useContextBreakdown made one refetch attempt per busy toggle, swallowed
failures, and kept serving the cached pre-compression breakdown whenever
fetched.sessionId still matched (it always does). After compression plus
a session.reclaimed resume, that single refetch races the agent rebuild:
a 4001 is swallowed and the meter freezes at the pre-compression
percentage; an in-flight rebuild answers a zeroed breakdown
(context_max: 0, the agent-is-None branch), which blanks the meter and
caches the zeros. No dep changes after the failed attempt, so nothing
ever retries — recovery required manually switching sessions.
Treat an untrustworthy answer as a transient window, not data: zeroed
breakdowns are never cached; failed fetches retry on a bounded backoff
(1s/4s/12s, re-running the fetch effect via an attempt counter); on
ladder exhaustion the cached breakdown is evicted so the meter goes dark
honestly rather than showing numbers known to be stale. Session switches
reset the retry state; the pending backoff timer is cancelled by the
fetch effect's own cleanup.
Fixes#94001 (scenarios 1, 2, 4).
32f146b07e