Read-only preflight for an extension-owned Codex VS Code chat on Windows, macOS, or Linux. Run after compaction_status and before schedule_compaction to verify the exact owner/thread, extension version, runtime layout, public schema, and IPC access. It does not compact or prove live compaction compatibility; layout_compatible means only that the required layout was found. Standalone Codex CLI sessions are unsupported because they have no VS Code extension owner. Use compaction_status instead to inspect an existing job.

Schedule ONE compaction after this answer. Only when the user authorizes compaction. Optional handoff describes what to keep/summarize and is saved exactly in a per-job file. resume:true explicitly requests ONE subsequent turn with that handoff and nextStep; use only for authorized continuation. Cancels on observed new user input or a stopped turn. Return the handoff in context before finishing. Compaction prompt itself is not overridden. Check status later; no automatic retries.

Read-only local job inspection. Run before probe_compaction or schedule_compaction to detect an unfinished job, and after scheduling or cancellation to inspect its exact outcome and metrics. It does not probe extension compatibility. scheduled, waiting_for_idle, requesting, and accepted are intermediate; completed requires a newly observed completed contextCompaction event. resumed identifies a returned continuation turn, not successful work. Missing or stale post-compaction telemetry can skip automatic continuation with insufficient_headroom.

Cancel pending compaction or continuation dispatches only for the exact job returned by schedule_compaction or compaction_status. Already sent requests cannot be undone. Use compaction_status for observation and inspect it after cancellation.