Standardize shell execution on unified exec (#39757)

## What changed

- Remove the legacy `shell_command` handler and runtime, leaving `exec_command`
  and `write_stdin` as the shell execution tools.
- Treat legacy `shell_command` model metadata as `unified_exec`, and normalize
  legacy user opt-outs so they do not disable command execution. Managed feature
  requirements and `shell_tool` can still disable it.
- Preserve shell approvals, sandboxing, zsh-fork support, and output truncation
  through the unified execution path.

## Testing

- Cover legacy configuration and model-metadata compatibility.
- Exercise unified shell execution, approvals, truncation, and `apply_patch`
  serialization across the app-server and core test suites.

GitOrigin-RevId: 5c2fd6164fc3519cdae4944cb9db276b8467311c

codex-rs/protocol/src/models.rs

@@ -1971,32 +1971,6 @@ pub struct SearchToolCallParams {
     pub limit: Option<usize>,
 }
 
-/// If the `name` of a `ResponseItem::FunctionCall` is `shell_command`, the
-/// `arguments` field should deserialize to this struct.
-#[derive(Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
-pub struct ShellCommandToolCallParams {
-    pub command: String,
-    pub workdir: Option<String>,
-
-    /// Whether to run the shell with login shell semantics
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub login: Option<bool>,
-    /// This is the maximum time in milliseconds that the command is allowed to run.
-    #[serde(alias = "timeout")]
-    pub timeout_ms: Option<u64>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    #[ts(optional)]
-    pub sandbox_permissions: Option<SandboxPermissions>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    #[ts(optional)]
-    pub prefix_rule: Option<Vec<String>>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    #[ts(optional)]
-    pub additional_permissions: Option<AdditionalPermissionProfile>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub justification: Option<String>,
-}
-
 /// Responses API compatible content items that can be returned by a tool call.
 /// This is a subset of ContentItem with the types we support as function call outputs.
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, JsonSchema, TS)]

codex-rs/protocol/src/openai_models.rs

@@ -299,9 +299,9 @@ pub enum ModelVisibility {
 pub enum ConfigShellToolType {
     Default,
     Local,
+    #[serde(alias = "shell_command")]
     UnifiedExec,
     Disabled,
-    ShellCommand,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash, TS, JsonSchema)]
@@ -886,6 +886,18 @@ mod tests {
     use serde_json::from_str;
     use serde_json::to_string;
 
+    #[test]
+    fn legacy_shell_model_metadata_deserializes_as_unified_exec() {
+        assert_eq!(
+            from_str::<ConfigShellToolType>("\"shell_command\"").expect("legacy shell type"),
+            ConfigShellToolType::UnifiedExec
+        );
+        assert_eq!(
+            to_string(&ConfigShellToolType::UnifiedExec).expect("serialize unified shell type"),
+            "\"unified_exec\""
+        );
+    }
+
     fn test_model(spec: Option<ModelMessages>) -> ModelInfo {
         ModelInfo {
             slug: "test-model".to_string(),
@@ -893,7 +905,7 @@ mod tests {
             description: None,
             default_reasoning_level: None,
             supported_reasoning_levels: vec![],
-            shell_type: ConfigShellToolType::ShellCommand,
+            shell_type: ConfigShellToolType::UnifiedExec,
             visibility: ModelVisibility::List,
             supported_in_api: true,
             priority: 1,
@@ -1530,7 +1542,7 @@ mod tests {
             "display_name": "Test Model",
             "description": null,
             "supported_reasoning_levels": [],
-            "shell_type": "shell_command",
+            "shell_type": "unified_exec",
             "visibility": "list",
             "supported_in_api": true,
             "priority": 1,