Chore: update plan mode output in prompt (#9592)

### Summary
* Update plan prompt output
* Update requestUserInput response to be a single key value pair
`answer: String`.

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

@@ -2327,8 +2327,7 @@ pub struct ToolRequestUserInputParams {
 #[ts(export_to = "v2/")]
 /// EXPERIMENTAL. Captures a user's answer to a request_user_input question.
 pub struct ToolRequestUserInputAnswer {
-    pub selected: Vec<String>,
-    pub other: Option<String>,
+    pub answers: Vec<String>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]

codex-rs/app-server/src/bespoke_event_handling.rs

@@ -1445,8 +1445,7 @@ async fn on_request_user_input_response(
                 (
                     id,
                     CoreRequestUserInputAnswer {
-                        selected: answer.selected,
-                        other: answer.other,
+                        answers: answer.answers,
                     },
                 )
             })

codex-rs/app-server/tests/suite/v2/request_user_input.rs

@@ -87,7 +87,7 @@ async fn request_user_input_round_trip() -> Result<()> {
         request_id,
         serde_json::json!({
             "answers": {
-                "confirm_path": { "selected": ["yes"], "other": serde_json::Value::Null }
+                "confirm_path": { "answers": ["yes"] }
             }
         }),
     )

codex-rs/core/templates/collaboration_mode/plan.md

@@ -33,7 +33,7 @@ Example: "I checked the readme and searched for the feature you mentioned, but d
 
 Use `request_user_input` only when you are genuinely blocked on a decision that materially changes the plan (requirements, trade-offs, rollout or risk posture).The maximum number of `request_user_input` tool calls should be **5**.
 
-Only include an "Other" option when a free-form answer is truly useful. If the question is purely free-form, leave `options` unset entirely.
+**The options should be mutually exclusive.** Only include an "Other" option when a free-form answer is truly useful. If the question is purely free-form, leave `options` unset entirely.
 
 Do **not** use `request_user_input` to ask "is my plan ready?" or "should I proceed?".
 
@@ -112,22 +112,12 @@ A well written and informative plan should be as detailed as a design doc or PRD
 
 - tools and frameworks you use, any dependencies you need to install
 - functions, files, or directories you're likely going to edit
-- QUestions that were asked and the responses from users
+- Questions that were asked and the responses from users
 - architecture if the code changes are significant
 - if developing features, describe the features you are going to build in detail like a PM in a PRD
 - if you are developing a frontend, describe the design in detail
 - include a list of todos in markdown format if needed. Please do not include a **plan** step given that we are planning here already
 
-### Output schema - — MUST MATCH _exactly_
+### Plan output
 
-When you present the plan, format the final response as a JSON object with a single key, `plan`, whose value is the full plan text.
-
-Example:
-
-```json
-{
-  "plan": "Title: Schema migration rollout\n\n1. Validate the current schema on staging...\n2. Add the new columns with nullable defaults...\n3. Backfill in batches with feature-flagged writes...\n4. Flip reads to the new fields and monitor...\n5. Remove legacy columns after one full release cycle..."
-}
-```
-
-PLEASE DO NOT confirm the plan with the user before ending. The user will be responsible for telling us to update, iterate or execute the plan.
+**The final output should contain the plan and plan only with a good title.** PLEASE DO NOT confirm the plan with the user before ending. The user will be responsible for telling us to update, iterate or execute the plan. The

codex-rs/core/tests/suite/request_user_input.rs

@@ -152,8 +152,7 @@ async fn request_user_input_round_trip_resolves_pending() -> anyhow::Result<()>
     answers.insert(
         "confirm_path".to_string(),
         RequestUserInputAnswer {
-            selected: vec!["yes".to_string()],
-            other: None,
+            answers: vec!["yes".to_string()],
         },
     );
     let response = RequestUserInputResponse { answers };
@@ -173,7 +172,7 @@ async fn request_user_input_round_trip_resolves_pending() -> anyhow::Result<()>
         output_json,
         json!({
             "answers": {
-                "confirm_path": { "selected": ["yes"], "other": Value::Null }
+                "confirm_path": { "answers": ["yes"] }
             }
         })
     );

codex-rs/protocol/src/request_user_input.rs

@@ -27,8 +27,7 @@ pub struct RequestUserInputArgs {
 
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
 pub struct RequestUserInputAnswer {
-    pub selected: Vec<String>,
-    pub other: Option<String>,
+    pub answers: Vec<String>,
 }
 
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]

codex-rs/tui/src/bottom_pane/request_user_input/mod.rs

@@ -2,10 +2,10 @@
 //!
 //! Core behaviors:
 //! - Each question can be answered by selecting one option and/or providing notes.
-//! - When options exist, notes are stored per selected option (notes become "other").
+//! - When options exist, notes are stored per selected option and appended as extra answers.
 //! - Typing while focused on options jumps into notes to keep freeform input fast.
 //! - Enter advances to the next question; the last question submits all answers.
-//! - Freeform-only questions submit "skipped" when empty.
+//! - Freeform-only questions submit an empty answer list when empty.
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::collections::VecDeque;
@@ -278,7 +278,7 @@ impl RequestUserInputOverlay {
             } else {
                 answer_state.selected
             };
-            // Notes map to "other". When options exist, notes are per selected option.
+            // Notes are appended as extra answers. When options exist, notes are per selected option.
             let notes = if options.is_some_and(|opts| !opts.is_empty()) {
                 selected_idx
                     .and_then(|selected| answer_state.option_notes.get(selected))
@@ -294,18 +294,15 @@ impl RequestUserInputOverlay {
                     .and_then(|opts| opts.get(selected_idx))
                     .map(|opt| opt.label.clone())
             });
-            let selected = selected_label.into_iter().collect::<Vec<_>>();
-            // For option questions, only send notes when present.
-            let other = if notes.is_empty() && options.is_some_and(|opts| !opts.is_empty()) {
-                None
-            } else if notes.is_empty() && selected.is_empty() {
-                Some("skipped".to_string())
-            } else {
-                Some(notes)
-            };
+            let mut answer_list = selected_label.into_iter().collect::<Vec<_>>();
+            if !notes.is_empty() {
+                answer_list.push(format!("user_note: {notes}"));
+            }
             answers.insert(
                 question.id.clone(),
-                RequestUserInputAnswer { selected, other },
+                RequestUserInputAnswer {
+                    answers: answer_list,
+                },
             );
         }
         self.app_event_tx
@@ -605,12 +602,11 @@ mod tests {
         };
         assert_eq!(id, "turn-1");
         let answer = response.answers.get("q1").expect("answer missing");
-        assert_eq!(answer.selected, vec!["Option 1".to_string()]);
-        assert_eq!(answer.other, None);
+        assert_eq!(answer.answers, vec!["Option 1".to_string()]);
     }
 
     #[test]
-    fn freeform_questions_submit_skipped_when_empty() {
+    fn freeform_questions_submit_empty_when_empty() {
         let (tx, mut rx) = test_sender();
         let mut overlay = RequestUserInputOverlay::new(
             request_event("turn-1", vec![question_without_options("q1", "Notes")]),
@@ -624,8 +620,7 @@ mod tests {
             panic!("expected UserInputAnswer");
         };
         let answer = response.answers.get("q1").expect("answer missing");
-        assert_eq!(answer.selected, Vec::<String>::new());
-        assert_eq!(answer.other, Some("skipped".to_string()));
+        assert_eq!(answer.answers, Vec::<String>::new());
     }
 
     #[test]
@@ -654,8 +649,13 @@ mod tests {
             panic!("expected UserInputAnswer");
         };
         let answer = response.answers.get("q1").expect("answer missing");
-        assert_eq!(answer.selected, vec!["Option 2".to_string()]);
-        assert_eq!(answer.other, Some("Notes for option 2".to_string()));
+        assert_eq!(
+            answer.answers,
+            vec![
+                "Option 2".to_string(),
+                "user_note: Notes for option 2".to_string(),
+            ]
+        );
     }
 
     #[test]