Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add chhoumann/t3-pstack --skill principle-guard-the-context-windowgit clone --depth 1 https://github.com/chhoumann/t3-pstackWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/chhoumann/t3-pstack/principle-guard-the-context-window)<a href="https://agentmods.dev/skills/chhoumann/t3-pstack/principle-guard-the-context-window"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/principle-guard-the-context-window/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/chhoumann/t3-pstack/principle-guard-the-context-window"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/principle-guard-the-context-window.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00046 | $0.00112 |
| Opus 5.5 | $0.00018 | $0.00045 |
| Sonnet 5.5 | $0.00009 | $0.00022 |
| Haiku 4.5 | $0.00005 | $0.00011 |
Grade A, and why
principle-guard-the-context-window scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- principle-guard-the-context-window — 86% identical, 0 lines differ
What it actually says
Guard the Context Window
Why: Context overflow degrades reasoning quality, creates compression artifacts, and halts progress.
Pattern:
- Size phases and cap scope. Limit files per phase, set turn budgets, account for mechanism costs.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday Changed af0b9dd70b43
- 3d ago First seen · 13 lines · 46 tokens per session scan A 6db84b7d5e67
principle-guard-the-context-window is a skill published in the GitHub repository chhoumann/t3-pstack (190 stars, last pushed yesterday), licensed MIT. It adds 46 tokens to every session and 112 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-13.
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