feat(agents): add Grok Build as a first-class ACP runtime

TESTING.md

@@ -179,8 +179,8 @@ header fallback. There is no REST API for fetching message threads — use
 
 ## ACP Harness (optional, end-to-end with a real agent)
 
-`buzz-acp` connects an ACP-speaking agent (goose, codex, claude code,
-buzz-agent) to the relay. The harness listens for events, drives the
+`buzz-acp` connects an ACP-speaking agent (goose, grok build, codex,
+claude code, buzz-agent) to the relay. The harness listens for events, drives the
 agent over stdio, and the agent replies through MCP tools.
 
 Minimum recipe — assumes the relay from step 3 is running and the channel
@@ -221,10 +221,12 @@ buzz-acp                                    # foreground; logs to stdout (run in
 ```
 
 > **Using a different ACP agent?** The default recipe assumes `goose` is on
-> `$PATH` and configured (`goose --version` should print). For codex / claude
-> code / buzz-agent, set `BUZZ_ACP_AGENT_COMMAND` and `BUZZ_ACP_AGENT_ARGS`
-> accordingly — see `crates/buzz-acp/README.md`. Without these, buzz-acp
-> will fail to spawn the agent subprocess on startup.
+> `$PATH` and configured (`goose --version` should print). For grok build /
+> codex / claude code / buzz-agent, set `BUZZ_ACP_AGENT_COMMAND` and
+> `BUZZ_ACP_AGENT_ARGS` accordingly — see `crates/buzz-acp/README.md`
+> (grok build: `BUZZ_ACP_AGENT_COMMAND=grok` with args
+> `agent --always-approve stdio`). Without these, buzz-acp will fail to
+> spawn the agent subprocess on startup.
 
 If you started the agent before adding it to the channel, just run the
 `add-member` afterwards — it picks up the membership notification live and

crates/buzz-acp/README.md

@@ -9,7 +9,7 @@ Buzz Relay ──WS──→ buzz-acp ──stdio──→ Your Agent
                                        (send_message, etc.)
 ```
 
-Supports any agent that speaks [ACP](https://agentclientprotocol.com/) over stdio: **goose**, **codex** (via [codex-acp](https://github.com/agentclientprotocol/codex-acp)), and **claude code** (via [claude-agent-acp](https://github.com/agentclientprotocol/claude-agent-acp)).
+Supports any agent that speaks [ACP](https://agentclientprotocol.com/) over stdio: **goose**, **grok build** (native, via `grok agent stdio`), **codex** (via [codex-acp](https://github.com/agentclientprotocol/codex-acp)), and **claude code** (via [claude-agent-acp](https://github.com/agentclientprotocol/claude-agent-acp)).
 
 ## Prerequisites
 

crates/buzz-acp/src/config.rs

@@ -617,6 +617,14 @@ pub(crate) fn normalize_agent_command_identity(command: &str) -> String {
 fn default_agent_args(command: &str) -> Option<Vec<String>> {
     match normalize_agent_command_identity(command).as_str() {
         "goose" => Some(vec!["acp".to_string()]),
+        // `--always-approve` is intentional: Buzz owns the approval layer for
+        // managed agents, so Grok-side tool prompts would deadlock a headless
+        // stdio session.
+        "grok" | "grok-build" => Some(vec![
+            "agent".to_string(),
+            "--always-approve".to_string(),
+            "stdio".to_string(),
+        ]),
         "codex" | "codex-acp" | "claude-agent-acp" | "claude-code-acp" | "claude-code"
         | "claudecode" | "buzz-agent" => Some(Vec::new()),
         _ => None,
@@ -1440,6 +1448,19 @@ mod tests {
         assert_eq!(normalize_agent_args("goose", vec!["".into()]), vec!["acp"]);
     }
 
+    #[test]
+    fn normalizes_grok_args_to_stdio_default() {
+        let expected = vec!["agent", "--always-approve", "stdio"];
+        assert_eq!(normalize_agent_args("grok", Vec::new()), expected);
+        assert_eq!(normalize_agent_args("grok", vec!["".into()]), expected);
+        assert_eq!(normalize_agent_args("grok-build", Vec::new()), expected);
+        // Explicit args are preserved verbatim — no default-arg injection.
+        assert_eq!(
+            normalize_agent_args("grok", vec!["agent".into(), "stdio".into()]),
+            vec!["agent", "stdio"]
+        );
+    }
+
     #[test]
     fn normalizes_codex_and_claude_args_to_empty() {
         assert_eq!(

crates/buzz-acp/src/lib.rs

@@ -60,7 +60,12 @@ fn is_subcommand(name: &str) -> bool {
 }
 
 /// Timeout for lightweight helper subcommands (spawn + initialize + model/method probes).
-const MODELS_TIMEOUT: Duration = Duration::from_secs(10);
+///
+/// 30s rather than 10s: some agents boot every user-configured MCP server
+/// during `session/new` (observed with Grok Build, where a handful of stdio
+/// MCP servers pushed session creation past 10s on a real machine). The
+/// happy path is unaffected — fast agents still return in ~2-5s.
+const MODELS_TIMEOUT: Duration = Duration::from_secs(30);
 
 /// Timeout for `buzz-acp authenticate`. Browser-based vendor auth can require
 /// human interaction, so it must not share the short probe timeout.

desktop/src-tauri/src/managed_agents/discovery.rs

@@ -17,6 +17,7 @@ pub(crate) use runtime_metadata::KnownAcpRuntime;
 const GOOSE_AVATAR_URL: &str = "https://goose-docs.ai/img/logo_dark.png";
 const CLAUDE_CODE_AVATAR_URL: &str = "https://anthropic.gallerycdn.vsassets.io/extensions/anthropic/claude-code/2.1.77/1773707456892/Microsoft.VisualStudio.Services.Icons.Default";
 const CODEX_AVATAR_URL: &str = "https://openai.gallerycdn.vsassets.io/extensions/openai/chatgpt/26.5313.41514/1773706730621/Microsoft.VisualStudio.Services.Icons.Default";
+const GROK_AVATAR_URL: &str = "https://x.ai/icon.png";
 const BUZZ_AGENT_AVATAR_URL: &str =
     "https://raw.githubusercontent.com/block/buzz/refs/heads/main/crates/buzz-agent/buzz-agent.png";
 
@@ -41,6 +42,7 @@ fn common_binary_paths() -> &'static [PathBuf] {
                 home.join(".local/bin"),
                 home.join(".volta/bin"),
                 home.join(".asdf/shims"),
+                home.join(".grok/bin"),
             ]);
         }
         // Windows well-known dirs for npm global shims and standalone installer targets.
@@ -163,6 +165,43 @@ const KNOWN_ACP_RUNTIMES: &[KnownAcpRuntime] = &[
         // Verified: `codex login status` exits 0 when logged in, non-zero otherwise.
         auth_probe_args: Some(&["codex", "login", "status"]),
     },
+    KnownAcpRuntime {
+        id: "grok",
+        label: "Grok Build",
+        commands: &["grok"],
+        aliases: &["grok-build"],
+        avatar_url: GROK_AVATAR_URL,
+        mcp_command: None,
+        mcp_hooks: false,
+        underlying_cli: Some("grok"),
+        cli_install_commands: &["curl -fsSL https://x.ai/cli/install.sh | bash"],
+        // No official PowerShell installer documented yet; Windows users get
+        // the Unix command as a hint alongside the instructions URL.
+        cli_install_commands_windows: &[],
+        adapter_install_commands: &[],
+        cli_install_instructions_url: "https://x.ai/cli",
+        adapter_install_instructions_url: "",
+        cli_install_hint: "Buzz requires the Grok CLI; `grok agent stdio` provides the ACP server.",
+        adapter_install_hint: "",
+        skill_dir: Some(".grok/skills"),
+        supports_acp_model_switching: false,
+        model_env_var: None,
+        provider_env_var: None,
+        provider_locked: true,
+        default_env: &[],
+        config_file_path: None,
+        config_file_format: None,
+        supports_acp_native_config: false,
+        thinking_env_var: None,
+        max_tokens_env_var: None,
+        context_limit_env_var: None,
+        required_normalized_fields: &[],
+        login_hint: Some("Run `grok login` (or set XAI_API_KEY) to authenticate."),
+        // Grok 0.2.x has no verified non-interactive auth-status command
+        // (`grok models` exits 0 when logged in, but the logged-out exit code
+        // is unverified), so the probe is intentionally omitted.
+        auth_probe_args: None,
+    },
     KnownAcpRuntime {
         id: "buzz-agent",
         label: "Buzz Agent",
@@ -457,6 +496,14 @@ pub fn try_record_agent_command(
 fn default_agent_args(command: &str) -> Option<Vec<String>> {
     match normalize_command_identity(command).as_str() {
         "goose" => Some(vec!["acp".to_string()]),
+        // `--always-approve` is intentional: Buzz owns the approval layer for
+        // managed agents, so Grok-side tool prompts would deadlock a headless
+        // stdio session.
+        "grok" | "grok-build" => Some(vec![
+            "agent".to_string(),
+            "--always-approve".to_string(),
+            "stdio".to_string(),
+        ]),
         "codex" | "codex-acp" | "claude-agent-acp" | "claude-code-acp" | "claude-code"
         | "claudecode" | "buzz-agent" => Some(Vec::new()),
         _ => None,

desktop/src-tauri/src/managed_agents/discovery/tests.rs

@@ -8,7 +8,7 @@ use super::{
     is_login_shell_path_uninit, is_safe_nvm_tag, managed_agent_avatar_url, normalize_agent_args,
     parse_semver_tag, preset_catalog_entry, probe_codex_acp_major_version, record_agent_command,
     refresh_login_shell_path, try_record_agent_command, PresetHarness, BUZZ_AGENT_AVATAR_URL,
-    CLAUDE_CODE_AVATAR_URL, CODEX_AVATAR_URL, GOOSE_AVATAR_URL,
+    CLAUDE_CODE_AVATAR_URL, CODEX_AVATAR_URL, GOOSE_AVATAR_URL, GROK_AVATAR_URL,
 };
 use crate::managed_agents::AcpAvailabilityStatus;
 
@@ -72,6 +72,44 @@ fn normalizes_claude_and_codex_args_to_empty() {
     );
 }
 
+#[test]
+fn normalizes_grok_args_to_stdio_default() {
+    let expected = vec![
+        "agent".to_string(),
+        "--always-approve".to_string(),
+        "stdio".to_string(),
+    ];
+    // Empty args resolve to the full agent-mode invocation.
+    assert_eq!(normalize_agent_args("grok", Vec::new()), expected);
+    // Path and alias forms normalize to the same identity.
+    assert_eq!(
+        normalize_agent_args("/home/dev/.grok/bin/grok", Vec::new()),
+        expected
+    );
+    assert_eq!(normalize_agent_args("grok-build", Vec::new()), expected);
+    // Explicit args are preserved verbatim — no default-arg injection.
+    assert_eq!(
+        normalize_agent_args("grok", vec!["agent".into(), "stdio".into()]),
+        vec!["agent".to_string(), "stdio".to_string()]
+    );
+}
+
+#[test]
+fn resolves_grok_avatar() {
+    assert_eq!(
+        managed_agent_avatar_url("grok"),
+        Some(GROK_AVATAR_URL.to_string())
+    );
+    assert_eq!(
+        managed_agent_avatar_url("/home/dev/.grok/bin/grok"),
+        Some(GROK_AVATAR_URL.to_string())
+    );
+    assert_eq!(
+        managed_agent_avatar_url("grok-build"),
+        Some(GROK_AVATAR_URL.to_string())
+    );
+}
+
 #[test]
 fn resolves_buzz_agent_avatar() {
     assert_eq!(

desktop/src/features/agents/ui/personaRuntimeModel.test.mjs

@@ -195,6 +195,7 @@ test("resolveRuntimeProviderCapability classifies known CLI-login runtimes as lo
   // The core fix: a not-yet-loaded catalog must not force these to "unknown".
   assert.equal(resolveRuntimeProviderCapability("claude", false), "locked");
   assert.equal(resolveRuntimeProviderCapability("codex", false), "locked");
+  assert.equal(resolveRuntimeProviderCapability("grok", false), "locked");
   assert.equal(resolveRuntimeProviderCapability(" claude ", false), "locked");
 });
 

desktop/src/features/agents/ui/personaRuntimeModel.ts

@@ -18,7 +18,8 @@ export type ProviderRuntimeCapability = "capable" | "locked" | "unknown";
  * provider. To avoid that, we resolve capability STATICALLY for known ids:
  *
  * - buzz-agent / goose → "capable" (`isProviderCapable`, id-based).
- * - claude / codex → "locked" (CLI-login runtimes; no LLM provider selection).
+ * - claude / codex / grok → "locked" (CLI-login runtimes; no LLM provider
+ *   selection).
  * - anything else (custom, empty, genuinely unknown) → "unknown".
  *
  * `isProviderCapable` is the caller-supplied {@link
@@ -33,7 +34,7 @@ export function resolveRuntimeProviderCapability(
     return "capable";
   }
   const id = runtimeId.trim();
-  if (id === "claude" || id === "codex") {
+  if (id === "claude" || id === "codex" || id === "grok") {
     return "locked";
   }
   return "unknown";