Create AGENTS.md file (#2070)

Author: ericallam

AGENTS.md

@@ -0,0 +1,68 @@
+# Guidance for Coding Agents
+
+This repository is a pnpm monorepo managed with Turbo. It contains multiple apps and packages that make up the Trigger.dev platform and SDK.
+
+## Repository layout
+- `apps/webapp` – Remix application that serves as the main API and dashboard.
+- `apps/supervisor` – Node application for executing built tasks.
+- `packages/*` – Published packages such as `@trigger.dev/sdk`, the CLI (`trigger.dev`), and shared libraries.
+- `internal-packages/*` – Internal-only packages used by the webapp and other apps.
+- `references/*` – Example projects for manual testing and development of new features.
+- `ai/references` – Contains additional documentation including an overview (`repo.md`) and testing guidelines (`tests.md`).
+
+See `ai/references/repo.md` for a more complete explanation of the workspaces.
+
+## Development setup
+1. Install dependencies with `pnpm i` (pnpm `8.15.5` and Node.js `20.11.1` are required).
+2. Copy `.env.example` to `.env` and generate a random 16 byte hex string for `ENCRYPTION_KEY` (`openssl rand -hex 16`). Update other secrets if needed.
+3. Start the local services with Docker:
+   ```bash
+   pnpm run docker
+   ```
+4. Run database migrations:
+   ```bash
+   pnpm run db:migrate
+   ```
+5. Build the webapp, CLI and SDK packages:
+   ```bash
+   pnpm run build --filter webapp && pnpm run build --filter trigger.dev && pnpm run build --filter @trigger.dev/sdk
+   ```
+6. Launch the development server:
+   ```bash
+   pnpm run dev --filter webapp
+   ```
+   The webapp runs on <http://localhost:3030>.
+
+For full setup instructions see `CONTRIBUTING.md`.
+
+## Running tests
+- Unit tests use **vitest**. Run all tests:
+  ```bash
+  pnpm run test
+  ```
+- Run tests for a specific workspace (example for `webapp`):
+  ```bash
+  pnpm run test --filter webapp
+  ```
+- Prefer running a single test file from within its directory:
+  ```bash
+  cd apps/webapp
+  pnpm run test ./src/components/Button.test.ts
+  ```
+  If packages in that workspace need to be built first, run `pnpm run build --filter webapp`.
+
+Refer to `ai/references/tests.md` for details on writing tests. Tests should avoid mocks or stubs and use the helpers from `@internal/testcontainers` when Redis or Postgres are needed.
+
+## Coding style
+- Formatting is enforced using Prettier. Run `pnpm run format` before committing.
+- Follow the existing project conventions. Test files live beside the files under test and use descriptive `describe` and `it` blocks.
+- Do not commit directly to the `main` branch. All changes should be made in a separate branch and go through a pull request.
+
+## Additional docs
+- The root `README.md` describes Trigger.dev and links to documentation.
+- The `docs` workspace contains our documentation site, which can be run locally with:
+  ```bash
+  pnpm run dev --filter docs
+  ```
+- `references/README.md` explains how to create new reference projects for manual testing.
+