split the proxy and model server protocols for easy reference

Author: ahg-g

docs/proposals/003-endpoint-picker-protocol/README.md docs/proposals/003-model-server-protocol/README.md

@@ -1,41 +1,4 @@
-# Endpoint Picker Protocol
-
-The Endpoint Picker, or EPP, is a core component of the inference extension. Ultimately it's
-responsible for picking an endpoint from the `InferencePool`. A reference implementation can be
-found [here](../../../pkg/epp/).
-
-## Proxy Protocol
-
-This is the protocol between the EPP and the proxy (e.g, Envoy).
-
-The EPP MUST implement the Envoy
-[external processing service](https://www.envoyproxy.io/docs/envoy/latest/api-v3/service/ext_proc/v3/external_processor)protocol.
-
-For each HTTP request, the EPP MUST communicate to the proxy the picked model server endpoint via:
-
-1. Setting the `x-gateway-destination-endpoint` HTTP header to the selected endpoint in <ip:port> format.
-
-2. Set an unstructured entry in the [dynamic_metadata](https://github.com/envoyproxy/go-control-plane/blob/c19bf63a811c90bf9e02f8e0dc1dcef94931ebb4/envoy/service/ext_proc/v3/external_processor.pb.go#L320) field of the ext-proc response. The metadata entry for the picked endpoint MUST be wrapped with an outer key (which represents the metadata namespace) with a default of `envoy.lb`.
-
-The final metadata necessary would look like: 
-```go
-dynamicMetadata: {
-  "envoy.lb": {
-    "x-gateway-destination-endpoint": <ip:port>"  
-  }
-}
-```
-
-Note:
-- If the EPP did not communicate the server endpoint via these two methods, it MUST return an error.
-- The EPP MUST not set two different values in the header and the inner response metadata value. 
-
-### Why envoy.lb namespace as a default? 
-The `envoy.lb` namesapce is a predefined namespace used for subsetting. One common way to use the selected endpoint returned from the server, is [envoy subsets](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/subsets) where host metadata for subset load balancing must be placed under `envoy.lb`.
-
-Setting different value leads to unpredictable behavior because proxies aren't guaranteed to support both paths, and so this protocol does not define what takes precedence.
-
-## Model Server Protocol
+# Model Server Protocol
 
 This is the protocol between the EPP and the model servers.
 

docs/proposals/004-endpoint-picker-protocol/README.md

@@ -0,0 +1,35 @@
+# Endpoint Picker Protocol
+
+The Endpoint Picker, or EPP, is a core component of the inference extension. Ultimately it's
+responsible for picking an endpoint from the `InferencePool`. A reference implementation can be
+found [here](../../../pkg/epp/).
+
+This doc defines the protocol between the EPP and the proxy (e.g, Envoy).
+
+The EPP MUST implement the Envoy
+[external processing service](https://www.envoyproxy.io/docs/envoy/latest/api-v3/service/ext_proc/v3/external_processor)protocol.
+
+For each HTTP request, the EPP MUST communicate to the proxy the picked model server endpoint via:
+
+1. Setting the `x-gateway-destination-endpoint` HTTP header to the selected endpoint in <ip:port> format.
+
+2. Set an unstructured entry in the [dynamic_metadata](https://github.com/envoyproxy/go-control-plane/blob/c19bf63a811c90bf9e02f8e0dc1dcef94931ebb4/envoy/service/ext_proc/v3/external_processor.pb.go#L320) field of the ext-proc response. The metadata entry for the picked endpoint MUST be wrapped with an outer key (which represents the metadata namespace) with a default of `envoy.lb`.
+
+The final metadata necessary would look like: 
+```go
+dynamicMetadata: {
+  "envoy.lb": {
+    "x-gateway-destination-endpoint": <ip:port>"  
+  }
+}
+```
+
+Note:
+- If the EPP did not communicate the server endpoint via these two methods, it MUST return an error.
+- The EPP MUST not set two different values in the header and the inner response metadata value. 
+
+## Why envoy.lb namespace as a default? 
+The `envoy.lb` namesapce is a predefined namespace used for subsetting. One common way to use the selected endpoint returned from the server, is [envoy subsets](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/subsets) where host metadata for subset load balancing must be placed under `envoy.lb`.
+
+Setting different value leads to unpredictable behavior because proxies aren't guaranteed to support both paths, and so this protocol does not define what takes precedence.
+