Merge pull request #25892 from mdelapenya/docs/t3-code-integration

docs(sandboxes): add T3 Code SSH integration page

Author: dvdksn

content/manuals/ai/sandboxes/integrations/_index.md

@@ -77,6 +77,7 @@ For example, if you mount `/Users/bob/src/my-project`, select
 - [Cursor](cursor.md)
 - [Claude Desktop](claude-desktop.md)
 - [ChatGPT](chatgpt.md)
+- [T3 Code](t3-code.md)
 
 ## How SSH connections work
 

content/manuals/ai/sandboxes/integrations/t3-code.md

@@ -0,0 +1,91 @@
+---
+title: Connect T3 Code to a sandbox
+linkTitle: T3 Code
+weight: 50
+description: Run T3 Code against a Docker Sandbox over SSH.
+keywords: docker sandboxes, t3 code, remote ssh, remote development, sbx
+---
+
+{{< summary-bar feature_name="Docker Sandboxes SSH" >}}
+
+T3 Code's SSH integration lets the desktop app drive coding agents inside a
+sandbox. T3 Code has no dedicated Docker Sandboxes integration — it treats the
+sandbox as an ordinary SSH host, connects to it, and starts a T3 server inside
+that tunnels back to the app.
+
+## Prerequisites
+
+- SSH access set up. See [Editor and app integrations](_index.md#enable-ssh-access).
+- T3 Code installed.
+
+## Connect
+
+Confirm that you can connect to the sandbox from a terminal:
+
+```console
+$ ssh demo.sbx
+```
+
+In T3 Code, add an SSH environment and enter the sandbox hostname, such as
+`demo.sbx`, as the host. The first connection installs the T3 server inside
+the sandbox, so it can take a moment. Later connections are faster.
+
+Then add a new project, select the SSH environment from the list, and
+[choose the mounted workspace](_index.md#select-the-workspace-folder) as the
+project directory inside the sandbox.
+
+## Troubleshoot a server that never becomes ready
+
+T3 Code can fail to connect with an error like the following, wrapped here
+for readability. It concatenates the connection failure with npm's install
+output from inside the sandbox into a single error dialog:
+
+```text
+Could not prepare the SSH environment: ... SshCommandError: Connecting to
+sandbox "sandboxes"… Remote T3 server did not become ready on
+127.0.0.1:3773. npm WARN EBADENGINE Unsupported engine { package:
+'ini@7.0.0', required: { node: '^22.22.2 || ^24.15.0 || >=26.0.0' },
+current: { node: 'v22.22.1', npm: '9.2.0' } }
+```
+
+The `npm WARN EBADENGINE` lines warn about the transitive `ini` dependency.
+They aren't the cause of the failure — npm doesn't enforce engine
+requirements by default, so this warning alone doesn't stop the install.
+Check free disk space in the sandbox. A full disk can fail the T3 server
+install partway through, and T3 Code reports this the same way as a
+connection timeout:
+
+```console
+$ sbx exec <sandbox> -- df -h /
+```
+
+Free up space and reconnect if the sandbox is close to full.
+
+## Troubleshoot `turn/setPermissionMode failed`
+
+If your organization manages Claude Code with a policy file, a local T3 Code
+thread can fail to start with `turn/setPermissionMode failed`. T3 Code's
+default runtime mode is Full access, which maps to the Claude Agent SDK's
+`bypassPermissions` mode. A managed policy that disables that mode rejects
+the request.
+
+On macOS, check whether this applies to you:
+
+```console
+$ cat "/Library/Application Support/ClaudeCode/managed-settings.json"
+```
+
+If `permissions.disableBypassPermissionsMode` is set to `disable`, switch T3
+Code to a different runtime mode, such as Supervised, Auto-accept edits, or
+Auto, then start a new thread. The permission mode is captured once when a
+thread starts, so switching modes in an already-failing thread doesn't
+recover it.
+
+This restriction applies to the host running Claude Code, not to a sandbox.
+A thread connected to a sandbox isn't subject to the host's managed policy,
+so Full access works normally there.
+
+## Related
+
+- [Editor and app integrations](_index.md) — how SSH access works and how to
+  set it up