refactor(web,server): match a turn to its reply by execution id, and clamp text through one primitive

surface/centaur-client/src/reducer.ts

@@ -24,6 +24,7 @@ export interface TextItem {
   type: 'text';
   id: string;
   text: string;
+  executionId: string | null;
   messageId?: string;
   uuid?: string;
   handle?: string | null;
@@ -37,6 +38,7 @@ export interface ToolCallItem {
   id: string;
   name: string;
   input: JsonObject;
+  executionId: string | null;
   result?: {
     content: string;
     is_error: boolean;
@@ -50,6 +52,7 @@ export interface ReasoningItem {
   type: 'reasoning';
   id: string;
   text: string;
+  executionId: string | null;
   summary?: string;
   messageId?: string;
   handle?: string | null;
@@ -61,6 +64,7 @@ export interface QuestionItem {
   type: 'question';
   id: string;
   questionId: string;
+  executionId: string | null;
   turnId?: string;
   questions: QuestionPrompt[];
   status: 'pending' | 'resolved';
@@ -74,6 +78,7 @@ export interface UserMessageItem {
   type: 'user_message';
   id: string;
   text: string;
+  executionId: string | null;
   handle?: string | null;
   ts?: string;
   sourceEventIds: number[];
@@ -149,6 +154,9 @@ export interface ArtifactPresentation {
 
 export interface SessionState {
   status: ExecutionStatus | 'idle';
+  /** Execution currently producing transcript items. Null for legacy frames
+   * that predate execution identity. */
+  executionId: string | null;
   /** Server-stamped start of the current turn — `turn/started` when the harness
    * emits it, else the execution_state frame that flipped us into running. */
   turnStartTs?: string;
@@ -198,6 +206,7 @@ export interface SessionState {
 export function initialSessionState(): SessionState {
   return {
     status: 'idle',
+    executionId: null,
     frameSeq: 0,
     deltaChars: 0,
     transport: 'ok',
@@ -249,6 +258,7 @@ function reduceSessionFrame(state: SessionState, frame: CentaurEventFrame): Sess
   if (frame.event === 'execution_state') {
     const wasActive = state.status !== 'idle' && !isTerminalExecutionStatus(state.status);
     next.status = frame.data.status;
+    next.executionId = frame.data.execution_id ?? null;
     if (frame.data.result_text) {
       next.resultText = frame.data.result_text;
     }
@@ -523,6 +533,7 @@ function upsertQuestionItem(
     type: 'question',
     id: `question:${event.question_id}`,
     questionId: event.question_id,
+    executionId: state.executionId,
     ...(event.turn_id !== undefined ? { turnId: event.turn_id } : {}),
     questions: event.questions,
     status: 'pending',
@@ -553,6 +564,7 @@ function resolveQuestionItem(
     type: 'question',
     id: `question:${questionId}`,
     questionId,
+    executionId: state.executionId,
     questions: [],
     status: 'resolved',
     reason,
@@ -640,6 +652,7 @@ function upsertClaudeReasoningItem(
     type: 'reasoning',
     id,
     text,
+    executionId: state.executionId,
     messageId: messageKey,
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
@@ -668,6 +681,7 @@ function appendStreamingText(state: SessionState, eventId: number, text: string,
     type: 'text',
     id: `text:${eventId}`,
     text,
+    executionId: state.executionId,
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
   });
@@ -709,6 +723,7 @@ function reconcileCompleteText(
     id: messageId ? `text:${messageId}` : `text:${uuid}`,
     text,
     uuid,
+    executionId: state.executionId,
     ...optionalProp('messageId', messageId),
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
@@ -738,6 +753,7 @@ function upsertToolCall(
     id: block.id,
     name: block.name,
     input: block.input,
+    executionId: state.executionId,
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
   };
@@ -1019,6 +1035,7 @@ function upsertReasoningItem(
     type: 'reasoning',
     id,
     text,
+    executionId: state.executionId,
     ...(summary !== undefined ? { summary } : {}),
     ...(itemId ? { messageId: itemId } : {}),
     ...(handle ? { handle } : {}),
@@ -1117,6 +1134,7 @@ function appendCodexStreamingText(
     type: 'text',
     id: itemId ? `text:codex:${itemId}` : `text:codex:${eventId}`,
     text,
+    executionId: state.executionId,
     ...optionalProp('messageId', itemId),
     sourceEventIds: [eventId],
   });
@@ -1155,6 +1173,7 @@ function reconcileCodexCompleteText(
     type: 'text',
     id: itemId ? `text:codex:${itemId}` : `text:codex:${eventId}`,
     text,
+    executionId: state.executionId,
     ...optionalProp('messageId', itemId),
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
@@ -1188,6 +1207,7 @@ function upsertCodexCommandExecution(
     id,
     name: 'command',
     input,
+    executionId: state.executionId,
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
   };
@@ -1234,6 +1254,7 @@ function upsertUserMessage(
     type: 'user_message',
     id,
     text,
+    executionId: state.executionId,
     ...(handle ? { handle } : {}),
     sourceEventIds: [eventId],
   };

surface/centaur-client/src/toolDisplay.test.ts

@@ -5,6 +5,7 @@ import type { ToolCallItem } from './reducer.js';
 const tool = (name: string, input: ToolCallItem['input'] = {}): ToolCallItem => ({
   type: 'tool_call',
   id: `tool:${name}`,
+  executionId: null,
   name,
   input,
   sourceEventIds: [1],

surface/centaur-client/src/transcriptRows.test.ts

@@ -8,7 +8,8 @@ import {
   toolDefaultOpen,
 } from './transcriptRows.js';
 
-const item = (id: string, type: SessionItem['type']): SessionItem => ({ id, type }) as SessionItem;
+const item = (id: string, type: SessionItem['type'], executionId: string | null = null): SessionItem =>
+  ({ id, type, executionId }) as SessionItem;
 
 describe('focus transcript rows', () => {
   it('groups contiguous reasoning, tools, and inline changes into one count', () => {
@@ -96,26 +97,26 @@ describe('tool default visibility', () => {
 describe('turn work folds', () => {
   it('groups work after each human input and before that turn’s final answer', () => {
     const items = [
-      { ...item('ask-1', 'user_message'), text: 'First', ts: '2026-07-14T12:00:00.000Z' },
-      { ...item('thought-1', 'reasoning'), text: 'Think', ts: '2026-07-14T12:00:01.000Z' },
+      { ...item('ask-1', 'user_message', 'exe-1'), text: 'First', ts: '2026-07-14T12:00:00.000Z' },
+      { ...item('thought-1', 'reasoning', 'exe-1'), text: 'Think', ts: '2026-07-14T12:00:01.000Z' },
       {
-        ...item('tool-1', 'tool_call'),
+        ...item('tool-1', 'tool_call', 'exe-1'),
         name: 'Bash',
         input: {},
         result: { content: 'ok', is_error: false },
         ts: '2026-07-14T12:00:02.000Z',
       },
-      { ...item('answer-1', 'text'), text: 'Done', ts: '2026-07-14T12:00:04.000Z' },
-      { ...item('ask-2', 'user_message'), text: 'Again', ts: '2026-07-14T12:01:00.000Z' },
-      { ...item('tool-2', 'tool_call'), name: 'Read', input: {}, ts: '2026-07-14T12:01:01.000Z' },
+      { ...item('answer-1', 'text', 'exe-1'), text: 'Done', ts: '2026-07-14T12:00:04.000Z' },
+      { ...item('ask-2', 'user_message', 'exe-2'), text: 'Again', ts: '2026-07-14T12:01:00.000Z' },
+      { ...item('tool-2', 'tool_call', 'exe-2'), name: 'Read', input: {}, ts: '2026-07-14T12:01:01.000Z' },
     ] as SessionItem[];
 
     const folds = foldedTurnRows(items);
     expect(folds).toHaveLength(2);
     expect(folds[0]).toMatchObject({
       items: [items[1], items[2]],
       toolNames: ['Bash'],
-      replyOrdinal: 0,
+      executionId: 'exe-1',
       triggerIndex: 0,
       triggerOrdinal: 0,
       replyIndex: 3,
@@ -125,25 +126,25 @@ describe('turn work folds', () => {
     expect(folds[1]).toMatchObject({
       items: [items[5]],
       toolNames: ['Read'],
-      replyOrdinal: null,
+      executionId: 'exe-2',
       triggerIndex: 4,
       triggerOrdinal: 1,
       replyIndex: null,
       completed: false,
     });
   });
 
-  it('preserves the reply ordinal when an earlier turn has no hidden work', () => {
+  it('takes identity from the fold’s own work and final reply', () => {
     const items = [
-      { ...item('ask-1', 'user_message'), text: 'First' },
-      { ...item('answer-1', 'text'), text: 'Immediate answer' },
-      { ...item('ask-2', 'user_message'), text: 'Second' },
-      { ...item('thought-2', 'reasoning'), text: 'Think' },
-      { ...item('answer-2', 'text'), text: 'Worked answer' },
+      { ...item('ask-1', 'user_message', 'exe-1'), text: 'First' },
+      { ...item('answer-1', 'text', 'exe-1'), text: 'Immediate answer' },
+      { ...item('ask-2', 'user_message', 'exe-2'), text: 'Second' },
+      { ...item('thought-2', 'reasoning', 'exe-2'), text: 'Think' },
+      { ...item('answer-2', 'text', 'exe-2'), text: 'Worked answer' },
     ] as SessionItem[];
 
     expect(foldedTurnRows(items)).toHaveLength(1);
-    expect(foldedTurnRows(items)[0]).toMatchObject({ replyOrdinal: 1, replyIndex: 4 });
+    expect(foldedTurnRows(items)[0]).toMatchObject({ executionId: 'exe-2', replyIndex: 4 });
   });
 });
 

surface/centaur-client/src/transcriptRows.ts

@@ -16,8 +16,7 @@ export interface FoldedTurnRow {
   kind: 'fold';
   key: string;
   turn: number;
-  /** Zero-based position among completed assistant replies; null for a live turn. */
-  replyOrdinal: number | null;
+  executionId: string | null;
   items: TurnWorkItem[];
   toolNames: string[];
   startIndex: number;
@@ -61,7 +60,6 @@ export function foldedTurnRows(items: readonly SessionItem[]): FoldedTurnRow[] {
   let triggerOrdinal: number | null = null;
   let nextTriggerOrdinal = 0;
   let turn = 0;
-  let replyOrdinal = 0;
 
   const flush = (segmentEnd: number) => {
     let replyIndex: number | null = null;
@@ -82,11 +80,15 @@ export function foldedTurnRows(items: readonly SessionItem[]): FoldedTurnRow[] {
       const first = indexedWork[0]!;
       const lastIndex = replyIndex ?? indexedWork[indexedWork.length - 1]!.index;
       const durationMs = elapsedMs(first.item, items[lastIndex]);
+      const executionId =
+        (replyIndex === null ? null : items[replyIndex]?.executionId) ??
+        [...workItems].reverse().find((item) => item.executionId !== null)?.executionId ??
+        null;
       folds.push({
         kind: 'fold',
         key: `turn-${turn}-${first.item.id}`,
         turn,
-        replyOrdinal: replyIndex === null ? null : replyOrdinal,
+        executionId,
         items: workItems,
         toolNames,
         startIndex: first.index,
@@ -98,7 +100,6 @@ export function foldedTurnRows(items: readonly SessionItem[]): FoldedTurnRow[] {
         completed: replyIndex !== null,
       });
     }
-    if (replyIndex !== null) replyOrdinal += 1;
     turn += 1;
   };
 

surface/centaur-client/test/reducer.test.ts

@@ -23,6 +23,23 @@ const userMessageFrame = (eventId: number, id: string, text: string): CentaurEve
 });
 
 describe('reduceSession', () => {
+  it('stamps items with the execution that produced them', () => {
+    const running = reduceSession(initialSessionState(), {
+      event: 'execution_state',
+      event_id: 1,
+      data: {
+        type: 'execution.state',
+        status: 'running',
+        thread_key: 'thread-1',
+        execution_id: 'exe-1',
+      },
+    });
+    const state = reduceSession(running, userMessageFrame(2, 'item-1', 'do the thing'));
+
+    expect(state.executionId).toBe('exe-1');
+    expect(state.items[0]).toMatchObject({ type: 'user_message', executionId: 'exe-1' });
+  });
+
   it('reduces A_pong without duplicating observed text projections', () => {
     const state = reduceAll(fixture('A_pong'));
 

surface/mobile/test/threadWorkFold.test.ts

@@ -12,6 +12,7 @@ describe('thread work fold view mapping', () => {
         type: 'user_message',
         text: 'Inspect it',
         ts: '2026-07-16T12:00:00.000Z',
+        executionId: null,
         sourceEventIds,
       },
       {
@@ -20,6 +21,7 @@ describe('thread work fold view mapping', () => {
         summary: 'Inspecting',
         text: 'I will read the file.',
         ts: '2026-07-16T12:00:01.000Z',
+        executionId: null,
         sourceEventIds,
       },
       {
@@ -29,6 +31,7 @@ describe('thread work fold view mapping', () => {
         questions: [{ id: 'prompt-1', header: 'Choice', question: 'Which file?' }],
         status: 'resolved',
         ts: '2026-07-16T12:00:02.000Z',
+        executionId: null,
         sourceEventIds,
       },
       {
@@ -38,13 +41,15 @@ describe('thread work fold view mapping', () => {
         input: { file_path: 'src/file.ts' },
         result: { content: 'file contents', is_error: false },
         ts: '2026-07-16T12:00:03.000Z',
+        executionId: null,
         sourceEventIds,
       },
       {
         id: 'answer',
         type: 'text',
         text: 'Done',
         ts: '2026-07-16T12:00:05.000Z',
+        executionId: null,
         sourceEventIds,
       },
     ];
@@ -73,12 +78,13 @@ describe('thread work fold view mapping', () => {
 
   it('maps an incomplete turn with no reply as live tool work', () => {
     const items: SessionItem[] = [
-      { id: 'ask', type: 'user_message', text: 'Run it', sourceEventIds },
+      { id: 'ask', type: 'user_message', text: 'Run it', executionId: null, sourceEventIds },
       {
         id: 'run',
         type: 'tool_call',
         name: 'Bash',
         input: { command: 'pnpm test' },
+        executionId: null,
         sourceEventIds,
       },
     ];

surface/mobile/test/turns.test.tsx

@@ -11,11 +11,11 @@ import { deriveTurns, type Turn } from '../src/components/work/turns';
 afterEach(cleanup);
 
 function textItem(id: string, text = 'Agent output'): SessionItem {
-  return { type: 'text', id, text, sourceEventIds: [1] };
+  return { type: 'text', id, text, executionId: null, sourceEventIds: [1] };
 }
 
 function steerItem(id: string, text: string): SessionItem {
-  return { type: 'user_message', id, text, sourceEventIds: [2] };
+  return { type: 'user_message', id, text, executionId: null, sourceEventIds: [2] };
 }
 
 describe('deriveTurns', () => {

surface/server/src/session-projection-triggers.test.ts

@@ -142,7 +142,7 @@ describe('session projection triggers', () => {
 
     const replies = await pool.query<{
       thread_root_event_id: number;
-      payload: { session_id: string; text: string; broadcast: boolean };
+      payload: { session_id: string; text: string; broadcast: boolean; execution_id: string };
     }>(
       `SELECT thread_root_event_id, payload
          FROM events
@@ -156,7 +156,7 @@ describe('session projection triggers', () => {
     expect(replies.rows).toEqual([
       {
         thread_root_event_id: rootId,
-        payload: { session_id: sessionId, text: 'done', broadcast: true },
+        payload: { session_id: sessionId, text: 'done', broadcast: true, execution_id: 'exec-test' },
       },
     ]);
   });