miti99bot/plans/260415-1010-d1-cron-infra/phase-04-retention-cron.md

Phase 04 — Retention Cron

Priority: P1 Status: Complete Depends on: Phases 02 + 03

Overview

Daily cron trims trading_trades to enforce caps:

• Per user: keep newest 1000 rows, delete older.
• Global: keep newest 10000 rows across all users, delete oldest (FIFO).

Requirements

Functional

• Schedule: "0 17 * * *" (daily 17:00 UTC = 00:00 ICT).
• Per-user pass first (bounded by user count), then global FIFO.
• Report count deleted via console.log (shows in Cloudflare logs).

Non-functional

• Safe to retry — idempotent (just deletes excess rows).
• Bounded execution time — large backlog handled in batches of 1000 deletes per statement if needed.

Architecture

Added to src/modules/trading/index.js:

crons: [{
  schedule: "0 17 * * *",
  name: "trim-trades",
  handler: trimTradesHandler,
}]

Per-user trim query

DELETE FROM trading_trades
WHERE id IN (
  SELECT id FROM trading_trades
  WHERE user_id = ?
  ORDER BY ts DESC
  LIMIT -1 OFFSET 1000
);

Run once per distinct user_id from a SELECT DISTINCT user_id FROM trading_trades.

Global FIFO trim

DELETE FROM trading_trades
WHERE id IN (
  SELECT id FROM trading_trades
  ORDER BY ts DESC
  LIMIT -1 OFFSET 10000
);

Related Code Files

Create

• src/modules/trading/retention.js — trimTradesHandler(event, { sql })
• tests/modules/trading/retention.test.js

Modify

• src/modules/trading/index.js — wire cron entry
• wrangler.toml — add "0 17 * * *" to [triggers] crons

Todo List

• retention.js with per-user + global trim
• Wire cron entry
• Tests: seed >1000 per user + >10000 global, assert trimmed counts

Success Criteria

• Given 1500 rows for user A, cron leaves 1000 newest.
• Given 15000 rows globally across users, cron leaves 10000 newest.
• Console logs deletion counts.

Risks

• Per-user pass cost scales with user count. At current scale (hobby) irrelevant; document limit for future.
• Competing writes during trim — acceptable since trades append-only.