Keep local preparation checks actionable when scratch space fills #1223

Observed failure

A local Deno preparation check failed during PR #1203 validation when the shared disk filled, then passed after removing this task's reproducible dependency directories. The first command started on signed 2de425dd02f00df1354c82f7cbd9443d67be94fd; the retry ran on signed successor 2cc94e2032c62bb98abb9dd2bd3761ef19fe8b3d. The only intervening source change is one retained-session diagnostic literal in packages/acp/src/provider.ts; Preparation workflow and fixture code are identical. This is a source-equivalent environmental reproduction, not an exact-SHA rerun claim. This records the intermittent environmental failure required by AGENTS.md; no source defect or CI failure is established.

Command: deno task test packages/cli/tests/adversarial-preparation.test.ts (the first run also selected adversarial-delivery.test.ts, which passed).

Runtime: Deno 2.9.7 on macOS. Local execution; no GitHub Actions run link exists. PR: #1203.

The first failing journey was R D H P missing: continuation publication retained a hold and a FilesError with operation=write, phase=temporary, target=unchanged, reason=no-space. Its outer diagnostic was Unknown ticket publication requires operator disposition; no state is adopted. A concurrent isolated pilot setup independently recorded npm ENOSPC.

Evidence

• First output: /private/tmp/xmd-staged-followup-delivery-final.log.
• Full failure journal: /private/tmp/xmd-staged-followup-20261110/.xmd/test-artifacts/2026-11-10T04-42-00.806Z-4015650d-bff2-4cbf-b2f3-4440aead5142/child-4.jsonl (close record contains the no-space failure).
• Passing successor output (Preparation files unchanged): /private/tmp/xmd-staged-followup-preparation-disk-retry.log: 1 group / 1 step passed, 2m53s.
• Independent setup failure: /private/tmp/xmd-staged-pilots-20261110/1178/setup.log; subsequent preparation passed after freeing space.

These are local evidence paths, not portable downloads. Source, original failures and pilot histories remain intact. No paid pilot had started.

Follow-up

Determine whether scratch-space admission, cleanup or clearer propagation of the retained no-space cause should improve local checks. Preserve the existing refusal and immutable-failure behavior. A passing rerun does not close this issue: close only after the selected cause is addressed and regression evidence is recorded.