Testy ACP Test Agent

testy is a deterministic ACP agent binary for exercising clients against the stable ACP v1 surface. It is built from the agent-client-protocol-test crate and communicates over stdio like a normal agent.

The default build enables agent-client-protocol-test’s unstable cargo feature, which forwards to the SDK’s unstable feature:

cargo build -p agent-client-protocol-test --bin testy

To build stable-only coverage:

cargo build -p agent-client-protocol-test --bin testy --no-default-features

The binary lands at target/debug/testy. Integration tests that need to spawn it should use agent_client_protocol_test::test_binaries::testy() after prebuilding test binaries.

Prompt Commands

Prompt text can be either plain text or a JSON-serialized TestyCommand.

Plain-text commands:

• help returns the supported commands and scenarios.
• echo <message> streams <message> back.
• session_updates emits every stable session/update variant.
• content emits prompt/content-focused updates, including every stable ContentBlock variant.
• tool_calls emits tool call create and update flows.
• callbacks sends every stable agent-to-client request.
• elicitations sends only unstable elicitation requests when built with default features.
• cancel_status reports whether session/cancel has been received.
• full runs all stable scenarios in deterministic order.

With default features, callbacks and full also run unstable protocol coverage.

JSON command form:

{"command":"run_scenario","scenario":"elicitations"}

Coverage

The binary handles every stable client-to-agent v1 request and notification: initialize, authenticate, logout, session/new, session/load, session/list, session/delete, session/resume, session/close, session/set_mode, session/set_config_option, session/prompt, and session/cancel.

The full scenario sends every stable agent-to-client callback request: session/request_permission, fs/write_text_file, fs/read_text_file, terminal/create, terminal/output, terminal/wait_for_exit, terminal/kill, and terminal/release. It also emits the stable session update variants, including message chunks, tool calls, plans, available commands, mode/config/session info, and usage.

With default features, elicitations, callbacks, and full cover elicitation/create form mode, URL mode, session scope, request scope, accept, decline, cancel, and elicitation/complete. If the client advertises form elicitation but not URL elicitation, the URL part returns a deterministic invalid-params prompt error.