update big picture mermaid

docs/walkthrough.md

@@ -26,11 +26,11 @@ NATSBridge implements the **Claim-Check pattern** for efficient handling of larg
 flowchart TD
     subgraph "Sender Application"
         A1[User Code]
-        A2[smartsend Function]
-        A3[Serialize Data]
+        A2[smartsend]
+        A3[_serialize_data]
         A4[Transport Selection]
-        A5[Publish to NATS]
-        A6[File Server Upload]
+        A5[Build Envelope]
+        A6[Publish to NATS]
     end
     
     subgraph "NATS Broker"
@@ -39,10 +39,10 @@ flowchart TD
     
     subgraph "Receiver Application"
         C1[Subscribe to NATS]
-        C2[smartreceive Function]
-        C3[Deserialize Data]
-        C4[Transport Selection]
-        C5[Fetch from File Server]
+        C2[smartreceive]
+        C3[Parse Envelope]
+        C4[Process Payloads]
+        C5[Deserialize Data]
     end
     
     A1 --> A2
@@ -50,21 +50,17 @@ flowchart TD
     A3 --> A4
     A4 -->|Direct| A5
     A4 -->|Link| A6
-    A6 --> A5
-    A5 --> B1
+    A6 --> B1
     B1 --> C1
     C1 --> C2
     C2 --> C3
-    C2 --> C4
-    C4 -->|Fetch| C5
-    C5 --> C3
     C3 --> C4
+    C4 --> C5
     
     style A1 fill:#e8f5e9,stroke:#4caf50
     style B1 fill:#fff3e0,stroke:#f57c00
     style C1 fill:#e3f2fd,stroke:#2196f3
-    style A6 fill:#fef3c7,stroke:#f59e0b
-    style C5 fill:#fef3c7,stroke:#f59e0b
+    style A4 fill:#fef3c7,stroke:#f59e0b
 ```
 
 ### Key Design Principles