feat: show changed files after completed turns

Add changed-file pills with per-file diff stats
Add a chat setting to disable the feature fully
Avoid changed-file projection work when disabled

packages/ui/src/components/chat/lib/turns/projectTurnRecords.ts

@@ -1,6 +1,6 @@
 import { projectTurnActivity } from './projectTurnActivity';
 import { projectTurnIndexes } from './projectTurnIndexes';
-import { projectTurnDiffStats, projectTurnSummary } from './projectTurnSummary';
+import { projectTurnChangedFiles, projectTurnDiffStats, projectTurnSummary } from './projectTurnSummary';
 import type {
     ChatMessageEntry,
     TurnMessageRecord,
@@ -83,11 +83,13 @@ const buildTurnStreamState = (userMessage: ChatMessageEntry, assistantMessages:
 interface ProjectTurnRecordsOptions {
     previousProjection?: TurnProjectionResult | null;
     showTextJustificationActivity: boolean;
+    showTurnChangedFiles: boolean;
 }
 
 const DEFAULT_OPTIONS: ProjectTurnRecordsOptions = {
     previousProjection: null,
     showTextJustificationActivity: false,
+    showTurnChangedFiles: false,
 };
 
 const areSameMessageRefs = (left: ChatMessageEntry[], right: ChatMessageEntry[]): boolean => {
@@ -180,6 +182,7 @@ export const projectTurnRecords = (
             hasTools: false,
             hasReasoning: false,
             diffStats: undefined,
+            changedFiles: undefined,
             stream: {
                 isStreaming: false,
                 isRetrying: false,
@@ -215,6 +218,9 @@ export const projectTurnRecords = (
         turn.summary = projectTurnSummary(turn.assistantMessages);
         turn.summaryText = turn.summary.text ?? getUserSummaryBody(turn.userMessage);
         turn.diffStats = projectTurnDiffStats(turn.userMessage);
+        turn.changedFiles = effectiveOptions.showTurnChangedFiles
+            ? projectTurnChangedFiles(turn.userMessage)
+            : undefined;
 
         const activity = projectTurnActivity({
             turnId: turn.turnId,

packages/ui/src/components/chat/lib/turns/projectTurnSummary.ts

@@ -1,6 +1,7 @@
-import type { ChatMessageEntry, TurnDiffStats, TurnSummaryRecord } from './types';
+import type { ChatMessageEntry, TurnChangedFile, TurnDiffStats, TurnSummaryRecord } from './types';
 
 interface SummaryDiff {
+    file?: string | null;
     additions?: number | null;
     deletions?: number | null;
 }
@@ -102,3 +103,31 @@ export const projectTurnDiffStats = (userMessage: ChatMessageEntry): TurnDiffSta
         files,
     };
 };
+
+export const projectTurnChangedFiles = (userMessage: ChatMessageEntry): TurnChangedFile[] | undefined => {
+    const summary = (userMessage.info as { summary?: UserSummaryPayload | null }).summary;
+    const diffs = summary?.diffs;
+    if (!Array.isArray(diffs) || diffs.length === 0) {
+        return undefined;
+    }
+
+    const files = diffs
+        .map((diff) => {
+            if (!diff || typeof diff.file !== 'string' || diff.file.trim().length === 0) {
+                return null;
+            }
+            const additions = typeof diff.additions === 'number' ? diff.additions : 0;
+            const deletions = typeof diff.deletions === 'number' ? diff.deletions : 0;
+            if (additions === 0 && deletions === 0) {
+                return null;
+            }
+            return {
+                file: diff.file,
+                additions,
+                deletions,
+            };
+        })
+        .filter((file): file is TurnChangedFile => file !== null);
+
+    return files.length > 0 ? files : undefined;
+};

packages/ui/src/components/chat/lib/turns/types.ts

@@ -34,6 +34,12 @@ export interface TurnDiffStats {
     files: number;
 }
 
+export interface TurnChangedFile {
+    file: string;
+    additions: number;
+    deletions: number;
+}
+
 export interface TurnActivityGroup {
     id: string;
     anchorMessageId: string;
@@ -70,6 +76,7 @@ export interface TurnRecord {
     hasTools: boolean;
     hasReasoning: boolean;
     diffStats?: TurnDiffStats;
+    changedFiles?: TurnChangedFile[];
     stream: TurnStreamState;
     startedAt?: number;
     completedAt?: number;
@@ -115,6 +122,7 @@ export interface TurnGroupingContext {
     hasTools: boolean;
     hasReasoning: boolean;
     diffStats?: TurnDiffStats;
+    changedFiles?: TurnChangedFile[];
     userMessageCreatedAt?: number;
     userMessageVariant?: string;
     isWorking: boolean;