chore(webapp): remove tests for deleted v3 services and tidy review nits

Delete the unit tests for the removed createCheckpoint and cancelDevSessionRuns
services, apply formatting, and reword the changeset plus agent-guidance docs to
note that a V1 branch may finalize (not only reject) gracefully.

Author: ericallam

.changeset/retire-v3-zod-namespace.md

@@ -2,4 +2,4 @@
 "@trigger.dev/core": patch
 ---
 
-Removed unused v3 (engine V1) exports that are no longer referenced now that the v3 engine is retired: the `@trigger.dev/core/v3/zodNamespace` subpath and the legacy v3 socket message catalogs (coordinator, provider, shared-queue, prod-worker, and background-worker websocket).
+Removed the unused `@trigger.dev/core/v3/zodNamespace` export and the legacy v3 socket message schemas. These were only used by the now-retired v3 engine and have no v4 consumers.

.claude/rules/legacy-v3-code.md

@@ -7,7 +7,7 @@ paths:
 
 The v3 engine (RunEngineVersion `V1`: MarQS queue + Graphile worker) is end-of-life and its execution code has been removed from the webapp. The `app/v3/` directory name is historical: everything under it now serves the current V2 engine (`@internal/run-engine` + `@trigger.dev/redis-worker`).
 
-There is no `V1` execution path anymore. If you find a `RunEngineVersion` branch, the `V1` arm should only ever produce a graceful rejection, never run work. Do not reintroduce MarQS, the graphile worker, or the v3 socket.io namespaces.
+There is no `V1` execution path anymore. If you find a `RunEngineVersion` branch, the `V1` arm should only reject or finalize gracefully (for example, mark a historical run cancelled in the DB), never run V1 work. Do not reintroduce MarQS, the graphile worker, or the v3 socket.io namespaces.
 
 ## The deprecation boundary (keep this)
 

AGENTS.md

@@ -142,7 +142,7 @@ User API call -> Webapp routes -> Services -> RunEngine -> Redis Queue -> Superv
 
 ### v3 (engine V1) removed
 
-v3 (engine V1: MarQS + Graphile worker) is end-of-life and its execution code has been removed. The `apps/webapp/app/v3/` directory name is historical - everything there now serves V2 (Run Engine 2.0, `@internal/run-engine` + redis-worker). There is no V1 execution path: a `RunEngineVersion` `V1` branch only rejects gracefully so v3 clients get a clean 4xx, never a 5xx. Do not reintroduce V1. See `apps/webapp/CLAUDE.md` and `.claude/rules/legacy-v3-code.md`.
+v3 (engine V1: MarQS + Graphile worker) is end-of-life and its execution code has been removed. The `apps/webapp/app/v3/` directory name is historical - everything there now serves V2 (Run Engine 2.0, `@internal/run-engine` + redis-worker). There is no V1 execution path: a `RunEngineVersion` `V1` branch only rejects or finalizes gracefully so v3 clients get a clean 4xx, never a 5xx. Do not reintroduce V1. See `apps/webapp/CLAUDE.md` and `.claude/rules/legacy-v3-code.md`.
 
 ### Documentation
 

apps/webapp/app/components/admin/debugRun.tsx

@@ -74,11 +74,7 @@ function DebugRunData(props: UseDataFunctionReturn<typeof loader>) {
   return <DebugRunDataEngineV2 {...props} />;
 }
 
-function DebugRunDataEngineV1({
-  run,
-}: {
-  run: UseDataFunctionReturn<typeof loader>["run"];
-}) {
+function DebugRunDataEngineV1({ run }: { run: UseDataFunctionReturn<typeof loader>["run"] }) {
   return (
     <Property.Table>
       <Property.Item>

apps/webapp/app/v3/services/changeCurrentDeployment.server.ts

@@ -173,7 +173,6 @@ export class ChangeCurrentDeploymentService extends BaseService {
         error: scheduleSyncError,
       });
     }
-
   }
 
   async #syncSchedulesForDeployment(deployment: WorkerDeployment) {