a2ui

# A2UI Agent Source of Truth (AGENTS.md)

This document is the authoritative guide for AI agents working within the A2UI repository. It outlines design philosophy, repository structure, and synchronization guidelines.

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## How to Use these Guides

> **INSTRUCTION FOR ALL AGENTS (Gemini CLI, Claude, OpenAI, Antigravity, etc.):**
> Before performing any specific tasks, load and read the respective skill recipe file in full:

- **For working with Spec-Driven Development (SDD) or repository blueprints:** Read [blueprints/README.md](blueprints/README.md)
- **For implementing new SDKs in a client language:** Read [.agents/skills/a2ui-implement-new-sdks-for-client-language/SKILL.md](.agents/skills/a2ui-implement-new-sdks-for-client-language/SKILL.md)
- **For developing Python code anywhere in the repository (libraries, agents, tools, scripts, best practices):** Read [.agents/skills/a2ui-python-development/SKILL.md](.agents/skills/a2ui-python-development/SKILL.md)
- **For developing in the Swift codebase (core, SwiftUI, sample):** Read [.agents/skills/a2ui-swift-development/SKILL.md](.agents/skills/a2ui-swift-development/SKILL.md)
- **For recording a change in the CHANGELOG of a Dart package under `dart/`, or releasing one:** Read [.agents/skills/a2ui-dart-versioning/SKILL.md](.agents/skills/a2ui-dart-versioning/SKILL.md)

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## 1. What is A2UI?

**A2UI (Agent-to-User Interface)** is a platform-agnostic, streaming-first UI protocol designed specifically to allow Large Language Models (LLMs) and autonomous agents to generate user interfaces.

Key capabilities:

- **Streaming UI:** Progressive rendering of components and values on the fly to minimize latency.
- **Two-Way Data Binding:** Seamless state synchronization between client and agent.
- **Local Function Evaluation:** Execution of validation/logic functions registered in Component Catalogs.

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## 2. Protocol Versioning & Authority

The repository supports multiple versions of the A2UI protocol:

- **v0.8**: Stable specification; not supported by the latest SDKs.
- **v0.9**: Stable specification; implemented in SDKs; very minor differences from v0.9.1.
- **v0.9.1**: **Latest published and active protocol version** implemented by our multi-language SDKs, renderers, and sample clients.
- **v1.0**: Candidate specification for stable release (previously v0.10).
- **Authority Rule:** Default to version **v0.9.1** as the primary authority when working on SDKs or adapters, unless the user specifies otherwise or a different version is requested.

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## 3. Spec-Driven Development (SDD)

> **IMPORTANT:** By default, agents should **IGNORE the `blueprints/` folder** unless explicitly instructed by the user to work with blueprints or Spec-Driven Development.

To scale development across multiple programming languages and UI frameworks, the A2UI repository adopts **Spec-Driven Development (SDD)**. Under this methodology:

- **Language-Agnostic Blueprints** define high-level architecture and features under the `blueprints/` directory (`blueprints/modules/` and `blueprints/features/`).
- **Concrete Codebases** track their module compliance by git commit hash using a `codebase.blueprint.md` file stored under `blueprints/codebases/<relative_codebase_path>/codebase.blueprint.md`.
- **SDD Skills**: SDD skills live in `blueprints/skills/` and can be symlinked into `.agents/skills/` by running `./blueprints/link_skills.sh`. To remove them when done, remove the `.agents/skills/a2ui-*` symlinks.

For a detailed explanation of the methodology, lifecycle, and workflows, read the [Spec-Driven Development Proposal](docs/proposals/spec_driven_development.md).

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## 4. Codebase & Repository Structure

- **`blueprints/`**: Isolated central repository for language-agnostic module blueprints (`modules/`), feature blueprints (`features/`, `features/archived/`), codebase compliance blueprints (`codebases/`), and SDD skills (`skills/`).
- **`docs/`**: Documentation hierarchy. Public site documentation published via MkDocs resides in `docs/public/`, while non-public contributor or internal documentation resides under `docs/` alongside `docs/scripts/`.
- **`catalogs/`**: Canonical `catalog.json` schemas for the catalogs maintained by the A2UI team (e.g. `catalogs/basic/v1/`, `catalogs/mcp/`). Catalogs are versioned independently of the protocol.
- **`specification/`**: Versioned subdirectories (`v0_8/`, `v0_9/`, `v0_9_1/`, `v1_0/`) containing JSON schemas and human-readable guides (older versions also bundle their basic catalog). The `specification/<version>/docs/a2ui_protocol.md` file is the most important source of truth for each protocol version, and the `specification/<version>/json` directory contains the associated schemas for the protocol.
- **`python/`**: Core state SDK (`a2ui_core/`), agent SDK (`a2ui_agent/`), and catalog packages (`catalogs/`) for Python.
- **`conformance/`**: Language-agnostic test suites (`core/`, `agent/`, `extensions/`) and test data (`test_data/`) for verifying behavioral parity across all SDK implementations.
- **`dart/`**: Dart implementations including core state model (`a2ui_core/`), agent SDK (`a2ui_agent/`), and Flutter framework adapter (`a2ui_flutter/`).
- **`kotlin/`**: Legacy Kotlin agent SDK (`agent_sdk_legacy/`).
- **`typescript/`**: Framework-agnostic Web Core state and protocol logic (`web_core/`), TypeScript agent SDK (`a2ui_agent/`), and TypeScript catalog packages (`catalogs/`).
- **`renderers/`**: Framework renderers only: Lit renderer (`lit/`), Angular renderer (`angular/`), React renderer (`react/`), and markdown parser (`markdown/`).
- **`samples/`**: Ready-to-run demo agents utilizing Python ADK (`agent/adk/`), MCP server (`agent/mcp/`), and sample clients (`client/lit/`, `client/angular/`, `client/react/`, `client/flutter/`).
- **`swift/`**: Native Apple implementation including core state engine (`core/`), SwiftUI adapter (`swiftui/`), and sample iOS client (`sample/`).
- **`tools/`**: Developer utility suite including visual Editor (`editor/`), visual Composer (`composer/`), payload Inspector (`inspector/`), and catalog builder (`build_catalog/`).

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## 5. Yarn Workspaces & Standard Script Targets

All Node.js and TypeScript projects inside the repository must be managed as **Yarn workspaces** registered inside the `"workspaces"` array of the root `package.json`.

When creating or modifying workspaces, guarantee strict script uniformity by implementing canonical targets:

- **`"build"`**: TypeScript compilation via `wireit` or `tsc -b`.
- **`"lint"` / `"lint:fix"`**: Standardized to `"eslint ."` / `"eslint . --fix"` extending root `eslint.preset.mjs` via modern `eslint.config.mjs` flat configs. Pure container folders lacking code must cleanly echo `"Workspace has no lint configuration."`.
- **`"test"`**: Unit test execution (`vitest`, `node --test`). Packages lacking tests must implement the standard auto-detecting Node fallback script to cleanly emit `"Workspace has no tests."` and exit 0.
- **`"format"` / `"format:check"`**: Natively runs local Prettier formatting (`"prettier --write ."` / `"prettier --check ."`).

**New Node Projects:** Guarantee that any newly initialized Node/TypeScript project uses Yarn Berry, is situated within the monorepo directory structure, is correctly registered in root `"workspaces"`, and fully defines these five canonical script targets.

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## 6. Running the Demos and Tools

Do not use hardcoded or guessed build/run sequences. Each subdirectory contains detailed setup, build, dependency resolution, and execution steps.

- **Prerequisite:** Consult the `README.md` files under `typescript/web_core/` and `renderers/` to build the shared web core and renderer packages before running any web tools or clients.
- **Running SDKs & Samples:** Consult the local `README.md` inside any targeted directory under `python/`, `kotlin/`, `samples/`, or `tools/` for specific run/test/build commands.

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## 7. Maintenance & Update Policy

As A2UI evolves, keep agent documentation and skills perfectly synchronized with specification and codebase changes:

- Update `AGENTS.md` and associated skill files when specifications, schemas, or directory layouts are added, modified, or removed.
- Enforce Yarn workspace script hygiene across all Node packages.
- Suggest updates to the user at the end of your task if any changes affect documented files.

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## 8. Core Guidelines for Agents

To ensure the integrity, consistency, and high quality of the repository, all agents must adhere to the following core guidelines:

- **Prioritize Authoritative Specifications**: Always base designs, protocol changes, and implementations on the formal schemas and documents under the versioned `specification/` directory (schemas first, catalogs second, protocol guides third) rather than general workspace markdown files.
- **Maintain Agent-Agnostic Instructions**: When creating or modifying agent instruction files, skills, or guides, write them in a generic, vendor-agnostic manner. Avoid proprietary or environment-specific names (e.g., model names, specific tool terms) and use generic terms (e.g., "assistant", "subagent", "retrieval tool").
- **Enforce Script Uniformity**: Strictly maintain Yarn workspace script hygiene. Ensure all Node/TypeScript packages implement the five canonical targets (`build`, `lint`, `lint:fix`, `test`, `format`, `format:check`).
- **Keep Inference Formats Catalog-Agnostic**: When implementing or updating inference formats (Express, Elemental, Atom, Direct JSON, etc.), system prompt rules, compilers, and parsers must remain catalog-agnostic. Catalog-specific constraints, component property rules, or syntax hints must be defined in and derived dynamically from the component catalog JSON schema, rather than hardcoding catalog-specific logic or string filters into format generators.
- **Export Public Facades and Ban Deep Imports**: Packages across all languages must expose their public API through root or versioned facade barrels (e.g. `__all__` in Python `__init__.py`, `exports` in Node `package.json`, `lib/*.dart` in Dart). Never expose, rely on, or demonstrate deep internal submodule import paths in code, tests, docstrings, or README examples.
- **Sort and Group Imports**: Across all languages (Python, TypeScript, Dart, Swift), maintain clean, predictable import ordering. Group imports into standard/system libraries, external third-party dependencies, and internal/local packages, separated by a single empty line. Within each group, sort module paths and imported symbols alphabetically. Never use wildcard imports.

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