Pin plugin Runner cleanup to its physical task (#19300)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work.
> - Plugin Runner owners manage a physical task through an environment
lease.
> - The existing replacement path can assign a new physical task to that
same lease.
> - A delayed old owner can then stop the replacement or mark it
stopped.
> - Cleanup must keep the original physical task identity across RPC and
database writes.
> - This pull request pins that identity and keeps cleanup available to
the new owner.

## Linked Issues or Issue Description

Refs #19134 and #19157. This fix is based on master and does not enable
repeated stopped-source recovery. A search found no duplicate fix.

**What happened?**

The maintained `createOwnedSandbox` replacement path changes
`providerLeaseId` on one lease. An old task owner uses that mutable
lease for a later Stop. A stopped-state response already in flight can
also update the new task's flags.

**Expected behavior**

The old owner must address its original task. Its late cleanup writes
must not alter the replacement. The replacement's own owner must still
stop and complete it.

**Steps to reproduce**

1. Create a plugin task owner for a stopped task.
2. Replace that task through the existing describe/startup path on the
same lease.
3. Resume an old checkpoint or a held old status response.
4. Observe a Stop for the replacement or an incorrect stopped flag
before this fix.

## What Changed

- Require each task owner to keep the physical ID returned by its
description. Reject a rebind to a different task.
- Carry the ID through the existing internal task context after startup
ends. Reject a changed physical task before RPC dispatch.
- Match the physical task in stopped-state, completion and
credential-handoff writes.
- Hold the exact lease row through the retained-session database update
and local checkpoint save.
- Cover the maintained replacement path with real PostgreSQL tests.
Preserve positive cleanup for the replacement owner. Document this
boundary.

## Verification

- Both replacement regressions failed on unmodified master `10a7d039c8`:
delayed old-owner Stop targeted the replacement, and a held old status
response marked it stopped.
- Six focused files passed 160 tests: task authority, task runtime, warm
tasks, execution target, credential writeback and task owner.
- Four selected executor factory cases passed. They cover task-only
providers and the physical task binding after the startup context ends.
- Runner TypeScript, plugin SDK and adapter-utils builds passed. Server
TypeScript check passed. Diff and added-line secret scans passed.
- All 15 setup-probe cases passed with the actual Runner and fake
provider binaries. The first local attempt lacked cargo on PATH. A
sandboxed native attempt timed out in seven process cases; the unchanged
run with loopback permission passed all 15. A separate initial DB
integration attempt was denied a loopback listener; its
permission-correct run passed.
- Review found three missed constructors in the existing SDK/Core
lifecycle fixture. They now use the actual describe result. All four
cases in that real PostgreSQL and worker RPC file passed.
- The first GitHub attempt failed in the unchanged GitHub recovery
pagination case in `chat-channels.integration.test.ts`: its zero-request
assertion observed a configuration GET. That exact case passed locally
without code or assertion changes. The one failed-job-only retry passed;
the initial failure log is retained.
- [GitHub workflow
42082587576](https://github.com/paperclipai/paperclip/actions/runs/42082587576)
passed on its second attempt. All CI checks completed, and Snyk passed.
Standard Greptile scored exact head `fb914d98b99e` 5/5 with no
unresolved threads. The branch is mergeable and ready for review.

## Risks

The task context change is internal. It adds no plugin wire field,
schema or Runner mode. A stale owner now gets an error and cannot clean
up a replacement. A new owner can still clean up that task. The retained
checkpoint write holds one existing lease row during a bounded local
file write.

Repeated stopped-source incarnation admission, runtime pins and
deployments are outside this change.

## Model Used

OpenAI GPT-6.1 Sol (`gpt-6.1-sol`), high reasoning. Used repository
tools, TypeScript and real PostgreSQL tests.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used with version and capability
details
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have described the issue in-PR using the bug template
- [x] I have not referenced internal or instance-local Paperclip issues
or links
- [x] My branch name describes the change
- [x] I have run the focused tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation
- [x] I have considered and documented risks
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no unresolved findings
- [x] I will address reviewer comments before requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

server/src/services/native-runtime/native-session-executor.ts

@@ -13257,10 +13257,11 @@ async function createRunnerdBackendWithinSessionClaim(
   const cloudArtifactRoot = input.execution.provider.kind === "cursor_cloud" ? join(runnerdStateRoot(input.execution), "cursor-cloud", "artifacts") : undefined;
   if (input.execution.provider.kind === "cursor_cloud" && remoteTarget) throw new Error("cursor_cloud_local_controller_required");
   const rawPluginTask = remoteTarget?.transport === "sandbox" ? remoteTarget.runnerTask : undefined;
-  const pluginTask = rawPluginTask && input.executionContext ? (operation: unknown) => {
+  const pluginTask = rawPluginTask && input.executionContext ? (operation: unknown, options?: { expectedTaskId?: string }) => {
     const startupOperation = ["describe", "prepare", "check_project_auth", "connection"].includes(String(record(operation).kind));
     if (startupOperation) input.executionContext?.signal.throwIfAborted();
-    return rawPluginTask(operation, input.executionContext?.active && startupOperation ? { executionContext: input.executionContext } : undefined);
+    return rawPluginTask(operation, { ...options,
+      ...(input.executionContext?.active && startupOperation ? { executionContext: input.executionContext } : {}) });
   } : rawPluginTask;
   let runnerControlPlane: DurablePrpControlPlane | undefined;
   if (pluginTask && input.runnerIngressAuthorized !== true) throw new Error("runner_ingress_unavailable");
@@ -13493,7 +13494,7 @@ async function createRunnerdBackendWithinSessionClaim(
       await registerPluginTaskCredentialHandoff(input.db, { companyId: input.execution.binding.companyId, leaseId: remoteTarget.leaseId },
         credentials.accountIdentity, input.managedAiCredentialWriteback);
     }
-    const ownerInput: Parameters<typeof createPluginRunnerTaskOwner>[0] = { ...credentials,
+    const ownerInput: Parameters<typeof createPluginRunnerTaskOwner>[0] = { ...credentials, taskId: description.taskId,
       executionContext: input.executionContext?.pluginSupported ? input.executionContext : undefined,
       // Warm retirement can outlive the run's temporary credential home; complete uses the durable handoff.
       onCredentials: input.execution.session.lifecyclePolicy.mode === "warm" ? undefined : credentials.onCredentials,
@@ -13511,14 +13512,19 @@ async function createRunnerdBackendWithinSessionClaim(
       } : undefined,
       credentialIdentity: input.managedAiCredentialIdentity,
       onSessionRetained: async state => {
-        savePluginRunnerCheckpoint(root, state, state);
-        await input.db.update(environmentLeases).set({ metadata: sql`coalesce(${environmentLeases.metadata}, '{}'::jsonb) || ${JSON.stringify({
-          runnerTaskSessionRetained: true, runnerTaskIdentity: {
-            runnerId: state.runnerInstanceId, leaseId: state.environmentLeaseId,
-            runId: state.runId, sessionId: state.normalizedSessionId, turnId: state.turnId, itemId: state.itemId,
-          },
-        })}::jsonb` })
-          .where(and(eq(environmentLeases.id, remoteTarget.leaseId!), eq(environmentLeases.companyId, input.execution.binding.companyId)));
+        await input.db.transaction(async tx => {
+          const saved = await tx.update(environmentLeases).set({ metadata: sql`coalesce(${environmentLeases.metadata}, '{}'::jsonb) || ${JSON.stringify({
+            runnerTaskSessionRetained: true, runnerTaskIdentity: {
+              runnerId: state.runnerInstanceId, leaseId: state.environmentLeaseId,
+              runId: state.runId, sessionId: state.normalizedSessionId, turnId: state.turnId, itemId: state.itemId,
+            },
+          })}::jsonb` })
+            .where(and(eq(environmentLeases.id, remoteTarget.leaseId!), eq(environmentLeases.companyId, input.execution.binding.companyId),
+              eq(environmentLeases.providerLeaseId, description.taskId))).returning({ id: environmentLeases.id });
+          if (saved.length !== 1) throw new Error("Plugin Runner physical task changed");
+          // Keep the lease row locked until its local checkpoint has been saved.
+          savePluginRunnerCheckpoint(root, state, state);
+        });
       }, onDispatched: input.onTaskDispatched,
     };
     if (input.execution.session.lifecyclePolicy.mode === "warm" && (!credentials.accountIdentity || description.warmTaskVersion !== 1)) throw new Error("Plugin warm task capability or account unavailable");