ADK-Rust

ACP testing and support matrix

ACP is bidirectional. A useful interoperability test must keep one connection open while notifications and nested requests arrive; a series of disconnected JSON lines cannot prove session behavior.

Verified tests

The adk-acp suite connects the official SDK Client to the ADK-Rust SDK Agent through an in-memory transport and exercises:

initialize
  → session/new
  → session/prompt
  ← session/update
  ← PromptResponse(end_turn)
  → session/close
  → session/list
  → session/resume
  → session/close
  → session/delete

Separate tests cover session cancellation, JSON-RPC request cancellation and recovery, event mapping, reject-first permission menus, opaque option IDs, fabricated selections, awaited human decisions, exact-call allow-once behavior, MCP configuration validation, and secret-redacted debug output. Phase 2 adds session/load replay-ordering tests (the replayed session/updates match the stored events' chronological order), multimodal prompt mapping and rejection tests (image and audio accepted; unadvertised content rejected), server permission-bridge approve/deny/cancel tests (cancellation maps to deny, correlated by function-call id), and client-fidelity tests proving the ToolCallUpdate and UsageUpdate surfaces appear without regressing the agent text surface. Phase 3 adds session-mode and configuration-option tests (set_mode / set_config_option record advertised values and reject unknown ones, and the selection persists across session/load), a session/fork isolation test (the fork's history equals the source's and the source is left unchanged), available-commands and session-info activation tests (updates emitted only when the agent declares commands or records a title), and a capability-accuracy test asserting the advertised capabilities correspond exactly to the registered handlers and enabled content mappings — including that modes and config options are advertised only when a SessionControls provider is present.

The live MCP lifecycle gate starts a real stdio MCP child, completes the handshake, and discovers its tools through the same McpToolset used by ACP sessions.

Run the gates

cargo test -p adk-acp --all-features
cargo test -p adk-agent --test tool_confirmation_tests
cargo test -p adk-tool --features mcp --test mcp_server_lifecycle_integration_tests test_tool_aggregation -- --ignored --exact

cargo test --manifest-path examples/acp_client_host/Cargo.toml
cargo check --manifest-path examples/acp_kiro/Cargo.toml
cargo check --manifest-path examples/acp_server/Cargo.toml
cargo test --manifest-path examples/acp_full_protocol/Cargo.toml

The acp_full_protocol gate is the runnable Phase 2 safety net: a no-API-key, Runner-backed AcpServer driven through the official SDK over an in-process channel, validating the full server-direction Phase 2 surface (embedded-resource and image/audio prompts, the permission bridge, session/load replay ordering, and UsageUpdate / ToolCallUpdate surfacing) without a subprocess or model credentials.

Current support

AreaStatusNotes
Stable wire protocol v1ImplementedOfficial Rust SDK 1.2; protocol version negotiated separately
Local stdio client transportImplementedOne-shot, streaming, and persistent sessions
Client permissionsImplementedDeny by default, semantic matching, opaque IDs, sync or async policy
Client filesystem callbacksImplemented APIRead and write advertised independently
Client terminal callbacksImplemented APIComplete create/output/wait/kill/release trait
Client-supplied MCPImplementedstdio required; HTTP/SSE capability-gated
ADK-Rust ACP serverImplementedNew, prompt, load, update, cancel, close, list, resume, fork, set_mode, set_config_option, delete
Server session load + replayImplementedReactivates a persisted session and replays stored events in chronological order; load_session advertised
Server session forkImplementedCopies history and relevant state into a new session id, leaving the source unchanged; fork advertised
Server session modes + config optionsImplementedProvider-gated via SessionControls; set_mode / set_config_option validated and persisted across load/resume/fork; advertised only when declared
Server available-commands + session-infoImplementedEmitted on activation when the agent declares commands or records a title; none otherwise
Server plan updatesDormantPlan SessionUpdate mapping exists but is inert until an ADK plan primitive surfaces plan entries
Server session MCPImplementedstdio, per session, bounded startup and cleanup
Text and resource-link promptsImplementedMapped through the shared content module
Multimodal prompts (image, audio)ImplementedMapped to Part::InlineData; image/audio advertised; unadvertised content rejected
Embedded-resource promptsImplementedMapped to Part::EmbeddedResource; embedded_context advertised
Server ADK tool approval to ACPImplementedToolConfirmationRequest bridged to session/request_permission; allow → approve, deny/cancel → deny, correlated by function-call id
Client tool-update and usage fidelityImplementedOutputChunk::ToolUpdate and OutputChunk::Usage surface an External_Agent's ToolCallUpdate/UsageUpdate; agent text unchanged
Client rich prompt contentImplementedprompt_agent_content_with_policy transmits non-text ADK content as the matching ACP block
Remote ACP HTTP/WebSocketNot advertisedThe stable implementation is local stdio
Experimental protocol featuresNot advertisedAdd only after implementation and interoperability tests

Manual editor test

Build examples/acp_server, then configure an ACP client to start that binary with an absolute manifest path and model credentials. Verify:

  1. the initialization response reports protocol version 1;
  2. a new session accepts the intended absolute project directory;
  3. text appears as live updates before the final response;
  4. read tool starts and completions appear in the client;
  5. cancellation closes the turn without closing the connection;
  6. a later prompt succeeds in the same session;
  7. close and resume preserve history when the session service is durable.

Do not use echo | cargo run for this test. Each pipe starts a different process and cannot preserve the connection or session.

Related examples