HERMES.md in git commits triggers extra billing in Claude Code
A bug in Claude Code causes requests to route to extra usage billing instead of plan quota when the case-sensitive string `HERMES.md` appears in a git repository's recent commit history.
Score breakdown
Watch git commit history for the string `HERMES.md` if using Claude Code on a Max plan — its presence can silently exhaust extra usage credits instead of drawing from included plan quota.
- 01The case-sensitive string `HERMES.md` in a git commit message causes Claude Code to route requests to extra usage billing instead of plan quota.
- 02The reporter states the bug silently consumed $200 in extra usage credits while their Max 20x plan was only at 13% weekly usage.
- 03The bug reproduces on Claude Code `v2.1.119` on macOS (Apple Silicon).
A GitHub issue (#53262) filed against the `anthropics/claude-code` repository describes a billing bug where the case-sensitive string `HERMES.md` in a git repository's recent commit history causes Claude Code to route API requests to extra usage billing instead of the user's included plan quota. The reporter states the issue silently burned through $200 in extra usage credits while their Max 20x plan ($200/month) remained at only 13% weekly usage. The bug reproduces on Claude Code `v2.1.119` on macOS (Apple Silicon) with models `claude-opus-4-6` and `claude-opus-4-7`.
The trigger is the string in commit messages, not the presence of a file with that name on disk.
The reproduction is minimal: initializing a git repo, creating a single commit whose message contains `HERMES.md` (uppercase), and then running any Claude Code prompt triggers a 400 API error reading "You're out of extra usage..." The same steps with `hermes.md` (lowercase) in the commit message work normally and route to plan quota. The trigger is the string in commit messages, not the presence of a file with that name on disk. The issue notes that Claude Code includes recent commits in its system prompt, and something server-side routes the request differently when `HERMES.md` is detected in that context. The source text is truncated before further details are provided.
Key facts
- 01The case-sensitive string `HERMES.md` in a git commit message causes Claude Code to route requests to extra usage billing instead of plan quota.
- 02The reporter states the bug silently consumed $200 in extra usage credits while their Max 20x plan was only at 13% weekly usage.
- 03The bug reproduces on Claude Code `v2.1.119` on macOS (Apple Silicon).
- 04Affected models include `claude-opus-4-6` and `claude-opus-4-7`.
- 05Lowercase `hermes.md` in a commit message does not trigger the behavior — the bug is case-sensitive.
- 06The trigger is the string in git commit messages, not the presence of a file named `HERMES.md` on disk.
- 07Claude Code includes recent commits in its system prompt, and something server-side routes requests differently when `HERMES.md` is present.