diff --git a/src/seclab_taskflow_agent/agent.py b/src/seclab_taskflow_agent/agent.py
index 3e6fc75..4191cd5 100644
--- a/src/seclab_taskflow_agent/agent.py
+++ b/src/seclab_taskflow_agent/agent.py
@@ -29,7 +29,7 @@
     set_tracing_disabled,
 )
 
-from .capi import COPILOT_INTEGRATION_ID, get_AI_endpoint, get_AI_token, AI_API_ENDPOINT_ENUM
+from .capi import get_AI_endpoint, get_AI_token, get_custom_header, AI_API_ENDPOINT_ENUM
 
 # grab our secrets from .env, this must be in .gitignore
 load_dotenv(find_dotenv(usecwd=True))
@@ -150,7 +150,7 @@ def __init__(
         client = AsyncOpenAI(
             base_url=api_endpoint,
             api_key=get_AI_token(),
-            default_headers={"Copilot-Integration-Id": COPILOT_INTEGRATION_ID},
+            default_headers=get_custom_header(),
         )
         set_default_openai_client(client)
         # CAPI does not yet support the Responses API: https://github.com/github/copilot-api/issues/11185
diff --git a/src/seclab_taskflow_agent/capi.py b/src/seclab_taskflow_agent/capi.py
index 2fc1d0d..ad0843f 100644
--- a/src/seclab_taskflow_agent/capi.py
+++ b/src/seclab_taskflow_agent/capi.py
@@ -56,6 +56,30 @@ def get_AI_token():
         return token
     raise RuntimeError("AI_API_TOKEN environment variable is not set.")
 
+def get_custom_header() -> dict[str, str]:
+    """
+    Get custom header from environment variable AI_API_CUSTOM_HEADER.
+    Expected format: name:value
+    Returns a dictionary that can be merged into request headers.
+    """
+    custom_header = os.getenv('AI_API_CUSTOM_HEADER')
+    if not custom_header:
+        return {}
+    
+    # Split on first colon to handle values that might contain colons
+    parts = custom_header.split(':', 1)
+    if len(parts) != 2:
+        logging.warning(f"Invalid AI_API_CUSTOM_HEADER format. Expected 'name:value', got: {custom_header}")
+        return {}
+    
+    name, value = parts
+    name = name.strip()
+    value = value.strip()
+    if not name or not value:
+        logging.warning(f"Invalid AI_API_CUSTOM_HEADER: header name and value must be non-empty after stripping. Got: '{custom_header}'")
+        return {}
+    return {name: value}
+
 
 # assume we are >= python 3.9 for our type hints
 def list_capi_models(token: str) -> dict[str, dict]:
@@ -76,13 +100,13 @@ def list_capi_models(token: str) -> dict[str, dict]:
                     f"Unsupported Model Endpoint: {api_endpoint}\n"
                     f"Supported endpoints: {[e.to_url() for e in AI_API_ENDPOINT_ENUM]}"
                 )
+        headers = {
+            'Accept': 'application/json',
+            'Authorization': f'Bearer {token}',
+        } | get_custom_header()
         r = httpx.get(
             httpx.URL(api_endpoint).join(models_catalog),
-            headers={
-                "Accept": "application/json",
-                "Authorization": f"Bearer {token}",
-                "Copilot-Integration-Id": COPILOT_INTEGRATION_ID,
-            },
+            headers=headers,
         )
         r.raise_for_status()
         # CAPI vs Models API