diff --git a/agent/anthropic_adapter.py b/agent/anthropic_adapter.py
index b58535914b3..740986203d4 100644
--- a/agent/anthropic_adapter.py
+++ b/agent/anthropic_adapter.py
@@ -1076,9 +1076,12 @@ def normalize_model_name(model: str, preserve_dots: bool = False) -> str:
         # These must not be converted to hyphens.  See issue #12295.
         if _is_bedrock_model_id(model):
             return model
-        # OpenRouter uses dots for version separators (claude-opus-4.6),
-        # Anthropic uses hyphens (claude-opus-4-6). Convert dots to hyphens.
-        model = model.replace(".", "-")
+        # Only convert dots to hyphens for Anthropic/Claude models.
+        # Non-Anthropic models (gpt-5.4, gemini-2.5, etc.) use dots
+        # as part of their canonical names.  See issue #17171.
+        _lower = model.lower()
+        if _lower.startswith("claude-") or _lower.startswith("anthropic/"):
+            model = model.replace(".", "-")
     return model