[kesku]

Problem

ACP v2 uses state_update to report when an agent starts and finishes work, rather than relying on the session/prompt response.

We already handle this for Claude Agent, but other ACP Registry agents negotiating v2 still use the v1 behavior.

This causes two issues:

• The agent's echo of the submitted prompt appears as a duplicate user message.
• Work started independently by the agent, such as from another client connected to the same session, doesn't appear in the thread.

Change

Enable followAgentWorkState for all ACP Registry agents instead of just Claude Agent.

This only takes effect when an agent negotiates ACP v2, so v1 behavior is unchanged. Claude-specific subagent handling also stays as it is.

Updated the ACP provider docs to explain this behavior.

Scope and approval

Nada, pls read

This builds on the existing ACP v2 handling introduced for Claude Agent in #21618, applying the same behavior to other agents that negotiate v2.

The work also overlaps with #22015 and #27524. I know that broader behavior hasn't been approved yet, but since both issues stem from the same lifecycle handling, I thought it made sense to address them together.

Happy to adjust the scope if maintainers would prefer to handle that separately tho!

Verification

Added a regression test in AcpRegistryAdapterV2.test.ts covering a non-Claude ACP v2 agent receiving a prompt and then starting work independently.

• Before: the prompt echo appeared as a duplicate user message, and the test timed out waiting for the independently started work.
• After: the test passes.
• All 134 tests across AcpRegistryAdapterV2.test.ts and AcpAdapterV2.test.ts pass.
• Format, lint and typecheck pass for the affected package and test.

Implemented with Claude Opus 5.5 in Claude Code via T3 Code. And some help from Kes :)

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — Agent-state-driven turn completion and autonomous-work visibility become the default for all ACP v2 Registry agents, rather than Claude alone. This default behavior expansion requires human confirmation; ACP v1 remains unaffected.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The ACP Registry adapter now follows reported work state for every agent. An ACP v2 test covers idle turn completion and work continued after a message from another client. The provider documentation describes this behavior.

Changes: ACP Registry work-state handling

Layer / File(s)	Summary
Work-state lifecycle and validation packages/provider-acp-registry/src/server/adapter.ts, apps/server/src/orchestration-v2/Adapters/AcpRegistryAdapterV2.test.ts, docs/user/providers-acp.md	The adapter enables followAgentWorkState for all ACP Registry agents. The test covers idle completion and continuation after a message from another client. The documentation describes ACP v2 turn completion and agent-initiated work in the thread.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related issues

• pingdotgg/t3code#28415: The PR covers ACP v2 agent work that continues after the foreground turn settles, which overlaps with the reported missing background work and follow-up response.
• pingdotgg/t3code#33936: The PR covers continuation for later ACP v2 agent work, but does not address the reported subagent classification or transcript lookup causes.

Suggested labels: bugfix

Suggested reviewers: juliusmarminge

Merge Risk: Minimal · up to 0f601

ACP v2 registry agents now follow reported work state. Turns end when the agent goes idle, and agent-initiated work appears in the thread. The author reports passing tests and green CI, and no actionable merge risk remains.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title names the ACP v2 prompt handling and state update change, which matches the changeset. It uses the conventional commit form. It is slightly broad, but it covers the main change, so the check…
Description check		The description covers the problem, the change, scope and approval context, and verification. It states the problem with duplicate echoed prompts and missing independent work. It explains that the cha…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title names the ACP v2 prompt handling and state update change, which matches the changeset. It uses the conventional commit form. It is slightly broad, but it covers the main change, so the check passes.

Full details: Description check

Explanation

The description covers the problem, the change, scope and approval context, and verification. It states the problem with duplicate echoed prompts and missing independent work. It explains that the change enables followAgentWorkState for all ACP Registry agents negotiating v2 and that v1 behavior is unchanged. It links related issues and reports a regression test and passing test runs. Scope approval is only partly addressed: it cites the existing ACP v2 work and related issues, and says the broader behavior is not yet approved. It does not link a maintainer approval comment. The verification section is detailed, and the author-stated test results support it.

Finishing Touches

Generate unit tests (beta)

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Recent review info

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Commits

Reviewing files that changed from the base of the PR and between fc3b78d and 0f60102.

Files selected for processing: 1

• apps/server/src/orchestration-v2/Adapters/AcpRegistryAdapterV2.test.ts

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[coderabbitai]

---

Prompt to fix all issues

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Failed pre-merge checks:
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Add a link to the triaged issue or maintainer discussion with explicit approval
of the scope, including the approval comment. Alternatively, narrow the change
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Review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: d1909d6
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Commits

Reviewing files that changed from the base of the PR and between d1909d6 and 45513cd.

Files selected for processing: 3

• apps/server/src/orchestration-v2/Adapters/AcpRegistryAdapterV2.test.ts
• docs/user/providers-acp.md
• packages/provider-acp-registry/src/server/adapter.ts

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[maria-rcks]

Note

Written by gpt-6.1-sol on behalf of Maria

Verified in a real dev environment

verified the unsolicited-work fix on Linux against exact head 45513cdd60862e7ec9c298d23f01ed0d1b35344a, after reproducing it on github/main at ac5e48c612. no source changes or pushes were needed.

ran vp i and background vp run dev separately for each checkout, with isolated state and one dev server at a time. used repository Playwright and /usr/bin/google-chrome. created the project, threads, and provider configuration through the web app. the project pointed to a real git checkout. the local ACP provider ran released codex-acp 2.6.0 with real Codex gpt-6.1-sol inference through the VM's Responses proxy. transparent tee logging captured the actual protocol without changing it. initialize negotiated ACP v2.

• main: submitted an ordinary prompt, then asked Codex to create a goal that responds with phase one and finishes with phase two in an automatic continuation. the provider emitted both phases and running/idle updates, but the web thread dropped phase two. only two client session/prompt requests produced these three provider work cycles.
• pr: the same prompts showed both phases, including a background activity update for the autonomous continuation. phase two survived a reload. the next user turn returned ACP_NEIGHBOR_OK. each of the three submitted prompts appeared once.
• nearby ACP v1: released codex-acp 0.16.0 negotiated protocol v1 and completed a real gpt-6.1-sol turn with ACP_V1_OK. that older provider also displayed a fallback-model-metadata warning.
• blacksmith: vp test run apps/server/src/orchestration-v2/Adapters/AcpRegistryAdapterV2.test.ts apps/server/src/orchestration-v2/Adapters/AcpAdapterV2.test.ts passed, 134 tests across two files. GitHub CI was green on this head.

sanitized runtime transcript

Not verified

• a second external client attached to the same private ACP process. the real autonomous goal continuation exercised unsolicited work instead.
• the original whole-user_message duplicate-echo case: this real Codex adapter emits user_message_chunk, and its duplicate prompt was not reproduced on main. the PR displayed each prompt once; the whole-message case was exercised by the focused regression test only.
• other registry agents, native desktop/mobile clients, and remote/tunnel connections. runtime verification here used the Linux web client.