fix: Improve session ID extraction from headers for MCP requests

README.md

@@ -14,24 +14,20 @@ A curated collection of production-ready Model Context Protocol (MCP) servers pu
 
 ## 📦 Available servers
 
-| Actor                                                    | Description                                     | Actor badge                                                                                                                                                    | Original author                                                                                             |
-|----------------------------------------------------------|-------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------|
-| **[Brave Search MCP Server](./brave-search-mcp-server/)** | Web search capabilities powered by Brave Search | [![Brave Search MCP Server](https://apify.com/actor-badge?actor=mcp-servers/brave-search-mcp-server)](https://apify.com/mcp-servers/brave-search-mcp-server)   | [MCP Community](https://github.com/modelcontextprotocol/servers-archived/tree/main/src/brave-search)        |
-| **[BrowserBase MCP Server](./browserbase-mcp-server/)** | Cloud web automation capabilities       | [![BrowserBase MCP Server](https://apify.com/actor-badge?actor=mcp-servers/browserbase-mcp-server)](https://apify.com/mcp-servers/browserbase-mcp-server) | [BrowserBase](https://github.com/browserbase/mcp-server-browserbase) |
-| **[Docfork MCP Server](./docfork-mcp-server/)**    | FreshFresh docs for your AI code editor | [![Docfork MCP Server](https://apify.com/actor-badge?actor=mcp-servers/brave-search-mcp-server)](https://apify.com/mcp-servers/brave-search-mcp-server) | [Docfork.AI](https://x.com/docfork_ai) |
-| **[Perplexity Sonar MCP Server](./perplexity-mcp-server/)** | AI-powered search and information retrieval | [![Perplexity Soner MCP Server](https://apify.com/actor-badge?actor=mcp-servers/perplexity-sonar-mcp-server)](https://apify.com/mcp-servers/perplexity-sonar-mcp-server) | [Perplexity AI](https://github.com/ppl-ai/modelcontextprotocol) |
-| **[Firecrawl MCP Server](./firecrawl-mcp-server/)** | Web crawling and content extraction | [![Firecrawl MCP Server](https://apify.com/actor-badge?actor=mcp-servers/firecrawl-mcp-server)](https://apify.com/actor/mcp-servers/firecrawl-mcp-server) | [Mendable AI](https://github.com/mendableai/firecrawl-mcp-server) |
-| **[Slide Speak MCP Server](./slide-speak-mcp-server/)** | Presentation and speech synthesis | [![Slide Speak MCP Server](https://apify.com/actor-badge?actor=mcp-servers/slidespeak-mcp-server)](https://apify.com/mcp-servers/slidespeak-mcp-server) | [SlideSpeak](https://github.com/slidespeak/slidespeak-mcp) |
-| **[Lara Translate MCP Server](./lara-translate-mcp-server/)** | Multi-language translation services | [![Lara Translate MCP Server](https://apify.com/actor-badge?actor=mcp-servers/lara-translate-mcp-server)](https://apify.com/mcp-servers/lara-translate-mcp-server) | [Translated](https://github.com/translated/lara-mcp) |
-| **[Calculator MCP Server](./calculator-MCP-server/)** | Mathematical computations and calculations | [![Calculator MCP Server](https://apify.com/actor-badge?actor=mcp-servers/calculator-mcp-server)](https://apify.com/mcp-servers/calculator-mcp-server) | [Githejie](https://github.com/githejie/mcp-server-calculator) |
-| **[Kiwi MCP Server](./kiwi-mcp-server/)** | Flight search and booking using Kiwi.com | [![Kiwi MCP Server](https://apify.com/actor-badge?actor=mcp-servers/kiwi-mcp-server)](https://apify.com/mcp-servers/kiwi-mcp-server) | [Kiwi.com](https://github.com/alpic-ai/kiwi-mcp-server-public) |
-| **[National Parks MCP Server](./national-parks/)** | Geographic and park information | [![National Parks MCP Server](https://apify.com/actor-badge?actor=mcp-servers/national-parks-mcp-server)](https://apify.com/mcp-servers/national-parks-mcp-server) | [KyrieTangSheng](https://github.com/KyrieTangSheng/mcp-server-nationalparks) |
-| **[Context7 MCP Server](./context7-mcp-server/)** | Up-to-date code docs for any programming library | [![Context7 MCP Server](https://apify.com/actor-badge?actor=mcp-servers/context7-mcp-server)](https://apify.com/mcp-servers/context7-mcp-server) | [Upstash](https://github.com/upstash/context7) |
-| **[DeepL MCP Server](./deepl-mcp-server/)**                   | Translation capabilities using the DeepL API     | [![DeepL MCP Server](https://apify.com/actor-badge?actor=mcp-servers/deepl-mcp-server)](https://apify.com/mcp-servers/deepl-mcp-server)                                  | [DeepLcom](https://github.com/DeepLcom/deepl-mcp-server)                                                      |
-| **[Pure.md MCP Server](./pure-md-mcp-server/)** | Web content extraction and search capabilities powered by Pure.md | [![Pure.md MCP Server](https://apify.com/actor-badge?actor=mcp-servers/pure-md-mcp-server)](https://apify.com/mcp-servers/pure-md-mcp-server) | [Pure.md](https://github.com/puremd/puremd-mcp) |
-| **[Financial Datasets MCP Server](./financial-datasets-mcp-server/)** | Stock market data, financial statements, and cryptocurrency information | [![Financial Datasets MCP Server](https://apify.com/actor-badge?actor=mcp-servers/financial-datasets-mcp-server)](https://apify.com/mcp-servers/financial-datasets-mcp-server) | [Financial Datasets](https://github.com/financial-datasets/mcp-server) |
-| **[Microsoft Docs MCP Server](./microsoft-docs-mcp-server/)** | Access Microsoft's official documentation with semantic search | [![Microsoft Docs MCP Server](https://apify.com/actor-badge?actor=mcp-servers/microsoft-docs-mcp-server)](https://apify.com/mcp-servers/microsoft-docs-mcp-server) | [Microsoft](https://github.com/MicrosoftDocs/mcp) |
-| **[TomTom MCP Server](./tomtom-mcp-server/)** | Geospatial services including search, routing, traffic and static maps | [![TomTom MCP Server](https://apify.com/actor-badge?actor=mcp-servers/tomtom-mcp-server)](https://apify.com/mcp-servers/tomtom-mcp-server) | [TomTom International](https://github.com/tomtom-international/tomtom-mcp) |
+| Actor                                                    | Description                                     | Actor badge                                                                                                                                                        | Original author                                                                                             |
+|----------------------------------------------------------|-------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------|
+| **[Brave Search MCP Server](./brave-search-mcp-server/)** | Web search capabilities powered by Brave Search | [![Brave Search MCP Server](https://apify.com/actor-badge?actor=agentify/brave-search-mcp-server)](https://apify.com/agentify/brave-search-mcp-server)             | [MCP Community](https://github.com/modelcontextprotocol/servers-archived/tree/main/src/brave-search)        |
+| **[BrowserBase MCP Server](./browserbase-mcp-server/)** | Cloud web automation capabilities       | [![BrowserBase MCP Server](https://apify.com/actor-badge?actor=agentify/browserbase-mcp-server)](https://apify.com/agentify/browserbase-mcp-server)                | [BrowserBase](https://github.com/browserbase/mcp-server-browserbase) |
+| **[Docfork MCP Server](./docfork-mcp-server/)**    | FreshFresh docs for your AI code editor | [![Docfork MCP Server](https://apify.com/actor-badge?actor=agentify/docfork-mcp-server)](https://apify.com/agentify/docfork-mcp-server)                            | [Docfork.AI](https://x.com/docfork_ai) |
+| **[Perplexity Sonar MCP Server](./perplexity-mcp-server/)** | AI-powered search and information retrieval | [![Perplexity Soner MCP Server](https://apify.com/actor-badge?actor=agentify/perplexity-sonar-mcp-server)](https://apify.com/agentify/perplexity-sonar-mcp-server) | [Perplexity AI](https://github.com/ppl-ai/modelcontextprotocol) |
+| **[Firecrawl MCP Server](./firecrawl-mcp-server/)** | Web crawling and content extraction | [![Firecrawl MCP Server](https://apify.com/actor-badge?actor=agentify/firecrawl-mcp-server)](https://apify.com/agentify/firecrawl-mcp-server)                      | [Mendable AI](https://github.com/mendableai/firecrawl-mcp-server) |
+| **[Slide Speak MCP Server](./slide-speak-mcp-server/)** | Presentation and speech synthesis | [![Slide Speak MCP Server](https://apify.com/actor-badge?actor=agentify/slidespeak-mcp-server)](https://apify.com/agentify/slidespeak-mcp-server)                                                                  |
+| **[Lara Translate MCP Server](./lara-translate-mcp-server/)** | Multi-language translation services | [![Lara Translate MCP Server](https://apify.com/actor-badge?actor=agentify/lara-translate-mcp-server)](https://apify.com/agentify/lara-translate-mcp-server)       | [Translated](https://github.com/translated/lara-mcp) |
+| **[Calculator MCP Server](./calculator-MCP-server/)** | Mathematical computations and calculations | [![Calculator MCP Server](https://apify.com/actor-badge?actor=agentify/calculator-mcp-server)](https://apify.com/agentify/calculator-mcp-server)                   | [Githejie](https://github.com/githejie/mcp-server-calculator) |
+| **[Kiwi MCP Server](./kiwi-mcp-server/)** | Flight search and booking using Kiwi.com | [![Kiwi MCP Server](https://apify.com/actor-badge?actor=agentify/kiwi-mcp-server)](https://apify.com/agentify/kiwi-mcp-server)                                     | [Kiwi.com](https://github.com/alpic-ai/kiwi-mcp-server-public) |
+| **[National Parks MCP Server](./national-parks/)** | Geographic and park information | [![National Parks MCP Server](https://apify.com/actor-badge?actor=agentify/national-parks-mcp-server)](https://apify.com/agentify/national-parks-mcp-server)       | [KyrieTangSheng](https://github.com/KyrieTangSheng/mcp-server-nationalparks) |
+| **[Context7 MCP Server](./context7-mcp-server/)** | Up-to-date code docs for any programming library | [![Context7 MCP Server](https://apify.com/actor-badge?actor=agentify/context7-mcp-server)](https://apify.com/agentify/context7-mcp-server)                         | [Upstash](https://github.com/upstash/context7) |
+| **[DeepL MCP Server](./deepl-mcp-server/)** | Translation capabilities using the DeepL API | [![DeepL MCP Server](https://apify.com/actor-badge?actor=agentify/deepl-mcp-server)](https://apify.com/agentify/deepl-mcp-server)                                  | [DeepLcom](https://github.com/DeepLcom/deepl-mcp-server) |
 
 ## 🙏 Credits
 These are wrappers—original code by: Brave Software, Perplexity AI, Mendable AI, SlideSpeak, Translated, Githejie, Kiwi.com, KyrieTangSheng, Upstash, Financial Datasets, Microsoft, and others.

calculator-MCP-server/src/server.py

@@ -160,7 +160,7 @@ def _log_request(request: Request) -> None:
             extra={
                 'method': request.method,
                 'path': str(request.url.path),
-                'mcp_session_id': request.headers.get('mcp-session-id'),
+                'mcp_session_id': ProxyServer._get_session_id_from_headers(request.headers),
             },
         )
 
@@ -229,6 +229,24 @@ def _cleanup_session_timer(self, session_id: str) -> None:
                 timer.cancel()
             del self._session_timers[session_id]
 
+    @staticmethod
+    def _get_session_id_from_headers(headers: Any) -> str | None:
+        """Extract session ID from headers, trying both hyphen and underscore variants.
+
+        HTTP headers are case-insensitive per spec, and Starlette's Request.headers
+        handles this automatically. We only need to check for hyphen vs underscore variants.
+
+        Args:
+            headers: Either a Starlette Request.headers object or a dict
+
+        Returns:
+            Session ID string if found, None otherwise
+        """
+        for key in ('mcp-session-id', 'mcp_session_id'):
+            if value := headers.get(key):
+                return value
+        return None
+
     @staticmethod
     def _validate_config(client_type: ServerType, config: ServerParameters) -> ServerParameters | None:
         """Validate and return the appropriate server parameters."""
@@ -252,7 +270,7 @@ def _create_capturing_send(
         async def capturing_send(message: dict[str, Any]) -> None:
             if message.get('type') == 'http.response.start':
                 headers = {k.decode('latin-1').lower(): v.decode('latin-1') for k, v in message.get('headers', [])}
-                if sid := headers.get('mcp-session-id'):
+                if sid := ProxyServer._get_session_id_from_headers(headers):
                     session_id_from_resp['sid'] = sid
             await send(message)
 
@@ -334,15 +352,15 @@ async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) ->
 
             if scope['method'] == 'DELETE':
                 await session_manager.handle_request(scope, receive, send)
-                if req_sid := request.headers.get('mcp-session-id'):
+                if req_sid := self._get_session_id_from_headers(request.headers):
                     self._cleanup_session_last_activity(req_sid)
                     self._cleanup_session_timer(req_sid)
                 return
 
             session_id_from_resp: dict[str, str | None] = {'sid': None}
             capturing_send = self._create_capturing_send(send, session_id_from_resp)
 
-            if req_sid := request.headers.get('mcp-session-id'):
+            if req_sid := self._get_session_id_from_headers(request.headers):
                 self._touch_session(req_sid, session_manager)
 
             await session_manager.handle_request(scope, receive, capturing_send)  # type: ignore[arg-type]

context7-mcp-server/src/server.py

@@ -165,7 +165,7 @@ def _log_request(request: Request) -> None:
             extra={
                 'method': request.method,
                 'path': str(request.url.path),
-                'mcp_session_id': request.headers.get('mcp-session-id'),
+                'mcp_session_id': ProxyServer._get_session_id_from_headers(request.headers),
             },
         )
 
@@ -234,6 +234,14 @@ def _cleanup_session_timer(self, session_id: str) -> None:
                 timer.cancel()
             del self._session_timers[session_id]
 
+    @staticmethod
+    def _get_session_id_from_headers(headers: Any) -> str | None:
+        """Extract session ID from headers supporting dash and underscore variants."""
+        for key in ('mcp-session-id', 'mcp_session_id'):
+            if value := headers.get(key):
+                return value
+        return None
+
     @staticmethod
     def _validate_config(client_type: ServerType, config: ServerParameters) -> ServerParameters | None:
         """Validate and return the appropriate server parameters."""
@@ -257,7 +265,7 @@ def _create_capturing_send(
         async def capturing_send(message: dict[str, Any]) -> None:
             if message.get('type') == 'http.response.start':
                 headers = {k.decode('latin-1').lower(): v.decode('latin-1') for k, v in message.get('headers', [])}
-                if sid := headers.get('mcp-session-id'):
+                if sid := ProxyServer._get_session_id_from_headers(headers):
                     session_id_from_resp['sid'] = sid
             await send(message)
 
@@ -341,7 +349,7 @@ async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) ->
 
             if scope['method'] == 'DELETE':
                 await session_manager.handle_request(scope, receive, send)
-                if req_sid := request.headers.get('mcp-session-id'):
+                if req_sid := self._get_session_id_from_headers(request.headers):
                     self._cleanup_session_last_activity(req_sid)
                     self._cleanup_session_timer(req_sid)
                 return
@@ -352,7 +360,7 @@ async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) ->
             capturing_send = self._create_capturing_send(send, session_id_from_resp)
 
             # Log and touch existing session if present on request
-            if req_sid := request.headers.get('mcp-session-id'):
+            if req_sid := self._get_session_id_from_headers(request.headers):
                 self._touch_session(req_sid, session_manager)
 
             await session_manager.handle_request(scope, receive, capturing_send)  # type: ignore[arg-type]

dictionary-mcp-server/src/server.py

@@ -165,7 +165,7 @@ def _log_request(request: Request) -> None:
             extra={
                 'method': request.method,
                 'path': str(request.url.path),
-                'mcp_session_id': request.headers.get('mcp-session-id'),
+                'mcp_session_id': ProxyServer._get_session_id_from_headers(request.headers),
             },
         )
 
@@ -234,6 +234,14 @@ def _cleanup_session_timer(self, session_id: str) -> None:
                 timer.cancel()
             del self._session_timers[session_id]
 
+    @staticmethod
+    def _get_session_id_from_headers(headers: Any) -> str | None:
+        """Extract session ID from headers supporting dash and underscore variants."""
+        for key in ('mcp-session-id', 'mcp_session_id'):
+            if value := headers.get(key):
+                return value
+        return None
+
     @staticmethod
     def _validate_config(client_type: ServerType, config: ServerParameters) -> ServerParameters | None:
         """Validate and return the appropriate server parameters."""
@@ -257,7 +265,7 @@ def _create_capturing_send(
         async def capturing_send(message: dict[str, Any]) -> None:
             if message.get('type') == 'http.response.start':
                 headers = {k.decode('latin-1').lower(): v.decode('latin-1') for k, v in message.get('headers', [])}
-                if sid := headers.get('mcp-session-id'):
+                if sid := ProxyServer._get_session_id_from_headers(headers):
                     session_id_from_resp['sid'] = sid
             await send(message)
 
@@ -341,7 +349,7 @@ async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) ->
 
             if scope['method'] == 'DELETE':
                 await session_manager.handle_request(scope, receive, send)
-                if req_sid := request.headers.get('mcp-session-id'):
+                if req_sid := self._get_session_id_from_headers(request.headers):
                     self._cleanup_session_last_activity(req_sid)
                     self._cleanup_session_timer(req_sid)
                 return
@@ -352,7 +360,7 @@ async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) ->
             capturing_send = self._create_capturing_send(send, session_id_from_resp)
 
             # Log and touch existing session if present on request
-            if req_sid := request.headers.get('mcp-session-id'):
+            if req_sid := self._get_session_id_from_headers(request.headers):
                 self._touch_session(req_sid, session_manager)
 
             await session_manager.handle_request(scope, receive, capturing_send)  # type: ignore[arg-type]