fix(build): rename threadSummary.ts — case-collision broke the Windows release

threadSummary.ts (pure helpers) and ThreadSummary.tsx (chip component) lived in
the same directory differing only by case. On the case-insensitive Windows
release runner, RoomTimeline's extensionless import of ./thread/ThreadSummary
resolved .ts BEFORE .tsx and matched the helper module → rolldown
MISSING_EXPORT "ThreadSummary" — invisible on every Linux/macOS build (and the
cause of the earlier masked pdf.worker failure). Helper module renamed to
threadSummaryData.ts (+ test), 3 importers updated.

Prevention: new caseCollision.test.ts walks src/ and fails on any same-directory
names differing only by case (extensionless compare, so Foo.tsx vs foo.ts is
caught) — verified it fails on the pre-rename tree. Runs in the hard CI gate.

Gates: tsc clean, eslint/prettier clean, build OK, 658/659 tests (1 IDB skip).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/room/thread/threadSummaryData.test.ts

@@ -0,0 +1,133 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { EventStatus, MatrixEvent, RelationType } from 'matrix-js-sdk';
+import { getThreadSummary, isPendingThreadReply } from './threadSummaryData';
+
+// getThreadSummary reads either the live Thread (preferred) or the
+// server-aggregated `m.thread` bundle. We stub only the members it touches and
+// cast through `unknown` to MatrixEvent, mirroring the light mocking used in
+// the state tests.
+
+type ThreadStub = { length: number; lastReplyTs?: number };
+type BundleStub = { count: number; latestTs?: number };
+
+const makeRootEvent = (opts: { thread?: ThreadStub; bundle?: BundleStub }): MatrixEvent => {
+  const thread = opts.thread
+    ? {
+        length: opts.thread.length,
+        lastReply: () =>
+          opts.thread?.lastReplyTs === undefined
+            ? null
+            : ({ getTs: () => opts.thread?.lastReplyTs } as unknown as MatrixEvent),
+      }
+    : undefined;
+
+  return {
+    getThread: () => thread,
+    getServerAggregatedRelation: (relType: string) => {
+      if (relType !== RelationType.Thread || !opts.bundle) return undefined;
+      return {
+        count: opts.bundle.count,
+        latest_event:
+          opts.bundle.latestTs === undefined
+            ? undefined
+            : { origin_server_ts: opts.bundle.latestTs },
+      };
+    },
+  } as unknown as MatrixEvent;
+};
+
+// ---------------------------------------------------------------------------
+// getThreadSummary
+// ---------------------------------------------------------------------------
+
+test('prefers the live thread: count from length, latestTs from lastReply', () => {
+  const rootEvent = makeRootEvent({
+    thread: { length: 3, lastReplyTs: 1700 },
+    bundle: { count: 99, latestTs: 1 },
+  });
+  assert.deepEqual(getThreadSummary(rootEvent), { count: 3, latestTs: 1700 });
+});
+
+test('live thread with no replies yields undefined latestTs', () => {
+  const rootEvent = makeRootEvent({ thread: { length: 0 } });
+  assert.deepEqual(getThreadSummary(rootEvent), { count: 0, latestTs: undefined });
+});
+
+test('falls back to the server bundle when no live thread', () => {
+  const rootEvent = makeRootEvent({ bundle: { count: 5, latestTs: 1234 } });
+  assert.deepEqual(getThreadSummary(rootEvent), { count: 5, latestTs: 1234 });
+});
+
+test('bundle without latest_event yields undefined latestTs', () => {
+  const rootEvent = makeRootEvent({ bundle: { count: 2 } });
+  assert.deepEqual(getThreadSummary(rootEvent), { count: 2, latestTs: undefined });
+});
+
+test('returns undefined when there is neither a thread nor a bundle', () => {
+  const rootEvent = makeRootEvent({});
+  assert.equal(getThreadSummary(rootEvent), undefined);
+});
+
+// ---------------------------------------------------------------------------
+// isPendingThreadReply
+// ---------------------------------------------------------------------------
+
+const ROOT = '$root:server';
+
+const makeReply = (opts: {
+  status: EventStatus | null;
+  threadRootId?: string;
+  relation?: { rel_type?: string; event_id?: string } | null;
+}): MatrixEvent =>
+  ({
+    status: opts.status,
+    threadRootId: opts.threadRootId,
+    getRelation: () => opts.relation ?? null,
+  }) as unknown as MatrixEvent;
+
+test('SENDING with matching threadRootId is pending', () => {
+  const event = makeReply({ status: EventStatus.SENDING, threadRootId: ROOT });
+  assert.equal(isPendingThreadReply(event, ROOT), true);
+});
+
+test('NOT_SENT with matching threadRootId is pending', () => {
+  const event = makeReply({ status: EventStatus.NOT_SENT, threadRootId: ROOT });
+  assert.equal(isPendingThreadReply(event, ROOT), true);
+});
+
+test('SENDING resolved via the m.thread relation content is pending', () => {
+  const event = makeReply({
+    status: EventStatus.SENDING,
+    relation: { rel_type: RelationType.Thread, event_id: ROOT },
+  });
+  assert.equal(isPendingThreadReply(event, ROOT), true);
+});
+
+test('SENT (confirmed) event is not pending', () => {
+  const event = makeReply({ status: EventStatus.SENT, threadRootId: ROOT });
+  assert.equal(isPendingThreadReply(event, ROOT), false);
+});
+
+test('null status is not pending', () => {
+  const event = makeReply({ status: null, threadRootId: ROOT });
+  assert.equal(isPendingThreadReply(event, ROOT), false);
+});
+
+test('SENDING but for a different thread is not pending', () => {
+  const event = makeReply({ status: EventStatus.SENDING, threadRootId: '$other:server' });
+  assert.equal(isPendingThreadReply(event, ROOT), false);
+});
+
+test('SENDING with a non-thread relation is not pending', () => {
+  const event = makeReply({
+    status: EventStatus.SENDING,
+    relation: { rel_type: RelationType.Reference, event_id: ROOT },
+  });
+  assert.equal(isPendingThreadReply(event, ROOT), false);
+});
+
+test('SENDING with no relation and no threadRootId is not pending', () => {
+  const event = makeReply({ status: EventStatus.SENDING });
+  assert.equal(isPendingThreadReply(event, ROOT), false);
+});

src/app/features/room/thread/threadSummaryData.ts

@@ -0,0 +1,55 @@
+import { EventStatus, IThreadBundledRelationship, MatrixEvent, RelationType } from 'matrix-js-sdk';
+
+export type ThreadSummaryData = {
+  count: number;
+  latestTs: number | undefined;
+};
+
+/**
+ * Summary data for a thread root's "N replies" chip.
+ *
+ * Prefers the live {@link Thread} object when it exists (it reflects local
+ * echo + pagination), otherwise falls back to the server-aggregated bundle
+ * (`unsigned['m.relations']['m.thread']`) so the chip renders before any
+ * Thread object has been created. Returns `undefined` when the root has no
+ * thread at all.
+ */
+export const getThreadSummary = (rootEvent: MatrixEvent): ThreadSummaryData | undefined => {
+  const thread = rootEvent.getThread();
+  if (thread) {
+    const lastReply = thread.lastReply();
+    return {
+      count: thread.length,
+      latestTs: lastReply?.getTs(),
+    };
+  }
+
+  const bundle = rootEvent.getServerAggregatedRelation<IThreadBundledRelationship>(
+    RelationType.Thread,
+  );
+  if (bundle) {
+    return {
+      count: bundle.count,
+      latestTs: bundle.latest_event?.origin_server_ts,
+    };
+  }
+
+  return undefined;
+};
+
+/**
+ * True when `event` is a still-in-flight (local echo) reply belonging to the
+ * given thread root. Used to render the pending strip, since pending thread
+ * sends never enter the thread's timelineSet.
+ */
+export const isPendingThreadReply = (event: MatrixEvent, threadRootId: string): boolean => {
+  const { status } = event;
+  if (status !== EventStatus.SENDING && status !== EventStatus.NOT_SENT) return false;
+
+  // Prefer the SDK's resolved thread root id; fall back to the raw relation
+  // content for events the SDK hasn't associated with a thread yet.
+  if (event.threadRootId === threadRootId) return true;
+
+  const relation = event.getRelation();
+  return relation?.rel_type === RelationType.Thread && relation.event_id === threadRootId;
+};

src/app/features/room/thread/useThread.ts

@@ -12,7 +12,7 @@ import {
   ThreadEvent,
 } from 'matrix-js-sdk';
 import { getLinkedTimelines } from '../RoomTimeline';
-import { isPendingThreadReply } from './threadSummary';
+import { isPendingThreadReply } from './threadSummaryData';
 
 /**
  * Resolve (or bootstrap) the live {@link Thread} for a root event.

src/app/hooks/useThreadSummary.ts

@@ -8,7 +8,7 @@ import {
   RoomEventHandlerMap,
   ThreadEvent,
 } from 'matrix-js-sdk';
-import { getThreadSummary, ThreadSummaryData } from '../features/room/thread/threadSummary';
+import { getThreadSummary, ThreadSummaryData } from '../features/room/thread/threadSummaryData';
 import { threadNotificationsAtom } from '../state/threadNotifications';
 import { getThreadNotificationMode, ThreadNotificationMode } from '../utils/threadNotifications';
 

src/app/utils/caseCollision.test.ts

@@ -0,0 +1,43 @@
+import { strict as assert } from 'node:assert';
+import { test } from 'node:test';
+import { readdirSync } from 'node:fs';
+import { join } from 'node:path';
+
+/**
+ * Guard against same-directory filenames that differ only by case (e.g.
+ * `threadSummary.ts` vs `ThreadSummary.tsx`). On case-insensitive filesystems
+ * (the Windows release runner) an extensionless import of one can resolve to
+ * the OTHER file — rolldown tries `.ts` before `.tsx` — producing
+ * MISSING_EXPORT failures that never reproduce on the Linux/macOS machines the
+ * project is developed and web-deployed on. This broke the desktop release
+ * build twice before being diagnosed; this test makes the collision a local,
+ * immediate failure instead.
+ */
+const findCaseCollisions = (dir: string, collisions: string[]): void => {
+  const entries = readdirSync(dir, { withFileTypes: true });
+  const seen = new Map<string, string>();
+  entries.forEach((entry) => {
+    // Compare basenames without extension: `Foo.tsx` collides with `foo.ts`
+    // because module resolution is extensionless.
+    const stem = entry.isDirectory() ? entry.name : entry.name.replace(/\.[^.]+$/, '');
+    const key = stem.toLowerCase();
+    const existing = seen.get(key);
+    if (existing !== undefined && existing !== stem) {
+      collisions.push(`${dir}: "${existing}" vs "${stem}"`);
+    }
+    if (existing === undefined) seen.set(key, stem);
+    if (entry.isDirectory()) {
+      findCaseCollisions(join(dir, entry.name), collisions);
+    }
+  });
+};
+
+test('no same-directory filenames differing only by case under src/', () => {
+  const collisions: string[] = [];
+  findCaseCollisions('src', collisions);
+  assert.deepEqual(
+    collisions,
+    [],
+    `Case-colliding names break Windows builds:\n${collisions.join('\n')}`,
+  );
+});