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fix: strip billing header from Anthropic system prompt for prefix cache #277

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Merged
waybarrios merged 1 commit into from
Apr 11, 2026
Merged

fix: strip billing header from Anthropic system prompt for prefix cache #277

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5 changes: 5 additions & 0 deletions vllm_mlx/api/anthropic_adapter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
"""

import json
import re
import uuid

from .anthropic_models import (
Expand Down Expand Up @@ -60,6 +61,10 @@ def anthropic_to_openai(request: AnthropicRequest) -> ChatCompletionRequest:
system_text = "\n".join(parts)
else:
system_text = str(request.system)
# Strip per-request billing/tracking headers injected by some
# clients (e.g. Claude Code). These contain a per-request hash
# that prevents prefix-cache reuse across turn boundaries.
system_text = re.sub(r"x-anthropic-billing-header:[^\n]*\n?", "", system_text)
messages.append(Message(role="system", content=system_text))

# Convert each message
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