issue when using it on copilot windows

[darklight9811]

the error translates to the token is not a valid instructions separator in this version

[DietrichGebert]

Thanks for the report and the screenshot.

That error ("the token is not a valid instructions separator in this version") looks like the Copilot CLI build rejecting the format the SessionStart hook uses to inject context, not ponytail's content itself.

Two things would help me pin it:

1. Which Copilot CLI version (copilot --version)?
2. Does the instruction-only fallback work for you? Drop AGENTS.md or .github/copilot-instructions.md in the project, or copy the rules into ~/.copilot/copilot-instructions.md. That path skips the hook entirely, so if it works it confirms the hook output is the culprit.

Leaving open while I dig in.

[maxfelker]

tl;dr (ponytail, on behalf of @maxfelker): the hook is the bug, not the rules. skip it. copilot-instructions.md is the fix right now.

---

ponytail audit of this issue:

yagni: the SessionStart hook is convenience scaffolding, not load-bearing. It injects context ponytail's rules don't need at runtime — they're static text. This Copilot version is rejecting the separator format the hook emits. The rules themselves are fine.

native: .github/copilot-instructions.md is the platform-native path. It bypasses the hook entirely, requires zero code change, and works on every version that supports instructions files.

shortest fix:

cp ~/.claude/plugins/.../ponytail/rules.md .github/copilot-instructions.md

(or copy the relevant rules block in manually)

If the hook separator format needs patching for your Copilot version, copilot --version will tell us which token format it expects — but try the instructions file first. The lazy path usually works.

[maxfelker]

@darklight9811 thanks for the issue report. Would love to hear what version you're on and if the @DietrichGebert recommendations work.

@DietrichGebert had ponytail run an audit on the and it confirmed your recommendation. I'm going debug locally in the mean time to see if I can reproduce

[maxfelker]

@DietrichGebert ponytail and I got together to resolve the issue. Found a leak in the activation which was a pretty simple fix and something I think I missed in the original PR. Please take a look at this and let me know what you think.

#181

Would still love to hear from @darklight9811 before we merge but wanted to have something for your review.