# hermes.md

> **TL;DR.** hermes.

- **Category:** AI / Developer Tools / Billing
- **Stage:** validating
- **Age:** 52 days
- **Origin date:** 2026-04-25
- **First detected:** 2026-04-30
- **Canonical URL:** https://earlyterms.com/term/hermes-md
- **Sources:** 8 primary URLs

## Definition

hermes.md is the project-specific configuration file used by [Hermes Agent](https://github.com/NousResearch/hermes-agent) (NousResearch), the 126k-star AI coding agent. Stored at the git root as `HERMES.md` or `.hermes.md`, it holds the agent's system prompt context and takes highest priority over `AGENTS.md` or `CLAUDE.md` when Hermes assembles its prompt.

The filename became a named incident on April 25, 2026, when it was discovered that the case-sensitive string `HERMES.md` appearing in any git commit message caused Claude Code to silently reroute API calls to pay-as-you-go "extra usage" billing — bypassing a user's Max plan quota and generating a [$200 overcharge](https://github.com/anthropics/claude-code/issues/53262). Anthropic initially refused a refund before reversing under public pressure.

## Analogy

A shipping label with the wrong carrier code — your package still moves, but you get billed full freight instead of your contract rate.

## Why it's emerging now

On April 25, 2026, a developer found that `HERMES.md` in any git commit message caused Claude Code to silently charge pay-as-you-go rates instead of their Max plan — draining $200 while 86% of quota sat unused. The thread hit 1,194 points on HN, exposing Anthropic's harness-detection as a content-filter false-positive on bare substring matching.

## Related terms

- *parent:* hermes-agent
- *related:* agent-harness
- *related:* openclaw
- *related:* agents-md
- *related:* claude-code
- *related:* stop-hook
- *related:* context-rot
- *related:* claude-opus-4-6
- *alias:* AGENTS.md
- *alias:* Hermes Agent config

## Sources

1. [GitHub Issue #53262 — HERMES.md in commit messages causes requests to route to extra usage billing](https://github.com/anthropics/claude-code/issues/53262)
2. [GitHub Issue #53171 — HERMES.md triggers 400 'out of extra usage' on Max OAuth (content filter false-positive)](https://github.com/anthropics/claude-code/issues/53171)
3. [TechCrunch — Anthropic says Claude Code subscribers will need to pay extra for OpenClaw support](https://techcrunch.com/2026/04/04/anthropic-says-claude-code-subscribers-will-need-to-pay-extra-for-openclaw-support/)
4. [Consumer Rights Wiki — Anthropic Claude Code HERMES.md billing flaw](https://consumerrights.wiki/w/Anthropic_Claude_Code_HERMES.md_billing_flaw)
5. [Hermes Agent prompt assembly docs — HERMES.md as top-priority context file](https://hermes-agent.nousresearch.com/docs/developer-guide/prompt-assembly)
6. [NousResearch/hermes-agent — GitHub (126k stars)](https://github.com/NousResearch/hermes-agent)
7. [Theo (t3.gg) on X — billing differently for certain words in prompt](https://x.com/theo/status/2048456227538231751)
8. [ThePrimeagen on X — Anthropic has no clue what's going on in their codebase](https://x.com/ThePrimeagen/status/2048847631015653456)

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_Generated by EarlyTerms · https://earlyterms.com/term/hermes-md_