fix(hopper): diagnose MCP provider failures with stage, state, and request context (#1044)

* fix(hopper): diagnose MCP provider failures with stage, state, and request context

* fix(hopper): retain health at the actual provider lifecycle boundary

* test(hopper): distinguish socket loss from later observed process exit

* test(hopper): cover observed exit separately from socket-first replies

---------

Co-authored-by: N0zoM1z0 <1705004398@qq.com>

scripts/verify-real-hopper.mjs

@@ -296,6 +296,7 @@ try {
     { name: "list_documents", arguments: {} },
     options,
   );
+  requireSuccessfulTool(documents, "list_documents");
   requireBridgeProgress(progressUpdates);
   const rejectedProcedure = await client.callTool(
     {
@@ -381,9 +382,13 @@ try {
     await client.callTool({ name: "list_documents", arguments: {} }, options),
     "list_documents after target switch",
   );
+  const expectedDocumentsAfterTargetSwitch =
+    process.platform === "linux"
+      ? firstDocuments.length
+      : firstDocuments.length + 1;
   if (
     !Array.isArray(documentsAfterTargetSwitch) ||
-    documentsAfterTargetSwitch.length !== firstDocuments.length + 1
+    documentsAfterTargetSwitch.length !== expectedDocumentsAfterTargetSwitch
   )
     throw new Error("A distinct target did not receive one Hopper document");
   const reopenedTarget = await client.callTool(