feat(session): add fenced logical owner cleanup coordination

[snowykr]

Summary

Install the complete managed logical task-owner cleanup helper on externally merged verified storage #6332. This is an independently reviewable API layer, not producer/admission activation or a partial caller stub.

• Require live scope ownership, a genuine ephemeral protocol inspector, authenticated receipt operations and exact target identity.
• Preserve original deletion evidence through preparation, artifact completion, actual native retirement outcomes, pending continuations and transcript-deletion persistence.
• Refuse missing/mismatched continuation state, foreign owner-bearing legacy targets, shared siblings and forged flags; preserve payload_retired/namespace-pending distinctions.
• Keep scope callbacks modular and named; no runtime scope import, serialized capability, global writer-readiness barrier or DTO-as-authority fallback.

Exact source and budget

Base dev df6c32605f666b2a3598650cbe985cd69313c1f5: external #6332 exact6c78 installation and upstream #6322 ACP acknowledged-cancellation settlement. Preserve readonly evidence capture, mandatory pre-artifact sibling fence, #6329 native/reaper and unrelated upstream changes.
Exact head 0a139e6e8bc9a1e5b34ef05dc4bc8e41e0df2bbb.
Owned AND actual dev production 472 additions+deletions, after formatting. Helper +472, tests +498 and per-package changelog +2 excluded. Three files, no native/generated descriptor change.

Verification

Independent clean exact-head QA qualifier 10c-independent-after6332-basedf6c3260, existing strict runner with explicit source/version/digest/build-tree agreement and missing-test-file refusal:

bun test packages/coding-agent/test/managed-task-owner-cleanup-api.test.ts packages/coding-agent/test/managed-gc-retirement-journal.test.ts packages/coding-agent/test/task-artifact-owner-storage.test.ts packages/coding-agent/test/task-artifact-owner-retirement.test.ts packages/coding-agent/test/session-storage.test.ts packages/coding-agent/test/gc-disk-retention.test.ts packages/coding-agent/test/acp/acp-cancel-settlement.test.ts
# 272 pass / 8 existing platform skips / 0 fail / 1535 assertions / 280 tests / 7 files
bun --cwd=packages/coding-agent run check
# exit0: vendor, Biome and TypeScript

QA re-executed on NEW exact head after rebase, clean before/after; warnings retained. Initial6838/base6a2 qualification is historical, not transferred. Include actual upstream ACP cancellation behavior in this fresh qualification.

Initial exact6838 Dev CI37219463412 failed its immutable-base planning gate after dev advanced to df6: affected helper plan/shards were unevaluated, not executed changed-code failures. Actual CHANGES_REQUESTED review found no blocking code defect and requested rebase; retain its posted needs-human beb08bbe7cb50696f0a38c9afc068a5e12ac628aaa7285c33a030a6c2897fc26. Rebased without changing helper code, with new source/base qualification and no approval/CI transfer. Fresh current code-event CI is required.

Native runtime remains genuine installed release0.18.7: addon SHA256 8d1c6b2dcaafc1889eeb5719c74075834d0088ba903bffdf1beac71606a93325, path_identity source 2617654e11e48dd58b5b591f5d0f0b21913ad75302bc6edbf66135e5cf27fd0d; native build source afbb254, crate tree413eef4a2281495c911651fc6f93446d98ddbed9 identical to this head. Installed descriptor unchanged; no QA metadata rewrite, old-byte relabeling or fabricated fallback.

Scope and limits

Managed/SDK/GC caller installation is intentionally unchanged in this API prerequisite and requires subsequent complete qualified layers. Existing conservative unsupported-owner fences stay in place until those consumers install. Persistent-owner production and trusted post-move task admission remain OFF. No whole-goal, frozen cohort/critic, real retained task execution or repaired official binary claim.

Darwin local runtime; existing skips are not Linux/Windows execution. Fresh code-event CI and exact-head write-access maintainer approval required independently. #6332 Linux/code-CI approval belongs to its exact6c78 head, not this helper head; no transfer.

Protected original HEAD1a12 with44staged files and reference #6240 HEAD7e5 remain untouched. Leader does not merge.

[probepark]

Review (head 6838bd6, gajae-reviewer on behalf of probepark)

CI: PR-caused (branch state), 1 — Affected path validation / plan failed at step Verify PR head contains exact base: Exact-head CI requires this PR head to contain base df6c32605f666b2a3598650cbe985cd69313c1f5; rebase onto current dev. (job). evidence producer and the Affected path validation aggregate failed downstream of it. No path logic ran, so the affected shards and the changelog guards are unevaluated, not passing. The managed-task-owner-cleanup-api.test.ts + package check results in the PR body are local-only evidence for this head. gjc-state-gates / native addon was still pending.
Scope: +972 / -0, 3 files. ocr reviewable: +472 (packages/coding-agent/src/session/internal/managed-task-owner-cleanup.ts). Excluded: test (+498) and changelog fragment (+2).
Conventions: changelog fragment changelog.d/task-owner-cleanup-helper.md present. No generated files. No labels. No console.*, no new Worker, no mock.module/spyOn. Body has no verdict line.

Branch state: head parent is ccdce81 → 6a2a4b9 (#6332). Current dev = df6c326 = merge of #6322 on top of 6a2a4b9, so head and base are siblings off 6a2a4b9 and git merge-base --is-ancestor df6c326 6838bd6 is false. The base-side delta is only modes/acp/acp-agent.ts + test/acp/acp-cancel-settlement.test.ts (+20/-1), which does not overlap this PR. The code review below therefore carries over verbatim after a rebase onto df6c326.

Notable:

• managed-task-owner-cleanup.ts:325-345 / :376-396: owner_pending receipts are published without ownerRetirementAttempt. I checked that this is correct. publishManagedGcSessionRetirementReceipt derives the attempt itself (managed-session-scope.ts:3521, current.ownerRetirementAttempt + 1 or 1) and enforces continuationExtendsPrevious (:3530). managedGcReceiptForPublication accepts an absent attempt (:2512-2514). The tombstone-sibling inheritance arm (:264-271) does not call verifyTaskArtifactOwnerPhysicalRetirement itself, but the publisher re-verifies physical retirement for every owner_retired publication (managed-session-scope.ts:3552). So that arm is not fail-open.
• managed-task-owner-cleanup.ts:237: if (!evidence) throw …evidence_missing is unreachable, because ManagedGcSessionRetirementReceipt.taskArtifactOwnerDeletionEvidence is non-optional (managed-gc-retirement-codec.ts:29) and the codec parser throws on corrupt evidence. Non-blocking. test/managed-task-owner-cleanup-api.test.ts:465 accepts either owner_retired or pending|payload_retired depending on the native outcome, so neither arm is pinned on any given platform. Consider forcing one deterministic arm per test.

Checked and clean: the 4c/legacy-scope fence (:106-117, :123-127), the prepared-receipt immutability checks (:128-163), the cross-scope inheritance guards (:277-296), the outcome/flag consistency check (:367-374), and the lock assertOwned bracketing around every sibling/protocol inspection and native retire call.

Blocking:

1. Rebase onto current dev (df6c32605f666b2a3598650cbe985cd69313c1f5) and push, so exact-head plan can run the affected shards for this helper and its test. No code change is requested. The code review above found no blocking defect.

Verdict: gajae.pr-review-verdict.v1 needs-human sha256:beb08bbe7cb50696f0a38c9afc068a5e12ac628aaa7285c33a030a6c2897fc26 reviewer:critic reviewer-id:gajae-reviewer evidence:head-not-containing-base-df6c326;plan-unevaluated;helper-code-read-no-defect;publisher-attempt-and-physical-verify-checked

[snowykr]

Rebased onto actual installed dev df6c326 as requested; new exact head0a139e6e8bc9a1e5b34ef05dc4bc8e41e0df2bbb contains that base. Helper code is unchanged, owned AND actual production472. Fresh independent clean exact-head QA: 272 pass / 8 existing skips / 0 fail / 1535 assertions, including upstream ACP cancellation settlement; full coding-agent vendor/Biome/types exit0. Existing strict native version/source/digest/build-tree checks passed. Previous6838 CI plan-unevaluated failure and review remain historical; no gate/approval transfer. Fresh code-event CI and review required on this new head.

[snowykr]

Current exact head 0a139e6e8bc9a1e5b34ef05dc4bc8e41e0df2bbb now has fresh pull_request Dev CI 37221677784 completed SUCCESS. The immutable-base planning failure and needs-human verdict belonged to old head 6838bd66; the current head contains actual dev df6c3260. Independent exact-clean helper + storage/journal/retirement/legacy GC + upstream ACP settlement qualification: 272 pass, 8 existing platform skips, 0 fail, 1535 assertions across 7 files, coding-agent package checks exit 0, genuine unchanged 0.18.7 native bytes/source/build-tree. Production diff remains 472 added+deleted against actual dev; complete inert helper API only. No producer/admission activation, review approval, or merge is being inferred. Please evaluate the current head rather than carrying the old-head base-planning verdict forward.

[probepark]

Review (head 0a139e6, gajae-reviewer on behalf of probepark; re-requested 2026-10-04T17:44:42Z)

CI: green. All checks are completed on this head: Affected path validation aggregate SUCCESS (18:02:49Z), which includes check:@gajae-code/coding-agent, ts-build for coding-agent, native-build, cli-smoke, and the 3 targeted test shards. gjc-state-gates SUCCESS. Virtual integration validation SUCCESS (18:12:10Z).
Scope: +972 / -0, 3 files: packages/coding-agent/src/session/internal/managed-task-owner-cleanup.ts (+472), its test (+498), and a changelog.d fragment (+2).
Conventions: changelog fragment present, no generated files changed, no labels.
Notable:

• This head is a pure rebase onto dev df6c326 (git merge-base --is-ancestor df6c326 0a139e6 passes). git diff --binary --full-index base...head sha256 is beb08bbe7cb50696f0a38c9afc068a5e12ac628aaa7285c33a030a6c2897fc26, the same digest as the 6838bd6 diff reviewed in 5407338592. That review found no code defects.
• The only blocking finding from 5407338592 was "head does not contain base, so exact-head plan failed". That is resolved: Affected path validation / plan SUCCESS at 17:45:34Z. Trigger: #6335 (comment)
  Blocking: none. The earlier CHANGES_REQUESTED on 6838bd6 is dismissed as superseded.

This is a COMMENT, not an APPROVE: the reviewer's local approve-gate check could not run in this pass (API budget guard). An approval will follow in a later pass once the gate runs.

Body has no verdict line; not edited. Suggested verdict line: gajae.pr-review-verdict.v1 merge-approved sha256:beb08bbe7cb50696f0a38c9afc068a5e12ac628aaa7285c33a030a6c2897fc26 reviewer:human reviewer-id:probepark evidence:rebase-only-same-digest;ci-green-incl-coding-agent-check;prior-blocker-resolved

Blocking findings resolved; superseded by the follow-up verdict.

[probepark]

Review (head 0a139e6, gajae-reviewer on behalf of probepark)

This is the approval promised in review 5407488609. The local approve gate has now run on this head: ALLOW, pending=0, failed=0, need_local=0, covered=check:@gajae-code/coding-agent.

CI: green. Only the human-approval gates are outstanding (Merge approval*, PR contract); they are waiting on this verdict.
Scope: +972 / -0, 3 files. ocr reviewable: +472 (packages/coding-agent/src/session/internal/managed-task-owner-cleanup.ts). Excluded: test (+498) and the changelog fragment (+2).
Conventions: changelog fragment changelog.d/task-owner-cleanup-helper.md present. No generated files. No labels. No console.*, no new Worker, no mock.module/spyOn.
Notable:

• I re-read the helper at this head. git diff --binary --full-index df6c326...0a139e6 has sha256 beb08bbe…6fc26, identical to the 6838bd6 diff reviewed in 5407338592, so that code review stands. The lock assertOwned bracketing wraps every sibling scan (:252-260, :311-319, :431-439) and the native retire call (:335-337). The cross-scope inheritance (:291-310) is fenced on agentDir, sessionsRoot, and directoryPath, and it re-verifies physical retirement before publishing.
• Non-blocking: managed-task-owner-cleanup.ts:251 (if (!evidence) throw …evidence_missing) is unreachable, because the receipt evidence field is non-optional. The test at managed-task-owner-cleanup-api.test.ts:465 accepts either native outcome arm, so neither arm is pinned on any given platform.
  Blocking: none.

Body has no verdict line; not edited. Suggested verdict line: gajae.pr-review-verdict.v1 merge-approved sha256:beb08bbe7cb50696f0a38c9afc068a5e12ac628aaa7285c33a030a6c2897fc26 reviewer:human reviewer-id:probepark evidence:approve-gate-allow;ci-green-incl-coding-agent-check;rebase-only-same-digest;helper-code-read-no-defect

Verdict: gajae.pr-review-verdict.v1 merge-approved sha256:beb08bbe7cb50696f0a38c9afc068a5e12ac628aaa7285c33a030a6c2897fc26 reviewer:human reviewer-id:probepark evidence:approve-gate-allow;ci-green-incl-coding-agent-check;rebase-only-same-digest;helper-code-read-no-defect