diff --git a/pctx-py/CHANGELOG.md b/pctx-py/CHANGELOG.md
index 66269b2..bc4e5b3 100644
--- a/pctx-py/CHANGELOG.md
+++ b/pctx-py/CHANGELOG.md
@@ -11,7 +11,21 @@ For changes to the underlying Rust crates and CLI, see the
 
 ## [UNRELEASED] - YYYY-MM-DD
 
-## [v0.4.0] - 2026-06-08
+### Added
+
+- `Pctx(headers=...)`: an arbitrary `dict[str, str]` of headers applied to every
+  HTTP request and the WebSocket connection request. Use this to authenticate
+  against deployments that expect custom headers (e.g. a
+  `{"authorization": "Bearer <token>"}` for GCP IAM-protected services).
+
+### Removed
+
+- **Breaking**: the deprecated `Pctx(api_key=...)` parameter and the
+  `x-pctx-api-key` header it set. The system that validated this key is no
+  longer maintained. Pass credentials via `headers=` instead — e.g.
+  `Pctx(api_key="k")` → `Pctx(headers={"x-pctx-api-key": "k"})`.
+
+## [v0.4.1] - 2026-06-08
 
 ### Added
 - `py.typed` for mypy
diff --git a/pctx-py/src/pctx_client/_client.py b/pctx-py/src/pctx_client/_client.py
index 6aed4cc..2f320c5 100644
--- a/pctx-py/src/pctx_client/_client.py
+++ b/pctx-py/src/pctx_client/_client.py
@@ -65,7 +65,7 @@ def __init__(
         tools: list[Tool | AsyncTool] | None = None,
         servers: list[ServerConfig] | None = None,
         url: str = "http://localhost:8080",
-        api_key: str | None = None,
+        headers: dict[str, str] | None = None,
         execute_timeout: float = 30.0,
     ):
         """
@@ -77,6 +77,8 @@ def __init__(
                 - HTTP server: {"name": "...", "url": "...", "auth": {...}}
                 - stdio server: {"name": "...", "command": "...", "args": [...], "env": {...}}
             url: PCTX server URL (default: http://localhost:8080)
+            headers: Additional headers applied to every request and the
+                WebSocket connection request
             execute_timeout: Timeout for code execution in seconds (default: 30.0)
         """
 
@@ -100,14 +102,14 @@ def __init__(
         ws_scheme = "wss" if http_scheme == "https" else "ws"
 
         self._ws_client = WebSocketClient(
-            url=f"{ws_scheme}://{host}{parsed.path}/ws", api_key=api_key, tools=tools
+            url=f"{ws_scheme}://{host}{parsed.path}/ws", headers=headers, tools=tools
         )
         self._client = AsyncClient(
             base_url=f"{http_scheme}://{host}{parsed.path}",
-            headers={"x-pctx-api-key": api_key or ""},
+            headers=headers or {},
         )
         self._session_id: str | None = None
-        self._api_key = api_key
+        self._headers = headers or {}
 
         self._tools = tools or []
         self._servers = servers or []
diff --git a/pctx-py/src/pctx_client/_websocket_client.py b/pctx-py/src/pctx_client/_websocket_client.py
index f076228..c50e5de 100644
--- a/pctx-py/src/pctx_client/_websocket_client.py
+++ b/pctx-py/src/pctx_client/_websocket_client.py
@@ -52,7 +52,7 @@ class WebSocketClient:
     def __init__(
         self,
         url: str,
-        api_key: str | None = None,
+        headers: dict[str, str] | None = None,
         tools: list[Tool | AsyncTool] | None = None,
     ):
         """
@@ -60,11 +60,12 @@ def __init__(
 
         Args:
             url: WebSocket server URL (e.g., "ws://localhost:8080/ws")
+            headers: Additional headers to send with the connection request
         """
         self.url = url
         self.ws: ClientConnection | None = None
         self.tools = tools or []
-        self._api_key = api_key
+        self._headers = headers or {}
         self._pending_executions: dict[str | int, asyncio.Future] = {}
         self._request_counter = 0
 
@@ -77,8 +78,8 @@ async def _connect(self, code_mode_session: str):
         """
         try:
             headers = {
+                **self._headers,
                 "x-code-mode-session": code_mode_session,
-                "x-pctx-api-key": self._api_key or "",
             }
             self.ws = await websockets.connect(self.url, additional_headers=headers)
         except Exception as e:
diff --git a/pctx-py/tests/scripts/manual_code_mode.py b/pctx-py/tests/scripts/manual_code_mode.py
index bd28261..2eed002 100755
--- a/pctx-py/tests/scripts/manual_code_mode.py
+++ b/pctx-py/tests/scripts/manual_code_mode.py
@@ -48,7 +48,7 @@ def multiply(a: float, b: float) -> MultiplyOutput:
 async def main():
     async with Pctx(
         # url="https://....",
-        # api_key="pctx_xxxx",
+        # headers={"authorization": "Bearer xxxx"},
         tools=[add, subtract, multiply, now_timestamp, search_logs],
         servers=[
             {