The range stream polls the corpus as well as the spool while it waits

The corpus fill claims chunks of a leased range ahead of the leased run (the
prefetcher's claim keys are per range and chunk), stores them in the corpus
only, and the run leaves them there. The stream looked at the corpus once per
chunk and then polled the spool only: when the store came seconds after that
look, the stream waited its whole hour and the worker lost the group and its
open batch (three groups on 2026-10-27, LOG.md (118)). Now the wait loop checks
both.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/functional/node_api.spec.ts

@@ -153,6 +153,38 @@ test.group('Node API', (group) => {
     }
   })
 
+  test('a chunk the corpus fill stores while the stream waits for it comes from the corpus', async ({ client, assert }) => {
+    const corpus = await mkdtemp(join(tmpdir(), 'corpus-'))
+    const saved = coordinatorConfig.corpus.dir
+    coordinatorConfig.corpus.dir = corpus
+    try {
+      const [g] = await db.table('groups').insert({ name: GROUP, priority: 1 }).returning('id')
+      // A capture range not in the corpus: its first chunk spooled by the leased run, the second claimed by
+      // the corpus fill, which stores it in the corpus only, after the stream started.
+      const [r] = await db.table('ranges').insert({ group_id: g.id, start_id: 1, end_id: 200, next_id: 1, capture: true }).returning('id')
+      const rangeId = Number(r.id)
+      await Spool.write(rangeId, { from: 1, to: 100 }, chunk(11))
+      const node = await Node.create({ name: 'n1' })
+      const token = (await Node.accessTokens.create(node)).value!.release()
+      await db.from('ranges').where('id', rangeId).update({ status: 'leased', node_id: node.id, leased_at: new Date(), heartbeat_at: new Date() })
+
+      const pending = client.get(`/api/v1/node/ranges/${rangeId}/stream`).bearerToken(token)
+      setTimeout(() => Corpus.write({ group: GROUP, start: 1, end: 200 }, { from: 101, to: 200 }, chunk(111), 2), 800)
+      const stream = await pending
+      stream.assertStatus(200)
+      const raw = stream.body() as unknown
+      const body: Buffer = Buffer.isBuffer(raw) ? raw : Buffer.from(stream.text(), 'binary')
+      const frames = []
+      for await (const frame of decodeFrames([body])) frames.push(frame)
+      assert.deepEqual(frames.map((f) => [f.from, f.to]), [[1, 100], [101, 200]])
+      assert.equal(parseOverviews(unzipSync(frames[1].data).toString('utf8')).length, 3)
+      assert.isFalse(await Spool.has(rangeId, { from: 101, to: 200 }))
+    } finally {
+      coordinatorConfig.corpus.dir = saved
+      await rm(corpus, { recursive: true, force: true })
+    }
+  })
+
   test('a chunk that does not inflate: reported, removed from the spool, the range goes back', async ({ client, assert }) => {
     const [g] = await db.table('groups').insert({ name: GROUP, priority: 1 }).returning('id')
     const [r] = await db.table('ranges').insert({ group_id: g.id, start_id: 1, end_id: 300, next_id: 1, spooled_chunks: 3 }).returning('id')