a44c486019
Found while writing the test for #1242. It affects ACP v1 and v2. ## Problem When Claude Code wedges after a cancel (issue #680), the force-cancel backstop aborts the consumer's cancel signal, so the consumer settles the turn as `cancelled`. The consumer races each next message against that signal by adding an `abort` listener on each iteration. But a listener added to an already-aborted signal never fires. So if the backstop fired while the consumer was busy outside the race, such as sending an update to a slow client, the consumer missed it. It then waited for a message from the wedged Claude Code that never came, and the cancelled `session/prompt` was never answered (v2: no `idle cancelled`). Teardown aborts the same signal, which is how #1242's test ran into it. ## Change The race also wakes for a signal that's already aborted: - The consumer re-arms its signal after each abort it handles, so an aborted signal there is always an unhandled abort. It can't loop. - A message that's already waiting still wins the race, since `Promise.race` checks it first, so no message is dropped. ## Verification A new turn-events test has Claude Code stream an answer and then wedge. The client takes the chunk slowly, the user cancels, and the backstop (10 ms in the test) fires while the consumer is still sending. The turn ends `cancelled`; without the change it never ends. Build, lint and all 2389 tests pass.
ACP adapter for the Claude Agent SDK
Use Claude Agent SDK from ACP-compatible clients!
This tool implements an ACP agent by using the official Claude Agent SDK, supporting:
- Context @-mentions
- Images
- Tool calls (with permission requests)
- Compact file changes through the negotiated AIR diff patch extension
- Following
- Edit review
- TODO lists
- Nested subagent transcripts
- Interactive (and background) terminals
- Custom Slash commands
- Client MCP servers
/mcpin the chat: the MCP server status as a list. The adapter runs/mcp reconnect,/mcp enable, and/mcp disablethrough the SDK control API, because Claude Code refuses them in SDK mode. A reconnect of an ACP server that needs authentication starts MCP OAuth through URL elicitation- Session-scoped long-running goals for AIR through the goal extension under
_meta.jetbrains.air.goal - Structured errors, recovery, and warnings through the opt-in session failure extension
- Concrete model and effort defaults through the opt-in recommended config value extension
- Tool permission presentation, editable choices, and durable effects through the permission extension
- One fact per field in every tool call report, as the ACP tool call contract defines
- All AIR extensions, capabilities, and
_metakeys: AIR extensions
Learn more about the Agent Client Protocol.
To try changes that have landed on main but are not released yet, install from the
preview channel — every push to main publishes one. See
docs/RELEASES.md.
npm install @agentclientprotocol/claude-agent-acp@preview
Subagent sessions
Subagents are exposed only after bilateral capability negotiation. Until the released ACP SDKs
preserve the draft clientCapabilities.subagents field, a supporting client may advertise
nativeSubagentSessions in _meta.jetbrains.air.capabilities; the adapter mirrors the capability
in its initialize response. The canonical field remains supported and takes precedence once it is
available. Without either client signal, Agent/Task lifecycle keeps its legacy ordinary ACP
tool-call representation and child interactions stay on the root session. Clients that use the
historical _meta["subagent-transcript"] capability or forwardSubagentText session option retain
the flattened child transcript behavior. See AIR extensions.
Contribution Policy
This project does not require a Contributor License Agreement (CLA). Instead, contributions are accepted under the following terms:
By contributing to this project, you agree that your contributions will be licensed under the Apache License, Version 2.0. You affirm that you have the legal right to submit your work, that you are not including code you do not have rights to, and that you understand contributions are made without requiring a Contributor License Agreement (CLA).