feat: improve health check diagnostics for port configuration issues

Enhanced error handling in test_agentic_mcp.py health check to help users
identify common port configuration mistakes:

- Clear distinction between HTTP server port (3000) and SurrealDB port (3004)
- Detailed troubleshooting steps for connection failures
- Example .env configuration showing correct port values
- Helpful commands to verify server status and connectivity

This addresses the common issue where users try to connect to the wrong
port (e.g., 3004 SurrealDB instead of 3000 HTTP server) and get confusing
406 errors with no diagnostic information.

Author: jruokola

test_agentic_mcp.py

@@ -322,18 +322,40 @@ async def run_http_tests():
     print(f"  URL: {mcp_url}")
 
     # Quick check if server is reachable
+    print(f"\nChecking HTTP server health...")
+    print(f"  Endpoint: http://{HTTP_HOST}:{HTTP_PORT}/health")
+
     try:
         import httpx
         async with httpx.AsyncClient() as client:
-            response = await client.get(f"http://{HTTP_HOST}:{HTTP_PORT}/health", timeout=2.0)
+            response = await client.get(
+                f"http://{HTTP_HOST}:{HTTP_PORT}/health",
+                timeout=2.0,
+                follow_redirects=True
+            )
             if response.status_code != 200:
-                print(f"❌ Server health check failed: {response.status_code}")
+                print(f"❌ Health check failed: HTTP {response.status_code}")
+                print(f"   Response: {response.text[:200] if response.text else 'empty'}")
+                print(f"\n⚠️  Common port configuration issues:")
+                print(f"   - Port {HTTP_PORT} may be wrong")
+                print(f"   - Default HTTP server port: 3000")
+                print(f"   - SurrealDB port (NOT for HTTP): 3004")
+                print(f"   - Check CODEGRAPH_HTTP_PORT in .env file")
+                print(f"\nStart CodeGraph HTTP server on correct port:")
+                print(f"  ./target/release/codegraph start http --host {HTTP_HOST} --port 3000")
                 return 1
         print("✓ Server is reachable\n")
     except Exception as e:
         print(f"❌ Cannot reach server: {e}")
-        print(f"\nStart server with:")
-        print(f"  ./target/release/codegraph start http --host {HTTP_HOST} --port {HTTP_PORT}")
+        print(f"\n⚠️  Troubleshooting:")
+        print(f"   - Is the server running? Check: ps aux | grep codegraph")
+        print(f"   - Wrong port? Common mistake: using 3004 (SurrealDB) instead of 3000 (HTTP)")
+        print(f"   - Check firewall/network: curl http://{HTTP_HOST}:{HTTP_PORT}/health")
+        print(f"\nExpected .env configuration:")
+        print(f"  CODEGRAPH_HTTP_HOST=127.0.0.1")
+        print(f"  CODEGRAPH_HTTP_PORT=3000  # HTTP server port (NOT SurrealDB 3004)")
+        print(f"\nStart HTTP server with:")
+        print(f"  ./target/release/codegraph start http --host 127.0.0.1 --port 3000")
         return 1
 
     results = []