Make unified exec session_id numeric (#14279)

It's a number on the write_stdin input, make it a number on the output
and also internally.

codex-rs/core/src/tools/context.rs

@@ -159,7 +159,7 @@ pub struct ExecCommandToolOutput {
     /// Raw bytes returned for this unified exec call before any truncation.
     pub raw_output: Vec<u8>,
     pub max_output_tokens: Option<usize>,
-    pub process_id: Option<String>,
+    pub process_id: Option<i32>,
     pub exit_code: Option<i32>,
     pub original_token_count: Option<usize>,
     pub session_command: Option<Vec<String>>,
@@ -194,7 +194,7 @@ impl ToolOutput for ExecCommandToolOutput {
             #[serde(skip_serializing_if = "Option::is_none")]
             exit_code: Option<i32>,
             #[serde(skip_serializing_if = "Option::is_none")]
-            session_id: Option<String>,
+            session_id: Option<i32>,
             #[serde(skip_serializing_if = "Option::is_none")]
             original_token_count: Option<usize>,
             output: String,
@@ -204,7 +204,7 @@ impl ToolOutput for ExecCommandToolOutput {
             chunk_id: (!self.chunk_id.is_empty()).then(|| self.chunk_id.clone()),
             wall_time_seconds: self.wall_time.as_secs_f64(),
             exit_code: self.exit_code,
-            session_id: self.process_id.clone(),
+            session_id: self.process_id,
             original_token_count: self.original_token_count,
             output: self.truncated_output(),
         };

codex-rs/core/src/tools/handlers/unified_exec.rs

@@ -190,7 +190,7 @@ impl ToolHandler for UnifiedExecHandler {
                     )
                 {
                     let approval_policy = context.turn.approval_policy.value();
-                    manager.release_process_id(&process_id).await;
+                    manager.release_process_id(process_id).await;
                     return Err(FunctionCallError::RespondToModel(format!(
                         "approval policy is {approval_policy:?}; reject command — you cannot ask for escalated permissions if the approval policy is {approval_policy:?}"
                     )));
@@ -211,7 +211,7 @@ impl ToolHandler for UnifiedExecHandler {
                     ) {
                         Ok(normalized) => normalized,
                         Err(err) => {
-                            manager.release_process_id(&process_id).await;
+                            manager.release_process_id(process_id).await;
                             return Err(FunctionCallError::RespondToModel(err));
                         }
                     };
@@ -228,7 +228,7 @@ impl ToolHandler for UnifiedExecHandler {
                 )
                 .await?
                 {
-                    manager.release_process_id(&process_id).await;
+                    manager.release_process_id(process_id).await;
                     return Ok(ExecCommandToolOutput {
                         event_call_id: String::new(),
                         chunk_id: String::new(),
@@ -271,7 +271,7 @@ impl ToolHandler for UnifiedExecHandler {
                 let args: WriteStdinArgs = parse_arguments(&arguments)?;
                 let response = manager
                     .write_stdin(WriteStdinRequest {
-                        process_id: &args.session_id.to_string(),
+                        process_id: args.session_id,
                         input: &args.chars,
                         yield_time_ms: args.yield_time_ms,
                         max_output_tokens: args.max_output_tokens,

codex-rs/core/src/tools/spec.rs

@@ -59,7 +59,7 @@ fn unified_exec_output_schema() -> JsonValue {
                 "description": "Process exit code when the command finished during this call."
             },
             "session_id": {
-                "type": "string",
+                "type": "number",
                 "description": "Session identifier to pass to write_stdin when the process is still running."
             },
             "original_token_count": {