Add a real Django/DB-backed integration test tier for the endpoint trust boundary

[whisper67265]

Close #160.

Summary by CodeRabbit

• New Features
  • Added DB-backed PostgreSQL integration tests for ORM idempotency/slug behavior and the add-or-update API trust boundary.
  • Introduced a dedicated CI PostgreSQL job (reusable workflow) running pytest -m postgres.
• Bug Fixes
  • Updated test selection so PostgreSQL tests run only when explicitly enabled.
  • Ensured DJANGO_SETTINGS_MODULE is honored when pre-set; improved transaction-related test isolation.
• Documentation
  • Expanded README and contributing guides with the PostgreSQL test layout, what it verifies, and local Docker + the exact pytest command.
  • Updated CI documentation to reflect the new PostgreSQL runner.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: e382794b-ff7b-40c8-96f4-0f7060db3a7c

📥 Commits

Reviewing files that changed from the base of the PR and between d3e8bc6 and 4855900.

📒 Files selected for processing (2)

• .github/WORKFLOWS.md
• README.md

✅ Files skipped from review due to trivial changes (2)

• .github/WORKFLOWS.md
• README.md

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📝 Walkthrough

Walkthrough

This PR adds a postgres-marked Django integration tier, wires it into CI, and updates pytest configuration, shared test fixtures, endpoint and ORM integration tests, and developer documentation.

Changes

PostgreSQL Integration Test Tier

Layer / File(s)	Summary
Pytest config and integration settings pyproject.toml, tests/conftest.py, tests/django_integration_settings.py	Adds pytest-django, sets default Django test settings, excludes postgres from default runs, preserves external settings overrides, and defines the DB-backed integration settings module.
Shared postgres fixtures tests/postgres/__init__.py, tests/postgres/conftest.py	Adds the postgres test package, collection filtering, cache and lock isolation, throttle overrides, authenticated integration user/client fixtures, and a mocked Celery delay helper.
Endpoint trust boundary tests tests/postgres/test_endpoint_trust_boundary.py, tests/endpoint/test_views.py	Adds integration tests for rejecting adversarial payloads and accepting valid enqueue requests, plus a unit-test monkeypatch to avoid a real transaction.
ORM service integration tests tests/postgres/test_services_orm.py	Adds integration tests for project slug generation, idempotency, language separation, post-create invocation, and rollback on failure.
CI wiring and docs .github/workflows/ci-postgres.yml, .github/workflows/ci.yml, CONTRIBUTING.md, README.md, .github/WORKFLOWS.md	Adds the reusable PostgreSQL workflow, wires it into CI, and updates contributor and README guidance for the new test tier.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant ci as .github/workflows/ci.yml
  participant workflow as .github/workflows/ci-postgres.yml
  participant postgres as postgres:16-alpine
  participant pytest as pytest -m postgres

  ci->>workflow: invoke postgres job
  workflow->>postgres: start database service
  workflow->>pytest: run integration tests with DB env vars
  pytest->>postgres: read/write test data
  postgres-->>pytest: query results

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Possibly related PRs

• cppalliance/cppa-weblate-plugin#154: Adds postgres trust-boundary integration coverage for the same add-or-update flow and enqueue behavior.

Suggested reviewers: henry0816191, wpak-ai

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: adding a Django/DB-backed integration test tier.
Linked Issues check	✅ Passed	The new postgres tests, settings, CI workflow, and docs match the issue's integration-tier acceptance criteria.
Out of Scope Changes check	✅ Passed	The changes appear focused on the PostgreSQL integration tier and supporting docs/config, with no obvious unrelated additions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

🧹 Nitpick comments (1)

tests/django_integration_settings.py (1)

30-34: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Redundant branching for INSTALLED_APPS append.

+= works identically for both list and tuple targets here (tuple concatenation vs. list extend), so the isinstance check adds complexity without behavioral difference.

♻️ Simplification

 if _ENDPOINT_APP_CONFIG not in INSTALLED_APPS:  # noqa: F405
-    if isinstance(INSTALLED_APPS, tuple):  # noqa: F405
-        INSTALLED_APPS = INSTALLED_APPS + (_ENDPOINT_APP_CONFIG,)  # noqa: F405
-    else:
-        INSTALLED_APPS += (_ENDPOINT_APP_CONFIG,)  # noqa: F405
+    INSTALLED_APPS += (_ENDPOINT_APP_CONFIG,)  # noqa: F405

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@tests/django_integration_settings.py` around lines 30 - 34, The
INSTALLED_APPS update in the Django integration settings has redundant type
branching, since the append behavior is the same for both list and tuple
targets. Simplify the logic around _ENDPOINT_APP_CONFIG by removing the
isinstance(INSTALLED_APPS, tuple) conditional and using a single += path in the
INSTALLED_APPS block so the code remains equivalent but easier to read and
maintain.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@tests/django_integration_settings.py`:
- Around line 30-34: The INSTALLED_APPS update in the Django integration
settings has redundant type branching, since the append behavior is the same for
both list and tuple targets. Simplify the logic around _ENDPOINT_APP_CONFIG by
removing the isinstance(INSTALLED_APPS, tuple) conditional and using a single +=
path in the INSTALLED_APPS block so the code remains equivalent but easier to
read and maintain.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 24bb8ef1-ec0f-4868-bb48-72d423784f37

📥 Commits

Reviewing files that changed from the base of the PR and between bcbffc3 and 7503c8c.

⛔ Files ignored due to path filters (1)

• uv.lock is excluded by !**/*.lock

📒 Files selected for processing (12)

• .github/workflows/ci-postgres.yml
• .github/workflows/ci.yml
• CONTRIBUTING.md
• README.md
• pyproject.toml
• tests/conftest.py
• tests/django_integration_settings.py
• tests/endpoint/test_views.py
• tests/postgres/__init__.py
• tests/postgres/conftest.py
• tests/postgres/test_endpoint_trust_boundary.py
• tests/postgres/test_services_orm.py

[henry0816191]

Add a row in .github/WORKFLOWS.md- Workflows table - lines 13–28 forci-postgres.ymlafterci-test.yml` (DB-backed integration tests, Python 3.12, PostgreSQL service container).