docs: add repository guidelines

AGENTS.md

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+# Repository Guidelines
+
+## Project Structure & Module Organization
+
+This repository is the internal TJWater agent service. Runtime TypeScript code is organized under `src/`; CLI-specific code is under `cli/src`; Node test files live in `node-tests/`. Agent extensions and OpenCode integration files are under `.opencode/`, including `.opencode/agents`, `.opencode/skills`, and `.opencode/tools`. Runtime data, session metadata, logs, and result references are stored under `data/` and `logs/` and should be treated as local/generated state.
+
+Deployment files are `Dockerfile`, `docker-compose.yml`, and `.gitea/workflows/package.yml`.
+
+## Build, Test, and Development Commands
+
+Use Bun for this project:
+
+```bash
+bun install
+bun run dev
+bun run check
+bun run test:cli
+bun run start
+```
+
+`bun run dev` starts `src/server.ts` in watch mode. `bun run check` runs TypeScript checks for the main project and `.opencode`. `bun run test:cli` runs Node CLI tests. `bun run start` starts the service without watch mode.
+
+## Coding Style & Naming Conventions
+
+Use TypeScript ESM and keep types explicit at module boundaries. Use two-space indentation, `camelCase` for functions and variables, `PascalCase` for classes/types, and kebab-case or descriptive lowercase names for scripts and data files. Prefer existing `src/` service, route, and runtime patterns before introducing new structure.
+
+## Testing Guidelines
+
+Tests use Node's built-in test runner for CLI coverage. Name test files with `.node.mjs` when using `node --test`, matching `node-tests/cli/*.node.mjs`. Add focused tests for CLI parsing, tool behavior, and session/runtime changes. Do not depend on mutable local files under `data/`.
+
+## Commit & Pull Request Guidelines
+
+History uses Conventional Commit messages such as `feat(tools): add search and map tools`, `fix(agent): warm up opencode on startup`, and `refactor(chat): ...`. Prefer `feat(scope):`, `fix(scope):`, or `refactor(scope):`.
+
+PRs should describe runtime behavior changes, list `bun run check` and any test commands run, and mention changes to `.opencode`, secrets, ports, or deploy workflow behavior.
+
+## Security & Configuration Tips
+
+Do not commit `.env`, logs, session transcripts, generated result references, or `node_modules/`. Keep registry and deploy credentials in Gitea secrets.