Share declared Fiji bundles independently of run caches and keep cold inspection responsive #224

Concrete failure and owner

Implementation owner: Lovelace, existing isolated worktree /home/ts/wt/openhcs-input-preparation-20260929, existing OpenHCS draft206 / paired PolyStore draft16. Parent owns disk recovery and integration; no competing patch.

Coordinator reports fresh isolated H001/H002 openhcs_inspect_plate_path initializing BioFormatsJavaContext -> FIJI_IMAGEJ_RUNTIME -> FijiArchiveDistribution.materialize. Per-run XDG_CACHE_HOME produced independent roughly859 MiB bundles, minutes of cold MCP blocking and uncertain queued10-second reads. Disk guard then stopped both before execution. Preserve those uncertain receipts; do not restart or replay them to establish absence/success. This issue is infrastructure, not biological coaching or acceptance.

Source witnesses

At parent6ffea8d61/paired childa14a4fc:

• FijiArchiveDistribution.cache_root is constructor-owned; materialize falls back to user_cache_path("polystore") / "imagej" and owns digest-addressed atomic materialization and file-lock coordination.
• Canonical FIJI_IMAGEJ_DISTRIBUTION does not project a process-configurable bundle-only root into that field. BioFormats context and Fiji viewer consume canonical FIJI_IMAGEJ_RUNTIME, not arbitrary application-created distribution instances. No supported application entrypoint projection found.
• InspectPlatePathCapability has no declared progress heartbeat. Existing MCP binding therefore invokes synchronous inspection on its event-loop thread. The existing declaration-owned heartbeat/worker mechanism already supports suitable long operations; reuse it instead of adding a second job/progress store.

Required owner extension and acceptance

1. First-class bundle-only configuration projected by the existing distribution owner into cache_root. Preserve per-run XDG logs/unrelated caches, immutable release/digest/overlay authority, checksum verification and atomic lock/staging. No per-caller symlink, monkeypatch, full-cache sharing or duplicate defaults/environment registry.
2. Canonical process-environment projection retains the dependency owner's declared key for launched processes.
3. Nonblocking inspection through the existing capability progress/worker mechanism, with evidence that progress and unrelated reads continue through controlled cold initialization, while failure/cancellation remain truthful. No timeout inflation or restart on observation timeout.
4. Tiny verified archive/cache-root and process-projection regressions; focused progress regression using the real existing binding. Real cold Fiji/JVM/installed acceptance remains gated on a finite runtime handoff and sufficient resources; source tests alone do not close this issue.

No frozen installation/skill/source changes, large archive download, JVM/GUI/MCP process startup or biological output inspection in source continuation. Existing draft206's original141-pass/26-failure receipt and not-run ROI profile remain explicit. Recorded parent gitlink stays pinned until validated paired adoption.