Add request_user_input auto-resolution window contract (#27256)

## Why

`request_user_input` is moving beyond its original plan-mode-only
workflow, and future default/goal-mode usage needs a way for the model
to ask helpful but non-blocking questions without forcing the turn to
wait forever. This PR adds an explicit `autoResolutionMs` contract so a
later client/runtime change can auto-resolve unanswered prompts after a
bounded window while leaving truly blocking questions unchanged.

This is contract plumbing only; it does not implement the client-side
timer or auto-selection behavior, and the model-facing description
treats the field as reserved unless the current runtime explicitly
supports auto-resolution.

## What Changed

- Added optional `autoResolutionMs` to the model-facing
`request_user_input` args and core `RequestUserInputEvent`.
- Added model-facing schema text for `autoResolutionMs` while marking it
reserved for runtimes that explicitly support auto-resolution.
- Bounds `autoResolutionMs` to `60_000..=240_000` ms during argument
normalization by clamping out-of-range model-provided values.
- Propagated the field through app-server v2
`ToolRequestUserInputParams`, app-server request forwarding, generated
TypeScript, and JSON schema fixtures.
- Updated app-server, core, protocol, and TUI call sites/tests so
omitted values preserve existing `None`/`null` behavior and coverage
verifies a `Some(60_000)` round trip.

## Verification

- `just test -p codex-app-server-protocol`
- `just test -p codex-core request_user_input`
- `just test -p codex-app-server request_user_input_round_trip`
- `just test -p codex-tui request_user_input`
- `just test -p codex-protocol`

codex-rs/app-server-protocol/schema/json/ServerRequest.json

@@ -1690,6 +1690,15 @@
     "ToolRequestUserInputParams": {
       "description": "EXPERIMENTAL. Params sent with a request_user_input event.",
       "properties": {
+        "autoResolutionMs": {
+          "default": null,
+          "format": "uint64",
+          "minimum": 0.0,
+          "type": [
+            "integer",
+            "null"
+          ]
+        },
         "itemId": {
           "type": "string"
         },

codex-rs/app-server-protocol/schema/json/ToolRequestUserInputParams.json

@@ -57,6 +57,15 @@
   },
   "description": "EXPERIMENTAL. Params sent with a request_user_input event.",
   "properties": {
+    "autoResolutionMs": {
+      "default": null,
+      "format": "uint64",
+      "minimum": 0.0,
+      "type": [
+        "integer",
+        "null"
+      ]
+    },
     "itemId": {
       "type": "string"
     },

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -5626,6 +5626,15 @@
       "$schema": "http://json-schema.org/draft-07/schema#",
       "description": "EXPERIMENTAL. Params sent with a request_user_input event.",
       "properties": {
+        "autoResolutionMs": {
+          "default": null,
+          "format": "uint64",
+          "minimum": 0.0,
+          "type": [
+            "integer",
+            "null"
+          ]
+        },
         "itemId": {
           "type": "string"
         },

codex-rs/app-server-protocol/schema/typescript/v2/ToolRequestUserInputParams.ts

@@ -6,4 +6,4 @@ import type { ToolRequestUserInputQuestion } from "./ToolRequestUserInputQuestio
 /**
  * EXPERIMENTAL. Params sent with a request_user_input event.
  */
-export type ToolRequestUserInputParams = { threadId: string, turnId: string, itemId: string, questions: Array<ToolRequestUserInputQuestion>, };
+export type ToolRequestUserInputParams = { threadId: string, turnId: string, itemId: string, questions: Array<ToolRequestUserInputQuestion>, autoResolutionMs: number | null, };

codex-rs/app-server-protocol/src/protocol/v2/item.rs

@@ -1464,6 +1464,9 @@ pub struct ToolRequestUserInputParams {
     pub turn_id: String,
     pub item_id: String,
     pub questions: Vec<ToolRequestUserInputQuestion>,
+    #[serde(default)]
+    #[ts(type = "number | null")]
+    pub auto_resolution_ms: Option<u64>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]