Add XAI Grok to the AI panel (#1558)

Grok Build is added as one more entry in the agent discovery list, over ACP, like the others. Thanks @cfaulkingham.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

docs/agent-chat.md

@@ -1,7 +1,7 @@
 # Agent chat
 
 Agent chat is a side panel where you talk to a coding agent you already use (Claude Code,
-Codex, Gemini CLI, OpenCode and others), or to a model behind an OpenAI-compatible endpoint you
+Codex, Gemini CLI, OpenCode, Grok Build and others), or to a model behind an OpenAI-compatible endpoint you
 choose (Ollama or LM Studio on your computer, OpenAI, any other URL), and have it work on the
 design that's open. A coding agent runs on your computer under **your own account** with that
 agent: SolidCraft doesn't sell or proxy a model and needs no key for it. An endpoint's key, if
@@ -53,7 +53,7 @@ conversation starts with), its own permission setting, and **Remove** for the on
 
 SolidCraft looks for agents that speak the [Agent Client Protocol](https://agentclientprotocol.com)
 on your `PATH` and in the usual install folders a desktop app's `PATH` often misses (npm's
-global folder, nvm, Volta, bun, `~/.local/bin`, Homebrew, `%APPDATA%\npm`). For each one it
+global folder, nvm, Volta, bun, `~/.local/bin`, `~/.grok/bin`, Homebrew, `%APPDATA%\npm`). For each one it
 shows its **version** (from `--version`, given three seconds) and whether it looks **signed in**.
 SolidCraft only checks whether the agent's own login file (`~/.claude/.credentials.json`,
 `~/.codex/auth.json`, `~/.gemini/oauth_creds.json`, …) or one of its key variables exists. It never
@@ -66,12 +66,26 @@ the keychain, so SolidCraft doesn't guess there.
 | Codex | `npm install -g @agentclientprotocol/codex-acp` |
 | Gemini CLI | `npm install -g @google/gemini-cli` (it speaks ACP itself: `gemini --acp`) |
 | OpenCode | `npm install -g opencode-ai` (`opencode acp`) |
+| XAI Grok | [Grok Build installer](https://docs.x.ai/build/overview), then `grok login` (`grok agent stdio` speaks ACP) |
 | GitHub Copilot CLI, Qwen Code, goose | listed with their install command when missing |
 
 The panel lists agents that aren't installed with their install command and a **Copy** button.
 **Refresh** looks again after you install one. **Test** starts an agent briefly, asks it for a
 session and ends it again.
 
+### XAI Grok
+
+Install **Grok Build** and run `grok login` in a terminal to sign in with your Grok account.
+In SolidCraft, open **AI → Refresh**, select
+**XAI Grok**, then **Connect**. You can make it the default under
+**Preferences → AI → Agents**.
+
+SolidCraft reuses Grok Build's sign-in in `~/.grok/auth.json`; it checks only whether that file
+exists and does not read or copy its tokens. If sign-in is needed, the panel offers Grok's own
+sign-in methods. You can also run `grok login` again and reconnect. Grok controls model access
+and usage limits for your account. This connection does not require an API key in SolidCraft.
+Grok Build also supports `XAI_API_KEY` for users who choose API authentication.
+
 ### Add agent…
 
 - **Installed agent:** your own entry for an installed agent, for example with other arguments.