Move exec command truncation into ExecCommandToolOutput (#14169)

Summary
- relocate truncation logic for exec command output into the new
`ExecCommandToolOutput` response helper instead of centralized handler
code
- update all affected tools and unified exec handling to use the new
response item structure and eliminate `Function(FunctionToolOutput)`
responses
- adjust context, registry, and handler interfaces to align with the new
response semantics and error fields

Testing
- Not run (not requested)

codex-rs/core/src/unified_exec/mod.rs

@@ -26,7 +26,6 @@ use std::collections::HashSet;
 use std::path::PathBuf;
 use std::sync::Arc;
 use std::sync::Weak;
-use std::time::Duration;
 
 use codex_network_proxy::NetworkProxy;
 use codex_protocol::models::PermissionProfile;
@@ -108,20 +107,6 @@ pub(crate) struct WriteStdinRequest<'a> {
     pub max_output_tokens: Option<usize>,
 }
 
-#[derive(Debug, Clone, PartialEq)]
-pub(crate) struct UnifiedExecResponse {
-    pub event_call_id: String,
-    pub chunk_id: String,
-    pub wall_time: Duration,
-    pub output: String,
-    /// Raw bytes returned for this unified exec call before any truncation.
-    pub raw_output: Vec<u8>,
-    pub process_id: Option<String>,
-    pub exit_code: Option<i32>,
-    pub original_token_count: Option<usize>,
-    pub session_command: Option<Vec<String>>,
-}
-
 #[derive(Default)]
 pub(crate) struct ProcessStore {
     processes: HashMap<String, ProcessEntry>,
@@ -192,6 +177,7 @@ mod tests {
     use crate::codex::make_session_and_context;
     use crate::protocol::AskForApproval;
     use crate::protocol::SandboxPolicy;
+    use crate::tools::context::ExecCommandToolOutput;
     use crate::unified_exec::ExecCommandRequest;
     use crate::unified_exec::WriteStdinRequest;
     use core_test_support::skip_if_sandbox;
@@ -218,7 +204,7 @@ mod tests {
         turn: &Arc<TurnContext>,
         cmd: &str,
         yield_time_ms: u64,
-    ) -> Result<UnifiedExecResponse, UnifiedExecError> {
+    ) -> Result<ExecCommandToolOutput, UnifiedExecError> {
         let context =
             UnifiedExecContext::new(Arc::clone(session), Arc::clone(turn), "call".to_string());
         let process_id = session
@@ -255,7 +241,7 @@ mod tests {
         process_id: &str,
         input: &str,
         yield_time_ms: u64,
-    ) -> Result<UnifiedExecResponse, UnifiedExecError> {
+    ) -> Result<ExecCommandToolOutput, UnifiedExecError> {
         session
             .services
             .unified_exec_manager
@@ -330,7 +316,7 @@ mod tests {
         )
         .await?;
         assert!(
-            out_2.output.contains("codex"),
+            out_2.truncated_output().contains("codex"),
             "expected environment variable output"
         );
 
@@ -366,7 +352,7 @@ mod tests {
             "short command should not report a process id if it exits quickly"
         );
         assert!(
-            !out_2.output.contains("codex"),
+            !out_2.truncated_output().contains("codex"),
             "short command should run in a fresh shell"
         );
 
@@ -382,7 +368,7 @@ mod tests {
         )
         .await?;
         assert!(
-            out_3.output.contains("codex"),
+            out_3.truncated_output().contains("codex"),
             "session should preserve state"
         );
 
@@ -420,7 +406,7 @@ mod tests {
         )
         .await?;
         assert!(
-            !out_2.output.contains(TEST_VAR_VALUE),
+            !out_2.truncated_output().contains(TEST_VAR_VALUE),
             "timeout too short should yield incomplete output"
         );
 
@@ -429,7 +415,7 @@ mod tests {
         let out_3 = write_stdin(&session, process_id, "", 100).await?;
 
         assert!(
-            out_3.output.contains(TEST_VAR_VALUE),
+            out_3.truncated_output().contains(TEST_VAR_VALUE),
             "subsequent poll should retrieve output"
         );
 
@@ -444,7 +430,7 @@ mod tests {
         let result = exec_command(&session, &turn, "echo codex", 120_000).await?;
 
         assert!(result.process_id.is_some());
-        assert!(result.output.contains("codex"));
+        assert!(result.truncated_output().contains("codex"));
 
         Ok(())
     }
@@ -459,7 +445,7 @@ mod tests {
             result.process_id.is_some(),
             "completed command should report a process id"
         );
-        assert!(result.output.contains("codex"));
+        assert!(result.truncated_output().contains("codex"));
 
         assert!(
             session