A global model/provider change must never stop a cron job. The #44585 guard
raised [drift_skip] for every unpinned job whose provider_snapshot /
model_snapshot no longer matched the live global default, so one `hermes model`
switch silently killed whole fleets (reported by fastfinge, nitinthewiz,
Dr-ilies; 13 of 60 jobs on the project lead's box after
claude-fable-5 -> claude-fable-5.1).
The snapshot is now the job's effective pin: _load_cron_job_config prefers
job['model_snapshot'] over the global default and _resolve_job_runtime passes
job['provider_snapshot'] as `requested` when neither a per-job pin nor a
cron.model / cron.model_provider fleet default covers the axis. One INFO line
per differing axis tells the operator what the job is running on and how to
move it. Jobs without a snapshot (legacy records) still follow the global
default; the existing fallback chain still handles a snapshot provider that
fails to resolve.
Both goals of #44585 hold: no silent inherit of a paid default (the job runs on
what it was created under) and no outage. Owner decision (Teknium): "main agent
model changing should not stop crons from executing, ever".
Removed as unreachable: _check_model_drift, DRIFT_SKIP markers, the
drift_alerted alert-once bit (mark_drift_alerted + the _record_run_outcome pop),
the drift special-cases in _compose_run_delivery and
_summarize_cron_failure_for_delivery, cron_model_drift_guard_enabled and the
cron.model_drift_guard config key (v42 migration drops it from existing
configs). The PLUGIN-COMPAT clear_drift_alerted block is untouched (scheduled
revert).
The `hermes config set model.default` notice and the Desktop model-change toast
are reworded from "will fail closed / will be skipped" to "keep running on the
model they were created under"; the impact payload drops guard_enabled (all six
desktop locales updated).
7e4d02fef5