fix(composer): trim prompt suggestion whitespace

src/crates/assembly/core/src/agentic/execution/AGENTS.md

@@ -34,8 +34,9 @@ a full cache miss. If the model call fails, retry it once unchanged. Both
 attempts share one 80-second deadline and session cancellation. Clear the
 turn's output schema, retain the request prefix and cache routing, and request
 plain text on both attempts. Empty output, the literal `null`, tool calls, and
-content filters do not trigger the retry; all other candidate text is kept
-verbatim. Do not add JSON parsing, format negotiation, correction retries, or
+content filters do not trigger the retry. Trim surrounding whitespace before
+publishing a candidate; preserve its internal whitespace and content verbatim.
+Do not add JSON parsing, format negotiation, correction retries, or
 text reconstruction.
 
 The prepended deferred tool listing renders the session's skill/agent listing

src/crates/assembly/core/src/agentic/execution/prompt_suggestion.rs

@@ -517,7 +517,7 @@ mod tests {
             let events = queue.dequeue_batch(10).await;
             assert_eq!(events.len(), 1);
             assert!(
-                matches!(&events[0].event, AgenticEvent::PromptSuggestionGenerated { suggestion, .. } if suggestion == text)
+                matches!(&events[0].event, AgenticEvent::PromptSuggestionGenerated { suggestion, .. } if suggestion == "Run the tests.")
             );
             assert_eq!(
                 session_client
@@ -594,8 +594,8 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn plain_text_response_emits_one_unchanged_candidate_without_output_schema() {
-        let text = "  运行测试，保留原文。  ";
+    async fn plain_text_response_emits_one_trimmed_candidate_without_output_schema() {
+        let text = " \r\n\tRun  the tests.\n\n  Keep this indentation.\t \r\n";
         let server = RetryTestServer::new(vec![suggestion_response(text)]);
         let mut request = test_suggestion_request(server.client());
         request.model_request_context.output_schema = Some(serde_json::json!({
@@ -616,7 +616,7 @@ mod tests {
         let events = queue.dequeue_batch(10).await;
         assert_eq!(events.len(), 1);
         assert!(
-            matches!(&events[0].event, AgenticEvent::PromptSuggestionGenerated { suggestion, .. } if suggestion == text)
+            matches!(&events[0].event, AgenticEvent::PromptSuggestionGenerated { suggestion, .. } if suggestion == "Run  the tests.\n\n  Keep this indentation.")
         );
         let requests = server.requests.lock().unwrap();
         assert_eq!(requests.len(), 1);

src/crates/execution/agent-runtime/AGENTS.md

@@ -162,8 +162,8 @@ so `autotests = false` cannot silently omit a new contract.
 
 ## Verification
 
-For next-input suggestion eligibility, plain-text output without text
-post-processing, and cancellation:
+For next-input suggestion eligibility, surrounding whitespace trimming with
+message content preservation, and cancellation:
 
 ```bash
 cargo test --locked -p openbitfun-agent-runtime --no-default-features --features agent-runtime --lib prompt_suggestion::tests

src/crates/execution/agent-runtime/src/prompt_suggestion.rs

@@ -36,12 +36,12 @@ pub fn prompt_suggestion_instruction() -> &'static str {
     PROMPT_SUGGESTION_INSTRUCTION
 }
 
-/// Empty output and the literal null decline a suggestion. Preserve all other
-/// model text verbatim; shape and length are guided only by the prompt.
+/// Trim surrounding whitespace before publishing a suggestion. Empty output
+/// and the literal null decline it; preserve the message content otherwise.
 pub fn prompt_suggestion_text(raw: String) -> Option<String> {
     match raw.trim() {
         "" | "null" => None,
-        _ => Some(raw),
+        text => Some(text.to_owned()),
     }
 }
 
@@ -233,9 +233,9 @@ mod tests {
     }
 
     #[test]
-    fn plain_text_suggestion_preserves_the_model_text_verbatim() {
+    fn plain_text_suggestion_preserves_message_content() {
         for text in [
-            "  Suggestion: \"Run the tests. Then commit.\"  ".to_string(),
+            "Suggestion: \"Run the tests. Then commit.\"".to_string(),
             "我来运行测试。然后提交。\n不要裁剪这段文本。".to_string(),
             "a".repeat(300),
             "NONE".to_string(),
@@ -246,6 +246,30 @@ mod tests {
         }
     }
 
+    #[test]
+    fn plain_text_suggestion_trims_only_surrounding_whitespace() {
+        for (raw, expected) in [
+            (
+                "\n\nSave these preferences in USER.md",
+                "Save these preferences in USER.md",
+            ),
+            (" \r\n\tRun the tests.\t \r\n", "Run the tests."),
+            (
+                "\u{00a0}\u{3000}Run the tests.\u{3000}\u{00a0}",
+                "Run the tests.",
+            ),
+            (
+                "\nRun  the tests.\n\n  Then commit.\n",
+                "Run  the tests.\n\n  Then commit.",
+            ),
+        ] {
+            assert_eq!(
+                prompt_suggestion_text(raw.to_string()),
+                Some(expected.to_string())
+            );
+        }
+    }
+
     #[test]
     fn empty_output_and_literal_null_decline_a_suggestion() {
         for raw in ["", " \n\t ", "null", " \nnull\t "] {

src/web-ui/AGENTS.md

@@ -212,6 +212,15 @@ For text-entry guards, composer sanitization, or keyboard focus routing, run
 These cover DOM event ownership, controlled fields, IME and selection preservation;
 they do not establish native OS keyboard or remote transport behavior.
 
+For prompt suggestion whitespace normalization, visibility, acceptance keys, and legacy host events:
+
+```bash
+pnpm --dir src/web-ui run test:run src/flow_chat/store/promptSuggestionStore.test.ts src/flow_chat/hooks/usePromptSuggestionsEnabled.test.tsx src/flow_chat/services/flow-chat-manager/EventHandlerModule.test.ts
+```
+
+These local store/event fixtures include simulated Peer identities and legacy payloads;
+they do not establish native WebView rendering or live remote behavior.
+
 For ecosystem discovery, import, or compatibility status presentation changes:
 
 ```bash

src/web-ui/src/flow_chat/services/flow-chat-manager/EventHandlerModule.test.ts

@@ -147,15 +147,15 @@ describe('prompt suggestion projection', () => {
     usePromptSuggestionStore.setState({ suggestions: {} });
   });
 
-  it('preserves the model text for the latest turn without post-processing', () => {
+  it('trims surrounding whitespace in legacy suggestion events while preserving message content', () => {
     createSessionWithTurn(createFinishingTurn());
 
     handlePromptSuggestion(createFlowChatContext(), {
-      sessionId: 'session-1', sourceTurnId: 'turn-1', suggestion: '  Run the tests  ',
+      sessionId: 'session-1', sourceTurnId: 'turn-1', suggestion: '\n\n  Run  the tests\n  Then commit.  \r\n',
     });
 
     expect(usePromptSuggestionStore.getState().suggestions[promptSuggestionKey('session-1')]).toEqual({
-      suggestion: '  Run the tests  ', sourceTurnId: 'turn-1',
+      suggestion: 'Run  the tests\n  Then commit.', sourceTurnId: 'turn-1',
     });
   });
 

src/web-ui/src/flow_chat/store/promptSuggestionStore.test.ts

@@ -20,6 +20,26 @@ afterEach(() => {
 });
 
 describe('prompt suggestion store', () => {
+  it.each([LOCAL_SURFACE_ID, 'legacy-peer'])('trims surrounding whitespace before displaying or accepting a suggestion from %s', surfaceId => {
+    const incoming = {
+      suggestion: '\r\n\n\t\u00a0\u3000Save  these preferences in USER.md\n\n  Keep the examples.\u3000\u00a0\t\r\n',
+      sourceTurnId: 't1',
+    };
+    usePromptSuggestionStore.getState().setSuggestion('session', incoming, surfaceId);
+
+    const stored = usePromptSuggestionStore.getState().suggestions[promptSuggestionKey('session', surfaceId)];
+    expect(stored).toEqual({
+      suggestion: 'Save  these preferences in USER.md\n\n  Keep the examples.', sourceTurnId: 't1',
+    });
+    expect(visiblePromptSuggestion(stored, idle)).toBe('Save  these preferences in USER.md\n\n  Keep the examples.');
+    expect(incoming.suggestion).toMatch(/^\r\n\n/);
+  });
+
+  it.each(['', ' \t\r\n', '\u00a0\u3000'])('ignores blank suggestions (%j)', suggestion => {
+    usePromptSuggestionStore.getState().setSuggestion('session', { suggestion, sourceTurnId: 't1' });
+    expect(usePromptSuggestionStore.getState().suggestions).toEqual({});
+  });
+
   it('clears disabled host hints, rejects late results, and keeps other hosts independent', () => {
     const store = usePromptSuggestionStore.getState();
     store.setSuggestion('a', candidate, LOCAL_SURFACE_ID);

src/web-ui/src/flow_chat/store/promptSuggestionStore.ts

@@ -28,11 +28,18 @@ export const usePromptSuggestionStore = create<PromptSuggestionState>((set) => (
     suggestions: enabled ? state.suggestions : Object.fromEntries(Object.entries(state.suggestions)
       .filter(([key]) => JSON.parse(key)[0] !== surfaceId)),
   })),
-  setSuggestion: (sessionId, suggestion, surfaceId = getActiveSurfaceId()) => set((state) => (
-    state.enabledBySurface[surfaceId] === false ? state : {
-      suggestions: { ...state.suggestions, [promptSuggestionKey(sessionId, surfaceId)]: suggestion },
-    }
-  )),
+  setSuggestion: (sessionId, suggestion, surfaceId = getActiveSurfaceId()) => set((state) => {
+    if (state.enabledBySurface[surfaceId] === false) return state;
+    // Older hosts may send padded model output. Display and accept the same clean text.
+    const text = suggestion.suggestion.trim();
+    if (!text) return state;
+    return {
+      suggestions: {
+        ...state.suggestions,
+        [promptSuggestionKey(sessionId, surfaceId)]: { ...suggestion, suggestion: text },
+      },
+    };
+  }),
   clearSuggestion: (sessionId, surfaceId) => set((state) => {
     const key = promptSuggestionKey(sessionId, surfaceId);
     if (!(key in state.suggestions)) return state;