Use --no-auto-update

Author: SteveSandersonMS

dotnet/src/FfiRuntimeHost.cs

@@ -167,6 +167,9 @@ private static byte[] BuildArgvJson(string cliEntrypoint)
             }
             writer.WriteStringValue(cliEntrypoint);
             writer.WriteStringValue("--embedded-host");
+            // Pin the worker to the bundled pkg matching the loaded cdylib, instead of
+            // drifting to a newer version under the user's ~/.copilot/pkg (ABI skew).
+            writer.WriteStringValue("--no-auto-update");
             writer.WriteEndArray();
         }
         return stream.ToArray();

nodejs/src/ffiRuntimeHost.ts

@@ -99,10 +99,12 @@ function loadLibrary(libraryPath: string): FfiLibrary {
 
 function buildArgvJson(cliEntrypoint: string): Buffer {
     // A `.js` entrypoint is launched via node; the packaged single-file CLI binary
-    // embeds its own Node and is invoked directly.
+    // embeds its own Node and is invoked directly. `--no-auto-update` pins the worker
+    // to the bundled pkg matching the loaded cdylib, instead of drifting to a newer
+    // version installed under the user's `~/.copilot/pkg` (which would cause ABI skew).
     const argv = cliEntrypoint.toLowerCase().endsWith(".js")
-        ? ["node", cliEntrypoint, "--embedded-host"]
-        : [cliEntrypoint, "--embedded-host"];
+        ? ["node", cliEntrypoint, "--embedded-host", "--no-auto-update"]
+        : [cliEntrypoint, "--embedded-host", "--no-auto-update"];
     return Buffer.from(JSON.stringify(argv), "utf8");
 }