diff --git a/doc/execution-semantics.md b/doc/execution-semantics.md
index d1ce86ca425..88afc2c8072 100644
--- a/doc/execution-semantics.md
+++ b/doc/execution-semantics.md
@@ -896,6 +896,11 @@ remote configuration. An unchanged follow-up reuses that configuration without
 reporting strategy drift. Real strategy, source, mode and environment changes
 retain their existing replacement checks.
 
+Managed sandbox reconciliation preserves the environment revision used by session
+and workspace freshness checks when only its name, description, or managed metadata
+changes. It still records the update in the activity log. Configuration or
+availability changes advance that revision and retain normal replacement checks.
+
 Older remote Git workspaces can retain the temporary `project_primary`
 fingerprint. That fingerprint alone cannot distinguish the old preparation bug
 from a genuinely configured `project_primary` strategy; the remote workspace row
diff --git a/server/src/__tests__/environment-service.test.ts b/server/src/__tests__/environment-service.test.ts
index ea382113bf3..161b748b5c1 100644
--- a/server/src/__tests__/environment-service.test.ts
+++ b/server/src/__tests__/environment-service.test.ts
@@ -26,6 +26,7 @@ import {
   startEmbeddedPostgresTestDatabase,
 } from "./helpers/embedded-postgres.js";
 import { environmentService } from "../services/environments.ts";
+import { attachPaperclipSessionMetadataToSessionParams, buildEffectiveRunSessionConfigMetadata, resolveTaskSessionConfigFreshness } from "../services/heartbeat/workspaces.js";
 
 const externalTestDatabaseUrl = process.env.PAPERCLIP_TEST_DATABASE_URL;
 if (externalTestDatabaseUrl && !new URL(externalTestDatabaseUrl).pathname.endsWith("_test")) {
@@ -1290,6 +1291,42 @@ describeEmbeddedPostgres("environmentService leases", () => {
     expect((await svc.ensureManagedSandboxEnvironment({ ...input, name: "Paperclip Sandbox" })).action).toBe("unchanged");
   });
 
+  it("preserves task sessions across cosmetic managed sandbox reconciliation", async () => {
+    const companyId = await seedCompany();
+    const input = { companyId, name: "Managed computer", description: "Original description", provider: "daytona",
+      config: { snapshot: "snapshot-a" }, platformFullyManaged: true };
+    const created = (await svc.ensureManagedSandboxEnvironment(input)).environment;
+    const revision = new Date("2026-01-01T00:00:00.000Z");
+    await db.update(environments).set({ updatedAt: revision }).where(eq(environments.id, created.id));
+    const metadata = (environment: typeof created) => buildEffectiveRunSessionConfigMetadata({
+      adapterType: "paperclip_runner", effectiveAdapterConfig: { model: "model-a" },
+      agentRuntimeConfig: {}, issueOverrides: null, workspaceConfig: null,
+      environment: { selectedEnvironmentId: environment.id, selectedEnvironment: {
+        id: environment.id, driver: environment.driver, config: environment.config,
+        configRevisionAt: new Date(environment.updatedAt).toISOString(),
+      } },
+      environmentEnv: environment.envVars, projectEnv: null, routineEnv: null, runtimeSkills: [],
+    });
+    const before = await metadata({ ...created, updatedAt: revision });
+    const taskSessionParams = attachPaperclipSessionMetadataToSessionParams({ sessionId: "saved-session" }, "model-a", before);
+    const reconciled = await svc.ensureManagedSandboxEnvironment({ ...input, name: "Managed sandbox",
+      description: "New description", extraMetadata: { platformLabel: "new label" } });
+    expect(reconciled.action).toBe("updated");
+    const freshness = resolveTaskSessionConfigFreshness({ hasTaskSession: true, configuredModel: "model-a",
+      taskSessionParams, configMetadata: await metadata(reconciled.environment) });
+    expect(freshness).toMatchObject({ reset: false, changedCategories: [] });
+    expect(reconciled.environment.updatedAt).toEqual(revision);
+    expect(await db.select().from(activityLog).where(and(eq(activityLog.companyId, companyId),
+      eq(activityLog.action, "environment.managed_stock_updated")))).toHaveLength(1);
+    const changed = await svc.ensureManagedSandboxEnvironment({ ...input, name: "Managed sandbox",
+      description: "New description", extraMetadata: { platformLabel: "new label" }, config: { snapshot: "snapshot-b" } });
+    expect(resolveTaskSessionConfigFreshness({ hasTaskSession: true, configuredModel: "model-a",
+      taskSessionParams, configMetadata: await metadata(changed.environment) })).toMatchObject({
+      reset: true, changedCategories: ["environment"],
+    });
+    expect(new Date(changed.environment.updatedAt).getTime()).toBeGreaterThan(revision.getTime());
+  });
+
   it("ensures and refreshes a managed sandbox environment for an arbitrary provider", async () => {
     const companyId = await seedCompany();
     const createdResult = await svc.ensureManagedSandboxEnvironment({
diff --git a/server/src/services/environments.ts b/server/src/services/environments.ts
index 785668c8d04..ec93b17a184 100644
--- a/server/src/services/environments.ts
+++ b/server/src/services/environments.ts
@@ -758,7 +758,9 @@ export function environmentService(db: Db) {
               mergeManagedEnvironmentMetadata(row.metadata, desiredMetadata, keys),
             ),
             status: "active",
-            updatedAt: new Date(),
+            updatedAt: row.status === "active" && stockHash(row.config) === stockHash(desiredConfig)
+              ? row.updatedAt
+              : new Date(),
           })
           .where(eq(environments.id, row.id))
           .returning()