yoi/docs/report/2026-10-09-subworker-workdir-recovery-ergonomics.md

SubWorker / Workdir execution ergonomics during T-730

Observed during Workdir removal implementation in a dedicated clean checkout:

• Children using profile: builtin:default were given explicit writable scope and command permission, but their available tools/context did not support the requested implementation. They performed read-only investigation and reported the missing capabilities. Recreating coding children with profile: inherit exposed the needed implementation/Ticket tools. No rejected capability was bypassed.
• Concurrent Workdir reads sometimes returned filesystem provider busy. This is transient provider contention, not an authorization rejection. A child initially treated it as a stop condition; a subsequent parent turn clarified the difference and sequential retries proceeded normally.
• After a user interruption, repository changes and parent tasks remained, but WorkerList no longer listed the previously active children. Their work was not treated as approved or complete: the parent inspected concrete diffs, reran Web/browser validation and delegated a fresh bounded Runtime follow-up.

Potential improvements:

1. Show effective child tool capabilities together with filesystem/command grants before spawn, so a writable scope is not mistaken for an available implementation tool surface.
2. Distinguish retryable provider contention from capability rejection in typed error metadata and recommended recovery text.
3. Make interruption disposition and retained child-session observation grants explicit. Preserved files are useful evidence, but they do not replace a committed final child report or verification of tests.

These observations concern development-tool ergonomics, not product removal requirements or permission to operate on live Workdirs/mounts. The T-730 work uses temporary fixtures and ordinary Git publication; no live cleanup, unmount, registry edits or runtime deployment were performed.