From fb9d09791ba6efaea6d9f9df44e1a04c32a23005 Mon Sep 17 00:00:00 2001
From: Madhu Korada <madhu.korada@nimble.ai>
Date: Tue, 28 Jul 2026 20:23:04 -0700
Subject: [PATCH] fix(acp): default Grok to ACP entrypoint args
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Empty agent_args on managed-agent records is intentional; spawn is
supposed to fill runtime defaults via normalize_agent_args. Grok was
missing from default_agent_args, so selecting Grok Build launched bare
`grok` (interactive TUI). Under the desktop (no controlling TTY) that
exits with ENXIO and every pool worker fails.

Also treat a sole legacy clap/env default of "acp" as omitted for known
runtimes, so `BUZZ_ACP_AGENT_COMMAND=grok` without explicit args does not
spawn `grok acp`.

- default_agent_args: grok → agent --always-approve stdio
- normalize: sole "acp" → runtime default
- tests for empty, path, and legacy-acp grok args

Fixes #3457

Signed-off-by: Madhu Korada <madhu.korada@nimble.ai>
---
 crates/buzz-acp/src/config.rs                 | 40 ++++++++++++++++---
 .../src-tauri/src/managed_agents/discovery.rs | 16 +++++++-
 .../src/managed_agents/discovery/tests.rs     | 25 ++++++++++++
 3 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/crates/buzz-acp/src/config.rs b/crates/buzz-acp/src/config.rs
index 19304bf186..8c6bbd302e 100644
--- a/crates/buzz-acp/src/config.rs
+++ b/crates/buzz-acp/src/config.rs
@@ -691,10 +691,19 @@ pub(crate) fn normalize_agent_command_identity(command: &str) -> String {
 }
 
 fn default_agent_args(command: &str) -> Option<Vec<String>> {
+    // Empty agent_args / clap's sole "acp" default must still launch Grok in
+    // ACP mode — bare `grok` opens the TUI and fails with ENXIO when Buzz has
+    // no controlling TTY (block/buzz#3457).
     match normalize_agent_command_identity(command).as_str() {
         "goose" => Some(vec!["acp".to_string()]),
         "codex" | "codex-acp" | "claude-agent-acp" | "claude-code-acp" | "claude-code"
         | "claudecode" | "buzz-agent" => Some(Vec::new()),
+        // Grok Build: `grok agent --always-approve stdio`
+        "grok" => Some(vec![
+            "agent".to_string(),
+            "--always-approve".to_string(),
+            "stdio".to_string(),
+        ]),
         _ => None,
     }
 }
@@ -786,11 +795,10 @@ pub fn normalize_agent_args(command: &str, agent_args: Vec<String>) -> Vec<Strin
         return default_args;
     }
 
-    // Older callers relied on the Goose-specific default even for runtimes like
-    // Codex and Claude. Treat that legacy fallback as "no args" for zero-arg
-    // providers so desktop- and env-based launches behave the same way.
-    if normalized.len() == 1 && normalized[0].eq_ignore_ascii_case("acp") && default_args.is_empty()
-    {
+    // Clap/env historically defaulted agent args to a sole `"acp"` (Goose's
+    // entrypoint). Treat that sentinel as omitted for known defaults so Grok
+    // gets `agent --always-approve stdio` rather than `grok acp` (#3457).
+    if normalized.len() == 1 && normalized[0].eq_ignore_ascii_case("acp") {
         return default_args;
     }
 
@@ -1592,6 +1600,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn normalizes_grok_empty_args_to_agent_stdio() {
+        assert_eq!(
+            normalize_agent_args("grok", Vec::new()),
+            vec!["agent", "--always-approve", "stdio"]
+        );
+        assert_eq!(
+            normalize_agent_args("/Users/test/.local/bin/grok", Vec::new()),
+            vec!["agent", "--always-approve", "stdio"]
+        );
+        // clap/env default is a sole "acp" when --agent-args is omitted
+        assert_eq!(
+            normalize_agent_args("grok", vec!["acp".into()]),
+            vec!["agent", "--always-approve", "stdio"]
+        );
+        assert_eq!(
+            normalize_agent_args("grok", vec!["agent".into(), "stdio".into()]),
+            vec!["agent", "stdio"]
+        );
+    }
+
+
     #[test]
     fn normalize_agent_command_identity_variants() {
         assert_eq!(normalize_agent_command_identity("goose"), "goose");
diff --git a/desktop/src-tauri/src/managed_agents/discovery.rs b/desktop/src-tauri/src/managed_agents/discovery.rs
index eecbf4de3e..59e009680b 100644
--- a/desktop/src-tauri/src/managed_agents/discovery.rs
+++ b/desktop/src-tauri/src/managed_agents/discovery.rs
@@ -461,10 +461,20 @@ pub fn try_record_agent_command(
 }
 
 fn default_agent_args(command: &str) -> Option<Vec<String>> {
+    // Empty `agent_args` on managed-agent records is intentional (see
+    // instanceInputForDefinition): spawn fills defaults from this table.
+    // Grok must be included or a command override alone launches bare `grok`
+    // (interactive TUI → ENXIO under the desktop, block/buzz#3457).
     match normalize_command_identity(command).as_str() {
         "goose" => Some(vec!["acp".to_string()]),
         "codex" | "codex-acp" | "claude-agent-acp" | "claude-code-acp" | "claude-code"
         | "claudecode" | "buzz-agent" => Some(Vec::new()),
+        // Grok Build: `grok agent --always-approve stdio` (matches PRESET_HARNESSES).
+        "grok" => Some(vec![
+            "agent".to_string(),
+            "--always-approve".to_string(),
+            "stdio".to_string(),
+        ]),
         _ => None,
     }
 }
@@ -484,8 +494,10 @@ pub fn normalize_agent_args(command: &str, agent_args: Vec<String>) -> Vec<Strin
         return default_args;
     }
 
-    if normalized.len() == 1 && normalized[0].eq_ignore_ascii_case("acp") && default_args.is_empty()
-    {
+    // Clap/env historically defaulted agent args to a sole `"acp"` (Goose's
+    // entrypoint). Treat that sentinel as omitted for known defaults so Grok
+    // gets `agent --always-approve stdio` rather than `grok acp` (#3457).
+    if normalized.len() == 1 && normalized[0].eq_ignore_ascii_case("acp") {
         return default_args;
     }
 
diff --git a/desktop/src-tauri/src/managed_agents/discovery/tests.rs b/desktop/src-tauri/src/managed_agents/discovery/tests.rs
index 1b587dca0e..8458eac164 100644
--- a/desktop/src-tauri/src/managed_agents/discovery/tests.rs
+++ b/desktop/src-tauri/src/managed_agents/discovery/tests.rs
@@ -94,6 +94,31 @@ fn normalizes_buzz_agent_args_to_empty() {
     );
 }
 
+#[test]
+fn normalizes_grok_empty_args_to_agent_stdio() {
+    // Managed records intentionally store empty agent_args; spawn must still
+    // enter ACP mode (block/buzz#3457).
+    assert_eq!(
+        normalize_agent_args("grok", Vec::new()),
+        vec!["agent", "--always-approve", "stdio"]
+    );
+    assert_eq!(
+        normalize_agent_args("/Users/test/.local/bin/grok", Vec::new()),
+        vec!["agent", "--always-approve", "stdio"]
+    );
+    // Legacy clap/env default is a sole "acp" when args are omitted.
+    assert_eq!(
+        normalize_agent_args("grok", vec!["acp".into()]),
+        vec!["agent", "--always-approve", "stdio"]
+    );
+    // Explicit non-empty args are preserved.
+    assert_eq!(
+        normalize_agent_args("grok", vec!["agent".into(), "stdio".into()]),
+        vec!["agent", "stdio"]
+    );
+}
+
+
 #[test]
 fn login_shell_lookup_treats_command_as_data() {
     let marker =