Initial scaffold: Flask webui + APScheduler + Playwright automation for MassPrice rule scheduling

Drives massprice.tcgplayer.com's Run Rule action per-rule on a
user-configured schedule (multiple times/day, day-of-week toggles),
replacing MassPrice's native scheduler (capped at 15 schedules
account-wide, one run/day, with observed clock drift). Deployed via
Forgejo push-to-deploy on Unraid, matching arr-summary/card-grader.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H6TgffxTvYhqxykAbVQg2v

scheduler.py

@@ -0,0 +1,93 @@
+"""In-process cron scheduling for rule runs.
+
+A single background worker thread owns every Playwright run — both
+APScheduler-triggered runs and manual "Run Now" clicks are pushed onto
+one queue.Queue so exactly one browser session is ever active at a time.
+This must run in exactly one process; see gunicorn.conf.py's workers=1.
+"""
+import logging
+import os
+import queue
+import threading
+
+import pytz
+from apscheduler.schedulers.background import BackgroundScheduler
+from apscheduler.triggers.cron import CronTrigger
+
+import automation
+import storage
+
+logger = logging.getLogger("massprice.scheduler")
+
+_work_queue: "queue.Queue" = queue.Queue()
+# Timezone must be set at construction time, not via a later .configure()
+# call — APScheduler resolves a timezone immediately in __init__ via
+# tzlocal's system lookup, which fails inside this container image for
+# an arbitrary $TZ (no zoneinfo/tzdata wiring), so the explicit TZ env
+# var has to win before that lookup ever runs.
+_scheduler = BackgroundScheduler(timezone=pytz.timezone(os.environ.get("TZ", "UTC")))
+_started = False
+
+VALID_DAYS = ["mon", "tue", "wed", "thu", "fri", "sat", "sun"]
+
+
+def _worker_loop():
+    while True:
+        rule_id, rule_name = _work_queue.get()
+        try:
+            automation.run_rule(rule_id, rule_name)
+        except Exception:
+            logger.exception("Unhandled error running rule %s", rule_id)
+        finally:
+            _work_queue.task_done()
+
+
+def enqueue_run(rule_id, rule_name=None):
+    _work_queue.put((rule_id, rule_name))
+
+
+def _job_id(rule_id, index):
+    return f"rule-{rule_id}-{index}"
+
+
+def rebuild_jobs():
+    """Clear and re-add every APScheduler job from schedules.json."""
+    for job in _scheduler.get_jobs():
+        job.remove()
+
+    schedules = storage.load("schedules.json", {})
+    for rule_id, rule in schedules.items():
+        if not rule.get("enabled", True):
+            continue
+        for idx, entry in enumerate(rule.get("schedules", [])):
+            days = [d for d in entry.get("days", []) if d in VALID_DAYS]
+            time_str = entry.get("time")
+            if not days or not time_str:
+                continue
+            hour, minute = time_str.split(":")
+            trigger = CronTrigger(
+                day_of_week=",".join(days),
+                hour=int(hour),
+                minute=int(minute),
+            )
+            _scheduler.add_job(
+                enqueue_run,
+                trigger=trigger,
+                args=[rule_id, rule.get("name")],
+                id=_job_id(rule_id, idx),
+                replace_existing=True,
+                misfire_grace_time=300,
+            )
+    logger.info("Rebuilt %d scheduled job(s)", len(_scheduler.get_jobs()))
+
+
+def start(tz=None):
+    # tz is accepted for backwards-compat call sites but is a no-op now
+    # that timezone is fixed at construction time above.
+    global _started
+    if _started:
+        return
+    rebuild_jobs()
+    _scheduler.start()
+    threading.Thread(target=_worker_loop, daemon=True).start()
+    _started = True