fix: derive reuse lineage from the fitted record on main

lib/app/distill-run.js

@@ -96,16 +96,16 @@ async function keptResult(ports, claimed, result) {
 }
 
 // A session file that cannot be read costs the distillation its lineage, never the distillation itself.
-async function reusedAssetIdsIn(ports, { sessionId, range }) {
+async function reusedAssetIdsIn(ports, { sessionId, range }, session) {
   try {
-    return reusedAssetIdsOf(sessionOf(await ports.sessions.read(sessionId)), range);
+    return reusedAssetIdsOf(sessionOf(await ports.sessions.read(sessionId)), { ...range, turns: session.turns });
   } catch {
     return [];
   }
 }
 
 async function posted(ports, claimed, session, { irs, usage, signal }) {
-  const reusedAssetIds = await reusedAssetIdsIn(ports, claimed);
+  const reusedAssetIds = await reusedAssetIdsIn(ports, claimed, session);
   const bodies = distillBodiesOf({ platform: ports.identity.agent, sessionId: taskSessionId(ports.identity, claimed.sessionId), trigger: claimed.trigger, session, irs, usage, reusedAssetIds });
   const results = [];
   for (const body of bodies) {

test/app/distill-session.test.js

@@ -108,6 +108,25 @@ test('a distillation names only the assets injected into the turns it read', asy
   assert.deepEqual(body.reused_asset_ids, [ASSET.asset_id]);
 });
 
+test('a fitted distillation names only assets from the turns the model still reads', async () => {
+  const lastAsset = { ...ASSET, asset_id: 'sha256:' + '1'.repeat(64), short_title: 'Weather lookups', signals_match: ['weather'] };
+  const made = memoryPorts({ assets: [ASSET, lastAsset], distillAnswer: DRAFTED, model: modelAnswering(IR) });
+  const steps = [
+    ...Array.from({ length: 56 }, (_, index) => ['run', `fixture-command-${index} ${'x'.repeat(940)}`]),
+    ['pass', 'npm test'],
+  ];
+  for (let turn = 1; turn <= 8; turn++) {
+    await turnOf(made.ports, 's1', { steps, ...(turn === 8 && { prompt: 'what is the weather like' }) });
+  }
+  await endedAndDistilled(made);
+  const [{ body }] = distills(made.requests);
+  const turns = body.record.filter(({ kind }) => kind === 'turn').map(({ text }) => text);
+  assert.ok(!turns.includes('Turn 1'), 'the oldest work was cut to meet the Proxy body limit');
+  assert.ok(turns.includes('Turn 8'));
+  assert.deepEqual(body.reused_asset_ids, [lastAsset.asset_id]);
+  assert.ok(bytesOf(body) <= 256 * 1024);
+});
+
 test('a session ledger that cannot be read leaves out the reused assets, never the distillation', async () => {
   const made = await fixedSession({ model: modelAnswering(IR) });
   await sessionEnded(made.ports, { sessionId: 's1', projectDir: '/proj' });