svcforge/AGENTS.md

AGENTS.md — working in svcforge-reference

Rules for any AI agent (Claude Code, Cursor, Codex, Copilot, Gemini CLI) editing this repo. Read this before your first edit.

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What this repo is, and the one rule that follows from it

This is a reference implementation: a complete, verified build of the system that ../learn-python/ teaches Phuc to build himself. It exists to be compared against, not copied from.

THE RULE: never propose copying domain/, repo/, services/worker/, or the claim query into learn-python/. Those four are the course. If asked to "help with Module 4", help him find his own bug; do not paste repo/tasks.py. Scaffolding — pyproject.toml, Dockerfiles, CI, the chart — is fair game to copy, because struggling with hatchling teaches nothing.

learn-python/AGENTS.md has its own, stricter rules. They still apply over there.

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Before you change anything

Read ARCHITECTURE.md. Every design choice here was paid for by a specific failure mode, and the comments say which. A change that removes a comment's subject usually removes a guard.

Four things that look like over-engineering and are not. Do not "simplify" them:

1. The claim query is one statement. repo/tasks.py::_CLAIM_SQL. Splitting the UPDATE ... WHERE id = (SELECT ... FOR UPDATE SKIP LOCKED) into select-then-update creates a double-provision race that testing will not catch.
2. complete() and fail() check locked_by. That check is a repro-confirmed bug fix, with regression tests in tests/integration/test_tasks.py. Removing it lets a worker whose lease expired clobber a task another worker now owns.
3. domain/ has no I/O and no async. CI greps for both.
4. Migrations never run at app startup. They are a Helm pre-upgrade,pre-install hook.

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Conventions

Layers. transport → domain ← repo/adapters. domain/ imports nothing from the other three. repo/ knows SQL and not HTTP. adapters/ owns every subprocess and network call.

Python 3.12. Full annotations everywhere including tests. X | None, StrEnum, Final, PEP 695 type aliases.

Errors. SvcforgeError in svcforge_core/errors.py is the base. New exception types inherit from it, plus a stdlib base when the behaviour matters (HelmError(SvcforgeError, RuntimeError)).

Logging. obs.get_logger(__name__), structlog kwargs. Never stdlib logging directly, and never extra={...} — the ProcessorFormatter bridge silently discards it. Never use message or event as a field name; both are reserved and raise.

SQL. Raw psycopg3, no ORM. Parameters, never f-strings. Rows come back as dicts (DictPool in repo/db.py); annotate with that alias rather than a bare AsyncConnectionPool, which mypy resolves to tuple rows.

Subprocess. create_subprocess_exec with start_new_session=True. Never shell=True — team is tenant input that reaches a helm release name. Timeouts kill the process group.

Protocols. A Protocol needs two implementations (a real one and a fake) or it should be a concrete class.

Datetimes. Always aware, always UTC. Domain functions take now as a parameter; only adapters hold a Clock.

Pinning. Everything by digest: base images, tool images, GitHub Actions by SHA. A SHA-pinned third-party action still resolves its own dependencies by mutable tag — that is how trivy-action broke. Prefer running tools directly from a digest-pinned image.

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Writing style

Plain declaratives. No back-and-forth phrasing, which means none of:

• Rhetorical setup-knockdowns: "That is not a nicety. It is the whole design."
• not-X-but-Y pivots used for rhythm: "It is not a lock, but a lease."
• Throat-clearing: "It is worth noting that", "The key insight here", "Here's the thing".
• Rhetorical questions you then answer.
• Dramatic fragments for rhythm: "Not slow. Not fast. Meaningless."

Write the claim directly. Keep the why — it is the most valuable content in this repo — and drop the scaffolding around it. Factual contrasts that carry information stay ("LEFT join, not inner"; "202, never 201").

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Testing

• Never mock the database. Integration tests run against real Postgres. Each pytest process clones its own database (tests/integration/conftest.py).
• Fakes, not mocks, for helm/kubectl/Redis/clock. tests/fakes.py.
• A test that cannot fail is worse than no test. Before adding one, ask what change would make it red. Bound assertions on both sides where it matters: max_concurrent <= cap alone passes on a fully serial worker.
• Markers: slow (>1s or hits real Upstash), e2e (needs a cluster). make test runs neither.

export SVCFORGE_TEST_DSN="postgresql://svcforge:svcforge@127.0.0.1:5432/svcforge_test"
make lint          # ruff + ruff format + mypy --strict
make test          # unit
make integration   # needs the DSN above
make ci            # every gate CI runs, same commands

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Environment facts that will bite you

• This host has no Docker daemon, and must not get one. Its containerd belongs to a Kubernetes kubelet; installing docker.io would evict the runtime and take down every pod. You cannot docker build here. Verify Dockerfiles by inspection and hadolint.
• Postgres is local (apt, v16) for tests. testcontainers is the CI path.
• Redis is real Upstash on a free tier: 500K commands/month. Redis-hitting tests are marked slow. Do not write loops that spend thousands of commands; use the fakes.
• Secrets live in ~/.config/svcforge/secrets.env, chmod 600, outside every repo. Never echo, log, commit, or paste a DSN or token. .env is gitignored.
• Infra changes go through Terraform/Ansible, never kubectl edit. The Gitea runner's config lives in oci-k8s/k8s/roles/addons/tasks/main.yml.

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CI/CD

.gitea/workflows/ci.yaml. Gates in order: ruff → mypy → unit+coverage → migrate+integration → bandit/gitleaks/pip-audit → hadolint → helm lint/template → build → trivy → push by digest → bump chart digests → ArgoCD syncs.

• CI holds no kubeconfig and must never hold one. Its last act is a git commit.
• Build once, promote by digest. The image is scanned before it is pushed.
• Every gate blocks. If a gate is failing, fix the cause. Do not add an ignore, lower a threshold, or mark it advisory. A CVE finding from trivy is real: bump the pinned version.

RUNBOOK.md has the setup steps and the traps that cost real time.

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When you are unsure

Say so, and check. This repo's value is that its claims were executed, not asserted — the race conditions have reproductions, the timeout kill has a negative control, the coverage gate was caught measuring 0%. Guessing and sounding confident is the one failure mode that makes it worthless.