The breaker conflates "this source is unhealthy" with "kill this call
now". Limiter rejections already choose between wait and fail_fast;
breaker rejections had no such choice, so a single-source scope loses
its whole retry budget the moment the gate opens.
Design adds {SCOPE}__CIRCUIT_OPEN (default fail_fast, so existing
deployments keep their control flow) and pins retry_after_s to "time
until a *certain* retry moment" across all six gate exits. The latter
also fixes a separate bug the issue missed: a half-open rejection fed
the probe lease (up to 2x timeout) into the source cooldown memo, whose
set_until only moves forward -- so a recovered source stayed blacklisted
in-process long after the gate closed. That one bites multi-source
deployments too, it is just hidden when other sources absorb the load.
Human-approved 2026-08-19; both documents revised after Codex review.
