diff --git a/litellm/anthropic_beta_headers_config.json b/litellm/anthropic_beta_headers_config.json
index d02afe37569..a0d63f5043c 100644
--- a/litellm/anthropic_beta_headers_config.json
+++ b/litellm/anthropic_beta_headers_config.json
@@ -129,7 +129,7 @@
     "bash_20241022": null,
     "bash_20250124": null,
     "code-execution-2025-08-25": null,
-    "compact-2026-01-12": null,
+    "compact-2026-01-12": "compact-2026-01-12",
     "computer-use-2025-01-24": "computer-use-2025-01-24",
     "computer-use-2025-11-24": "computer-use-2025-11-24",
     "context-1m-2025-08-07": "context-1m-2025-08-07",
diff --git a/tests/test_litellm/test_anthropic_beta_headers_filtering.py b/tests/test_litellm/test_anthropic_beta_headers_filtering.py
index 84867a6e905..9cd27e88c33 100644
--- a/tests/test_litellm/test_anthropic_beta_headers_filtering.py
+++ b/tests/test_litellm/test_anthropic_beta_headers_filtering.py
@@ -402,6 +402,16 @@ class TestAnthropicBetaHeadersFiltering:
                 test_case["expected"] in filtered
             ), f"Header '{test_case['input']}' should be mapped to '{test_case['expected']}' for {test_case['provider']}, but got: {filtered}"
 
+    def test_filter_and_transform_beta_headers_vertex_ai_keeps_compact(self):
+        """Vertex AI supports compact context edits, so the compact beta header
+        must be forwarded instead of stripped (it was previously mapped to null,
+        which broke compact_20260112 context edits over /v1/messages)."""
+        filtered = filter_and_transform_beta_headers(
+            beta_headers=["compact-2026-01-12"], provider="vertex_ai"
+        )
+
+        assert filtered == ["compact-2026-01-12"]
+
     def test_null_value_headers_filtered(self):
         """Test that headers with null values are always filtered out."""
         for provider in [