HERMES.md — the five-character bug that drained a Claude Code wallet
HN's top story right now, 828 points in three hours. A user found that putting the literal string HERMES.md in any git commit message—case-sensitive, the .md extension matters—causes Claude Code v2.1.119 to route every API request to extra-usage billing instead of the Max plan quota. The reporter burned through $200.98 in credits while still having 86%+ of their weekly plan capacity available.
Reproduction is trivially simple. git commit -m "add HERMES.md" and run Claude Code, immediately get "you're out of extra usage." Change to lowercase hermes, works. Change .md to .txt, works. Strip the extension, works. The bug is exact-string-match.
What's happening underneath: Claude Code includes recent git commit context in its system prompt to the model. Anthropic's server-side routing logic intercepts requests containing HERMES.md and treats them as a special path that bypasses plan quota. The string is almost certainly an internal codename—a Hermes model variant or internal Hermes Agent project—and the routing rule leaked into customer-facing inference paths.
The issue is now closed, labeled area:cost and bug, but no public response from Anthropic.
The actual bug is solvable. The structural exposure isn't. Agent clients pull git history into system prompts by default. Vendor servers route on string matches against internal codenames. Every enterprise customer's git log is now an unaudited input to vendor billing routing. Cursor deleted a production database last week. Claude Code now has an agent-harness-can-drain-your-wallet-via-a-string-in-a-commit-message bug. The reliability of agent harnesses is becoming a discrete engineering problem distinct from model quality.
Link: https://github.com/anthropics/claude-code/issues/53262
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Reproduction is trivially simple. git commit -m "add HERMES.md" and run Claude Code, immediately get "you're out of extra usage." Change to lowercase hermes, works. Change .md to .txt, works. Strip the extension, works. The bug is exact-string-match.
What's happening underneath: Claude Code includes recent git commit context in its system prompt to the model. Anthropic's server-side routing logic intercepts requests containing HERMES.md and treats them as a special path that bypasses plan quota. The string is almost certainly an internal codename—a Hermes model variant or internal Hermes Agent project—and the routing rule leaked into customer-facing inference paths.
The issue is now closed, labeled area:cost and bug, but no public response from Anthropic.
The actual bug is solvable. The structural exposure isn't. Agent clients pull git history into system prompts by default. Vendor servers route on string matches against internal codenames. Every enterprise customer's git log is now an unaudited input to vendor billing routing. Cursor deleted a production database last week. Claude Code now has an agent-harness-can-drain-your-wallet-via-a-string-in-a-commit-message bug. The reliability of agent harnesses is becoming a discrete engineering problem distinct from model quality.
Link: https://github.com/anthropics/claude-code/issues/53262
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