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hya is an event-sourced, multi-agent coding agent. hya-backend owns the runtime: it normalizes OpenAI Chat/Responses/Codex, Grok Build, Anthropic, and Google provider routes into one canonical event stream and executes tools behind a permission plane. Every client-facing surface speaks one consolidated contract — hya.v1 — served identically over HTTP/JSON+SSE+WebSocket (/v1) and gRPC (HYA_GRPC_BIND); the legacy Compat and native HTTP routes are gone. There is currently no bundled interactive TUI; clients drive the backend through hya-sdk-v1, hya-client, or any hya.v1 client.

If no provider is configured, hya still runs: it falls back to an offline "dev" provider that echoes prompts, so the whole stack is usable without API keys while you set things up.

Status

hya is under active development (workspace version 0.36.55, MIT OR Apache-2.0). The latest public binary release is v0.35.1; the checked-out 0.36.49 workspace is newer and is not published to crates.io. Build this checkout from source as described below. APIs, config, and command surfaces may still change between versions.

Build From Source

Requires a Rust toolchain matching the workspace manifest (Cargo.toml; currently edition 2024, Rust 1.91), Git, and Bun (pinned at 1.3.14 for the Compat adapter runtime).

git clone <this-repo> hya
cd hya
./install.sh --prefix "$HOME/.local"
export PATH="$HOME/.local/bin:$PATH"
hya-backend serve

The installer places the hya-backend binary plus lib/hya/compat-adapter/ with its production dependencies.

Configure a Provider and Log In

By default hya-backend starts offline. To use a live model, create ~/.config/hya/config.yaml (or $XDG_CONFIG_HOME/hya/config.yaml):

default_model: claude-sonnet-4-6
providers:
  anthropic:
    kind: anthropic
    base_url: https://api.anthropic.com/v1
    api_key: "{env:ANTHROPIC_API_KEY}"
    models: [claude-sonnet-4-6]

You can supply the key inline (via {env:VAR}, {file:/path}, or a literal) or store it with hya-backend login, which takes precedence over an inline api_key:

hya-backend login anthropic "$ANTHROPIC_API_KEY"
hya-backend models  # inspect the resolved catalog
hya-backend serve   # start the HTTP/SSE server against the live provider

For ChatGPT Codex or Grok Build subscription OAuth (no API key):

hya-backend oauth login --provider codex --type openai-codex
hya-backend oauth login --provider grok --type grok-build
hya-backend oauth status

See docs/configuration.md for first-run behavior, the HYA_* (and related) environment-variable tables, and a fully-commented sample config.

What hya Can Do

• Headless single-turn execution (hya-backend exec / hya-backend run) and iterative goal mode (hya-backend -p "<goal>").
• HTTP/SSE/WebSocket server (hya-backend serve) exposing the consolidated hya.v1 contract under /v1, plus optional gRPC via HYA_GRPC_BIND; see the protocol guide and generated API reference. Typed clients: hya-sdk-v1 and hya-client (crates), or any generated hya.v1 stub.
• MCP servers, plugins (including a Compat plugin adapter), and a formatter plane, all driven from the same config.

Public AgentBundles may remain static/process-free or supply selected Bundle-local Bun sidecar capabilities. Public WorkflowBundles package one compiled Workflow with its exact reachable Agent closure. Both kinds can be inspected and installed with hya-backend bundle info -f example.hyabundle and hya-backend bundle install example.hyabundle. See the AgentBundle authoring guide, Workflow and WorkflowBundle guide, static example, transient Bun example, resident Bun example, disjoint Bun example, and the full Argus WorkflowBundle example plus the CLI reference.

Documentation

The Rust workspace is licensed under either MIT or Apache-2.0 at your option. The checked-out Compat adapter has no separate license file; consult the repository license files for the complete applicable terms.