fix: replace socat with caddy to correctly proxy JetBrains MCP

README.md

@@ -48,7 +48,7 @@ The bundled `config.json` configures two MCP servers:
 | Server | Type | Notes |
 |---|---|---|
 | `chrome-devtools` | local (`npx`) | Browser automation via Chromium |
-| `jetbrains` | remote (SSE) | JetBrains IDE integration, host configured via `JETBRAINS_IDE_HOST` |
+| `jetbrains` | remote (SSE) | JetBrains IDE integration via `host.docker.internal:${JETBRAINS_MCP_PORT}` (default `64343`) |
 
 ## Usage
 
@@ -64,8 +64,9 @@ services:
       - opencode-state:/home/skpr/.local/state/opencode
     environment:
       ANTHROPIC_API_KEY: ${ANTHROPIC_API_KEY}
-      JETBRAINS_IDE_HOST: ${JETBRAINS_IDE_HOST:-host.docker.internal}
-    network_mode: "${OPENCODE_NETWORK_MODE:-}"
+      JETBRAINS_MCP_PORT: ${JETBRAINS_MCP_PORT:-64343}
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
     stdin_open: true
     tty: true
     restart: unless-stopped
@@ -75,12 +76,21 @@ volumes:
   opencode-state:
 ```
 
-> **macOS (Docker Desktop):** `host.docker.internal` is provided automatically — no extra config needed.
+> **JetBrains MCP:** The JetBrains MCP server only binds to `127.0.0.1` and validates the `Host`
+> header. Use `caddy` on the host to reverse-proxy it so the container can reach it via
+> `host.docker.internal` with the correct `Host` header.
 >
-> **Linux:** PHPStorm binds to `127.0.0.1` only. Set the following in your `.env` file or shell:
-> ```
-> OPENCODE_NETWORK_MODE=host
-> JETBRAINS_IDE_HOST=127.0.0.1
+> ```bash
+> # Install
+> brew install caddy   # macOS
+> # or
+> apt install caddy    # Linux
+>
+> # Run on the host before starting the container.
+> # caddy listens on 64343 (JETBRAINS_MCP_PORT) and forwards to JetBrains MCP on 64342,
+> # rewriting the Host header to 127.0.0.1:64342 as PhpStorm expects.
+> # If 64343 is already in use, pick any free port and set JETBRAINS_MCP_PORT in your .env.
+> caddy reverse-proxy --from :64343 --to 127.0.0.1:64342
 > ```
 
 Start the container in the background. It will restart automatically after a reboot:
@@ -111,4 +121,5 @@ Pass your API key via a `.env` file (ensure it is in `.gitignore`) — do not ba
 
 ```
 ANTHROPIC_API_KEY=sk-ant-...
+JETBRAINS_MCP_PORT=64343  # only needed if 64343 is already in use
 ```

config.json

@@ -17,7 +17,7 @@
     },
     "jetbrains": {
       "type": "remote",
-      "url": "http://{env:JETBRAINS_IDE_HOST}:64342/sse",
+      "url": "http://host.docker.internal:{env:JETBRAINS_MCP_PORT}/sse",
       "enabled": true
     }
   }

docker-compose.example.yml

@@ -12,15 +12,17 @@ services:
       # Pass your Anthropic API key at runtime. Never hard-code it here.
       # Add ANTHROPIC_API_KEY to a .env file (gitignored) or export it in your shell.
       ANTHROPIC_API_KEY: ${ANTHROPIC_API_KEY}
-      # JetBrains MCP server host.
-      # macOS (Docker Desktop): host.docker.internal resolves to the host automatically.
-      # Linux: PHPStorm binds to 127.0.0.1 only, so use network_mode: host (below)
-      #        and set this to 127.0.0.1.
-      JETBRAINS_IDE_HOST: ${JETBRAINS_IDE_HOST:-host.docker.internal}
-    # Linux: PHPStorm only listens on 127.0.0.1, so set JETBRAINS_IDE_HOST=127.0.0.1
-    # and OPENCODE_NETWORK_MODE=host in your .env file or shell.
-    # network_mode: host is Linux-only and not required on macOS (Docker Desktop).
-    network_mode: "${OPENCODE_NETWORK_MODE:-}"
+      # Port socat is listening on (forwarding to the JetBrains MCP server on the host).
+      # 64342 is taken by JetBrains itself, so socat must use a different port (default: 64343).
+      # Override if 64343 is already in use on your machine.
+      JETBRAINS_MCP_PORT: ${JETBRAINS_MCP_PORT:-64343}
+    # Expose host.docker.internal on Linux (Docker Desktop provides this automatically on macOS).
+    # JetBrains MCP only binds to 127.0.0.1 and validates the Host header; run caddy on the host
+    # to reverse-proxy it: caddy reverse-proxy --from :64343 --to 127.0.0.1:64342 — see README.
+    # Alternatively, if opencode shares a Compose project with your app (e.g. alongside nginx), you can use
+    # network_mode: "service:nginx" to share its network namespace — remove extra_hosts if you do this.
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
     stdin_open: true
     tty: true
     # Restart automatically so the container survives reboots.