fix: Add idempotency to swizzling cache and update Jules.md

- Re-implemented the idempotency check in
  ClassMethodImplementationCache::ReplaceOrAddMethod in app/src/util_ios.mm.
  This prevents re-swizzling if a method already has the target IMP,
  addressing potential recursion issues.

- Updated Jules.md:
  - Integrated learnings from the recent iOS App Delegate refactoring task
    into relevant existing sections (covering robust swizzling, callback
    lifecycles, naming, logging safety, and agent interaction).
  - Added a document convention note to maintain 80-character line wrapping.
  - Word-wrapped the entire document to 80 characters for readability.

This commit consolidates the fix for the swizzling cache and the comprehensive
updates and formatting for Jules.md.

Author: google-labs-jules[bot]

app/src/util_ios.mm

@@ -425,8 +425,25 @@ void RunOnBackgroundThread(void (*function_ptr)(void *function_data), void *func
   const char *class_name = class_getName(clazz);
   Method method = class_getInstanceMethod(clazz, name);
   NSString *selector_name_nsstring = NSStringFromSelector(name);
-  const char *selector_name = selector_name_nsstring.UTF8String;
-  IMP original_method_implementation = method ? method_getImplementation(method) : nil;
+  const char *selector_name = selector_name_nsstring.UTF8String; // Used for logging later
+
+  IMP current_actual_imp = method ? method_getImplementation(method) : nil;
+
+  // === Begin idempotency check ===
+  if (current_actual_imp == imp) {
+    // Assuming GetLogLevel() and kLogLevelDebug are available here.
+    // Based on previous file content, GetLogLevel is available in this file from util_ios.h.
+    if (GetLogLevel() <= kLogLevelDebug) {
+      NSLog(@"Firebase Cache: Method %s on class %s is already swizzled with the target IMP. Skipping re-swizzle.",
+            selector_name, class_name);
+    }
+    return; // Already swizzled to the desired implementation
+  }
+  // === End idempotency check ===
+
+  // If we reach here, current_actual_imp is different from imp, or the method didn't exist.
+  // We now assign original_method_implementation to be current_actual_imp for the rest of the function.
+  IMP original_method_implementation = current_actual_imp;
 
   // Get the type encoding of the selector from a type_encoding_class (which is a class which
   // implements a stub for the method).
@@ -436,7 +453,7 @@ void RunOnBackgroundThread(void (*function_ptr)(void *function_data), void *func
 
   NSString *new_method_name_nsstring = nil;
   if (GetLogLevel() <= kLogLevelDebug) {
-    NSLog(@"Registering method for %s selector %s", class_name, selector_name);
+     NSLog(@"Firebase Cache: Attempting to register method for %s selector %s", class_name, selector_name);
   }
   if (original_method_implementation) {
     // Try adding a method with randomized prefix on the name.