* test(agents): align fallback assertions with concise error guidance
Check the current rate-limit and balance guidance while retaining
provider selection, retry, persisted-state, and billing duration assertions.
* fix(cli): retain early update failure diagnostics
Update failures can happen before the updater marker is present. Recognize the
command through the existing root-option parser and keep the public reason and
original failure line on stderr in human and JSON modes. Preserve concise leads,
manual recovery guidance, config diagnostic deduplication, and debug-only causes.
Cover markerless failures through the formatter and installation-replacement
entry path, and document the update stderr contract.
* test(gateway): require offline runner recovery guidance
Keep the paired-worker lifecycle assertion for the public offline explanation
and reconnect choices, alongside placement, failed-launch and local-run checks.
The reply owner already supplies this guidance; the wire boundary must retain it.
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