Implement background jobs for ingestion or long-running agent…

1. 01

   Concepts & system design

   60 min· read · map the mechanismtimer

   R01 — FastAPI background tasks vs. worker queues

   R09 — PostgreSQL transactional job state

   Read the assigned sections; map the mechanism, threat model and trade-offs.

2. 02

   Project implementation

   120 min· build · integrate · debugtimer

   Implement durable background jobs for P2 document ingestion and P3 long-running workflows. Add idempotency keys, bounded retries, dead-letter queue (DLQ) state, schema-drift validation hooks (C3), and job-ownership checks.

   Build, integrate, debug and improve the increment in the active project.

3. 03

   Security lab

   60 min· attack your own systemtimer

   Replay duplicate job messages and attempt cross-tenant job status polling/cancellation.

   Test the abuse case, failure path, authorization bypass or resource limit.

4. 04

   Verification & evidence

   30 min· test · record evidencetimer

   Idempotency and job-ownership test suite + DLQ recovery test.

   Add or run regression tests; record the 9-point evidence record.

5. 05

   Deliberate practice & Socratic review

   30 min· explain aloud · update gapstimer

   Answer the 8 Socratic questions without notes: What? Why? How? What if? Why not? How can I prove it? Where can it break? What have I learned?

   Re-explain the hardest concept aloud, inspect one edge case, update the gap log.

6. total5 h

• R01Python, FastAPI & Pydantic↗ fastapi.tiangolo.com

  FastAPI tutorial, request bodies, dependencies, async, and Pydantic model validation.

• R09PostgreSQL Documentation↗ postgresql.org

  Foreign-key constraints, indexes, ACID transactions, row-level security (RLS), and query planning.

Read only the named sections needed for today's task. Reading sits inside the 60-minute concepts block; it is not extra time.

• docsFastAPI (official docs)
  Background Tasks

  Shows FastAPI's in-process BackgroundTasks hook, its dependency-injection form, and the explicit caveat that the work is not durable — the baseline you must leave behind for P2 ingestion jobs.

  R01moved 2026-11-11
• docsPostgreSQL (official docs)
  PostgreSQL: Documentation: 18: 13.3. Explicit Locking

  Covers advisory locks and transaction-scoped locks, the primitive for job-ownership checks and single-writer claims so two workers cannot process the same ingestion job.

  R09checked 2026-11-11
• videoSsali Jonathan · 43 min
  Background Tasks with FastAPI Background Tasks and Celery + Redis - FastAPI Beyond CRUD (Part 20)

  Builds the Celery + Redis worker path end to end, including broker configuration, worker startup, and Flower monitoring for retry/DLQ visibility.

  R01checked 2026-11-11
• videoFANATICUS
  Background tasks in Python : ARQ VS Celery

  Compares ARQ and Celery for FastAPI workers and explains retry configuration and deployment differences that decide how bounded-retry and DLQ behaviour is implemented.

  R01checked 2026-11-11
• articlemicroservices.io (Chris Richardson)
  Pattern: Transactional outbox

  Explains why an enqueue and a database write must share one transaction, and why the relay only gives at-least-once delivery — forcing idempotency keys and duplicate-safe job handlers.

  R09checked 2026-11-11

A lab is complete only when it produces evidence. Installing PyRIT, Garak, Presidio or TransformerLens is not completion. Saved on this device only.