Adds an opt-in mechanism to route a configurable percentage of
organizations onto the compute (MicroVM) backing of their region at
trigger time, without changing their stored region settings.
Routing is gated by three global feature flags -
`computeMigrationEnabled`, `computeMigrationFreePercentage`,
`computeMigrationPaidPercentage` - plus a per-org
`computeMigrationEnabled` override that wins in both directions. A
region's compute backing is resolved from a new
`WorkerInstanceGroup.region` column: a container group and its MicroVM
group share one geo `region`, so the migration swaps the resolved worker
queue to the backing group's queue. Orgs are bucketed deterministically
by id, so ramping a percentage down keeps a strict subset rather than
reshuffling, and a region with no compute backing is never touched.
Everything is off by default - behaviour is unchanged unless the flags
are set.
The flags and the worker-region groups are read on the trigger hot path
from in-memory snapshots rather than the database: a small
`createReloadingRegistry` helper loads each at startup and refreshes
them on an interval, so no per-trigger query is added and a percentage
or kill-switch change propagates within the reload interval. A cold
replica whose snapshot hasn't loaded yet reads as not-migrated (the
container path) and self-corrects on the next load - the same cold-start
contract as the datastore / LLM-pricing registries, with a
`reloading_registry_loaded` metric so a never-loaded registry is
alertable.
The same migration decision is consulted at deploy-time template
creation so a migrated org gets a compute template built ahead of its
first run. This runs in shadow mode (best-effort, never fails the
deploy) by default, or - when the `computeMigrationRequireTemplate` flag
is on - in required mode, built synchronously at deploy so the first run
never builds on-demand and template errors surface at deploy time.
So operators keep "which runs ran where" while customers only see
geography: the run's actual worker queue is stored raw, and the geo
region is stamped separately on `TaskRun.region` (and a new ClickHouse
`region` column) at trigger time. Read surfaces - the dashboard, the
API, and the Query/Logs page - show the geo region, falling back to the
worker queue for runs written before the column existed.
Minor follow-ups left out of scope: the percentage flags render as text
inputs on the admin flags page (the catalog UI has no numeric control
type yet), and `createReloadingRegistry` could later gain pub/sub for
sub-second cross-replica propagation if the reload interval proves too
slow.
nicktrn
7aa871f37b