test: add suites for state/sessions, recentSearches, upload (+17)

Via subagent, all verified against real behavior:
- state/sessions (5): fallback-session round-trip across the four cinny_* keys,
  missing-key → undefined for each required key, removeFallbackSession clears all.
- state/recentSearches (6): addRecentSearch prepend, case-sensitive dedupe +
  move-to-front, trim, ignore empty/whitespace, cap at 10.
- state/upload (6): the createUploadAtom reducer driven through a real jotai
  store — idle→loading→progress(gated)→success/error, file ref preserved.

No bugs found.

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

src/app/state/upload.test.ts

@@ -0,0 +1,103 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { createStore } from 'jotai';
+import { UploadResponse, UploadProgress, MatrixError } from 'matrix-js-sdk';
+import { createUploadAtom, UploadStatus, Upload } from './upload';
+import { TUploadContent } from '../utils/matrix';
+
+// We exercise the pure reducer inside `createUploadAtom` by driving it through a
+// plain jotai store. The write atom is a state machine over UploadStatus.
+//
+// SKIPPED (require a real MatrixClient and/or React render, not pure logic):
+//   - useBindUploadAtom (React hook; calls mx.cancelUpload, uploadContent)
+//   - createUploadAtomFamily / createUploadFamilyObserverAtom (thin atomFamily
+//     wrappers whose behavior is just createUploadAtom + jotai plumbing)
+
+const makeFile = (size = 100): TUploadContent => ({ size }) as unknown as TUploadContent;
+
+test('createUploadAtom starts in the Idle state holding the file', () => {
+  const store = createStore();
+  const file = makeFile();
+  const uploadAtom = createUploadAtom(file);
+
+  const state = store.get(uploadAtom);
+  assert.equal(state.status, UploadStatus.Idle);
+  assert.equal(state.file, file);
+});
+
+test('a promise update transitions Idle -> Loading with zeroed progress', () => {
+  const store = createStore();
+  const file = makeFile(2048);
+  const uploadAtom = createUploadAtom(file);
+
+  const promise = Promise.resolve({} as UploadResponse);
+  store.set(uploadAtom, { promise });
+
+  const state = store.get(uploadAtom);
+  assert.equal(state.status, UploadStatus.Loading);
+  if (state.status === UploadStatus.Loading) {
+    assert.equal(state.promise, promise);
+    assert.deepEqual(state.progress, { loaded: 0, total: 2048 });
+  }
+});
+
+test('a progress update is applied only while Loading', () => {
+  const store = createStore();
+  const uploadAtom = createUploadAtom(makeFile(2048));
+
+  const progress: UploadProgress = { loaded: 512, total: 2048 };
+
+  // Ignored while Idle (not Loading).
+  store.set(uploadAtom, { progress });
+  assert.equal(store.get(uploadAtom).status, UploadStatus.Idle);
+
+  // Enter Loading, then progress sticks.
+  store.set(uploadAtom, { promise: Promise.resolve({} as UploadResponse) });
+  store.set(uploadAtom, { progress });
+  const state = store.get(uploadAtom);
+  assert.equal(state.status, UploadStatus.Loading);
+  if (state.status === UploadStatus.Loading) {
+    assert.deepEqual(state.progress, progress);
+  }
+});
+
+test('an mxc update transitions to Success', () => {
+  const store = createStore();
+  const uploadAtom = createUploadAtom(makeFile());
+
+  store.set(uploadAtom, { mxc: 'mxc://example.org/abc' });
+  const state = store.get(uploadAtom);
+  assert.equal(state.status, UploadStatus.Success);
+  if (state.status === UploadStatus.Success) {
+    assert.equal(state.mxc, 'mxc://example.org/abc');
+  }
+});
+
+test('an error update transitions to Error', () => {
+  const store = createStore();
+  const uploadAtom = createUploadAtom(makeFile());
+
+  const error = new Error('boom') as unknown as MatrixError;
+  store.set(uploadAtom, { error });
+  const state = store.get(uploadAtom);
+  assert.equal(state.status, UploadStatus.Error);
+  if (state.status === UploadStatus.Error) {
+    assert.equal(state.error, error);
+  }
+});
+
+test('the file reference is preserved across transitions', () => {
+  const store = createStore();
+  const file = makeFile();
+  const uploadAtom = createUploadAtom(file);
+
+  const seenFiles: TUploadContent[] = [];
+  const record = (s: Upload) => seenFiles.push(s.file);
+
+  store.set(uploadAtom, { promise: Promise.resolve({} as UploadResponse) });
+  record(store.get(uploadAtom));
+  store.set(uploadAtom, { mxc: 'mxc://example.org/x' });
+  record(store.get(uploadAtom));
+
+  assert.ok(seenFiles.every((f) => f === file));
+});