fix(acp): preserve async-result continuation agent_end correlation

[probepark]

Why

On a dev build that already contains #6333 (3239206), dbe46ae and 8aa5049 (tank, gjc built from f4b3d1a), ACP still logs acp_prompt_terminal_dropped terminalType=agent_end reason=incomplete_correlation, then acp_prompt_watchdog_expired 340s later (G4 gate FAIL, 15 drops in ~4.5h).

Session evidence (jsonl, UTC):

• 24e6e6b4: 05:23:18.376 assistant stop -> 05:23:18.382 custom_message async-result -> 05:25:17.058 assistant stop -> 05:25:17.168 custom_message irc:incoming -> 05:25:17.189 dropped agent_end (incomplete_correlation)
• d76cd5c1: 06:18:05.208 assistant stop -> 06:18:05.212 custom_message async-result -> 06:18:13.803 assistant stop -> 06:18:13.826 dropped

The remaining path: the prompt's turn ends while an async job or subagent is still running. When its result arrives, the yield-queue async-result delivery starts a continuation turn through injectIdle / injectStreaming / the trigger-turn follow-up. That turn was accepted without the active SDK run token, so its terminal agent_end carried no commandId/turnId and ACP dropped it.

Note: the binary's lack of activePromptOwnerHolder/adoptLifecycleBatch symbols is expected. The build uses --minify (scripts/compile-args.ts), and the log site acp_prompt_terminal_dropped is present, so dist == source.

What

• agent-session.ts: when async-result custom messages become continuations, capture #activeSdkRunToken and pass it through:
  • the streaming follow-up (#queueFollowUpAfterReservation(..., { sdkRunToken }))
  • the idle injection (#acceptSdkAttemptRun(handle, sdkRunToken) in both prompt branches)
  • the trigger-turn follow-up path
• changelog fragment fix-acp-async-result-terminal-correlation.md
• one whitespace cleanup in agent-session-concurrent.test.ts

This PR does not touch the provider-error retry path (#handleRetryableError), which open PR #6354 fixes, or the todo-reminder continuation pinned by #6344.

Risk

• low-risk
• regression-risk
• high-risk

Touches continuation run-token ownership in AgentSession, so a wrong token could mis-attribute a terminal to a prompt.

Merge approval is expected to stay red on this agent-authored PR until a maintainer approves the exact head (human-review path, #6037); the contract check itself should be green.

Local tests (command + result)

Run on tank (worktree g4-asyncres-corr):

• bun test packages/coding-agent/test/session-runtime.test.ts -> 180 pass, 0 fail
• bun test packages/coding-agent/test/agent-session-retry-busy-recovery.test.ts -> 7 pass, 0 fail
• bun test packages/coding-agent/test/agent-session-concurrent.test.ts -> 35 pass, 0 fail
• bun run lint -> rc 0

Local CI gate (prepush)

PREPUSH_CMD rc=0 bun run --workspaces --if-present check:types
PREPUSH_CMD rc=0 bun scripts/telegram-daemon-generation-guard.ts "$(git merge-base origin/dev HEAD)" "$(git rev-parse HEAD)"

Needs e2e

• After a build with this head is installed on tank, re-measure G4 (gjc-acp-guard.py): the count of acp_prompt_terminal_dropped terminalType=agent_end reason=incomplete_correlation after an async-result continuation should be 0, and acp_prompt_watchdog_expired should not rise.

Acceptance

AC	Implementation	Local test
AC-1 async-result continuation agent_end keeps active prompt commandId/turnId	agent-session.ts injectIdle / streaming injector / trigger-turn follow-up pass sdkRunToken	session-runtime.test.ts 180/0, agent-session-concurrent.test.ts 35/0 (existing lifecycle tests; no new dedicated regression test: NOT DONE, see Open questions)
AC-2 check whether dist == source	build is --minify; log site present in binary	n/a (static check on tank)
AC-3 G4 drop count 0 on new build	needs e2e	tester re-measure

Open questions

• No dedicated regression test that drives an async-result continuation through ACP and asserts a correlated agent_end was added (agent assumption: existing lifecycle tests cover it). A reviewer may want one.

Agent

gjc via paseo on tank (worktree g4-asyncres-corr), commits 908a49f, 88c4d15. No fallback.

[snowykr]

Verdict

APPROVED

Summary

Reviewed PR #6356 at 88c4d1561f5c3d6ccbfc57eea75ce914c532f71e against base/merge-base 0f2560745bc3d44b60c4698dfcd0cc0560b620a9. The change propagates the existing SDK run token through async continuation paths so accepted attempts retain the command/turn correlation consumed by the SDK host and ACP. The five review scopes found no actionable defects.

Findings / Required Changes

No blocking or actionable findings.

Non-blocking Observations

• The diff adds no dedicated regression assertion for an async-result continuation producing an ACP agent_end with the expected commandId/turnId; the changed test file only removes whitespace. A focused end-to-end assertion would directly cover this scenario. This is an optional coverage improvement, not a merge blocker.

CI / Verification

The exact-head Dev CI run 37277112952 completed successfully, including agent-session-concurrent.test.ts, the coding-agent package check, the affected-path aggregate, state-gate shards, and virtual integration validation. A second Dev CI run for the same SHA (37277574967) was skipped; its trigger/reason was not established. No local tests or gates were run during this read-only review.

Axis Coverage

Axis	Verdict	Coverage
A1 — Intent / Policy / Contract	APPROVED	No concrete mismatch with the stated fix or existing SDK/ACP correlation contract.
A2 — Architecture / Correctness / Failure	APPROVED	Existing token ownership and attempt-scope binding are reused; no reachable regression was established.
A3 — Security / Privacy / Trust	APPROVED	No new trust boundary, authorization decision, or attacker-controlled token source was introduced.
A4 — Verification / Tests / CI	APPROVED	Exact-head required affected tests and aggregate CI passed; missing dedicated end-to-end coverage is optional.
A5 — Context / Compatibility / Platform	APPROVED	Consumers, cleanup, and existing ownership abstractions remain consistent; no compatibility or platform defect found.

Limitations

This was a static review of the exact head and its base; no dynamic ACP reproduction was run. No separate intent_projection artifact was supplied or found, so intent was assessed from the pinned implementation, changelog, and contracts. The reason for the skipped same-SHA CI rerun was not verified.

[Yeachan-Heo]

Merged into dev as bddbf37e.

• snowykr approved the exact head 88c4d15.
• CI on that head: 22 passed, 0 failed.
• The branch was 13 commits behind dev. The only overlapping file was agent-session.ts (from fix(acp): keep SDK prompt owner across session continuations #6354), and it auto-merged cleanly.
• I merged it locally with dev 380f4aaa and ran the 80 test files that import agent-session: no failures on the merged tree, vs 1 on unmodified dev.

—
[repo owner's gaebal-gajae (clawdbot) 🦞]