Preserve sandbox work through provider launches and failed saves

Resume retained ephemeral leases, pin managed-agent imports against link replacement, carry scoped home settings through native provider boundaries, and keep file transfer arguments below Linux limits. Restrict acceptance exclusions to the engines explicitly deferred by the user.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tests/runner-e2e/deployed-stack.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { isStagingOrigin } from "./deployed-stack.js";
+import { isStagingOrigin, assertDeployedAdapterExclusions } from "./deployed-stack.js";
 
 describe("deployed stack target", () => {
   it("requires an explicit HTTPS staging tenant and rejects credential-bearing URLs", () => {
@@ -10,3 +10,10 @@ describe("deployed stack target", () => {
     }
   });
 });
+
+it("allows only the four explicitly deferred adapters to be excluded", () => {
+  expect(() => assertDeployedAdapterExclusions([{ adapterType: "cursor", reason: "Explicitly deferred by the user" }])).not.toThrow();
+  for (const adapterType of ["codex_local", "claude_local", "opencode_local", "pi_local", "paperclip_runner"]) {
+    expect(() => assertDeployedAdapterExclusions([{ adapterType, reason: "skip" }])).toThrow("cannot be excluded");
+  }
+});