## Summary
v3 (the engine that ran the SDK v3 era, internally
`RunEngineVersion.V1`) is end-of-life. Following the removal of the v3
execution apps
([#4194](https://github.com/triggerdotdev/trigger.dev/pull/4194)) and
the legacy dev websocket
([#4198](https://github.com/triggerdotdev/trigger.dev/pull/4198)), this
removes the remaining v3 execution stack from the server.
Clients still on v3 (an old SDK or CLI that has not upgraded) keep
getting a clear "upgrade to v4" response. Triggers, batch triggers,
reschedules, and deploys that resolve to v3 are rejected with a graceful
4xx pointing at the migration guide, never a 5xx, so a stale client
cannot affect server health. Self-hosted instances still running v3
should stay on the 4.5.x release line until they migrate.
## What is removed
- The MarQS queue and its shared/dev queue consumers.
- The v3 socket.io namespaces (coordinator, provider, shared-queue) and
the v3 run lifecycle services (attempt, checkpoint, and batch-resume).
- The graphile-worker background job system; all live jobs already run
on `@trigger.dev/redis-worker`.
- The `DEPRECATE_V3_ENABLED` flag: v3 is now rejected unconditionally,
so the flag is gone.
- Unused v3 exports from `@trigger.dev/core` (the `v3/zodNamespace`
subpath and the legacy socket message catalogs) and the now-dead MarQS
environment variables.
## What stays
The v4 engine is untouched. The graceful v3 rejection boundary stays,
`determineEngineVersion` still detects a v3 project so it can reject it,
and the batch service plus batch-completion worker stay for current
clients. Live queue concurrency limits and metrics now read from the v4
run engine instead of MarQS, and a brand-new dev environment now
defaults to v4.
## Dependency cleanup
Removes webapp dependencies left unused by this change: `seedrandom` and
`semver` (only the removed v3 code used them) plus a set that was
already dead, their orphaned `@types` packages, and two dead files. Adds
a `knip:deps` script and a `knip.json` config so unused dependencies can
be found the same way going forward.
Once this is merged, oxlint is at a pretty sensible baseline.
**Enable `no-unused-vars`, `typescript/consistent-type-imports`, and
`import/no-duplicates` lint rules**
Turns on three previously-disabled oxlint rules across the monorepo and
fixes all violations:
- **`no-unused-vars`** – enabled as an error with standard ignore
patterns: unused function arguments are ignored by default (`args:
"none"`), variables/caught errors/destructured array elements prefixed
with `_` are allowed, and rest siblings are permitted.
- **`typescript/consistent-type-imports`** – enforced as an error; all
type-only imports now use the `import type` syntax.
- **`import/no-duplicates`** – enforced as an error; duplicate import
statements from the same module have been merged.
The remaining commits clean up the violations found across the codebase:
removing unused variables/imports/type aliases, adding `_` prefixes to
intentionally unused bindings, fixing duplicate imports, and converting
value imports to `import type` where appropriate.
* Refill release concurrency tokens when a run is cancelled
* Improved release concurrency accounting system + a sweeper to auto-refill tokens for snapshots that are no longer the latest snapshot on a run (e.g. the run has moved to a new snapshot state)
* Fix order of arguments to the releasings sweeper
* Add a heartbeat for SUSPENDED snapshots, where when stalled will attempt to continue the run if unblocked
* run engine v1: orgs are no longer considered for concurrency
* Add reserve concurrency concept to allow waiting to resume parent tasks to release concurrency at the env level for child tasks to use (or else there is a deadlock). WIP recursive tasks
* child tasks inherit the queue timestamp from their parent tasks to prioritize completing child tasks based on when their parent started
* handle reserve concurrency with recursive deadlocks
* Finish docs update for concurrency
* Some fixes from badge conflict resolution
* WIP priority queues
* Implement MarQS priority queues
* Fix the migrations
Eric Allam