diff --git a/packages/agent/docs/harness-v2-test-matrix.md b/packages/agent/docs/harness-v2-test-matrix.md
index 3babd3829..060cbc883 100644
--- a/packages/agent/docs/harness-v2-test-matrix.md
+++ b/packages/agent/docs/harness-v2-test-matrix.md
@@ -122,10 +122,12 @@ Removed files:
 | builds context from the branch storage without loading complete history | Inapplicable / Covered | Old branch-storage optimization was deleted; v4 context behavior is covered by `session/context.test.ts`. |
 | rejects repository operations and session writes after disposal | Covered / Inapplicable | The v4 core `SessionRepo` contract has no disposable state, and the in-memory/JSONL repos do not implement permanent disposal. SQLite disposal is resource release rather than repo poisoning; `packages/session-backends/sqlite-node/test/repository.test.ts` covers the remaining applicable behavior in `closes active sessions when the repository is disposed`, proving active session writes reject after repository disposal. |
 | supports lexical ownership with await using | Inapplicable | The old test covered permanent disposal on the deleted in-memory repository. The v4 core `SessionRepo` contract has no disposable surface, and memory/JSONL repos do not implement lexical ownership. SQLite `await using` is resource cleanup rather than repo poisoning; active-session closure is covered by `closes active sessions when the repository is disposed` in `packages/session-backends/sqlite-node/test/repository.test.ts`. |
+| serializes conflicting create and fork destinations | Uncovered / J3 | The old test covered JSONL backend-wide serialization for concurrent create/create and create/fork operations targeting the same id. V4 intentionally removed global repository serialization, but the remaining format-4 lifecycle/concurrency question is whether conflicting destination creation can duplicate files or silently overwrite; assign to J3 lifecycle/concurrency edge cases. |
 | encodes custom session IDs used in filenames | Covered | J2 JSONL repository lifecycle validates file-safe ids; `jsonl.test.ts` rejects invalid coding-agent filenames. |
 | allows appends to different sessions to run concurrently | Covered | J2/v4 repository conformance and JSONL concurrent write tests cover accepted concurrent writes without the old keyed queue. |
 | caps concurrent operations across JSONL sessions at four by default | Inapplicable | Old JSONL keyed-operation-queue implementation detail was deleted. |
 | allows overriding the JSONL concurrency limit | Inapplicable | Old JSONL keyed-operation-queue implementation detail was deleted. |
+| rejects invalid JSONL concurrency limits | Inapplicable | Old `maxConcurrentOperations` configuration was deleted with the JSONL keyed-operation queue. |
 | releases JSONL concurrency capacity after an operation fails | Inapplicable | Old JSONL keyed-operation-queue implementation detail was deleted. |
 | serializes appends to the same session | Covered | v4 single-writer/session mutation conformance and JSONL shared-sequence tests. |
 | uses listing as a barrier between accepted session operations | Inapplicable | The old test covered deleted JSONL `KeyedOperationQueue.enqueueBarrier()` behavior. V4 JSONL intentionally does not retain created/opened storages in the repository and does not serialize repository operations; `harness-v2.md` says callers must await operations with ordering dependencies, so no listing barrier should be restored. The replacement serialization invariant is per opened session storage and is already covered by backend conformance `linearizes concurrent writes across two lanes` plus JSONL-specific `persists concurrent cross-lane writes in shared sequence order`. |