phase0: add architecture guardrails, CI gates, per-language AGENTS.md

Non-negotiable structural rules that apply to every Claude Code session in
this repo and to every commit, enforced via three defense-in-depth layers:

  1. PreToolUse hook in .claude/settings.json blocks any Write/Edit that
     would push a file past the 500-line hard cap. Auto-loads for any
     Claude session in this repo regardless of who launched it.
  2. scripts/githooks/pre-commit (installed via scripts/install-hooks.sh)
     enforces the LOC cap, freezes migrations/ unless [migration-approved],
     and protects guardrail files unless [guardrail-change] is present.
  3. .gitea/workflows/ci.yaml gets loc-budget + guardrail-integrity jobs,
     plus mypy --strict on new Python packages, tsc --noEmit on Node
     services, and a syft+grype SBOM scan.

Per-language conventions are documented in AGENTS.python.md / AGENTS.go.md /
AGENTS.typescript.md at the repo root — layering (router->service->repo for
Python, hexagonal for Go, colocation for Next.js), tooling baseline, and
explicit "what you may NOT do" lists.

Adds scripts/check-loc.sh (soft 300 / hard 500, reports 205 hard and 161
soft violations in the current codebase) plus .claude/rules/loc-exceptions.txt
(initially empty — the list is designed to shrink over time).

Per-service READMEs for all 10 services + PHASE1_RUNBOOK.md for the
backend-compliance refactor. Skeleton packages (compliance/{domain,
repositories,schemas}) are the landing zone for the clean-arch rewrite that
begins in Phase 1.

CLAUDE.md is prepended with the six non-negotiable rules.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/rules/architecture.md

@@ -0,0 +1,43 @@
+# Architecture Rules (auto-loaded)
+
+These rules apply to **every** Claude Code session in this repository, regardless of who launched it. They are non-negotiable.
+
+## File-size budget
+
+- **Soft target:** 300 lines per non-test, non-generated source file.
+- **Hard cap:** 500 lines. The PreToolUse hook in `.claude/settings.json` blocks Write/Edit operations that would create or push a file past 500. The git pre-commit hook re-checks. CI is the final gate.
+- Exceptions live in `.claude/rules/loc-exceptions.txt` and require a written rationale plus `[guardrail-change]` in the commit message. The exceptions list should shrink over time, not grow.
+
+## Clean architecture
+
+- Python (FastAPI): see `AGENTS.python.md`. Layering: `api → services → repositories → db.models`. Routers ≤30 LOC per handler. Schemas split per domain.
+- Go (Gin): see `AGENTS.go.md`. Standard Go Project Layout + hexagonal. `cmd/` thin, wiring in `internal/app`.
+- TypeScript (Next.js): see `AGENTS.typescript.md`. Server-by-default, push the client boundary deep, colocate `_components/` and `_hooks/` per route.
+
+## Database is frozen
+
+- No new Alembic migrations. No `ALTER TABLE`. No `__tablename__` or column renames.
+- The pre-commit hook blocks any change under `migrations/` or `alembic/versions/` unless the commit message contains `[migration-approved]`.
+
+## Public endpoints are a contract
+
+- Any change to a path/method/status/request schema/response schema in a backend service must update every consumer in the same change set.
+- Each backend service has an OpenAPI baseline at `tests/contracts/openapi.baseline.json`. Contract tests fail on drift.
+
+## Tests
+
+- New code without tests fails CI.
+- Refactors must preserve coverage. Before splitting an oversized file, add a characterization test that pins current behavior.
+- Layout: `tests/unit/`, `tests/integration/`, `tests/contracts/`, `tests/e2e/`.
+
+## Guardrails are themselves protected
+
+- Edits to `.claude/settings.json`, `scripts/check-loc.sh`, `scripts/githooks/pre-commit`, `.claude/rules/loc-exceptions.txt`, or any `AGENTS.*.md` require `[guardrail-change]` in the commit message. The pre-commit hook enforces this.
+- If you (Claude) think a rule is wrong, surface it to the user. Do not silently weaken it.
+
+## Tooling baseline
+
+- Python: `ruff`, `mypy --strict` on new modules, `pytest --cov`.
+- Go: `golangci-lint` strict config, `go vet`, table-driven tests.
+- TS: `tsc --noEmit` strict, ESLint type-aware, Vitest, Playwright.
+- All three: dependency caching in CI, license/SBOM scan via `syft`+`grype`.

.claude/rules/loc-exceptions.txt

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+# loc-exceptions.txt — files allowed to exceed the 500-line hard cap.
+#
+# Format: one repo-relative path per line. Comments start with '#' and are ignored.
+# Each exception MUST be preceded by a comment explaining why splitting is not viable.
+#
+# Phase 0 baseline: this list is initially empty. Phases 1-4 will add grandfathered
+# entries as we encounter legitimate exceptions (e.g. large generated data tables).
+# The goal is for this list to SHRINK over time, never grow.