feat: VS Code Copilot Chat proxy integration

.gitignore

@@ -251,3 +251,4 @@ uv.lock
 # package shadows the maturin overlay on sys.path.
 /headroom/_core.*.so
 /headroom/_core.so
+plugin/

Dockerfile.vscode-plugin

@@ -0,0 +1,24 @@
+FROM node:24-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+ARG VSCODE_FORK_REPO=https://github.com/damnthonyy/vscode.git
+ARG VSCODE_FORK_BRANCH=main
+
+WORKDIR /build
+RUN git clone --depth=1 --branch=${VSCODE_FORK_BRANCH} ${VSCODE_FORK_REPO} vscode
+
+WORKDIR /build/vscode/extensions/copilot
+
+# Install deps without running postinstall (needs source files already present from the clone)
+RUN npm install --ignore-scripts
+
+# Run postinstall now that sources are present, build, then package
+RUN npm run postinstall && \
+    npx tsx .esbuild.mts --sourcemaps && \
+    mkdir -p /plugin && \
+    npx vsce package --out /plugin/copilot-proxy.vsix --allow-missing-repository
+
+CMD ["sh", "-c", "cp /plugin/copilot-proxy.vsix /output/ && echo 'Done:' && ls -lh /output/*.vsix"]

docker-compose.yml

@@ -1,12 +1,14 @@
 services:
   headroom-proxy:
-    build: .
+    build:
+      context: .
+      args:
+        HEADROOM_EXTRAS: "proxy,code,ml"
     command: ["--host", "0.0.0.0"]
     environment:
       - HEADROOM_HOST=0.0.0.0
-      # if you want to use a custom OpenAI-compatible API endpoint,
-      # uncomment and set the following line with the desired URL
-      # - OPENAI_TARGET_API_URL=https://api.x.ai
+      - OPENAI_TARGET_API_URL=https://api.githubcopilot.com
+      - GITHUB_TOKEN=${GITHUB_TOKEN}
     ports:
       - "8787:8787"
     healthcheck:
@@ -45,6 +47,22 @@ services:
       - NEO4J_apoc_import_file_enabled=true
       - NEO4J_apoc_import_file_use__neo4j__config=true
 
+  # Build the patched Copilot Chat VSIX that routes LLM requests through headroom.
+  # Usage:
+  #   docker compose --profile plugin run --rm vscode-plugin-builder
+  #   code --install-extension ./plugin/copilot-proxy.vsix --force
+  vscode-plugin-builder:
+    build:
+      context: .
+      dockerfile: Dockerfile.vscode-plugin
+      args:
+        VSCODE_FORK_REPO: ${VSCODE_FORK_REPO:-https://github.com/damnthonyy/vscode.git}
+        VSCODE_FORK_BRANCH: ${VSCODE_FORK_BRANCH:-main}
+    volumes:
+      - ./plugin:/output
+    profiles:
+      - plugin
+
 volumes:
   qdrant_data:
   neo4j_data:

headroom/providers/proxy_routes.py

@@ -848,6 +848,8 @@ async def gemini_delete_cached_content(request: Request, cache_id: str):
     @app.api_route("/{path:path}", methods=["GET", "POST", "PUT", "DELETE"])
     async def passthrough(request: Request, path: str):
         custom_base = request.headers.get("x-headroom-base-url")
+        if not custom_base and "x-original-host" in request.headers:
+            custom_base = f"https://{request.headers['x-original-host']}"
         if custom_base:
             return await proxy.handle_passthrough(request, custom_base.rstrip("/"))
 

tests/test_provider_proxy_routes.py

@@ -175,6 +175,26 @@ async def fake_gemini_count(
             ).json()["base_url"]
             == "https://custom.example/base"
         )
+        # X-Original-Host support: patched VS Code Copilot extension sends this header
+        # instead of x-headroom-base-url to avoid modifying the path.
+        assert (
+            client.post(
+                "/chat/completions",
+                headers={"x-original-host": "api.githubcopilot.com"},
+            ).json()["base_url"]
+            == "https://api.githubcopilot.com"
+        )
+        # x-headroom-base-url still wins over x-original-host when both are present
+        assert (
+            client.get(
+                "/chat/completions",
+                headers={
+                    "x-headroom-base-url": "https://explicit.example",
+                    "x-original-host": "api.githubcopilot.com",
+                },
+            ).json()["base_url"]
+            == "https://explicit.example"
+        )
         assert client.get("/another/path", headers={"x-goog-api-key": "test"}).json()[
             "base_url"
         ] == ("https://api.gemini.test")