Cover read-only runtime manifest replacement in the build contract

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

server/src/__tests__/server-package-build-script.test.ts

@@ -1,4 +1,7 @@
-import { readFileSync } from "node:fs";
+import { execFileSync } from "node:child_process";
+import { mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import path from "node:path";
 import { fileURLToPath } from "node:url";
 import { describe, expect, it } from "vitest";
 
@@ -58,17 +61,39 @@ describe("server package build script", () => {
       "pnpm --filter @paperclipai/paperclip-runner build",
     );
     expect(packageJson.scripts?.build).toContain(
-      "cp -R ../packages/paperclip-runner/dist/. dist/vendor/paperclip-runner/",
+      "cp -Rf ../packages/paperclip-runner/dist/. dist/vendor/paperclip-runner/",
     );
   });
 
+  it("replaces an existing read-only image manifest with the build's copy step", () => {
+    const packageJson = JSON.parse(readFileSync(packageJsonPath, "utf8"));
+    const step = packageJson.scripts.build.split(" && ").find((command: string) =>
+      command.includes("../packages/paperclip-runner/dist/."));
+    expect(step).toBeDefined();
+    const [command, ...args] = step.split(" ");
+    const root = mkdtempSync(path.join(tmpdir(), "runner-vendor-copy-"));
+    try {
+      const relative = "remote-provider-packs/linux-x64/provider-pack.json";
+      const source = path.join(root, "packages/paperclip-runner/dist", relative);
+      const destination = path.join(root, "server/dist/vendor/paperclip-runner", relative);
+      mkdirSync(path.dirname(source), { recursive: true });
+      mkdirSync(path.dirname(destination), { recursive: true });
+      writeFileSync(source, "qualified image identity", { mode: 0o444 });
+      writeFileSync(destination, "previous image identity", { mode: 0o444 });
+      execFileSync(command, args, { cwd: path.join(root, "server") });
+      expect(readFileSync(destination, "utf8")).toBe("qualified image identity");
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+
   it("verifies vendored runner dependencies are mirrored before building", () => {
     const packageJson = JSON.parse(readFileSync(packageJsonPath, "utf8")) as {
       scripts?: Record<string, string>;
     };
 
     // See scripts/verify-runner-vendor-dependencies.mjs: packages/paperclip-runner
-    // is vendored with a raw `cp -R` of its compiled dist/, so every runtime
+    // is vendored with a raw copy of its compiled dist/, so every runtime
     // dependency it imports must also be a direct dependency of server. This
     // check derives that requirement from an esbuild scan of the vendored
     // entry points instead of relying on a human to have kept a hand-copied