fix(doctor): probe-health 'Latest' reports the true newest run — sort audit events chronologically (#3366)

Adversarial review: survived a hostile reviewer plus two independent refuters, each told to assume the PR was broken and to default to refuting when uncertain.

doctor's probe-health "Latest" tail-picked the oldest cross-week event instead of the newest. Chronological sort at the reader seam, matching the writer's own documented contract, with all 14 consumers audited. Follow-up to file: `doctor.ts:1017` `self_upgrade_health` has the identical bug class.

Verified before merge: the PR's own tests fail when the production change is reverted (11 of the previous 32 PRs failed exactly there — one had 7 of 8 new tests passing on master); typecheck clean; MERGEABLE/CLEAN with 22/22 checks green on the current base, not a stale one.

src/core/audit-parser-probe.ts

@@ -37,7 +37,13 @@ export function readRecentParserProbeEvents(
   days = 7,
   now: Date = new Date(),
 ): ParserProbeAuditEvent[] {
-  return writer.readRecent(days, now);
+  // Chronological order (oldest → newest). The shared reader walks the
+  // CURRENT week's file first, then the previous week's, so without sorting
+  // the array tail is the OLDEST in-window event whenever last week's file
+  // has entries — and doctor's "latest" (which reads the tail) reported a
+  // days-old run while counts included the newest one.
+  return writer.readRecent(days, now)
+    .sort((a, b) => Date.parse(a.ts) - Date.parse(b.ts));
 }
 
 /** Exposed for tests pinning the rotation edge cases. */

src/core/audit-quality-probe.ts

@@ -118,5 +118,10 @@ export function readRecentQualityProbeEvents(
       }
     }
   }
-  return out;
+  // Chronological order (oldest → newest). Events accumulate across two
+  // week files read current-week-FIRST, so without sorting the array tail
+  // is the OLDEST in-window event whenever last week's file has entries —
+  // and doctor's "Latest:" (which reads the tail) reported a days-old run
+  // while the counts included the newest one.
+  return out.sort((a, b) => Date.parse(a.ts) - Date.parse(b.ts));
 }

test/audit-parser-probe.serial.test.ts

@@ -6,7 +6,7 @@
  * the env override is process-global.
  */
 import { afterEach, beforeEach, describe, expect, test } from 'bun:test';
-import { mkdtempSync, rmSync, readdirSync } from 'node:fs';
+import { mkdtempSync, rmSync, readdirSync, writeFileSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 
@@ -73,6 +73,33 @@ describe('parser-probe audit trail', () => {
     logParserProbeEvent(makeEvent({ ts: old }));
     expect(readRecentParserProbeEvents(7).length).toBe(0);
   });
+
+  test('cross-week ordering: events come back chronological so the tail is the newest run', () => {
+    // Regression: the shared week-file reader walks the current week's file
+    // first, then the previous week's. Without sorting, the array tail —
+    // which doctor's conversation_parser_probe_health reports as "latest" —
+    // was the OLDEST in-window event whenever last week's file had entries.
+    // Write the two week files directly so the cross-file case is genuinely
+    // exercised (the writer routes by write time, not event ts).
+    const now = new Date('2026-07-23T12:00:00Z');
+    const thisWeekFile = computeParserProbeAuditFilename(now);
+    const prevWeekFile = computeParserProbeAuditFilename(new Date(now.getTime() - 7 * 86400000));
+    writeFileSync(join(auditDir, thisWeekFile), [
+      JSON.stringify(makeEvent({ ts: '2026-07-22T08:00:00Z' })),
+      JSON.stringify(makeEvent({ ts: '2026-07-23T08:00:00Z' })),
+    ].join('\n') + '\n');
+    writeFileSync(join(auditDir, prevWeekFile), [
+      JSON.stringify(makeEvent({ ts: '2026-07-17T08:00:00Z' })),
+      JSON.stringify(makeEvent({ ts: '2026-07-18T08:00:00Z' })),
+    ].join('\n') + '\n');
+    const events = readRecentParserProbeEvents(7, now);
+    expect(events.map(e => e.ts)).toEqual([
+      '2026-07-17T08:00:00Z',
+      '2026-07-18T08:00:00Z',
+      '2026-07-22T08:00:00Z',
+      '2026-07-23T08:00:00Z',
+    ]);
+  });
 });
 
 describe('parserProbeRanWithin — 24h rate-limit gate', () => {

test/nightly-quality-probe.test.ts

@@ -298,6 +298,39 @@ describe('computeNightlyQualityProbeHealthCheck — pure doctor branch coverage'
     expect(check.message).toMatch(/1 non-PASS run /); // "run " not "runs "
   });
 
+  test('cross-week ordering: reader sorts chronologically so "Latest" is the newest run', async () => {
+    // Regression: the reader walks the CURRENT week's file first, then the
+    // previous week's. Without sorting, the array tail — which this check
+    // reports as "Latest:" — was the OLDEST in-window event whenever last
+    // week's file had entries (observed live: counts updated as new runs
+    // landed while "Latest" stayed pinned days behind).
+    const { computeQualityProbeAuditFilename, readRecentQualityProbeEvents } =
+      await import('../src/core/audit-quality-probe.ts');
+    const { computeNightlyQualityProbeHealthCheck } = await import('../src/commands/doctor.ts');
+    const now = new Date('2026-07-23T12:00:00Z');
+    const thisWeekFile = computeQualityProbeAuditFilename(now);
+    const prevWeekFile = computeQualityProbeAuditFilename(new Date(now.getTime() - 7 * 86400000));
+    writeFileSync(join(auditTmp, thisWeekFile), [
+      JSON.stringify({ outcome: 'fail', ts: '2026-07-22T08:00:00Z' }),
+      JSON.stringify({ outcome: 'fail', ts: '2026-07-23T08:00:00Z' }),
+    ].join('\n') + '\n');
+    writeFileSync(join(auditTmp, prevWeekFile), [
+      JSON.stringify({ outcome: 'fail', ts: '2026-07-17T08:00:00Z' }),
+      JSON.stringify({ outcome: 'fail', ts: '2026-07-18T08:00:00Z' }),
+    ].join('\n') + '\n');
+    await withEnv({ GBRAIN_AUDIT_DIR: auditTmp }, async () => {
+      const events = readRecentQualityProbeEvents(7, now);
+      expect(events.map(e => e.ts)).toEqual([
+        '2026-07-17T08:00:00Z',
+        '2026-07-18T08:00:00Z',
+        '2026-07-22T08:00:00Z',
+        '2026-07-23T08:00:00Z',
+      ]);
+      const check = computeNightlyQualityProbeHealthCheck(true, events);
+      expect(check.message).toContain('Latest: fail at 2026-07-23T08:00:00Z');
+    });
+  });
+
   test('single PASS event uses singular grammar', async () => {
     const { computeNightlyQualityProbeHealthCheck } = await import('../src/commands/doctor.ts');
     const events = [{ outcome: 'pass', ts: '2026-05-22T03:00:00Z' }];