Monitor 1.2.3 — single startup and awaited cleanup

OpenCode could instantiate the monitor twice and return from shutdown while owned jobs or delivery were still active. Version 1.2.3 adds a dedicated opencode-monitor-plugin/server entry and awaited, idempotent disposal. The existing package-root helper API remains available.

Cancellation now joins concurrent callers through physical child close, preserves process ownership on established-child errors, reports unresolved cleanup failures and avoids signalling a closed child. Pending schedules, delivery and status writes are drained on disposal.

Validation: 339 tests across 23 files, build and typecheck passed; 18 independent behavioral regressions cover the repaired paths. Independent source/package reviews and native startup from the final tarball passed with one factory and six unique tools. The dependency graph is unchanged.

Published package SHA256: bb3138f7c4361addb73e47881d29c1a66c8da50453fc9bc93613267c3910c9f7. The npm download matches the reviewed package byte for byte. Source: PR #1, reviewed commit c1bee2cdd5ed1c120806d356f58a68c277cf223c.

This component release is part of the harness 4.3.1 correction. Fleet installation acceptance is recorded with that harness release; this publication does not claim it has already completed.