diff --git a/headroom/proxy/handlers/anthropic.py b/headroom/proxy/handlers/anthropic.py
index d6820f680..212858534 100644
--- a/headroom/proxy/handlers/anthropic.py
+++ b/headroom/proxy/handlers/anthropic.py
@@ -1673,7 +1673,13 @@ class AnthropicHandlerMixin:
                         )
                 except Exception:  # advisory hint only — must never fail a request
                     pass
-            ccr_workspace_key = ccr_workspace_label = None
+            # Initialize before the gated block so the proactive-expansion
+            # gate below (which references ``ccr_workspace_key`` regardless of
+            # the inject flags) does not raise ``UnboundLocalError`` when the
+            # block is skipped — e.g. ``--no-ccr-inject-tool`` with the default
+            # ``ccr_inject_system_instructions=False``, or when ``_bypass`` is
+            # set. The downstream uses already treat falsy as "unresolved".
+            ccr_workspace_key, ccr_workspace_label = None, None
             if (
                 self.config.ccr_inject_tool or self.config.ccr_inject_system_instructions
             ) and not _bypass:
diff --git a/tests/test_anthropic_ccr_workspace_unbound.py b/tests/test_anthropic_ccr_workspace_unbound.py
new file mode 100644
index 000000000..d1ee63f51
--- /dev/null
+++ b/tests/test_anthropic_ccr_workspace_unbound.py
@@ -0,0 +1,82 @@
+"""Regression: ``ccr_workspace_key`` UnboundLocalError when CCR inject is off.
+
+``handle_anthropic_messages`` previously assigned ``ccr_workspace_key`` /
+``ccr_workspace_label`` only inside the ``if (ccr_inject_tool or
+ccr_inject_system_instructions) and not _bypass:`` block, but referenced
+``ccr_workspace_key`` unconditionally later (the proactive-expansion gate). When
+the proxy is started with ``--no-ccr-inject-tool`` and
+``ccr_inject_system_instructions`` left at its ``False`` default — a real,
+user-supported configuration — the assignment block was skipped and the later
+reference raised ``UnboundLocalError``. FastAPI translated that into HTTP 500 on
+every ``/v1/messages`` request.
+
+Reproducer config matches the deployment that surfaced the bug:
+
+  * ``ccr_inject_tool=False``                  (user passed ``--no-ccr-inject-tool``)
+  * ``ccr_inject_system_instructions=False``  (default)
+  * ``ccr_context_tracking=True``             (default — installs the tracker)
+  * ``ccr_proactive_expansion=True``          (default — reaches the gate)
+"""
+
+from __future__ import annotations
+
+import httpx
+from fastapi.testclient import TestClient
+
+from headroom.proxy.server import ProxyConfig, create_app
+
+
+def _client() -> TestClient:
+    config = ProxyConfig(
+        optimize=False,
+        cache_enabled=False,
+        rate_limit_enabled=False,
+        cost_tracking_enabled=False,
+        log_requests=False,
+        # The two flags that gate the assignment block:
+        ccr_inject_tool=False,
+        ccr_inject_system_instructions=False,
+        # Tracker + proactive expansion enabled (defaults) reach the unbound use:
+        ccr_context_tracking=True,
+        ccr_proactive_expansion=True,
+        image_optimize=False,
+    )
+    return TestClient(create_app(config))
+
+
+def test_proactive_expansion_does_not_raise_when_ccr_inject_disabled() -> None:
+    with _client() as client:
+        proxy = client.app.state.proxy
+        # Sanity: the tracker is wired up (necessary for the bug to trigger).
+        assert proxy.ccr_context_tracker is not None
+
+        async def _fake_retry(method, url, headers, body, stream=False, **kwargs):  # noqa: ANN001
+            return httpx.Response(
+                200,
+                json={
+                    "id": "msg_1",
+                    "type": "message",
+                    "role": "assistant",
+                    "content": [{"type": "text", "text": "ok"}],
+                    "usage": {
+                        "input_tokens": 1,
+                        "output_tokens": 1,
+                        "cache_read_input_tokens": 0,
+                        "cache_creation_input_tokens": 0,
+                    },
+                },
+            )
+
+        proxy._retry_request = _fake_retry
+
+        response = client.post(
+            "/v1/messages",
+            headers={"x-api-key": "test-key", "anthropic-version": "2023-06-01"},
+            json={
+                "model": "claude-sonnet-4-6",
+                "max_tokens": 16,
+                "messages": [{"role": "user", "content": "hi"}],
+            },
+        )
+
+        assert response.status_code == 200, response.text