Alex StanfieldandGitHub 223478bf8f V1 to CHASM scheduler migration RPC (#9261) ...

## What changed

Adds an admin RPC (`MigrateSchedule`) that migrates workflow-backed (V1)
schedulers to CHASM (V2) schedulers.

The flow:
1. Admin API signals the V1 scheduler workflow with `migrate-to-chasm`
2. V1 workflow runs a local activity that snapshots state and calls
`CreateFromMigrationState` on the CHASM scheduler service
3. On success, the V1 workflow closes. On failure, a `PendingMigration`
flag persists so the next run loop iteration retries automatically

Key details:
- `CreateSchedulerFromMigration` initializes the full CHASM scheduler
tree (generator, invoker, backfillers, visibility) from V1 state
- Running/completed workflows are converted to buffered starts; ongoing
backfills are preserved
- Migration is idempotent -- if the CHASM schedule already exists, it's
treated as success
- Metrics: `schedule_migration_started`, `schedule_migration_completed`,
`schedule_migration_failed` (with direction tag)
- Local activity uses 10m schedule-to-close timeout; retries happen at
the workflow level via the persistent flag

## Why

Needed for migrating existing V1 schedulers to CHASM without downtime or
data loss.

## Follow-up items

- V2 to V1 migration (rollback path)
- Sentinel key handling when `EnableCHASMSchedulerCreation` was
previously enabled
- Attach completion callbacks to running workflows after migration

2026-03-12 10:18:02 -05:00

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v1

V1 to CHASM scheduler migration RPC (#9261)

2026-03-12 10:18:02 -05:00