diff --git a/frontend/src/capture/session.batch.test.ts b/frontend/src/capture/session.batch.test.ts
new file mode 100644
index 0000000..cffe4a8
--- /dev/null
+++ b/frontend/src/capture/session.batch.test.ts
@@ -0,0 +1,154 @@
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { test, beforeEach } from 'node:test';
+import { get } from 'svelte/store';
+import type { Draft, Source } from './capture.types';
+import { createCaptureSession, type DraftStore } from './session';
+
+const here = dirname(fileURLToPath(import.meta.url));
+
+function tinyJpeg(label: string): File {
+  // Minimal valid-ish JPEG bytes are unnecessary; Blob type is what session stores.
+  const bytes = new Uint8Array([0xff, 0xd8, 0xff, 0xe0, label.charCodeAt(0) & 0xff]);
+  return new File([bytes], `${label}.jpg`, { type: 'image/jpeg' });
+}
+
+function memStore(): DraftStore & { peek: () => Draft | null; reset: () => void } {
+  let mem: Draft | null = null;
+  return {
+    loadDraft: async () => mem,
+    saveDraft: async (d) => {
+      mem = d;
+    },
+    clearDraft: async () => {
+      mem = null;
+    },
+    peek: () => mem,
+    reset: () => {
+      mem = null;
+    },
+  };
+}
+
+let store: ReturnType<typeof memStore>;
+
+beforeEach(() => {
+  store = memStore();
+});
+
+test('session starts on batch with zero photos (replaces single addPhoto)', () => {
+  const s = createCaptureSession({ draft: store });
+  const cap = get(s.capture);
+  assert.equal(cap.k, 'batch');
+  if (cap.k === 'batch') assert.equal(cap.photos.length, 0);
+  s.dispose();
+});
+
+test('addToBatch accumulates photos and stays on batch', async () => {
+  const s = createCaptureSession({ draft: store });
+  await s.addToBatch(tinyJpeg('a'));
+  await s.addToBatch(tinyJpeg('b'));
+  const cap = get(s.capture);
+  assert.equal(cap.k, 'batch');
+  if (cap.k === 'batch') {
+    assert.equal(cap.photos.length, 2);
+    assert.ok(cap.photos[0].blob instanceof Blob);
+    assert.ok(cap.photos[1].blob instanceof Blob);
+    assert.notEqual(cap.photos[0].blob, cap.photos[1].blob);
+  }
+  s.dispose();
+});
+
+test('continueBatch is a no-op when batch is empty', () => {
+  const s = createCaptureSession({ draft: store });
+  s.continueBatch();
+  assert.equal(get(s.capture).k, 'batch');
+  s.dispose();
+});
+
+test('continueBatch with ≥1 photo advances (M1 bridge: mask on first photo)', async () => {
+  const s = createCaptureSession({ draft: store });
+  await s.addToBatch(tinyJpeg('a'));
+  await s.addToBatch(tinyJpeg('b'));
+  s.continueBatch();
+  const cap = get(s.capture);
+  assert.equal(cap.k, 'mask');
+  if (cap.k === 'mask') {
+    assert.ok(cap.source.blob instanceof Blob);
+  }
+  s.dispose();
+});
+
+test('adding photos persists batch blobs in device draft', async () => {
+  const s = createCaptureSession({ draft: store });
+  await s.addToBatch(tinyJpeg('a'));
+  await s.addToBatch(tinyJpeg('b'));
+  // allow async persist
+  await new Promise((r) => setTimeout(r, 20));
+  const d = store.peek();
+  assert.ok(d, 'draft must exist after adding photos');
+  assert.equal(d!.stage, 'batch');
+  const batch = d!.batch ?? [];
+  assert.equal(batch.length, 2, 'draft must store both batch blobs (not a UI-only list)');
+  assert.ok(batch[0].blob instanceof Blob);
+  assert.ok(batch[1].blob instanceof Blob);
+  s.dispose();
+});
+
+test('refresh: resumeProbe + Continue restores the batch photos', async () => {
+  const s1 = createCaptureSession({ draft: store });
+  await s1.addToBatch(tinyJpeg('a'));
+  await s1.addToBatch(tinyJpeg('b'));
+  await new Promise((r) => setTimeout(r, 20));
+  s1.dispose();
+
+  const s2 = createCaptureSession({ draft: store });
+  await s2.resumeProbe();
+  assert.equal(get(s2.capture).k, 'resume');
+  s2.continueDraft();
+  await new Promise((r) => setTimeout(r, 20));
+  const cap = get(s2.capture);
+  assert.equal(cap.k, 'batch');
+  if (cap.k === 'batch') {
+    assert.equal(cap.photos.length, 2);
+    assert.ok(cap.photos.every((p: Source) => p.blob instanceof Blob));
+  }
+  s2.dispose();
+});
+
+test('Batch UI: AddPhoto/Batch panel supports multi-add and Continue when ≥1', () => {
+  // Prefer BatchPhotos.svelte; fall back to AddPhoto.svelte if renamed later.
+  const candidates = ['BatchPhotos.svelte', 'AddPhoto.svelte'].map((n) => join(here, n));
+  let src = '';
+  let found = '';
+  for (const p of candidates) {
+    try {
+      src = readFileSync(p, 'utf8');
+      found = p;
+      break;
+    } catch {
+      /* try next */
+    }
+  }
+  assert.ok(src, 'expected BatchPhotos.svelte or AddPhoto.svelte');
+  assert.match(src, /Continue|continue/i, `${found} must expose Continue`);
+  assert.match(src, /photos|batch/i, `${found} must talk about batch/photos`);
+  // Must allow adding more than once (not a one-shot that leaves the screen).
+  const fileInputs = src.match(/type="file"/g) ?? [];
+  assert.ok(fileInputs.length >= 1, 'must have file picker(s)');
+  assert.ok(
+    /addToBatch|onAdd|onPicked/.test(src) || /on:change/.test(src),
+    'must wire photo add',
+  );
+});
+
+test('legacy addPhoto alias still appends to batch (no silent single-photo-only path)', async () => {
+  const s = createCaptureSession({ draft: store });
+  await s.addPhoto(tinyJpeg('only'));
+  const cap = get(s.capture);
+  assert.equal(cap.k, 'batch', 'addPhoto must not jump straight to mask anymore');
+  if (cap.k === 'batch') assert.equal(cap.photos.length, 1);
+  s.dispose();
+});