diff --git a/doc/sandbox-work-folders.md b/doc/sandbox-work-folders.md
index 7e20f54294d..627b348d63b 100644
--- a/doc/sandbox-work-folders.md
+++ b/doc/sandbox-work-folders.md
@@ -517,3 +517,9 @@ requires an explicit controller rotation event for that exact transition before
 accepting a changed PID/process fingerprint; other process changes still fail.
 See [GitHub execution identity](execution-github-identity.md) and the
 [run-log contract](run-log-events.md#native-process-rotation).
+
+Process metadata updates apply only while their run is active and unfinished.
+Late callbacks from warm-session inspection or maintenance cannot rewrite a
+completed run's process identity. Remote native process timestamps come from
+the validated remote marker; an unrelated host process with the same PID must
+not replace them. Active local execution retains its host process lookup.
diff --git a/server/src/__tests__/heartbeat-process-metadata.test.ts b/server/src/__tests__/heartbeat-process-metadata.test.ts
new file mode 100644
index 00000000000..141e74e4db6
--- /dev/null
+++ b/server/src/__tests__/heartbeat-process-metadata.test.ts
@@ -0,0 +1,63 @@
+import { randomUUID } from "node:crypto";
+import { eq } from "drizzle-orm";
+import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from "vitest";
+import { agents, companies, createDb, heartbeatRuns, startEmbeddedPostgresTestDatabase, type Db } from "@paperclipai/db";
+import * as processes from "../services/hot-restart.js";
+import { persistHeartbeatRunProcessMetadata } from "../services/heartbeat.js";
+
+describe("heartbeat process identity persistence", () => {
+  let database: Awaited<ReturnType<typeof startEmbeddedPostgresTestDatabase>>;
+  let db: Db;
+  const companyId = randomUUID(), agentId = randomUUID();
+  beforeAll(async () => {
+    database = await startEmbeddedPostgresTestDatabase("paperclip-process-metadata-");
+    db = createDb(database.connectionString);
+    await db.insert(companies).values({ id: companyId, name: "Process identity" });
+    await db.insert(agents).values({ id: agentId, companyId, name: "Runner", role: "engineer", status: "idle", adapterType: "codex_local" });
+  }, 60_000);
+  afterEach(() => vi.restoreAllMocks());
+  afterAll(async () => { await database?.cleanup(); });
+  async function running() {
+    const [run] = await db.insert(heartbeatRuns).values({ companyId, agentId, status: "running", invocationSource: "on_demand", startedAt: new Date(),
+      processPid: 123, processGroupId: null, processStartedAt: new Date("2026-09-09T23:19:42Z") }).returning();
+    return run!;
+  }
+
+  it("uses the remote marker even when its PID exists on the host", async () => {
+    const run = await running();
+    const host = vi.spyOn(processes, "readProcessStartedAt");
+    const meta = { pid: process.pid, processGroupId: null, startedAt: "2026-09-09T23:19:43.123Z" };
+    const updated = await persistHeartbeatRunProcessMetadata(db, run.id, meta, "remote");
+    expect(updated?.processPid).toBe(process.pid);
+    expect(updated?.processStartedAt?.toISOString()).toBe(meta.startedAt);
+    expect(host).not.toHaveBeenCalled();
+  });
+
+  it("retains observed local-process identity during an active run", async () => {
+    const run = await running();
+    const start = "2026-09-09T23:19:43.456Z";
+    vi.spyOn(processes, "readProcessStartedAt").mockResolvedValue(start);
+    const updated = await persistHeartbeatRunProcessMetadata(db, run.id, { pid: 456, processGroupId: 456, startedAt: "2026-09-09T23:19:44Z" });
+    expect(updated).toMatchObject({ processPid: 456, processGroupId: 456, processStartedAt: new Date(start) });
+  });
+
+  it.each(["succeeded", "failed", "cancelled", "timed_out", "running"] as const)("does not change finished %s history from a late spawn callback", async (status) => {
+    const run = await running();
+    const [finished] = await db.update(heartbeatRuns).set({ status, finishedAt: new Date() }).where(eq(heartbeatRuns.id, run.id)).returning();
+    expect(await persistHeartbeatRunProcessMetadata(db, run.id, { pid: 6365, processGroupId: null, startedAt: "2026-09-09T23:20:09.344Z" }, "remote")).toBeNull();
+    const [actual] = await db.select().from(heartbeatRuns).where(eq(heartbeatRuns.id, run.id));
+    expect(actual).toEqual(finished);
+  });
+
+  it("fences finalization racing an in-flight local identity lookup", async () => {
+    const run = await running();
+    let resume!: (start: string) => void;
+    vi.spyOn(processes, "readProcessStartedAt").mockImplementation(() => new Promise((resolve) => { resume = resolve; }));
+    const pending = persistHeartbeatRunProcessMetadata(db, run.id, { pid: 456, processGroupId: 456, startedAt: "2026-09-09T23:19:43Z" });
+    const [finished] = await db.update(heartbeatRuns).set({ status: "succeeded", finishedAt: new Date() }).where(eq(heartbeatRuns.id, run.id)).returning();
+    resume("2026-09-09T23:19:43Z");
+    expect(await pending).toBeNull();
+    const [actual] = await db.select().from(heartbeatRuns).where(eq(heartbeatRuns.id, run.id));
+    expect(actual).toEqual(finished);
+  });
+});
diff --git a/server/src/services/heartbeat.ts b/server/src/services/heartbeat.ts
index 16a6049bc63..59524f275e6 100644
--- a/server/src/services/heartbeat.ts
+++ b/server/src/services/heartbeat.ts
@@ -7813,10 +7813,13 @@ export async function persistHeartbeatRunProcessMetadata(
   db: Db,
   runId: string,
   meta: { pid: number; processGroupId: number | null; startedAt: string },
+  processLocation: "local" | "remote" = "local",
 ) {
-  const observedStartedAt = await readProcessStartedAt(meta.pid).catch(
-    () => null,
-  );
+  // A remote PID can collide with an unrelated control-plane process. Its
+  // validated remote marker, not the host's process table, owns this identity.
+  const observedStartedAt = processLocation === "local"
+    ? await readProcessStartedAt(meta.pid).catch(() => null)
+    : null;
   const startedAt = new Date(observedStartedAt ?? meta.startedAt);
   return db
     .update(heartbeatRuns)
@@ -7828,7 +7831,14 @@ export async function persistHeartbeatRunProcessMetadata(
         : startedAt,
       updatedAt: new Date(),
     })
-    .where(eq(heartbeatRuns.id, runId))
+    // Warm-session inspection and idle maintenance can invoke a captured spawn
+    // callback after this run ended. Keep completed process history immutable,
+    // including when finalization races the asynchronous identity lookup above.
+    .where(and(
+      eq(heartbeatRuns.id, runId),
+      eq(heartbeatRuns.status, "running"),
+      isNull(heartbeatRuns.finishedAt),
+    ))
     .returning()
     .then((rows) => rows[0] ?? null);
 }
@@ -11923,8 +11933,9 @@ export function heartbeatService(
   async function persistRunProcessMetadata(
     runId: string,
     meta: { pid: number; processGroupId: number | null; startedAt: string },
+    processLocation: "local" | "remote" = "local",
   ) {
-    return persistHeartbeatRunProcessMetadata(db, runId, meta);
+    return persistHeartbeatRunProcessMetadata(db, runId, meta, processLocation);
   }
 
   async function clearDetachedRunWarning(runId: string) {
@@ -21560,7 +21571,7 @@ export function heartbeatService(
                       enqueueWakeup,
                       onSpawn: async (meta) => {
                         markDispatchStarted();
-                        await measureSandboxOperation("heartbeat.persist_run_process_metadata", { operationIndex: 141 }, async () => (persistRunProcessMetadata(run.id, meta)));
+                        await measureSandboxOperation("heartbeat.persist_run_process_metadata", { operationIndex: 141 }, async () => (persistRunProcessMetadata(run.id, meta, executionTarget?.kind === "remote" ? "remote" : "local")));
                       },
                     }),
                 )));