feat: add configurable write_stdin timeout (#12228)

Add max timeout as config for `write_stdin`. This is only used for empty
`write_stdin`.

Also increased the default value from 30s to 5mins.

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

@@ -54,6 +54,7 @@ pub(crate) const MIN_YIELD_TIME_MS: u64 = 250;
 // Minimum yield time for an empty `write_stdin`.
 pub(crate) const MIN_EMPTY_YIELD_TIME_MS: u64 = 5_000;
 pub(crate) const MAX_YIELD_TIME_MS: u64 = 30_000;
+pub(crate) const DEFAULT_MAX_BACKGROUND_TERMINAL_TIMEOUT_MS: u64 = 300_000;
 pub(crate) const DEFAULT_MAX_OUTPUT_TOKENS: usize = 10_000;
 pub(crate) const UNIFIED_EXEC_OUTPUT_MAX_BYTES: usize = 1024 * 1024; // 1 MiB
 pub(crate) const UNIFIED_EXEC_OUTPUT_MAX_TOKENS: usize = UNIFIED_EXEC_OUTPUT_MAX_BYTES / 4;
@@ -129,13 +130,22 @@ impl ProcessStore {
 
 pub(crate) struct UnifiedExecProcessManager {
     process_store: Mutex<ProcessStore>,
+    max_write_stdin_yield_time_ms: u64,
+}
+
+impl UnifiedExecProcessManager {
+    pub(crate) fn new(max_write_stdin_yield_time_ms: u64) -> Self {
+        Self {
+            process_store: Mutex::new(ProcessStore::default()),
+            max_write_stdin_yield_time_ms: max_write_stdin_yield_time_ms
+                .max(MIN_EMPTY_YIELD_TIME_MS),
+        }
+    }
 }
 
 impl Default for UnifiedExecProcessManager {
     fn default() -> Self {
-        Self {
-            process_store: Mutex::new(ProcessStore::default()),
-        }
+        Self::new(DEFAULT_MAX_BACKGROUND_TERMINAL_TIMEOUT_MS)
     }
 }