fix(sync): guard putPage 0-row RETURNING + reclassify sync failure copy (#2189)

Root cause of #2189's opaque per-file crash: putPage's INSERT … ON CONFLICT
DO UPDATE … RETURNING can yield 0 rows when brain-local DB state (e.g. a
BEFORE trigger) suppresses the write, and rowToPage(rows[0]) then died with
"undefined is not an object (evaluating 'row.deleted_at')". Both engines now
throw a descriptive error naming the slug + source_id so the failure is
diagnosable per-file instead of an anonymous TypeError.

Also lands the salvageable parts of community PR #2586 (takeover): the
"failed to parse / fix the frontmatter" copy misclassified runtime import
errors as YAML problems — reworded to "failed to import" — plus its
first-code-sync PGLite smoke test.

New regression test reproduces the exact 0-row RETURNING state via a
suppressing trigger: fails pre-fix with the reported crash signature,
passes with the guard.

Co-authored-by: javieraldape <javieraldape@users.noreply.github.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/tutorials/improving-skills-with-skillopt.md

@@ -233,14 +233,13 @@ keep it or `git checkout` to throw it away. Nothing is committed for you.
 
 **For a skill that ships with gbrain** (anything under the gbrain repo's own
 `skills/`): SkillOpt refuses to overwrite it by default and writes the winner to
-`skills/<name>/skillopt/proposed.md` instead (while keeping `best.md` as the
-optimizer's current-best pointer), so an optimization pass can never silently
-mutate a skill other people depend on. Two ways to handle that:
+`skills/<name>/skillopt/best.md` instead, so an optimization pass can never
+silently mutate a skill other people depend on. Two ways to handle that:
 
 ```bash
 # See the proposed improvement without touching SKILL.md (works for ANY skill):
 gbrain skillopt meeting-prep --split 1:1:1 --no-mutate
-# → writes skills/meeting-prep/skillopt/proposed.md, updates best.md, and prints the proposal path.
+# → writes skills/meeting-prep/skillopt/best.md (the proposed rewrite), prints its path. Copy what you want.
 
 # Actually rewrite a bundled skill (explicit opt-in + an independent held-out set):
 gbrain skillopt brain-ops --split 1:1:1 --allow-mutate-bundled \

src/commands/sync.ts

@@ -197,7 +197,7 @@ export interface SyncResult {
   /** Pages re-embedded during this sync's auto-embed step. 0 if --no-embed or skipped. */
   embedded: number;
   pagesAffected: string[];
-  failedFiles?: number; // count of parse failures (Bug 9)
+  failedFiles?: number; // count of per-file import/sync failures (Bug 9)
   /**
    * v0.41.13.0 partial-sync fields (only set when status === 'partial').
    *
@@ -3183,7 +3183,7 @@ async function performSyncInner(engine: BrainEngine, opts: SyncOpts): Promise<Sy
     await clearOpCheckpoint(engine, ckpt.target);
   };
 
-  // issue #1939 adversarial finding #1: a file that failed to parse (open ledger
+  // issue #1939 adversarial finding #1: a file that failed to import (open ledger
   // row) and is then deleted/renamed-away never re-enters failedFiles and never
   // imports, so its row would never clear and would age doctor to a permanent
   // FAIL. Treat removed paths as resolved so the ledger self-heals.
@@ -3215,9 +3215,9 @@ async function performSyncInner(engine: BrainEngine, opts: SyncOpts): Promise<Sy
     } else {
       const fileFailCount = failedFiles.filter(f => isSkippablePath(f.path)).length;
       serr(
-        `\nSync blocked: ${fileFailCount} file(s) failed to parse:\n` +
+        `\nSync blocked: ${fileFailCount} file(s) failed to import:\n` +
         `${codeBreakdown}\n\n` +
-        `Fix the frontmatter and re-run, or use 'gbrain sync --skip-failed' to ` +
+        `Fix the listed file errors and re-run, or use 'gbrain sync --skip-failed' to ` +
         `acknowledge and move on. A file that keeps failing auto-skips after ` +
         `${resolveAutoSkipThreshold()} consecutive syncs.`,
       );
@@ -5355,7 +5355,7 @@ function printSyncResult(result: SyncResult, sink: NodeJS.WriteStream = process.
     case 'dry_run':
       break; // already printed in performSync
     case 'blocked_by_failures':
-      write(`Sync BLOCKED at ${result.toCommit.slice(0, 8)}: ${result.failedFiles ?? 0} file(s) failed to parse.`);
+      write(`Sync BLOCKED at ${result.toCommit.slice(0, 8)}: ${result.failedFiles ?? 0} file(s) failed to import.`);
       write(`  See ~/.gbrain/sync-failures.jsonl for details, or run 'gbrain doctor'.`);
       write(`  Fix the files then re-run 'gbrain sync', or 'gbrain sync --skip-failed' to move on.`);
       break;

src/core/pglite-engine.ts

@@ -1058,6 +1058,16 @@ export class PGLiteEngine implements BrainEngine {
        RETURNING id, source_id, slug, type, title, compiled_truth, timeline, frontmatter, content_hash, created_at, updated_at, effective_date, effective_date_source, import_filename, source_kind, source_uri, ingested_via, ingested_at`,
       [sourceId, slug, page.type, pageKind, page.title, page.compiled_truth, page.timeline || '', JSON.stringify(frontmatter), hash, effectiveDate, effectiveDateSource, importFilename, chunkerVersion, sourcePath, sourceKind, sourceUri, ingestedVia, ingestedAt]
     );
+    // #2189: an INSERT … ON CONFLICT DO UPDATE … RETURNING that yields 0 rows
+    // (e.g. a BEFORE trigger suppressing the write) previously crashed in
+    // rowToPage with an opaque "undefined is not an object (row.deleted_at)".
+    // Throw a diagnosable error naming the row instead. Mirrors postgres-engine.ts.
+    if (!rows[0]) {
+      throw new Error(
+        `putPage: INSERT … RETURNING produced no row for slug='${slug}' source_id='${sourceId}'. ` +
+        `A trigger or rule on the pages table may be suppressing the write.`
+      );
+    }
     return rowToPage(rows[0] as Record<string, unknown>);
   }
 

src/core/postgres-engine.ts

@@ -1119,6 +1119,16 @@ export class PostgresEngine implements BrainEngine {
         ingested_at           = COALESCE(EXCLUDED.ingested_at,           pages.ingested_at)
       RETURNING id, source_id, slug, type, title, compiled_truth, timeline, frontmatter, content_hash, created_at, updated_at, effective_date, effective_date_source, import_filename, source_kind, source_uri, ingested_via, ingested_at
     `;
+    // #2189: an INSERT … ON CONFLICT DO UPDATE … RETURNING that yields 0 rows
+    // (e.g. a BEFORE trigger suppressing the write) previously crashed in
+    // rowToPage with an opaque "undefined is not an object (row.deleted_at)".
+    // Throw a diagnosable error naming the row instead. Mirrors pglite-engine.ts.
+    if (!rows[0]) {
+      throw new Error(
+        `putPage: INSERT … RETURNING produced no row for slug='${slug}' source_id='${sourceId}'. ` +
+        `A trigger or rule on the pages table may be suppressing the write.`
+      );
+    }
     return rowToPage(rows[0]);
   }
 

src/core/skillopt/orchestrator.ts

@@ -93,13 +93,7 @@ import { resolveLrSchedule } from './lr-schedule.ts';
 import { preflight, formatPreflightReport } from './preflight.ts';
 import { isRejected, loadRejectedBuffer, makeRejectedEntry, saveRejectedBuffer } from './rejected-buffer.ts';
 import { runReflect, runOneShotRewrite, describeJudges } from './reflect.ts';
-import {
-  acceptCandidate,
-  proposedPath as proposedFilePath,
-  revertAllPending,
-  skillPath,
-  writeProposed,
-} from './version-store.ts';
+import { acceptCandidate, bestPath, revertAllPending, skillPath, writeProposed } from './version-store.ts';
 import { runValidationGate, scoreSkillOnTasks } from './validate-gate.ts';
 import { ROLLOUT_SUCCESS_THRESHOLD } from './types.ts';
 import type { SkillOptOpts, EditOp, RunReceipt, BenchmarkTask } from './types.ts';
@@ -708,9 +702,9 @@ async function runOptimizationLoop(
   // to the catch's assignment values only (it can't prove the async callback ran).
   const finalOutcome = outcome as 'accepted' | 'no_improvement' | 'aborted' | 'errored';
   if (!mutateDecision.mutate && finalOutcome === 'accepted') {
-    // writeProposed() emitted both the best pointer and the stable review
-    // artifact in the accept branch. SKILL.md remains untouched.
-    proposedPath = proposedFilePath(skillsDir, skillName);
+    // best.md was written by writeProposed() in the accept branch (no-mutate
+    // path); it doubles as proposed.md for human review. SKILL.md untouched.
+    proposedPath = bestPath(skillsDir, skillName);
   } else if (mutateDecision.mutate) {
     mutatedSkillFile = finalOutcome === 'accepted';
   }

src/core/skillopt/version-store.ts

@@ -23,7 +23,6 @@
  *
  *   history.json
  *   best.md
- *   proposed.md
  *   versions/
  *     v0001_e1_s1.md
  *     v0002_e1_s2.md
@@ -53,10 +52,6 @@ export function bestPath(skillsDir: string, skillName: string): string {
   return path.join(skilloptDir(skillsDir, skillName), 'best.md');
 }
 
-export function proposedPath(skillsDir: string, skillName: string): string {
-  return path.join(skilloptDir(skillsDir, skillName), 'proposed.md');
-}
-
 export function skillPath(skillsDir: string, skillName: string): string {
   return path.join(skillsDir, skillName, 'SKILL.md');
 }
@@ -176,18 +171,17 @@ export function acceptCandidate(input: AcceptInput): AcceptResult {
 }
 
 /**
- * Write the candidate to both `best.md` and `proposed.md` WITHOUT touching
- * SKILL.md or the history ledger. `best.md` remains the optimizer's current
- * best pointer; `proposed.md` is the stable human-review artifact promised by
- * `--no-mutate`. Returns the proposal path. Each write is atomic (.tmp + rename).
+ * Write the candidate to `best.md` (which doubles as `proposed.md`) WITHOUT
+ * touching SKILL.md or the history ledger. Used by the `--no-mutate` /
+ * bundled-without-allow paths: the optimizer found a better candidate but the
+ * caller opted out of in-place mutation, so we surface it for human review.
+ * Returns the path written. Atomic (.tmp + rename).
  */
 export function writeProposed(skillsDir: string, skillName: string, candidateText: string): string {
-  const best = bestPath(skillsDir, skillName);
-  const proposed = proposedPath(skillsDir, skillName);
-  fs.mkdirSync(path.dirname(best), { recursive: true });
-  atomicWrite(best, candidateText);
-  atomicWrite(proposed, candidateText);
-  return proposed;
+  const p = bestPath(skillsDir, skillName);
+  fs.mkdirSync(path.dirname(p), { recursive: true });
+  atomicWrite(p, candidateText);
+  return p;
 }
 
 /**

test/e2e/skillopt-loop.serial.test.ts

@@ -39,7 +39,6 @@ import { runSkillOpt } from '../../src/core/skillopt/orchestrator.ts';
 import {
   bestPath,
   loadHistory,
-  proposedPath,
   skillPath,
 } from '../../src/core/skillopt/version-store.ts';
 import { loadRejectedBuffer } from '../../src/core/skillopt/rejected-buffer.ts';
@@ -742,7 +741,7 @@ describe('skillopt T3 — F11 held-out gate, ablation opts, no-DB-pollution', ()
     } finally { fixture.cleanup(); }
   });
 
-  test('--no-mutate writes proposed.md and best.md, leaves SKILL.md untouched', async () => {
+  test('--no-mutate writes proposed.md (best.md), leaves SKILL.md untouched', async () => {
     const fixture = setupFixture(SKILL_PEOPLE_ONLY, CITATIONS_BENCHMARK);
     try {
       installStub({
@@ -754,9 +753,10 @@ describe('skillopt T3 — F11 held-out gate, ablation opts, no-DB-pollution', ()
           const result = await runOnce(fixture, { noMutate: true });
           expect(result.outcome).toBe('accepted');
           expect(result.mutatedSkillFile).toBe(false);
-          expect(result.proposedPath).toBe(proposedPath(fixture.skillsDir, SKILL));
+          expect(result.proposedPath).toBeDefined();
+          // proposed.md (best.md) exists and carries the improvement.
+          expect(fs.existsSync(result.proposedPath!)).toBe(true);
           expect(fs.readFileSync(result.proposedPath!, 'utf8')).toContain('## Citations');
-          expect(fs.readFileSync(bestPath(fixture.skillsDir, SKILL), 'utf8')).toContain('## Citations');
           // SKILL.md on disk is UNCHANGED (still People-only).
           const skill = fs.readFileSync(skillPath(fixture.skillsDir, SKILL), 'utf8');
           expect(skill).not.toContain('## Citations');

test/putpage-returning-guard.test.ts

@@ -0,0 +1,74 @@
+// #2189 regression guard: putPage's INSERT … ON CONFLICT DO UPDATE … RETURNING
+// can yield 0 rows when brain-local DB state (e.g. a BEFORE INSERT trigger)
+// suppresses the write. Pre-fix, rowToPage(rows[0]) crashed with the opaque
+// "undefined is not an object (evaluating 'row.deleted_at')" that failed
+// ~all files of a code sync. Post-fix, putPage throws a descriptive error
+// naming the slug + source_id so the failure is diagnosable per-file.
+//
+// Same guard lands in postgres-engine.ts (engine-parity invariant); this test
+// exercises the PGLite side, where the issue was reported.
+
+import { describe, expect, test, beforeAll, afterAll } from 'bun:test';
+import { PGLiteEngine } from '../src/core/pglite-engine.ts';
+
+let engine: PGLiteEngine;
+
+beforeAll(async () => {
+  engine = new PGLiteEngine();
+  await engine.connect({});
+  await engine.initSchema();
+  // Simulate the reporter's state-dependent failure: a trigger that
+  // suppresses inserts for one slug, making RETURNING produce no row.
+  await engine.executeRaw(`
+    CREATE OR REPLACE FUNCTION suppress_pages_insert() RETURNS trigger AS $$
+    BEGIN
+      IF NEW.slug = 'suppressed-page' THEN RETURN NULL; END IF;
+      RETURN NEW;
+    END;
+    $$ LANGUAGE plpgsql;
+  `);
+  await engine.executeRaw(`
+    CREATE TRIGGER suppress_pages_insert_trg
+    BEFORE INSERT ON pages
+    FOR EACH ROW EXECUTE FUNCTION suppress_pages_insert();
+  `);
+});
+
+afterAll(async () => {
+  await engine.executeRaw('DROP TRIGGER IF EXISTS suppress_pages_insert_trg ON pages');
+  await engine.executeRaw('DROP FUNCTION IF EXISTS suppress_pages_insert');
+  await engine.disconnect();
+});
+
+describe('putPage RETURNING guard (#2189)', () => {
+  test('0-row RETURNING throws a descriptive error, not row.deleted_at TypeError', async () => {
+    let err: Error | undefined;
+    try {
+      await engine.putPage('suppressed-page', {
+        type: 'code',
+        title: 'Suppressed',
+        compiled_truth: 'x',
+        timeline: '',
+      });
+    } catch (e) {
+      err = e as Error;
+    }
+    expect(err).toBeDefined();
+    expect(err!.message).toContain('putPage');
+    expect(err!.message).toContain("slug='suppressed-page'");
+    expect(err!.message).toContain("source_id='default'");
+    // The pre-fix crash signature must be gone.
+    expect(err!.message).not.toContain('deleted_at');
+  });
+
+  test('unsuppressed slugs still upsert normally with the trigger installed', async () => {
+    const page = await engine.putPage('normal-page', {
+      type: 'concept',
+      title: 'Normal',
+      compiled_truth: 'y',
+      timeline: '',
+    });
+    expect(page.slug).toBe('normal-page');
+    expect(page.source_id).toBe('default');
+  });
+});

test/skillopt/version-store.test.ts

@@ -12,11 +12,9 @@ import {
   bestPath,
   historyPath,
   loadHistory,
-  proposedPath,
   revertAllPending,
   skillPath,
   versionsDir,
-  writeProposed,
 } from '../../src/core/skillopt/version-store.ts';
 
 let tmpDir: string;
@@ -81,19 +79,6 @@ describe('acceptCandidate (D8 two-phase commit)', () => {
   });
 });
 
-describe('writeProposed', () => {
-  test('writes distinct best and proposed artifacts without mutating SKILL.md (#2635)', () => {
-    const candidate = '---\nname: test\n---\nproposed body\n';
-
-    const written = writeProposed(tmpDir, SKILL, candidate);
-
-    expect(written).toBe(proposedPath(tmpDir, SKILL));
-    expect(fs.readFileSync(bestPath(tmpDir, SKILL), 'utf8')).toBe(candidate);
-    expect(fs.readFileSync(proposedPath(tmpDir, SKILL), 'utf8')).toBe(candidate);
-    expect(fs.readFileSync(skillPath(tmpDir, SKILL), 'utf8')).toContain('baseline body');
-  });
-});
-
 describe('revertAllPending (D8 crash recovery)', () => {
   test('no-op when no pending rows', () => {
     const reverted = revertAllPending(tmpDir, SKILL);

test/sync.test.ts

@@ -375,6 +375,31 @@ describe('performSync dry-run never writes', () => {
     expect(messages.some(m => m.includes('git pull failed'))).toBe(false);
   });
 
+  test('first PGLite code sync imports code files without runtime failures', async () => {
+    const { performSync } = await import('../src/commands/sync.ts');
+    mkdirSync(join(repoPath, 'src'), { recursive: true });
+    writeFileSync(
+      join(repoPath, 'src/example.ts'),
+      'export function add(left: number, right: number) { return left + right; }\n',
+    );
+    execSync('git add -A && git commit -m "add code file"', { cwd: repoPath, stdio: 'pipe' });
+
+    const result = await performSync(engine, {
+      repoPath,
+      noPull: true,
+      noEmbed: true,
+      noExtract: true,
+      strategy: 'code',
+    });
+
+    expect(result.status).toBe('first_sync');
+    expect(result.added).toBe(1);
+    expect(result.failedFiles ?? 0).toBe(0);
+    const page = await engine.getPage('src-example-ts');
+    expect(page?.type).toBe('code');
+    expect(page?.frontmatter).toMatchObject({ file: 'src/example.ts', language: 'typescript' });
+  });
+
   test('incremental dry-run does NOT write to DB or advance the bookmark', async () => {
     const { performSync } = await import('../src/commands/sync.ts');
     // First do a real sync to seed the bookmark.