fix(schema-pack): narrow stats catch-all so masked errors surface, not fake 0 pages (#2466)

fetchCountRows and detectDeadPrefixes in src/core/schema-pack/stats.ts
swallowed EVERY engine error into empty results, so any real failure
printed 'Total pages: 0' + a vacuous 100% coverage on a populated brain.
Both catches now swallow only isUndefinedTableError (pre-init brain,
missing pages table) and rethrow everything else. Four regression tests:
real non-zero count on a populated PGLite brain, rethrow on non-missing-
table errors in both catch sites, and the missing-table degrade path.

Takeover of #2493.

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

src/commands/migrate-engine.ts

@@ -3,11 +3,7 @@
  *
  * Usage:
  *   gbrain migrate --to supabase [--url <connection_string>]
- *     (--url is persisted to config.json, mode 0600, so the migrated brain
- *      works without env — #1271)
  *   gbrain migrate --to pglite [--path <db_path>]
- *     (an explicit --path destination is bootstrapped with its own
- *      <path>/.gbrain/config.json so GBRAIN_HOME=<path> just works — #1271)
  *   gbrain migrate --to <engine> --force  (overwrite non-empty target)
  */
 
@@ -15,9 +11,9 @@ import { createEngine } from '../core/engine-factory.ts';
 import { loadConfig, saveConfig, toEngineConfig, gbrainPath, effectiveEnvDatabaseUrl, type GBrainConfig } from '../core/config.ts';
 import type { BrainEngine } from '../core/engine.ts';
 import type { EngineConfig } from '../core/types.ts';
-import { writeFileSync, readFileSync, existsSync, unlinkSync, mkdirSync, chmodSync } from 'fs';
+import { writeFileSync, readFileSync, existsSync, unlinkSync } from 'fs';
 import { createHash } from 'crypto';
-import { resolve, join } from 'path';
+import { resolve } from 'path';
 import { createProgress } from '../core/progress.ts';
 import { getCliOptions, cliOptsToProgressOptions } from '../core/cli-options.ts';
 
@@ -63,31 +59,6 @@ export interface MigrateManifest {
   started_at: string;
 }
 
-/**
- * #1271 Finding 1: make an explicit `--to pglite --path P` destination usable
- * as a standalone brain. Writes `P/.gbrain/config.json` (mode 0600, plus a
- * `*` .gitignore) so `GBRAIN_HOME=P` resolves without a manual `gbrain init`.
- * Never clobbers an existing config at the destination. Returns the written
- * config path, or null when skipped.
- */
-export function bootstrapDestinationConfig(dbPath: string): string | null {
-  const abs = resolve(dbPath);
-  const dir = join(abs, '.gbrain');
-  const file = join(dir, 'config.json');
-  if (existsSync(file)) return null;
-  mkdirSync(dir, { recursive: true });
-  const cfg: GBrainConfig = { engine: 'pglite', database_path: abs };
-  writeFileSync(file, JSON.stringify(cfg, null, 2) + '\n', { mode: 0o600 });
-  try { chmodSync(file, 0o600); } catch { /* platform-specific */ }
-  // Same worktree-safety pattern as saveConfig()'s ensureGitignore, scoped
-  // to the destination home. Don't clobber a user-customized .gitignore.
-  const gitignore = join(dir, '.gitignore');
-  if (!existsSync(gitignore)) {
-    writeFileSync(gitignore, '*\n', { mode: 0o600 });
-  }
-  return file;
-}
-
 export function migrationTargetId(config: EngineConfig): string {
   const locator = config.engine === 'postgres'
     ? config.database_url ?? ''
@@ -381,25 +352,6 @@ export async function runMigrateEngine(sourceEngine: BrainEngine, args: string[]
   };
   saveConfig(newConfig);
 
-  // #1271 Finding 2 (by design, but say it out loud): the connection string
-  // is persisted so the migrated brain works without env. Mode 0600.
-  if (opts.targetEngine === 'postgres' && opts.targetUrl) {
-    console.error('Note: the --url connection string (including credentials) is persisted to config.json (mode 0600).');
-  }
-
-  // #1271 Finding 1: an explicit --path destination doubles as a standalone
-  // GBRAIN_HOME. Best-effort — never fail a completed migration over it.
-  if (opts.targetEngine === 'pglite' && opts.targetPath) {
-    try {
-      const written = bootstrapDestinationConfig(opts.targetPath);
-      if (written) {
-        console.log(`Destination bootstrapped: ${written} (usable via GBRAIN_HOME=${resolve(opts.targetPath)})`);
-      }
-    } catch (e) {
-      console.warn(`  WARN could not bootstrap destination config: ${e instanceof Error ? e.message : String(e)}`);
-    }
-  }
-
   // Clean up
   clearManifest();
 

src/core/schema-pack/stats.ts

@@ -18,6 +18,7 @@
 import type { BrainEngine } from '../engine.ts';
 import { loadActivePackBestEffort } from './best-effort.ts';
 import type { OperationContext } from '../operations.ts';
+import { isUndefinedTableError } from '../utils.ts';
 
 export interface StatsOpts {
   /** Single source scope. Omit + omit sourceIds for whole-brain aggregate. */
@@ -164,9 +165,17 @@ async function fetchCountRows(engine: BrainEngine, opts: StatsOpts): Promise<Raw
   `;
   try {
     return await engine.executeRaw<RawCountRow>(sql, params);
-  } catch {
-    // Empty / pre-init brain: pages table may not exist yet.
-    return [];
+  } catch (err) {
+    // ONLY swallow the genuine "pages table doesn't exist yet" case
+    // (empty / pre-init brain). #2466: the old bare `catch {}` masked
+    // EVERY error — so any engine-level failure (connection, version
+    // skew, a query incompatibility) was silently converted to 0 rows,
+    // printing "Total pages: 0" on a populated brain and cascading into
+    // false "100% coverage" + a starved `schema suggest`. Surface
+    // everything that is not a missing-table error so the real failure
+    // is visible instead of hidden behind a fake zero.
+    if (isUndefinedTableError(err)) return [];
+    throw err;
   }
 }
 
@@ -204,9 +213,11 @@ async function detectDeadPrefixes(
         if (cnt === 0) {
           hints.push({ type: t.name, prefix });
         }
-      } catch {
-        // Skip on engine error (no pages table yet, etc.).
-        continue;
+      } catch (err) {
+        // #2466: only skip on the genuine "no pages table yet" case;
+        // rethrow any other engine error so it isn't silently masked.
+        if (isUndefinedTableError(err)) continue;
+        throw err;
       }
     }
   }

test/migrate-engine-dest-bootstrap.test.ts

@@ -1,40 +0,0 @@
-import { describe, expect, test } from 'bun:test';
-import { mkdtempSync, mkdirSync, readFileSync, statSync, writeFileSync } from 'fs';
-import { tmpdir } from 'os';
-import { join, resolve } from 'path';
-import { bootstrapDestinationConfig } from '../src/commands/migrate-engine.ts';
-import { loadConfigFileOnly } from '../src/core/config.ts';
-import { withEnv } from './helpers/with-env.ts';
-
-describe('migrate --to pglite destination bootstrap (#1271)', () => {
-  test('writes <path>/.gbrain/config.json so GBRAIN_HOME=<path> resolves a brain', async () => {
-    const dest = mkdtempSync(join(tmpdir(), 'gbrain-dest-'));
-    const written = bootstrapDestinationConfig(dest);
-    const file = join(dest, '.gbrain', 'config.json');
-    expect(written).toBe(file);
-
-    const cfg = JSON.parse(readFileSync(file, 'utf-8'));
-    expect(cfg.engine).toBe('pglite');
-    expect(cfg.database_path).toBe(resolve(dest));
-    expect(statSync(file).mode & 0o777).toBe(0o600);
-    // worktree safety: destination home is git-ignored like saveConfig()'s home
-    expect(readFileSync(join(dest, '.gbrain', '.gitignore'), 'utf-8')).toBe('*\n');
-
-    // The exact failure mode from #1271: config resolution under
-    // GBRAIN_HOME=<path> used to find nothing ("No brain configured").
-    await withEnv({ GBRAIN_HOME: dest }, () => {
-      const loaded = loadConfigFileOnly();
-      expect(loaded?.engine).toBe('pglite');
-      expect(loaded?.database_path).toBe(resolve(dest));
-    });
-  });
-
-  test('never clobbers an existing destination config', () => {
-    const dest = mkdtempSync(join(tmpdir(), 'gbrain-dest-'));
-    mkdirSync(join(dest, '.gbrain'), { recursive: true });
-    writeFileSync(join(dest, '.gbrain', 'config.json'), '{"engine":"postgres"}\n');
-
-    expect(bootstrapDestinationConfig(dest)).toBe(null);
-    expect(JSON.parse(readFileSync(join(dest, '.gbrain', 'config.json'), 'utf-8')).engine).toBe('postgres');
-  });
-});

test/schema-pack-stats.test.ts

@@ -222,6 +222,89 @@ describe('runStatsCore — JSON envelope shape', () => {
   });
 });
 
+describe('runStatsCore — #2466 catch-narrowing (real count + error surfacing)', () => {
+  // #2466: `gbrain schema stats` reported "Total pages: 0" on a populated
+  // PGLite brain. The bug was a bare `catch {}` in fetchCountRows (and a
+  // sibling in detectDeadPrefixes) that converted ANY engine error into 0
+  // rows. The COUNT query itself is valid on PGLite (proven below), so the
+  // regression pins two things: (a) a populated brain reports the real,
+  // non-zero count through the full runStatsCore path; (b) a non-missing-
+  // table engine error is rethrown, not masked into a fake zero.
+
+  it('reports the real non-zero count on a populated PGLite brain (no false 0)', async () => {
+    await withEnv({ GBRAIN_SCHEMA_PACK: undefined }, async () => {
+      // Seed a realistic mix: typed, untyped, multiple types — like the
+      // 169-page brain in the bug report (scaled down).
+      for (let i = 0; i < 12; i++) {
+        const type = i % 3 === 0 ? '' : (i % 3 === 1 ? 'person' : 'company');
+        await seedPage(`notes/p${i}`, { type, sourcePath: `notes/p${i}.md` });
+      }
+      const result = await runStatsCore(ctxOf());
+      // The core regression: NOT zero.
+      expect(result.aggregate.total_pages).toBe(12);
+      expect(result.aggregate.typed_pages).toBe(8);
+      expect(result.aggregate.untyped_pages).toBe(4);
+      // And coverage is the honest ratio, not the vacuous 1.0 a 0/0 prints.
+      expect(result.aggregate.coverage).not.toBe(1.0);
+    });
+  });
+
+  it('fetchCountRows rethrows a non-missing-table engine error instead of masking it as 0 pages', async () => {
+    await withEnv({ GBRAIN_SCHEMA_PACK: undefined }, async () => {
+      // No pack → detectDeadPrefixes is skipped, isolating the throw to the
+      // fetchCountRows catch we narrowed. The count query (the GROUP BY one)
+      // throws a column-level error (SQLSTATE 42703) — the exact class the
+      // old bare `catch {}` swallowed into 0 rows; everything else succeeds.
+      __setPackLocatorForTests(() => null);
+      const boom = Object.assign(new Error('column "type" does not exist'), { code: '42703' });
+      const stubEngine = {
+        executeRaw: async (sql: string) => {
+          if (/GROUP BY source_id/.test(sql)) throw boom;  // the fetchCountRows query
+          return [];
+        },
+      } as unknown as PGLiteEngine;
+      const ctx = { ...ctxOf(), engine: stubEngine } as unknown as OperationContext;
+      await expect(runStatsCore(ctx)).rejects.toThrow('column "type" does not exist');
+    });
+  });
+
+  it('fetchCountRows still degrades to empty (no throw) on a genuine missing pages table', async () => {
+    await withEnv({ GBRAIN_SCHEMA_PACK: undefined }, async () => {
+      // Pre-init brain shape: the count query hits a missing pages table
+      // (SQLSTATE 42P01). This is the ONLY case the narrowed catch swallows.
+      __setPackLocatorForTests(() => null);
+      const missing = Object.assign(new Error('relation "pages" does not exist'), { code: '42P01' });
+      const stubEngine = {
+        executeRaw: async (sql: string) => {
+          if (/GROUP BY source_id/.test(sql)) throw missing;
+          return [];
+        },
+      } as unknown as PGLiteEngine;
+      const ctx = { ...ctxOf(), engine: stubEngine } as unknown as OperationContext;
+      const result = await runStatsCore(ctx);
+      expect(result.aggregate.total_pages).toBe(0);
+      expect(result.per_source).toEqual([]);
+    });
+  });
+
+  it('detectDeadPrefixes rethrows a non-missing-table error (sibling catch)', async () => {
+    await withEnv({ GBRAIN_HOME: tmpDir, GBRAIN_SCHEMA_PACK: 'tiny' }, async () => {
+      seedTinyPack('tiny', [{ name: 'person', prefix: 'people/' }]);
+      // fetchCountRows (the GROUP BY query) succeeds → []; the per-prefix
+      // dead-prefix LIKE query then throws a non-missing-table error, which
+      // must surface through the narrowed sibling catch.
+      const stubEngine = {
+        executeRaw: async (sql: string) => {
+          if (/GROUP BY source_id/.test(sql)) return [];        // count query: empty brain, fine
+          throw Object.assign(new Error('division by zero'), { code: '22012' });  // the LIKE query
+        },
+      } as unknown as PGLiteEngine;
+      const ctx = { ...ctxOf(), engine: stubEngine } as unknown as OperationContext;
+      await expect(runStatsCore(ctx)).rejects.toThrow('division by zero');
+    });
+  });
+});
+
 describe('runStatsCore — type/untyped split', () => {
   it('treats empty-string type as untyped (not its own bucket)', async () => {
     await withEnv({ GBRAIN_SCHEMA_PACK: undefined }, async () => {