96acfeccf9
Part of step 6 of opt-in ACP v2 support. Compaction and session notices are both Preview features of the v2 draft that are expected to stabilize soon, and v2 requires no client capability for either. Nothing changes on ACP v1. ## Compaction The agent already implements the compaction RFD for v1 clients that declare `clientCapabilities.session.compaction`, live and on replay. A v2 client got the legacy "Compact conversation" tool call instead, because the v2 surface didn't declare it. - `v1InitializeRequest` now tells the agent that every v2 client takes compaction updates, as it already did for notices. - `v2SessionUpdate` passes `compaction_update` and `compaction_summary_chunk` through: their v1 and v2 shapes are identical. So a v2 client now gets: - **live:** `compaction_update` `in_progress`, the summary as `compaction_summary_chunk`, then `completed` (or `failed` with the standard `error`); - **on replay:** one completed `compaction_update` with the summary, at the summary's position in the transcript. That's the materialized form the v2 draft asks for, without the start/chunk/finish sequence. The token counts and duration that the tool call's `rawOutput` carried have no v2 field. Only AIR gets them, in `_meta`. ## Notices These were already sent to every v2 client, but no test covered one on v2. A new end-to-end test sends Claude Code's `informational` warning as a live `notice`. The agent sends notices only live, never during replay, which matches the draft's "SHOULD NOT be replayed". ## Not changed **A replayed compaction's id differs from its live id.** Live, the id is the uuid of Claude Code's `compacting` status, which the transcript doesn't keep. Replay uses the summary message's uuid. The draft and the RFD ask for the original, stable ids. As with replayed message ids, a client that kept its view would see the compaction twice. Matching them needs Claude Code to persist the live id. ## Verification - The 3 compaction scenarios change their v2 golden files: the tool call becomes the compaction entity. The scenario names still say `legacy` because they're named for the v1 capability. - Unit tests cover the pass-through and the capability. End-to-end tests cover the live notice, and the replayed compaction between the messages around it. - Removing the capability or the pass-through fails tests. - Build, lint and all 2409 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).