[open-swe] feat: Add AGENTS.md with development guidelines and repository context (#303)

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Co-authored-by: open-swe-dev[bot] <open-swe-dev@users.noreply.github.com>
Co-authored-by: Brace Sproul <braceasproul@gmail.com>

AGENTS.md

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+<general_rules>
+- Always use Yarn as the package manager - never use npm or other package managers
+- Run all general commands (e.g. not for starting a server) from the repository root using Turbo orchestration (yarn build, yarn lint, yarn format)
+- Before creating new utilities or shared functions, search in packages/shared/src to see if one already exists
+- When importing from the shared package, use the @open-swe/shared namespace with specific module paths
+- Follow strict TypeScript practices - the codebase uses strict mode across all packages
+- Use ESLint and Prettier for code quality - run yarn lint:fix and yarn format before committing
+- Console logging is prohibited in the open-swe app (ESLint error) - use the `createLogger` function to create a new logger instance instead
+- Build the shared package first before other packages can consume it (yarn build from the root handles this automatically via turbo repo)
+- Follow existing code patterns and maintain consistency with the established architecture
+- Include as few inline comments as possible
+</general_rules>
+
+<repository_structure>
+This is a Yarn workspace monorepo with Turbo build orchestration containing three main packages:
+
+**apps/open-swe**: LangGraph agent application
+- Core LangChain/LangGraph agent implementation with TypeScript
+- Contains three graphs: programmer, planner, and manager (configured in langgraph.json)
+- Uses strict ESLint rules including no-console errors
+
+**apps/web**: Next.js 15 web interface
+- React 19 frontend with Shadcn UI components (wrapped Radix UI) and Tailwind CSS
+- Modern web stack with TypeScript, ESLint, and Prettier with Tailwind plugin
+- Serves as the user interface for the LangGraph agent
+
+**packages/shared**: Common utilities package
+- Central workspace dependency providing shared types, constants, and utilities
+- Exports modules via @open-swe/shared namespace (e.g., @open-swe/shared/open-swe/types)
+- Must be built before other packages can import from it
+- Contains crypto utilities, GraphState types, and open-swe specific modules
+
+**Root Configuration**:
+- turbo.json: Build orchestration with task dependencies and parallel execution
+- .yarnrc.yml: Yarn 3.5.1 configuration with node-modules linker
+- tsconfig.json: Base TypeScript configuration extended by all packages
+</repository_structure>
+
+<dependencies_and_installation>
+**Package Manager**: Use Yarn exclusively (configured in .yarnrc.yml)
+
+**Installation Process**:
+- Run `yarn install` from the repository root - this handles all workspace dependencies automatically
+
+**Key Dependencies**:
+- LangChain ecosystem: @langchain/langgraph, @langchain/anthropic for agent functionality
+- Next.js 15 with React 19 for web interface
+- Shadcn UI (wrapped Radix UI) and Tailwind CSS for component library and styling
+- TypeScript with strict mode across all packages
+- Jest with ts-jest for testing framework
+
+**Workspace Structure**: Dependencies are managed on a per-package basis, meaning dependencies should only be installed in their specific app/package. Individual packages reference the shared package via @open-swe/shared workspace dependency.
+</dependencies_and_installation>
+
+<testing_instructions>
+**Testing Framework**: Jest with TypeScript support via ts-jest preset and ESM module handling
+
+**Test Types**:
+- Unit tests: *.test.ts files (e.g., take-action.test.ts in __tests__ directories)
+- Integration tests: *.int.test.ts files (e.g., sandbox.int.test.ts)
+
+**Running Tests**:
+- `yarn test` - Run unit tests across all packages
+- `yarn test:int` - Run integration tests (apps/open-swe only)
+- `yarn test:single <file>` - Run a specific test file
+
+**Test Configuration**:
+- 20-second timeout for longer-running tests
+- Environment variables loaded via dotenv integration
+- ESM module support with .js extension mapping
+- Pass-with-no-tests setting for CI/CD compatibility
+
+**Writing Tests**: Focus on testing core business logic, utilities, and agent functionality. Integration tests should verify end-to-end workflows. Use the existing test patterns and maintain consistency with the established testing structure.
+</testing_instructions>
+