Improve orchestration agent model selection

app/src/ai/blocklist/action_model/execute/run_agents.rs

@@ -1247,7 +1247,7 @@ pub fn compose_run_agents_child_prompt(base_prompt: &str, per_agent_prompt: &str
     }
 }
 
-/// Translates run-wide config into a per-child
+/// Translates shared config and the child's model selection into a per-child
 /// [`StartAgentExecutionMode`]. Returns `Err` for rejected
 /// combinations (e.g. OpenCode+Remote).
 ///
@@ -1262,12 +1262,15 @@ pub fn run_agents_to_start_agent_mode(
     run_auth_secret_name: Option<&str>,
     cfg: &RunAgentsAgentRunConfig,
 ) -> Result<StartAgentExecutionMode, String> {
+    let child_model_id = if cfg.model_id.trim().is_empty() {
+        run_model_id.trim()
+    } else {
+        cfg.model_id.trim()
+    };
     match run_execution_mode {
         RunAgentsExecutionMode::Local => {
             let trimmed = run_harness_type.trim();
-            // Propagate run-wide model selection for local launches.
-            let trimmed_model_id = run_model_id.trim();
-            let model_id = (!trimmed_model_id.is_empty()).then(|| trimmed_model_id.to_string());
+            let model_id = (!child_model_id.is_empty()).then(|| child_model_id.to_string());
             if trimmed.is_empty() || trimmed.eq_ignore_ascii_case("oz") {
                 Ok(StartAgentExecutionMode::Local {
                     harness_type: None,
@@ -1299,7 +1302,7 @@ pub fn run_agents_to_start_agent_mode(
             Ok(StartAgentExecutionMode::Remote {
                 environment_id: environment_id.clone(),
                 skill_references: run_skills.to_vec(),
-                model_id: run_model_id.to_string(),
+                model_id: child_model_id.to_string(),
                 computer_use_enabled: *computer_use_enabled,
                 worker_host: worker_host.clone(),
                 harness_type: run_harness_type.to_string(),

app/src/ai/blocklist/action_model/execute/run_agents_tests.rs

@@ -266,6 +266,7 @@ fn execute_denies_mixed_batch_containing_launched_agent() {
             name: "new-child".to_string(),
             prompt: "Do separate work".to_string(),
             title: String::new(),
+            model_id: String::new(),
         });
 
         let execution = state.executor.update(&mut app, |executor, ctx| {
@@ -306,6 +307,7 @@ fn validate_request_rejects_blank_and_duplicate_agent_names() {
         name: " child ".to_string(),
         prompt: "Do separate work".to_string(),
         title: String::new(),
+        model_id: String::new(),
     });
     assert_eq!(
         validate_request(&request),
@@ -323,6 +325,7 @@ fn validate_request_allows_unique_sibling_names() {
         name: "second-child".to_string(),
         prompt: "Do separate work".to_string(),
         title: String::new(),
+        model_id: String::new(),
     });
 
     assert_eq!(validate_request(&request), Ok(()));
@@ -384,6 +387,7 @@ fn recovered_run_agents_reattaches_existing_child_and_launches_only_missing_chil
             name: "missing-child".to_string(),
             prompt: "Do separate work".to_string(),
             title: String::new(),
+            model_id: String::new(),
         });
         state.executor.update(&mut app, |executor, _| {
             executor
@@ -454,12 +458,12 @@ fn recovered_run_agents_reattaches_existing_child_and_launches_only_missing_chil
         assert_eq!(agents.len(), 2);
         assert!(matches!(
             &agents[0].kind,
-            RunAgentsAgentOutcomeKind::Launched { agent_id }
+            RunAgentsAgentOutcomeKind::Completed { agent_id, .. }
                 if agent_id == &existing_child_id.to_string()
         ));
         assert!(matches!(
             &agents[1].kind,
-            RunAgentsAgentOutcomeKind::Launched { agent_id }
+            RunAgentsAgentOutcomeKind::Completed { agent_id, .. }
                 if agent_id == &missing_child_id.to_string()
         ));
     });
@@ -766,6 +770,7 @@ fn remote_run_agents_action(harness_type: &str) -> AIAgentAction {
                 name: "child".to_string(),
                 prompt: "Help".to_string(),
                 title: String::new(),
+                model_id: String::new(),
             }],
             plan_id: String::new(),
             harness_auth_secret_name: None,
@@ -789,6 +794,7 @@ fn local_codex_run_agents_maps_to_local_harness_mode_when_flag_enabled() {
         name: "child".to_string(),
         prompt: "Investigate the failure".to_string(),
         title: String::new(),
+        model_id: String::new(),
     };
 
     let mode = run_agents_to_start_agent_mode(
@@ -810,6 +816,34 @@ fn local_codex_run_agents_maps_to_local_harness_mode_when_flag_enabled() {
     );
 }
 
+#[test]
+fn child_model_overrides_the_run_wide_model() {
+    let cfg = RunAgentsAgentRunConfig {
+        name: "child".to_string(),
+        prompt: "Investigate".to_string(),
+        title: String::new(),
+        model_id: "child-model".to_string(),
+    };
+
+    let mode = run_agents_to_start_agent_mode(
+        &RunAgentsExecutionMode::Local,
+        "oz",
+        "fallback-model",
+        &[],
+        None,
+        &cfg,
+    )
+    .unwrap();
+
+    assert_eq!(
+        mode,
+        StartAgentExecutionMode::Local {
+            harness_type: None,
+            model_id: Some("child-model".to_string()),
+        }
+    );
+}
+
 fn persist_default_auth_secret(app: &mut App, harness_config_name: &str, secret_name: &str) {
     CloudAgentSettings::handle(app).update(app, |settings, ctx| {
         let mut secrets = settings.last_selected_auth_secret.value().clone();