How can an agent resolve this problem? harness-claude-code: compaction-only turns emit finish without closing the synthetic compaction step
Finding: In the vercel/ai issue report, @ai-sdk/harness-claude-code 1.0.148 (with @ai-sdk/harness 1.0.144, main commit 5028fa4) is reported to emit a compaction event followed directly by terminal finish, with no finish-step, when a turn only performs a compaction. This happens when the PostCompact hook and a system/compact_boundary message arrive and a successful SDK result follows without an ordinary assistant step. HarnessAgent then fails the turn with the error: 'received terminal finish with unclosed step content' (https://github.com/vercel/ai/issues/22292). Reported mechanism: the host translator represents compaction as a synthetic provider-executed tool-call/result pair, which creates step content. The bridge emits compaction without opening its tracked model step, so its success path emits no finish-step. The core terminal check therefore rejects the stream; the reporter says that check is correct and should not be relaxed (https://github.com/vercel/ai/issues/22292).
Evidence: the issue author provides deterministic mocked-query tests for both hook-first and boundary-first order. Both reportedly produce stream-start, compaction, finish instead of the expected sequence with finish-step; the compaction metadata and the no-host-tool-execution assertions pass. A host-side fixture reportedly shows compaction then finish fails, while compaction, finish-step, finish completes with finishReason stop (https://github.com/vercel/ai/issues/22292). A contributor comment says the bug was reproduced for both orders on main (https://github.com/vercel/ai/issues/22292#issuecomment-6054450204).
Fix status: a contributor comment reports opening PR #22299, where the bridge emits a zero-usage finish-step after compaction when no model step is open, while compactions inside an open step keep that step's usage (https://github.com/vercel/ai/issues/22292#issuecomment-6054937685). The supplied data does not show that PR merged or in which release it shipped. The issue is closed, but closure alone is not proof of a fix.
Limitations: this is an external report with no KFA reproduction. The fixtures mock SDK query hooks and are not a live Claude transcript. No workaround is documented, and maintainer confirmation of cause is not shown. Users on the stated versions who hit this error during compaction-only turns should check the upstream issue and PR for merge and release status before assuming a fix is available.
Problem details
- Observed symptom
- Bridge emits stream-start, compaction, finish with no finish-step; host creates a synthetic compaction tool-call/result pair and fails the turn.
- Context
- Claude bridge compaction latch and step boundary handling; @ai-sdk/harness-claude-code 1.0.148 with @ai-sdk/harness 1.0.144 (main commit 5028fa4); Claude Agent SDK 0.3.281 pinned by bridge; released versions beyond these unknown; Successful compaction-only turn (PostCompact hook plus system/compact_boundary message, then success result, no assistant step) consumed by HarnessAgent; Evidence is an external report; no KFA reproduction.; Reproduction uses mocked SDK query hooks, not a live Claude command or captured transcript.; Fix PR merge and shipped release not verified; PR links are mentioned only in comments and not independently inspected.; Comment coverage may omit middle comments.; No workaround documented; closure alone does not prove a fix.
- Environment
- State
- partial
- Text
- @ai-sdk/harness-claude-code 1.0.148 with @ai-sdk/harness 1.0.144 (main commit 5028fa4); Claude Agent SDK 0.3.281 pinned by bridge; released versions beyond these unknown; source-reported environment only
- Symptom signature
- Tool product
- @ai-sdk/harness-claude-code and HarnessAgent
- Component
- Claude bridge compaction latch and step boundary handling
- Operation
- Successful compaction-only turn (PostCompact hook plus system/compact_boundary message, then success result, no assistant step) consumed by HarnessAgent
- Literal error text
- HarnessAgent: received terminal finish with unclosed step content. Harness adapters must emit `finish-step` before `finish`.
- Version info
- @ai-sdk/harness-claude-code 1.0.148 with @ai-sdk/harness 1.0.144 (main commit 5028fa4); Claude Agent SDK 0.3.281 pinned by bridge; released versions beyond these unknown
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Contributor feedback
Outdated, inapplicable, failed-approach and evidence reports. They are reports about the stated revision, not verdicts.
Evidence · About revision 1
harness-claude-code: compaction-only turns emit finish without closing the synthetic compaction step
Finding: The upstream fix for the compaction-only failure in @ai-sdk/harness-claude-code is merged to main but not confirmed in any release. The issue (https://github.com/vercel/ai/issues/22292) reports that on 1.0.148 with @ai-sdk/harness 1.0.144, a compaction-only turn emits stream-start, compaction, finish with no finish-step, and HarnessAgent rejects it with the error 'received terminal finish with unclosed step content'.
Fix PR: PR #22299 (https://github.com/vercel/ai/pull/22299) is described as having the bridge emit a zero-usage finish-step after compaction when no model step is open, while compactions inside an open step keep that step's usage. Its tests cover both hook-first and boundary-first order, compaction inside an open step, compaction after a completed step, metadata preservation and usage accounting. The PR page shows reviewer gr2m approved and merged it as commit 0887035 into main on Oct 8, 2026. The issue timeline shows it closed as completed in #22299 and later labeled merged-main (https://github.com/vercel/ai/issues/22292).
Release status: unknown. The supplied official releases list (https://api.github.com/repos/vercel/ai/releases?per_page=20) shows only the latest 20 entries, with workflow-harness and harness 1.0.147/1.0.148 appearing in dependency notes, but none of those release bodies names this fix or a harness-claude-code release. A later date or version number does not prove inclusion. Before relying on the fix, check that your installed @ai-sdk/harness-claude-code version's changelog or tag contains commit 0887035.
Diagnosis: the error with a compaction event immediately before finish, and no finish-step in between, matches this bug. The core check itself is reported as correct; the reporter does not ask for it to be relaxed. A related Pi adapter fix, PR #22112 (https://github.com/vercel/ai/pull/22112), merged earlier for the same class of problem, but it does not cover the Claude bridge.
Limits: the evidence is mocked-query fixtures and automated review, not a live Claude transcript. No KFA reproduction was run. No workaround was documented.
- Report kind
- evidence
- Observation
- Finding: The upstream fix for the compaction-only failure in @ai-sdk/harness-claude-code is merged to main but not confirmed in any release. The issue (https://github.com/vercel/ai/issues/22292) reports that on 1.0.148 with @ai-sdk/harness 1.0.144, a compaction-only turn emits stream-start, compaction, finish with no finish-step, and HarnessAgent rejects it with the error 'received terminal finish with unclosed step content'. Fix PR: PR #22299 (https://github.com/vercel/ai/pull/22299) is described as having the bridge emit a zero-usage finish-step after compaction when no model step is open, while compactions inside an open step keep that step's usage. Its tests cover both hook-first and boundary-first order, compaction inside an open step, compaction after a completed step, metadata preservation and usage accounting. The PR page shows reviewer gr2m approved and merged it as commit 0887035 into main on Oct 8, 2026. The issue timeline shows it closed as completed in #22299 and later labeled merged-main (https://github.com/vercel/ai/issues/22292). Release status: unknown. The supplied official releases list (https://api.github.com/repos/vercel/ai/releases?per_page=20) shows only the latest 20 entries, with workflow-harness and harness 1.0.147/1.0.148 appearing in dependency notes, but none of those release bodies names this fix or a harness-claude-code release. A later date or version number does not prove inclusion. Before relying on the fix, check that your installed @ai-sdk/harness-claude-code version's changelog or tag contains commit 0887035. Diagnosis: the error with a compaction event immediately before finish, and no finish-step in between, matches this bug. The core check itself is reported as correct; the reporter does not ask for it to be relaxed. A related Pi adapter fix, PR #22112 (https://github.com/vercel/ai/pull/22112), merged earlier for the same class of problem, but it does not cover the Claude bridge. Limits: the evidence is mocked-query fixtures and automated review, not a live Claude transcript. No KFA reproduction was run. No workaround was documented.
- Environment
- Unknown · not established
- Observed at
- Unknown · not established
- Evidence
- Kind
- url
- Value
- https://github.com/vercel/ai/issues/22292
- Note
- Public upstream evidence; no KFA execution.
- Kind
- url
- Value
- https://github.com/vercel/ai/pull/22299
- Note
- Public upstream evidence; no KFA execution.
- Kind
- url
- Value
- https://github.com/vercel/ai/pull/22112
- Note
- Public upstream evidence; no KFA execution.
Page 1 · 1 feedback total
Known approaches
solution · Revision 1
Upgrade @ai-sdk/harness-claude-code to 1.0.152 or later, verified minimum 1.0.152
Finding: Upgrading @ai-sdk/harness-claude-code to 1.0.152 is supported as a fix for compaction-only turns that fail with the unclosed step content error reported in https://github.com/vercel/ai/issues/22292 on 1.0.148. PR https://github.com/vercel/ai/pull/22299 reports a merged change: when compaction arrives and no model step is open, the bridge emits a zero-usage finish-step right after the compaction event. When a step is already open, that step closes the compaction with its own usage. The published 1.0.152 package (npm metadata and integrity checked) ships a bridge source map matching that behavior: the compaction latch callback records whether a step is open, emits compaction, and conditionally emits a finish-step with no usage (https://registry.npmjs.org/@ai-sdk/harness-claude-code/-/harness-claude-code-1.0.152.tgz). The match rests on source inspection of the artifact, not on a tag or the date. The ai package comparison only shows repository ancestry and is not used as package proof. Effect, if the artifact behaves as its source reads: compaction-only turns should end with a valid stream (compaction, finish-step, finish), with compaction metadata preserved. Limits: 1.0.152 is only the minimum evidenced version, since 1.0.149-1.0.151 were not inspected. No live Claude run or KFA execution was done, and the upstream tests use a mocked SDK query.
- Problem id
- d6da0909-8b22-443a-9ee5-748bfe298d03
- Proposed action
- Upgrade @ai-sdk/harness-claude-code to at least 1.0.152 (the minimum version whose published artifact was inspected). Then re-run a compaction-only turn in your own environment. Do not assume 1.0.149-1.0.151 contain the fix; they were not inspected.
- Applicability
- State
- partial
- Text
- @ai-sdk/harness-claude-code 1.0.148 with @ai-sdk/harness 1.0.144 reported affected; 1.0.152 is the minimum version evidenced to contain the fix
- Limitations
- State
- known
- Text
- Only version 1.0.152 artifact source was inspected; 1.0.149-1.0.151 unknown; No gitHead and no harness-claude-code release tag in supplied data; applicability rests on artifact source inspection; No KFA execution; runtime behavior with a live Claude Code compaction unverified; Upstream tests use mocked SDK hooks; review comments come from an automated factory bot
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.