Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add sangrokjung/claude-forge/plugin install claude-forgeWrote 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/sangrokjung/claude-forge/harness-diet)<a href="https://agentmods.dev/skills/sangrokjung/claude-forge/harness-diet"><img src="https://agentmods.dev/badge/skills/sangrokjung/claude-forge/harness-diet/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/sangrokjung/claude-forge/harness-diet"><img src="https://agentmods.dev/badge/skills/sangrokjung/claude-forge/harness-diet.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 | $0.00140 | $0.01868 |
| Opus 5 | $0.00070 | $0.00934 |
| Sonnet 5 | $0.00028 | $0.00374 |
| Haiku 4.5 | $0.00014 | $0.00187 |
Grade A, and why
harness-diet 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 8d ago.
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.
How it starts
The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
harness-diet — put your always-loaded context back under budget
A harness gains weight automatically (every incident note, every boss directive, every fix lands as another paragraph in an always-loaded rule) but only loses weight when someone runs a diet. Field measurement on a mature harness: growth-to-reduction commit ratio of ~60:1, natural growth of ~70KB/month, and adherence degrading as the pile grows. Anthropic's guidance is blunt: "target under 200 lines per CLAUDE.md file. Longer files consume more context and reduce adherence", and rules without
pathsfrontmatter load "with the same priority as CLAUDE.md" — every session, every token (memory docs).
Result you should expect: one field run took a harness from 146KB always-loaded (143% of budget) to 100.6KB (98%) with zero governance loss — every killswitch, decision table, trigger keyword, and canonical command verified present after the diet.
Budgets (defaults — override via flags)
| Metric | Budget | Why |
|---|---|---|
| CLAUDE.md | < 200 lines | Anthropic official guidance |
| Per always-loaded rule file | 8,192 B | Keeps any single rule scannable; forces narrative out |
| Total always-loaded rules | 102,400 B | Attention-budget ceiling; beyond this, adherence drops |
Bundled script paths: commands below use
$HOME/.claude/skills/harness-diet/…(theinstall.shlayout). For marketplace (/plugin install) installs, resolve under${CLAUDE_PLUGIN_ROOT}/skills/harness-diet/…instead. The scripts are stdlib-only Python; if unavailable, perform the step manually from the described contract.
Phase 0 — Measure
DIET="$HOME/.claude/skills/harness-diet" # or "${CLAUDE_PLUGIN_ROOT}/skills/harness-diet"
python3 "$DIET/scripts/harness_diet_audit.py" # human summary
python3 "$DIET/scripts/harness_diet_audit.py" --json # machine output
python3 "$DIET/scripts/harness_diet_audit.py" --strict # exit 2 if over budget (CI/ratchet)
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 8d ago First seen · 125 lines · 140 tokens per session scan A 78cb11bfe568
harness-diet is a skill published in the GitHub repository sangrokjung/claude-forge (835 stars, last pushed 8d ago), licensed MIT. It adds 140 tokens to every session and 1,868 once invoked, about $0.0007 per session on Opus 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 2026-09-03.
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