fix(normalizer): 移除 Claude system 中的 billing header

tests/core/api_format/conversion/test_claude_normalizer.py

@@ -369,8 +369,8 @@ def test_claude_request_metadata_preserved() -> None:
     assert out["metadata"]["user_id"] == "user_abc123_session_xyz456"
 
 
-def test_claude_system_array_format() -> None:
-    """测试 Claude CLI 风格的 system 数组格式"""
+def test_claude_system_array_format_drops_billing_header() -> None:
+    """Claude system 数组中的 Anthropic billing header 不应进入内部 instructions。"""
     n = ClaudeNormalizer()
 
     req = {
@@ -386,12 +386,51 @@ def test_claude_system_array_format() -> None:
 
     internal = n.request_to_internal(req)
 
-    # system 数组中的多个 text 应该用 \n\n 连接
+    # billing header 应被移除，其余 system 文本仍按顺序保留
     assert internal.system is not None
-    assert "x-anthropic-billing-header" in internal.system
+    assert "x-anthropic-billing-header" not in internal.system
     assert "You are Claude Code" in internal.system
     assert "Extract file paths" in internal.system
     assert "\n\n" in internal.system
+    assert internal.extra["raw"]["dropped_blocks"]["claude_system_billing_header_removed"] == 1
+
+
+def test_claude_system_string_strips_billing_header_and_keeps_following_prompt() -> None:
+    n = ClaudeNormalizer()
+
+    req = {
+        "model": "claude-3-opus",
+        "messages": [{"role": "user", "content": "hello"}],
+        "system": "x-anthropic-billing-header: cc_version=2.1.19\n\nYou are Claude Code.\nKeep answers terse.",
+        "max_tokens": 4096,
+    }
+
+    internal = n.request_to_internal(req)
+
+    assert internal.system == "You are Claude Code.\nKeep answers terse."
+    assert internal.extra["raw"]["dropped_blocks"]["claude_system_billing_header_removed"] == 1
+
+
+def test_claude_system_array_strips_billing_header_prefix_but_keeps_same_block_prompt() -> None:
+    n = ClaudeNormalizer()
+
+    req = {
+        "model": "claude-3-opus",
+        "messages": [{"role": "user", "content": "hello"}],
+        "system": [
+            {
+                "type": "text",
+                "text": "x-anthropic-billing-header: cc_version=2.1.19\n\nYou are Claude Code.",
+            },
+            {"type": "text", "text": "Extract file paths."},
+        ],
+        "max_tokens": 4096,
+    }
+
+    internal = n.request_to_internal(req)
+
+    assert internal.system == "You are Claude Code.\n\nExtract file paths."
+    assert internal.extra["raw"]["dropped_blocks"]["claude_system_billing_header_removed"] == 1
 
 
 def test_claude_request_reuses_raw_tool_choice_and_stabilizes_message_sequence() -> None:

tests/core/api_format/conversion/test_cli_conversion.py

@@ -71,6 +71,67 @@ def test_claude_request_to_openai_cli_places_instructions_before_input() -> None
     assert openai_cli_req["input"][0]["role"] == "user"
 
 
+def test_claude_request_to_openai_cli_drops_anthropic_billing_header() -> None:
+    reg = _make_registry_with_cli()
+
+    claude_req = {
+        "model": "claude-3-5-sonnet-latest",
+        "system": [
+            {
+                "type": "text",
+                "text": "x-anthropic-billing-header: cc_version=2.1.74.705; cc_entrypoint=claude-vscode; cch=4fb9f;",
+            },
+            {"type": "text", "text": "You are Claude Code."},
+            {"type": "text", "text": "Keep answers terse."},
+        ],
+        "messages": [{"role": "user", "content": "hi"}],
+        "max_tokens": 12,
+    }
+
+    openai_cli_req = reg.convert_request(claude_req, "claude:chat", "openai:cli")
+
+    assert openai_cli_req["instructions"] == "You are Claude Code.\n\nKeep answers terse."
+    assert "x-anthropic-billing-header" not in openai_cli_req["instructions"]
+
+
+def test_claude_request_to_openai_cli_keeps_prompt_after_billing_header_prefix() -> None:
+    reg = _make_registry_with_cli()
+
+    claude_req = {
+        "model": "claude-3-5-sonnet-latest",
+        "system": [
+            {
+                "type": "text",
+                "text": "x-anthropic-billing-header: cc_version=2.1.74.705\n\nYou are Claude Code.",
+            },
+            {"type": "text", "text": "Keep answers terse."},
+        ],
+        "messages": [{"role": "user", "content": "hi"}],
+        "max_tokens": 12,
+    }
+
+    openai_cli_req = reg.convert_request(claude_req, "claude:chat", "openai:cli")
+
+    assert openai_cli_req["instructions"] == "You are Claude Code.\n\nKeep answers terse."
+    assert "x-anthropic-billing-header" not in openai_cli_req["instructions"]
+
+
+def test_claude_request_to_openai_cli_strips_billing_header_from_string_system() -> None:
+    reg = _make_registry_with_cli()
+
+    claude_req = {
+        "model": "claude-3-5-sonnet-latest",
+        "system": "x-anthropic-billing-header: cc_version=2.1.74.705\n\nYou are Claude Code.\nKeep answers terse.",
+        "messages": [{"role": "user", "content": "hi"}],
+        "max_tokens": 12,
+    }
+
+    openai_cli_req = reg.convert_request(claude_req, "claude:chat", "openai:cli")
+
+    assert openai_cli_req["instructions"] == "You are Claude Code.\nKeep answers terse."
+    assert "x-anthropic-billing-header" not in openai_cli_req["instructions"]
+
+
 def test_claude_response_to_openai_cli() -> None:
     reg = _make_registry_with_cli()