Add auto memory distillation scheduler (APScheduler)

- scheduler.py: AsyncIOScheduler with three cron jobs
    short  daily     03:00 (no LLM, always fast)
    mid    weekly    Sun 03:30 (LLM)
    long   monthly   1st 04:00 (LLM — off by default)
- config.py: AUTO_DISTILL, AUTO_DISTILL_SHORT/MID/LONG .env flags
- main.py: start/stop scheduler in FastAPI lifespan
- routers/distill.py: GET /distill/status — next run times + config
- requirements.txt: apscheduler>=3.10
- HELP.md: updated planned items, added /distill/status to API table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/scheduler.py

@@ -0,0 +1,99 @@
+"""
+Auto memory distillation scheduler.
+
+Default schedule (all overridable via .env flags):
+  short  — daily         at 03:00  (no LLM — fast)
+  mid    — weekly Sun    at 03:30  (LLM call)
+  long   — monthly 1st  at 04:00  (LLM call — off by default)
+
+Set AUTO_DISTILL=false to disable entirely.
+Set AUTO_DISTILL_LONG=true to enable monthly long-term integration.
+"""
+import logging
+from apscheduler.schedulers.asyncio import AsyncIOScheduler
+from config import settings
+
+logger = logging.getLogger(__name__)
+
+_scheduler: AsyncIOScheduler | None = None
+
+
+async def _run_short() -> None:
+    from memory_distiller import distill_short
+    try:
+        result = distill_short()
+        logger.info("auto distill short: %d files, %d chars", result["files_included"], result["chars_written"])
+    except Exception as e:
+        logger.error("auto distill short failed: %s", e)
+
+
+async def _run_mid() -> None:
+    from memory_distiller import distill_mid
+    try:
+        result = await distill_mid()
+        if "error" in result:
+            logger.warning("auto distill mid skipped: %s", result["error"])
+        else:
+            logger.info("auto distill mid: %d chars via %s", result["chars_written"], result["backend"])
+    except Exception as e:
+        logger.error("auto distill mid failed: %s", e)
+
+
+async def _run_long() -> None:
+    from memory_distiller import distill_long
+    try:
+        result = await distill_long()
+        if "error" in result:
+            logger.warning("auto distill long skipped: %s", result["error"])
+        else:
+            logger.info("auto distill long: %d chars via %s", result["chars_written"], result["backend"])
+    except Exception as e:
+        logger.error("auto distill long failed: %s", e)
+
+
+def start() -> None:
+    global _scheduler
+    if not settings.auto_distill:
+        logger.info("auto distillation disabled (AUTO_DISTILL=false)")
+        return
+
+    _scheduler = AsyncIOScheduler(timezone="local")
+
+    if settings.auto_distill_short:
+        _scheduler.add_job(_run_short, "cron", hour=3, minute=0, id="distill_short")
+        logger.info("scheduled: distill_short daily at 03:00")
+
+    if settings.auto_distill_mid:
+        _scheduler.add_job(_run_mid, "cron", day_of_week="sun", hour=3, minute=30, id="distill_mid")
+        logger.info("scheduled: distill_mid weekly Sun at 03:30")
+
+    if settings.auto_distill_long:
+        _scheduler.add_job(_run_long, "cron", day=1, hour=4, minute=0, id="distill_long")
+        logger.info("scheduled: distill_long monthly on 1st at 04:00")
+
+    if _scheduler.get_jobs():
+        _scheduler.start()
+        logger.info("auto distillation scheduler started (%d jobs)", len(_scheduler.get_jobs()))
+    else:
+        logger.info("auto distillation: no jobs enabled")
+
+
+def stop() -> None:
+    global _scheduler
+    if _scheduler and _scheduler.running:
+        _scheduler.shutdown(wait=False)
+        logger.info("auto distillation scheduler stopped")
+
+
+def status() -> list[dict]:
+    """Return next-run info for all scheduled jobs."""
+    if not _scheduler or not _scheduler.running:
+        return []
+    jobs = []
+    for job in _scheduler.get_jobs():
+        next_run = job.next_run_time
+        jobs.append({
+            "id": job.id,
+            "next_run": next_run.isoformat() if next_run else None,
+        })
+    return jobs