`, `.mts`, `.cts`, or `.tsx`. An ES module.
`types/index.d.ts`, unless `types` in the manifest names another path	When the mod uses `$.state` or adds a namespace to the mods API	Declares `PluginState` values and any namespace the mod adds. To leave `types` out of the manifest, you need v2.1.299 or later.
Files whose names end in `.test.ts` or `.test.tsx`	No	Tests that `claude plugin test` runs

register receives on and options. options holds the values of the userConfig fields the manifest declares, with defaults filled in.

The hook function

A mod registers each of its hooks, which are event handlers, by calling on inside register. on takes the event’s name, an optional matcher, which is a filter on the event’s fields, and the hook, as in on('tool.call', { tool: 'Bash' }, async ($, e, next) => next(e)). on returns a registration with one method, .catch(handler), which sets the hook’s error handler.

Argument	What it is
`$`	The mods API: every method in mods API methods. Write each call in full, namespace then method, as in `$.fs.read('notes.md')`.
`e`	The event’s input, as deeply frozen plain data. To change it, pass a copy to `next`.
`next(e)`	The next handler, as in middleware. Runs the hooks after this one, then Claude Code’s behavior. Resolves to the event’s result.
`next.signal`	An `AbortSignal` that aborts when the event is abandoned
`next.origin`	`{ plugin, tier }` of whoever fired the event. Claude Code itself is `{ plugin: 'engine', tier: 'core' }`. A mod’s `tier` is its priority group in the order mods run in: `prepend`, `user`, `append`, or `builtin`.
`next.budget`	The hook’s time limit in milliseconds: `next.budget.ms` is the whole limit, and `next.budget.remainingMs` is what’s left now
`next.to(e, tier)`	Skips to a later tier, which is `append`, `builtin`, or `core`. `next.to(e, 'append')` skips the mods a user installed. Only a mod in `prependPlugins` or `appendPlugins` can call it.
`next.error`	In a `.catch` handler only. `kind` is `throw` or `timeout` when the hook failed, and `message` is the error’s text. `kind` is `re-entry` when the hook was skipped because the event came from inside a mods API call by that hook or by your mod’s code outside its hooks. `re-entry` requires Claude Code v2.1.292 or later.
`next.error.cause`	Set only when `kind` is `re-entry`. `rewritten` if a `tool.call` or `PreToolUse` hook changed the mods API call the event came from, or an `agent.spawn` hook changed an agent started by that call. `lent` when a method another mod adds to the mods API fired that event, unless `rewritten` also applies. `lent` requires Claude Code v2.1.292 or later and `rewritten` v2.1.300 or later.
`next.called`	In a `.catch` handler only. `true` when the hook had called `next`.

Events

Events are grouped by what they concern, each with when it fires and what a hook on it can return. Hooks on turn.step and process.spawn are async generators, and other hooks are async functions. The last column of each table uses shorthand. next(e) passes the event on unchanged. next({ ...e, text }) passes on a copy with the named field changed, as in next({ ...e, text: e.text.trim() }). An object answers the event without calling next, and a word such as reason stands for a string you write, as in { deny: 'Use the file tools.' }.

Tools

Tool events fire around each tool call Claude makes, from the description Claude reads to the decision on whether the call runs:

Event	Fires when	A hook can return
`tool.call`	A tool is about to run	`next(e)`, `{ deny: reason }`, or `{ result }`
`tool.check`	Claude Code decides whether a tool call may run, after the `tool.call` and `PreToolUse` hooks. `next(e)` resolves to the decision the rules, the permission mode, and those hooks reached.	`next(e)` or `{ decision }`, with `decision` set to `allow`, `ask`, or `deny` and an optional `reason`
`tool.describe`	Once for each tool, when its description is first sent to Claude. A second time for an MCP tool when Claude loads it through tool search, with `e.description` set to the text Claude reads for the loaded tool.	`{ description }`, optionally with `isDeferred` set to `true` to put the tool behind tool search or `false` to load it upfront

Agent and organization fields on `tool.check`

In a tool.check hook, read these fields to tell a subagent’s call from the main conversation’s, and to see whether your organization requires approval for a connector tool:

e.agentId: set when a subagent or an in-process teammate makes the call, and absent when the main conversation does
e.ceiling: ask for a connector tool your organization set to ask, in sessions where that setting reaches Claude Code

On tool.check, e.agentId and e.ceiling require Claude Code v2.1.290 or later.

The `e.isReadOnly` field on `tool.check`

In a tool.check hook, e.isReadOnly is true when the tool reports this call as read-only. Otherwise the field is absent, not false. The value is the tool’s own report, so read Check whether a tool call is read-only before you approve a call on this field alone. On tool.check, e.isReadOnly requires Claude Code v2.1.304 or later.

Prompts and what Claude reads

Prompt events cover the text the user types and the text Claude Code sends to Claude on its own, such as the system prompt and reminders:

Event	Fires when	A hook can return
`prompt.submit`	A prompt is submitted	`next({ ...e, text })`, `next({ ...e, context })`, or `{ drop: reason }`
`prompt.fill`, `prompt.suggest`	Text is about to go into the prompt box as a draft, or as a dim suggestion	`next(e)` with changed text
`prompt.edit`	The user edits the prompt box	`next(e)`
`prompt.autocomplete`	The user types in the prompt box and a word ends at the cursor. `e.token` is that word. Claude Code doesn’t wait for the hook: its own autocomplete rows show first.	`{ suggestions }`, a list of `{ text, label, description }` rows shown below Claude Code’s own. Choosing a row writes its `text` over the word.
`prompt.compose`	Claude Code renders a system prompt	`{ sections }`, a list of `{ id, text, scope }` in the order they’re sent
`prompt.section`	Once for each named section of the system prompt. `e.name` is the section’s `id` in `prompt.compose`.	`{ text }`, or `{ text: null }` to omit the section
`prompt.context`	Once for each conversation, for the context sent with the first message	`{ blocks }`
`prompt.attachment`	Claude Code adds a message of its own for Claude, such as a reminder. `e.type` names the kind, and for the kinds the types declare, `e.detail` holds the facts the text was written from.	`{ text }`, or `{ text: null }` to omit it
`prompt.mention`	Claude Code is about to read a file that a prompt @-mentions. Requires Claude Code v2.1.290 or later.	`next({ ...e, path })` to read a different file, or `{ deny: reason }`
`skill.prompt`	A skill’s text is expanded for Claude	`{ text }`
`attribution.text`	Claude Code composes commit or pull request attribution text	`{ text }`

Source and frontmatter fields on `skill.prompt`

In a skill.prompt hook, you can read these fields along with the skill’s name in e.skill and the text Claude reads in e.text:

Field	Type	What it holds
`e.source`	string	Who provides the skill: `policySettings`, `userSettings`, or `projectSettings` for a skill in the enterprise, personal, or project location, respectively. Other sources give a word such as `plugin`, `mcp`, `syncedSkills`, or `built-in`.
`e.pluginName`	string	The plugin’s name, for a skill whose `e.source` is `plugin`
`e.path`	string	The absolute path of the skill’s `SKILL.md` file, or of its `.md` file for a skill written as a command file. Absent when the skill has no file on this machine, as with a built-in skill.
`e.frontmatter`	object	The frontmatter of the skill’s file, as plain data
`e.frontmatterProblem`	string	The reason `e.frontmatter` is missing the file’s frontmatter or one of its keys, as in `is a list or a single value, not a table`. Absent when `e.frontmatter` holds the whole frontmatter or the skill has none.

A hook can pass a changed text or frontmatter to next: the hooks after it read both, and Claude reads the final text. A hook that changes any other field fails. On skill.prompt, e.source, e.pluginName, e.path, e.frontmatter, and e.frontmatterProblem require Claude Code v2.1.299 or later.

Commands and configuration

Event	Fires when	A hook can return
`command.run`	A command is about to run	`{ text }`, `{}`, or `next(e)`
`command.describe`	Once for each command, for the command list	`{ description, argumentHint, isHidden }`
`config.set`	A `/config` row is about to change	`next({ ...e, value })` or `{ deny: reason }`
`config.describe`	Once for each `/config` row	`{ label, description, isHidden }`
`settings.read`	A mod calls `$.settings.read`, or Claude Code builds the session’s merged settings. Requires Claude Code v2.1.304 or later on Claude Code’s own read and for `e.layers`	`next(e)`, `{ value }`, or `{ deny: reason }`

`e.layers` and `e.source` on `settings.read`

e.layers: one { source, settings } object for each source in use that holds settings, lowest precedence first. See What a settings.read hook receives.
e.source: the one source a mod asked for, as in $.settings.read({ source: 'policy' }). Absent on Claude Code’s own read and on a read of the merged settings

Turns

Turn events follow one answer from start to finish, including each request to the model within it:

Event	Fires when	A hook can return
`turn.start`	A turn begins	`next(e)`
`turn.step`	One request is about to go to the model	`yield* next(e)`, or `next({ ...e, model })`, `next({ ...e, effort })`
`turn.complete`	A turn ended	`next(e)`, or `{ text }` to show a line under the answer

Session

Session events mark the session starting, ending, compacting, and exchanging messages with other sessions:

Event	Fires when	A hook can return
`session.start`	Once for each loaded mod, before the first prompt, and again after a reload of that mod. Not after `/clear`, `/resume`, or `/branch`.	`next(e)`
`session.end`	The session ends, or `/clear`, `/resume`, or `/branch` runs. `e.reason` is `clear`, `resume`, `logout`, `prompt_input_exit`, or `other`. `/branch` reports `resume`.	`next(e)`
`session.compact`	The conversation is about to be compacted	`{ skip: reason }`
`session.receive`, `session.send`	A message arrives from, or is about to go to, another agent or session. See Send and receive messages between sessions.	`{ consumed: reason }` for `receive`, `{ isDelivered: false, reason }` for `send`
`session.append`	Once for each row the conversation keeps, such as a prompt, a response block, a tool result, or a notice, before it’s stored	`next({ ...e, message })` with a changed `message.content`, to rewrite the row’s text blocks or the `content` of a `tool_result` block in it
`session.attach`, `session.detach`	Another app connects to or disconnects from the session	`next(e)`
`session.measure`	After each turn, and when a plan limit’s percent used changes	`next(e)`

Subagents

Subagent events fire when a subagent type is offered to Claude and when a subagent or an agent-team teammate is about to start:

Event	Fires when	A hook can return
`agent.offer`	A subagent type is offered to Claude	`{ isOffered: false }` to withhold it
`agent.spawn`	A subagent or an agent team teammate is about to start. For a teammate, `e.isTeammate` is `true`.	`next({ ...e, model })` to choose its model, or `{ deny: reason }`

When Claude resumes a subagent with the SendMessage tool, your agent.spawn hook doesn’t run again. To refuse the SendMessage calls that resume a subagent, match that tool in a tool.call hook.

Interface

Interface events fire when Claude Code draws a render site and when the user uses a control a mod drew. Draw in the interface shows what a ui.render hook returns:

Event	Fires when
`ui.render`	A render site is about to be drawn
`ui.resolve`	Mods load, once for each app, render site, and mod. The result is the element table that `$.ui.resolve(e)` reads.
`ui.press`, `ui.input`, `ui.select`	A `Button`, `Input`, or `Select` a mod drew is used
`ui.focus`, `ui.scroll`	The focused control or the scroll position of a pane or the band is about to change
`ui.close`	A pane is about to close. `e.id` is the pane and `e.origin.kind` is `plugin`, `person`, or `unload`.
`ui.message`	A `Client` element posts data to its mod
`ui.fault`	A `Client` element your mod drew failed to load, draw, or run. `e.phase` is `load`, `render`, or `run`, and `e.reason` is the error message. Requires Claude Code v2.1.289 or later.

Other mods

These events let a mod act on other mods as they load, to refuse one or change the mods API it receives:

Event	Fires when	A hook can return
`plugin.register`	A hooks module is about to load. `e.uses` lists its events, mods API calls, environment variables, and state, as `claude plugin validate` prints them. Each call is written without the `$.` prefix, such as `fs.read`.	`{ refuse: reason }`
`engine.create`	The mods API is being built for this mod	A changed mods API, to add a namespace. A mod outside the `user` tier can also withhold one.

When another mod’s hook calls a method on a namespace you added in engine.create, your method’s $ calls run in that hook’s context until every hook on that event returns. For example, a relative path resolves against that hook’s working directory, and $.prompt.submit rejects while the turn is waiting on that hook. Calls your method makes after that run in your mod’s own context.

Telemetry

Telemetry events fire for the usage records Claude Code logs:

Event	Fires when	A hook can return
`telemetry.log`, `telemetry.mark`	A telemetry record is about to be logged, or one use of a feature is marked. In a mod you install, give a telemetry hook the filter `{ to: 'collector' }`, as in `on('telemetry.log', { to: 'collector' }, hook)`. Without the filter, the mod fails `claude plugin validate`. `*` doesn’t match these events.	`next(e)`, or `{ deny: reason }`

Settings hook events

Each settings hook event is an event named classic.<Event>, such as classic.Stop or classic.PostToolUse. e is the hook’s stdin JSON.

Mods API calls

Every mods API method is also an event, named for its namespace and method, such as fs.read, model.complete, or ui.open. A hook on one intercepts calls from the mods that run after it, and can return next(e), { deny: reason }, or { value }.

Mods API methods

The mods API is the $ argument every hook receives. Its methods are grouped in namespaces, such as $.ui. This table lists each namespace’s methods by name, so open in the $.ui row is the call $.ui.open(...). The guides show the common ones in use, and the types for your build document every method with an example.

Namespace	Methods
`$.plugin`	`name`, `root`: this plugin’s name and directory
`$.ui`	`resolve`, `invalidate`, `open`, `close`, `panes`, `focus`, `scroll`, `toast`, `notify`, `status`, `log`, `notice`, `ask`, `copy`, `selection`, `blit`
`$.command`	`register`, `run`, `list`
`$.tool`	`register`, `call`, `check`, `list`
`$.agent`	`register`, `spawn`, `list`. `list()` returns this session’s subagents and teammates, each with a `status` of `pending`, `running`, `waiting`, `idle`, `completed`, `failed`, or `killed`, where `idle` and `waiting` require Claude Code v2.1.289 or later.
`$.model`	`complete`, `fork`, `classify`
`$.prompt`	`submit`, `read`, `fill`, `suggest`, `compose`. Claude reads text from `submit({ text })` after a sentence that names your mod as the sender. `submit({ text, asUser: true })` sends the text as the user’s own words, without that sentence.
`$.turn`	`abort`
`$.session`	`messages`, `cwd`, `root`, `model`, `turns`, `id`, `repo`, `surfaces`, `usage`, `version`, `compact`, `send`, `append`, `authorize`. `usage()` returns `{ startedAt, context, rateLimits, cost }`: `context` has `tokens`, `window`, and `percent`, and `rateLimits` is a list of `{ kind, percentUsed, resetsAt }`.
`$.config`	`list`, `set`
`$.settings`	`read`
`$.env`	`get`, `set`
`$.fs`	`read`, `write`, `list`, `exists`, `stat`, `ancestors`. `write` isn’t atomic: it replaces the file’s content in place, so another process can read a partly written file. Keep data that several sessions change in `$.store`.
`$.store`	`get`, `set`, `delete`, `keys`. A key-value store that every session on the machine shares. See Save from more than one session.
`$.state`	Reactive state: `get`, `set`, with the helpers `atom`, `read`, `update`, `derive`, and `memberOf` imported from `claude-code`
`$.clock`	`now`, `sleep`, `after`, `every`
`$.http`	`fetch`
`$.process`	`run`, `spawn`
`$.mcp`	`call`, `connect`. `connect(server)` connects an MCP server that your own plugin’s manifest lists.
`$.audio`	`play`, `speak`
`$.telemetry`	`log`, `mark`. A record is sent only when Claude Code or a built-in mod makes the call.

Render sites

A render site is an extension point in Claude Code’s interface. Each row is a value of e.component in a ui.render hook, with the fields of e.props and the apps that render it. e.surface names the app that’s drawing, such as terminal, desktop, or vscode. Change what Claude Code already draws shows what a hook can do at a site, with an example of each choice. Rendering in the VS Code extension requires extension version 2.1.299 or later. A session that doesn’t fetch feature flags needs 2.1.304 or later. Draw in the VS Code extension lists what the extension draws differently.

Site	`e.props`	`e.requestId`	Rendered on
`Pane`	`title`, `isFocused`, `bodyColumns`, `placement`, `scroll`, `view`	The pane’s `id`	Terminal, Desktop, VS Code
`AbovePrompt`	`hasSurvey`, `isWorking`, `maxRows`, `bodyColumns`, `scroll`, `view`	One instance	Terminal, Desktop
`UserMessage`	`text`, `origin`, `isExpanded`, and `task` or `from` by origin	The message id	Terminal, Desktop, VS Code
`AssistantMessage`	The reply’s text	The message id	Terminal, Desktop, VS Code
`ToolUse`, `ToolResult`, `ToolGroup`	The tool’s name, input, and result	The tool call id	Terminal, Desktop, VS Code
`CommandOutput`	`command`, `text`	The message id	Terminal, Desktop
`AskUserQuestion`	The question and options	The tool call id	Terminal, Desktop, VS Code
`ToolProgress`	`kind`	The tool call id	Terminal
`Spinner`	`word`, `message`, `suffix`, `mode`	The agent id	Terminal, Desktop, VS Code
`TurnDuration`	`word`, `durationMs`	The message id	Terminal
`InfoNotice`	`text`, `command`	The message id	Terminal
`SessionMode`	`modes`	One instance	Terminal, Desktop
`PromptHint`	`isDraft`, `isWorking`, `hint`	One instance	Terminal, Desktop

e.viewport holds columns, rows, and isFullscreen. In the terminal and the Desktop app, it’s absent until the app has measured its window. There, its rows is the height of the whole window, not of your pane. In the VS Code extension, it’s always present. To fit a tree to its site, read these props in the hook:

Width of a Pane or the band: draw to e.props.bodyColumns
Height of a Pane beside the transcript: where e.props.placement is 'dock', e.props.scroll.bodyRows is the number of rows the pane has for your tree
Height of a Pane above the prompt: where e.props.placement is 'inline', the pane grows with your tree up to a limit, and bodyRows is that limit. To ask for a different limit, see the rows field of $.ui.open.

A tree taller than the pane scrolls as a whole.

Elements

Elements are the building blocks of a tree a ui.render hook returns, and you get them from $.ui.resolve(e). Build a tree from elements shows the common ones with how the terminal draws them, and the interface gallery has screenshots of most. A check mark means the app can draw the element.

Element	Main props	Terminal	Desktop	VS Code
`Box`	`key`, flex layout, `gap`, `padding`, `margin`, `width`, `height`, `minWidth`, `minHeight`, `borderStyle`, `borderColor`, `borderDimColor`, `backgroundColor`, `position`, `top`, `left`, `right`, `bottom`, `overflow`, `display`, `hover`	✓	✓	✓
`Text`	`color`, `backgroundColor`, `bold`, `italic`, `underline`, `strikethrough`, `dimColor`, `inverse`, `wrap`, `size`, `weight`, `mono`, `tabular`, `hover`	✓	✓	✓
`Button`	`key`, `label`, `children`, `onPress`, `hotkey`, `plain`, `dimColor`, `autoFocus`, `action`, `variant`, `role`, `hover`	✓	✓	✓
`Link`	`href`, `label`. See Limits.	✓	✓	✓
`Code`	`source`, `language`, `path`, `startLine`, `format`, `wrap`	✓	✓	✓
`Markdown`	`text`, `key`, `dimColor`, `onLinkPress`, `pressableLinks`	✓	✓	✓
`Input`	`key`, `label`, `placeholder`, `value`, `submitLabel`, `rows`, `onSubmit`, `onInput`, `autoFocus`	✓	✓	✓
`Select`	`key`, `label`, `options`, `value`, `onSelect`, `autoFocus`	✓	✓	✓
`Svg`	a `source` of SVG markup up to 131,072 characters, `alt` text, `width`, `height`, and `isInteractive`		✓	✓
`Client`	`module`, `key`, `props`, `width`, `height`, `flexGrow`	✓	✓
`Raster`	`key`, `columns` up to 512, `rows` up to 256, `cells`. See Draw a grid of colored cells.	✓
`Image`	`key`, a `source` such as PNG or RGBA bytes up to 2 MiB, or a file path, `columns` and `rows` up to 255, and `alt` text. See which terminals draw it.	✓

More Button rules:

action: names one of Claude Code’s own keybinding actions, and the user’s binding for it presses the button when that binding is a chord or a modified key
Digit hotkeys on the band: a digit hotkey on a button in the band also fires when the user types that digit alone into an empty prompt and pauses
A collapsed band: while the band is collapsed, neither an action binding nor a hotkey presses a button in it
Two buttons on one hotkey: when two buttons in one drawing name the same hotkey, the later one gets it
variant: primary or secondary, and any other value throws. In the terminal, a primary button draws in the accent color unless it’s plain.
role: dismiss marks a close button, and any other value throws. Do the closing in your onPress. In a band that holds text and a row of buttons, the Desktop app can draw the row’s first dismiss button as its own close control. The terminal draws the button as it would without role.

A Button can hold children in place of a label:

What children can be: strings and Text elements, such as a name followed by a dim detail or a colored chip. Claude Code refuses any other element inside a Button.
Naming the button: the label names the button and defaults to the text of its children. Give a button with children other than one string a key or a label.
In the terminal: the children draw where the label would be, and a press anywhere on them counts as one press, so you can make each row of a list a single button
In the Desktop app and the VS Code extension: the button draws its label

A Button with children other than a single string requires Claude Code v2.1.295 or later.

autoFocus accepts only true on any control, so omit the prop to leave it off. The VS Code extension ignores some element props and draws the element as if you had left them out:

Box: position with its top, left, right, and bottom, alignSelf, borderDimColor, and hover
Text: size, mono, tabular, and hover
Button: hotkey, plain, autoFocus, action, and hover, so the user presses a button there with a click, or with Enter once it has focus. The extension also ignores variant and role.
Code: language, path, startLine, format, and wrap, so code draws without colors or line numbers, and a format: 'diff' block shows the diff’s raw text
Input and Select: autoFocus, and rows on an Input
Svg: isInteractive

`Box` border styles

To draw a border around a Box, set its borderStyle to one of these names, as in borderStyle: 'round'. Each row says what the terminal draws for that name and shows the top edge of the border.

`borderStyle`	What the terminal draws	Top edge
`'single'`	Thin lines with square corners	`┌──┐`
`'double'`	Double lines	`╔══╗`
`'round'`	Thin lines with rounded corners	`╭──╮`
`'bold'`	Thick lines	`┏━━┓`
`'singleDouble'`	Thin lines on the top and bottom, double lines on the sides	`╓──╖`
`'doubleSingle'`	Double lines on the top and bottom, thin lines on the sides	`╒══╕`
`'classic'`	The ASCII characters `+`, `-`, and `\|`	`+--+`
`'arrow'`	Arrows that point into the `Box`	`↘↓↓↙`
`'dashed'`	Dashed lines with blank corners	`╌╌`
`'quote'`	A bar, `▎`, down the left side and blank cells on the other three sides	Blank

A Box whose borderStyle names anything else, such as 'rounded', draws with no border.

`Box` spacing steps

The Box spacing props are gap, columnGap, rowGap, padding, margin, and the one-side and one-axis forms of padding and margin, such as paddingX and marginTop. Each takes a number of terminal cells such as gap: 1, or a step name such as gap: 'md'. In the terminal and the VS Code extension, each step is this many cells:

Step	Cells across	Cells down
`'xs'`	1	0
`'sm'`	1	0
`'md'`	2	1
`'lg'`	3	1
`'xl'`	4	2

If you set gap, padding, or margin to a step, the step applies across and down at once. For example, in the terminal and the VS Code extension, padding: 'md' is two cells at each side and one row above and below. Step names require Claude Code v2.1.299 or later. On an earlier release, a tree that uses a step name doesn’t draw.

`Text` typography props

Set size, weight, mono, or tabular on a Text to ask the app drawing your tree for a text size, a weight, a monospaced typeface, or equal-width digits. Before you rely on a prop, check what the terminal and the VS Code extension do with it. If an app ignores a prop you set, your tree still draws there, with the text as if you’d left that prop out.

Prop	Values	In the terminal	In the VS Code extension
`size`	`'caption'`, `'footnote'`, `'body'`, `'heading'`, or `'title'`	Ignored: the terminal has one text size	Ignored
`weight`	`'regular'`, `'medium'`, `'semibold'`, or `'bold'`	`semibold` and `bold` draw as bold text	`semibold` and `bold` draw as bold text
`mono`	`true` to ask for the app’s monospaced typeface	Ignored: the terminal is always monospaced	Ignored, so text keeps the extension’s own typeface
`tabular`	`true` to ask for digits of equal width, so that a number that updates in place or a column of numbers stays aligned	Ignored: the terminal’s digits are already one cell wide	Ignored

These four props require Claude Code v2.1.299 or later. On an earlier release, a tree that sets size, weight, mono, or tabular doesn’t draw.

Replace `bold` with `weight`

bold on a Text is deprecated in favor of weight and still works. To replace it on a Text with no weight, change bold: true to weight: 'semibold' for the same result on Claude Code v2.1.299 or later. On a release earlier than v2.1.299, a tree that sets weight doesn’t draw. If you set both bold and weight on a Text, bold has no effect.

Limits

Hooks and mods API calls run under time and size limits. Claude Code skips a hook that exceeds a time limit. A tree over the nesting, element, Raster cell, or Image byte limit isn’t drawn.

Limit	Value
A hook’s own execution time for one event, not counting time inside `next` or a mods API call other than `$.clock.sleep`	10 seconds, or 50 milliseconds for a `prompt.edit` hook
A `.catch` handler’s execution time	1 second
All `session.end` hooks together	As long as the SessionEnd hook budget, 1.5 seconds unless you change it, counted from when your settings `SessionEnd` hooks finish
`$.process.run` timeout	30 seconds by default, 10 minutes at most
`$.process.run` `stdout` and `stderr`	4 MiB each. `isStdoutTruncated` or `isStderrTruncated` is `true` when one was cut.
`$.model.complete` `maxTokens`	1024 by default, up to 64,000 or the model’s output limit
`$.fs.read` and `$.fs.write`	4 MiB for one file
A `$.http.fetch` request body	4 MiB, counted in characters. A call with a larger body rejects.
A `$.http.fetch` response body	4 MiB. `text` holds the first 4 MiB and the rest isn’t read. When the `Content-Length` header declares more, the call rejects instead, with a reason that ends `is over the 4194304-byte limit`, except when the last request after any redirects uses the `HEAD` method. The `HEAD` exemption requires Claude Code v2.1.296 or later.
One `$.http.fetch` call, redirects and body included	30 seconds
Redirects one `$.http.fetch` call follows	5
A hook’s `drop` reason or `config.set` `deny` reason	4,096 characters. The end of a longer reason is cut, and the drop or deny still applies. The cut requires Claude Code v2.1.292 or later, and on earlier versions the hook fails instead.
Text in one tree	The first 100,000 characters are drawn
A `Code`’s `language` or `path`, a `Select` option’s `value`, or a `Client`’s `module`	10,000 characters. If one is longer, the `ui.render` hook that returned it fails.
A `Link`’s `href`	2,048 characters. If it’s longer, the `ui.render` hook that returned it fails.
Nesting depth of one tree	32 levels below the root element
Elements and text children in one tree	20,000
`Raster` cells in one tree, each `Raster`’s `columns` times its `rows`	262,144
PNG or RGBA bytes of all the `Image`s in one tree	2 MiB
`$.store`	4 MiB of JSON in total
`$.session.messages()`	The newest 4,096 entries
`$.ui.invalidate('ui.render')` redraws	Throttled to 10 a second, or 30 in the terminal for the visible pane, the expanded band, and the hint line under the prompt. Calls that come sooner are coalesced.
`$.ui.toast`	Shown for 4 seconds unless you pass `{ timeoutMs }`. In the classic renderer, a mod’s newer toast can take the place of its older one that’s showing or waiting to show.
A pane opened without the user asking	Placed from 144 terminal columns, 110 after they’ve opened it once
Nesting depth of a mods API call’s arguments	28,000 levels. Past that, the call rejects with a message ending `nesting deeper than 28000 levels is not supported`. Requires Claude Code v2.1.299 or later.
Nesting depth of a changed event passed to `next`, outside async generator hooks such as one on `turn.step`	28,000 levels. Past that, `next` rejects with a message ending `nesting deeper than 28000 levels is not supported`. Requires Claude Code v2.1.299 or later.
Nesting depth of a hook’s return value, outside `ui.render`, `ui.resolve`, and async generator hooks	28,000 levels. Past that, the hook’s result is refused, and the notice that reports it includes `nesting deeper than 28000 levels is not supported`. Requires Claude Code v2.1.299 or later.
Scopes, such as functions, blocks, and loops, nested inside one another in one file of a hooks module	2,000
Command, tool, subagent type, and pane names	Letters, digits, `_`, and `-`, up to 64 characters
One `claude plugin test` test	5 seconds unless the test sets `timeoutMs`

Settings and environment variables

These are the settings and environment variables that affect mods. The Where column says which settings file or environment each one is read from:

Name	Where	What it does
`CLAUDE_CODE_PLUGIN_DIRS`	Environment, or `env` in `~/.claude/settings.json`	Plugin directories to load as `--plugin-dir` does, for apps you can’t pass a flag to. Absolute paths separated by `:`, or `;` on Windows.
`CLAUDE_CODE_PLUGIN_DIR_WATCH`	Environment	`1` makes a long-running non-interactive session reload `--plugin-dir` mods on save
`prependPlugins`, `appendPlugins`	Managed settings. User settings only on a machine with no managed settings, in a session whose credential isn’t a Team or Enterprise `/login`.	Lists of plugin ids, such as `acme-guard@acme-tools`. Mods in `prependPlugins` run before every mod a user installs, and mods in `appendPlugins` run after, in the listed order. See The order mods run in.
`allowManagedModsOnly`	Managed settings, as an option on the built-in guard	Only mods that count as your organization’s, and mods built into Claude Code, run their hooks. Users’ settings hooks keep running.
`allowModsToOverrideDenyRules`	Managed settings, as an option on the built-in guard	Lets a mod a user installed approve a tool call that a `deny` rule refuses
`allowManagedHooksOnly`	Managed settings	Blocks hooks and installed mods that aren’t your organization’s. See what keeps running.
`disableAllHooks`	Any settings file	In managed settings, no mod or hook from an installed plugin runs. In your own settings, what your organization manages keeps running. See `disableAllHooks`.
`disableSideloadFlags`	Managed settings	Rejects `--plugin-dir` and `--plugin-url` at startup
`pluginConfigs`	User or managed settings	Holds `userConfig` values for a mod, keyed by the plugin’s id, such as `acme-guard@acme-tools`, or its name and `@inline`, such as `first-mod@inline`, for one loaded with `--plugin-dir`

sec-default@builtin is a guard built into Claude Code, listed as cc-plugin-sec-default in /plugin and the debug log. It loads ahead of every mod a person installs on a machine with managed settings, or in a session whose credential is a Team or Enterprise /login. If managed prependPlugins is set, the guard loads only when that list names it, at the position listed. Its source is in the mods/sec-default directory of the Claude Code repository.

Commands

These commands and flags load, inspect, and test a mod. The claude commands run in your shell and the / commands at the Claude Code prompt. In the table, <directory> stands for a path you type, as in claude plugin validate ./first-mod. Square brackets mark an optional argument.

Command	What it does
`/plugin`	Shows a line such as `1 mod active · first-mod` under its tabs when a mod that isn’t built in has loaded
`claude plugin validate <directory>`	Reads a plugin’s manifest and hooks module and reports errors, the events it handles, and the mods API calls it makes. `--strict` treats warnings as errors and `--json` prints a machine-readable report.
`claude plugin test [directory]`	Runs every file under the directory, or the current directory when you give none, whose name ends in `.test.ts` or `.test.tsx`. Exits with status 1 when a test fails.
`claude --plugin-dir <directory>`	Loads a plugin directory for one session and reloads its hooks module when you save. Repeat the flag to load several.
`/reload-plugins`	Reloads plugins when you run it

Plugins

Use plugins

Create plugins

Mods

Run a marketplace

Manage plugins for your organization

Troubleshooting

Reference

Files

The hook function

Events

Tools

Agent and organization fields on `tool.check`

The `e.isReadOnly` field on `tool.check`

Prompts and what Claude reads

Source and frontmatter fields on `skill.prompt`

Commands and configuration

`e.layers` and `e.source` on `settings.read`

Turns

Session

Subagents

Interface

Other mods

Telemetry

Settings hook events

Mods API calls

Mods API methods

Render sites

Elements

`Box` border styles

`Box` spacing steps

`Text` typography props

Replace `bold` with `weight`

Limits

Settings and environment variables

Commands

​Files

​The hook function

​Events

​Tools

​Agent and organization fields on tool.check

​The e.isReadOnly field on tool.check

​Prompts and what Claude reads

​Source and frontmatter fields on skill.prompt

​Commands and configuration

​e.layers and e.source on settings.read

​Turns

​Session

​Subagents

​Interface

​Other mods

​Telemetry

​Settings hook events

​Mods API calls

​Mods API methods

​Render sites

​Elements

​Box border styles

​Box spacing steps

​Text typography props

​Replace bold with weight

​Limits

​Settings and environment variables

​Commands

Files

The hook function

Events

Tools

Agent and organization fields on `tool.check`

The `e.isReadOnly` field on `tool.check`

Prompts and what Claude reads

Source and frontmatter fields on `skill.prompt`

Commands and configuration

`e.layers` and `e.source` on `settings.read`

Turns

Session

Subagents

Interface

Other mods

Telemetry

Settings hook events

Mods API calls

Mods API methods

Render sites

Elements

`Box` border styles

`Box` spacing steps

`Text` typography props

Replace `bold` with `weight`

Limits

Settings and environment variables

Commands