add: receiver side diagrams

Signed-off-by: Mahdi Baghbani <mahdi-baghbani@azadehafzar.io>

Author: MahdiBaghbani

diagrams/receiver-discovery-policy.md

@@ -0,0 +1,15 @@
+```mermaid
+flowchart TD
+    A["Provider acts as Receiving Server"]
+    A --> B{"Does it support the code flow"}
+
+    B -- "Yes" --> C["Advertise exchange-token"]
+    C --> D{"Does it require code flow for all inbound shares"}
+    D -- "Yes" --> E["Advertise token-exchange in criteria"]
+    E --> F["Reject inbound shares that omit must-exchange-token"]
+    D -- "No" --> G["Do not advertise token-exchange"]
+    G --> H["Strict inbound shares may still be accepted share by share"]
+
+    B -- "No" --> I["Do not advertise exchange-token"]
+    I --> J["Cannot honor strict inbound shares"]
+```

diagrams/receiver-share-handling.md

@@ -0,0 +1,17 @@
+```mermaid
+flowchart TD
+    A["Receiving Server gets a share and later accesses the resource"]
+    A --> B["Inspect protocol.webdav.requirements"]
+    B --> C{"must-exchange-token present"}
+
+    C -- "Yes" --> D["Exchange sharedSecret at the sender tokenEndPoint"]
+    D --> E["Use only the bearer token"]
+
+    C -- "No" --> F["Inspect sender discovery"]
+    F --> G{"Sender exposes exchange-token and tokenEndPoint"}
+    G -- "Yes" --> H["Receiver may try token exchange"]
+    H --> I{"Exchange succeeds"}
+    I -- "Yes" --> E
+    I -- "No" --> J["Fall back to sharedSecret access"]
+    G -- "No" --> J
+```

diagrams/share-creation-preflight.md

@@ -10,8 +10,8 @@ flowchart TD
     F --> G["Do not fall back to legacy access for that share"]
     D -- "No" --> H["Do not create the share"]
 
-    C -- "No" --> I{"Sender still wants strict code flow"}
-    I -- "Yes" --> J["Include must-exchange-token voluntarily"]
+    C -- "No" --> I{"What is the sender policy for this share"}
+    I -- "Strict" --> J["Include must-exchange-token voluntarily"]
     J --> F
-    I -- "No" --> K["Create legacy compatible share"]
+    I -- "Legacy" --> K["Send legacy share without must-exchange-token"]
 ```