> ## Documentation Index > Fetch the complete documentation index at: https://ccsafetynet.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Install CC Safety Net in Devin CLI > Install CC Safety Net in Devin CLI with one PreToolUse hook in config.json, see how the hook checks exec and write_to_process calls, remove it, and read the doctor messages for a broken config. Run `npx -y cc-safety-net@latest install --devin`. It adds one `PreToolUse` hook to Devin CLI's `config.json`, so every tool call reaches CC Safety Net first. Then run `npx cc-safety-net doctor` to confirm the hook is active. Devin CLI hooks fail open, which means a hook that times out or dies before it answers lets the call proceed. ## Install CC Safety Net in Devin CLI **1. Run the installer** ```bash theme={"dark"} npx -y cc-safety-net@latest install --devin ``` **2. Confirm the hook is active** ```bash theme={"dark"} npx cc-safety-net doctor ``` ## What the Devin CLI install changes The installer writes this managed entry into `hooks.PreToolUse` in Devin CLI's `config.json`: ```json theme={"dark"} { "hooks": [{ "type": "command", "command": "npx -y cc-safety-net hook --devin", "timeout": 30 }] } ``` The file is `$XDG_CONFIG_HOME/devin/config.json`, which defaults to `~/.config/devin/config.json`. On Windows it is `%APPDATA%\devin\config.json`. See [Where Devin CLI keeps its configuration](#where-devin-cli-keeps-its-configuration) for the exact rules. * The entry has no matcher, so every tool call reaches the hook, not only `exec`. * Install keeps every other key, hook event, and `PreToolUse` entry in the file. When `config.json` does not exist, install creates it with that one `hooks` key. * Devin CLI accepts comments and trailing commas in `config.json`. Install and uninstall write the file back as plain JSON, so your comments are lost. ## What the Devin CLI hook checks * `exec` is the only command tool. The hook detects its shell dialect. * The hook analyzes the text that `write_to_process` calls type into a running process. See [How the Devin CLI hook checks typed input](#how-the-devin-cli-hook-checks-typed-input). * For other tools, the hook inspects the tool input for protected paths. For an allowed call, the hook writes nothing, so Devin CLI's own permission prompt still applies. ### Which directory the Devin CLI hook analyzes commands in Devin CLI does not tell the hook the session's working directory, so the hook uses the directory it runs in. An `exec` call can name another directory in `workdir`, and the hook then analyzes the command there. * A relative `workdir` resolves against the session directory. * The `workdir` does not have to be inside the session directory. * The hook denies a `workdir` that is blank or not a string. * The hook denies a `workdir` that is not an existing directory, and the denial names that directory. ### How the Devin CLI hook checks typed input A `write_to_process` call types into a process that is already running. The hook analyzes the typed text from `text_input` or `bytes_input` as a shell command. A `text_input` of `y` with a `bytes_input` of `` analyzes `y`. The hook denies the call when it cannot know the line the receiving program runs: * Text arrives together with ``, ``, an arrow key, or a `` key. * `bytes_input` carries a `` key that Devin CLI does not document. * Both `text_input` and `bytes_input` carry text. Keys sent on their own, such as `` or ``, are not commands, and the hook does not analyze them. ## What happens when the Devin CLI check fails Devin CLI hooks fail open. Only exit code 2 or a `block` decision blocks a tool call. A timeout, a missing `npx`, or a hook process that dies before it answers lets the call proceed. An error the hook catches itself still blocks, because the hook answers `block` for it. ## Devin CLI coverage limits * **Project hooks.** CC Safety Net supports only the user-level `config.json` that install writes. Hooks in a project `.devin/hooks.v1.json` run with the repository root as their working directory, and Devin CLI gives the hook no way to correct for that. * **Split input.** The hook analyzes each `write_to_process` call on its own, so it does not check a command typed across several writes as one command. * **Devin Cloud.** CC Safety Net does not cover Devin Cloud sessions. * **Claude Code hooks.** Devin loads Claude Code hook files by default, so a CC Safety Net hook installed for Claude Code can also run in a Devin session. That only duplicates denials. ## Uninstall CC Safety Net from Devin CLI ```bash theme={"dark"} npx -y cc-safety-net@latest uninstall --devin ``` Uninstall removes only the managed handler and writes the file back. It never deletes `config.json`, even when `hooks.PreToolUse` ends up empty. When the file holds no managed handler, uninstall writes nothing and reports the hook as not installed. ## Where Devin CLI keeps its configuration Devin CLI lets you move its configuration directory. CC Safety Net follows the same override, so it still finds a relocated config: * `$XDG_CONFIG_HOME/devin` when `XDG_CONFIG_HOME` is set and not empty. * Otherwise `/.config/devin`. * On Windows, `%APPDATA%\devin`, or `\AppData\Roaming\devin` when `APPDATA` is unset or empty. The file is `config.json` in that directory. CC Safety Net uses the variable's value as written, with no `~` expansion. ## Troubleshoot Devin CLI When `config.json` has a problem, install stops and writes nothing. `doctor` prints the same message as `Error (Devin CLI): `, counts Devin CLI as not configured, and exits `1`. Fix the file, then run the install again. | Problem | Message | | - | - | | The file does not parse | `Failed to parse Devin CLI config : ` | | The root is not a JSON object | `Devin CLI config must be a JSON object` | | `hooks` is not an object | `Devin CLI config "hooks" must be an object` | | `hooks.PreToolUse` is not an array | `Devin CLI config "hooks.PreToolUse" must be an array` | If `doctor` warns about a changed hook entry, run the install again. [Managed hook drift](/docs/reference/cli/doctor.md#managed-hook-drift) lists the warnings. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.