fix(propose-takes): negative-cache zero-proposal pages with a sentinel row (#2106)

propose_takes claims idempotency (an unchanged page never re-spends LLM
tokens) but only stored the key for pages that produced >=1 take. A page
yielding zero proposals never got a take_proposals row, so it was re-sent
to the LLM every cycle — the common case in a steady brain.

Insert a '__no_proposals__' sentinel row when the extractor returns [].
The existing composite unique index (source_id, page_slug, content_hash,
prompt_version) makes the next cycle's SELECT hit and skip the LLM call.
Edited pages (new content_hash) and prompt bumps still re-extract, and
extractor errors deliberately do NOT write a sentinel.

Takeover of #2261: preserves modelId routing for the model_id column
(the original branch hardcoded a fallback, breaking gateway model-routing
tests) and drops an unrelated .gitignore hunk.

Co-authored-by: Quoc Vu <quocvu2640@gmail.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/core/cycle/propose-takes.ts

@@ -391,12 +391,17 @@ class ProposeTakesPhase extends BaseCyclePhase {
       // Write proposals to take_proposals. Each row is a separate INSERT
       // because the composite idempotency key is on the per-page tuple — a
       // bulk UPSERT would collapse a same-page-multi-claim run into one row.
-      for (const p of proposals) {
+      if (proposals.length === 0) {
+        // #2106 negative cache: insert a sentinel row when the extractor
+        // found nothing, so the idempotency check skips this page on future
+        // cycles. Without it, pages with no gradeable claims (the common
+        // case) re-spend LLM tokens every cycle. Same composite key rules:
+        // an edited page (new content_hash) or a prompt bump re-extracts.
         await engine.executeRaw(
           `INSERT INTO take_proposals
              (source_id, page_slug, content_hash, prompt_version, proposal_run_id,
               claim_text, kind, holder, weight, domain, dedup_against_fence_rows, model_id)
-           VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)
+           VALUES ($1, $2, $3, $4, $5, '__no_proposals__', 'take', 'brain', 0, NULL, $6, $7)
            ON CONFLICT (source_id, page_slug, content_hash, prompt_version) DO NOTHING`,
           [
             sourceId,
@@ -404,16 +409,35 @@ class ProposeTakesPhase extends BaseCyclePhase {
             ch,
             promptVersion,
             proposalRunId,
-            p.claim_text,
-            p.kind,
-            p.holder,
-            p.weight,
-            p.domain ?? null,
             JSON.stringify(existingTakes),
             modelId,
           ],
         );
-        result.proposals_inserted += 1;
+      } else {
+        for (const p of proposals) {
+          await engine.executeRaw(
+            `INSERT INTO take_proposals
+               (source_id, page_slug, content_hash, prompt_version, proposal_run_id,
+                claim_text, kind, holder, weight, domain, dedup_against_fence_rows, model_id)
+             VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)
+             ON CONFLICT (source_id, page_slug, content_hash, prompt_version) DO NOTHING`,
+            [
+              sourceId,
+              page.slug,
+              ch,
+              promptVersion,
+              proposalRunId,
+              p.claim_text,
+              p.kind,
+              p.holder,
+              p.weight,
+              p.domain ?? null,
+              JSON.stringify(existingTakes),
+              modelId,
+            ],
+          );
+          result.proposals_inserted += 1;
+        }
       }
     }
 

test/propose-takes.test.ts

@@ -334,6 +334,22 @@ New prose appended here.`;
     expect((details.warnings as string[])[0]).toContain('LLM timeout');
   });
 
+  test('zero-proposal page writes a __no_proposals__ sentinel so the next cycle cache-hits (#2106)', async () => {
+    const pages = [buildPage({ slug: 'wiki/no-claims', body: 'reference prose with nothing takeable' })];
+    const { engine, captured } = buildMockEngine({ pages });
+    const extractor: ProposeTakesExtractor = async () => [];
+    const result = await runPhaseProposeTakes(buildCtx(engine), { extractor });
+
+    expect(result.status).toBe('ok');
+    const details = result.details as Record<string, unknown>;
+    expect(details.proposals_inserted).toBe(0); // sentinel is not a proposal
+    const inserts = captured.filter(c => c.sql.includes('INSERT INTO take_proposals'));
+    expect(inserts).toHaveLength(1);
+    expect(inserts[0]!.sql).toContain("'__no_proposals__'");
+    expect(inserts[0]!.sql).toContain('ON CONFLICT (source_id, page_slug, content_hash, prompt_version)');
+    expect(inserts[0]!.params).toHaveLength(7); // model_id rides as the last param
+  });
+
   test('pages with empty compiled_truth are skipped silently (no extractor call)', async () => {
     const pages = [
       buildPage({ slug: 'wiki/empty', body: '' }),