Implement session/fork#183
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benbrandt merged 11 commits intoagentclientprotocol:mainfrom Dec 12, 2025
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This is a proof of concept for two new methods: "session/resume" and
"session/fork". The idea is to be able to continue an existing chat
using Claude's resume and forkSession functionalities, without the need
to stream all the existing conversation history (which prevents us from
having session/load with the Claude Agent SDK).
For now, I implemented this as extension methods, but I could see it
fit into the core protocol as optional agent capabilities. The methods
accept the same parameters as session/new and also return the same
response format. The only extra parameter that is required is the
"claudeSessionId", but it could also be called "resumeSessionToken".
It is required because Claude internally has its own session ID that is
independent from the ACP ID (it is only created when sending the first
message). Currently, there's a special extension notification called
"claude/sessionId", that send a mapping `{ sessionId, claudeSessionId }`.
Again, for a proper implementation, this could be called `resumeSessionToken`
instead.
SteffenDE
commented
Dec 9, 2025
src/acp-agent.ts
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| // TODO: find a way to make this work for fork | ||
| extraArgs: { ...userProvidedOptions?.extraArgs, ...(creationOpts.resume ? {} : {"session-id": sessionId }) }, |
SteffenDE
commented
Dec 9, 2025
Member
|
@SteffenDE I merged in the upstream changes and went back to the upstream sdk as well |
Contributor
Author
|
Nice, I'll also update this once agentclientprotocol/agent-client-protocol#333 is in and we have the changes in the TS SDK as well. |
Member
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@SteffenDE you should be good now. One of these days I'll get release please to stop bumping the versions so high.. but today is not that day. |
Contributor
Author
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Updated to use the options passed to fork now! |
Member
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@SteffenDE does that mean it is working?? |
Contributor
Author
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It's working as long as you fork a new session. Until we fix the session ids, forks cannot be forked. |
benbrandt
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Work in progress! Uses a fork for now. See agentclientprotocol/agent-client-protocol#277. --------- Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>
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Work in progress! Uses a fork for now.
See agentclientprotocol/agent-client-protocol#277.