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 ondrej-svec/heart-of-gold-toolkit --skill harness-syncgit clone --depth 1 https://github.com/ondrej-svec/heart-of-gold-toolkitWrote 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/ondrej-svec/heart-of-gold-toolkit/harness-sync)<a href="https://agentmods.dev/skills/ondrej-svec/heart-of-gold-toolkit/harness-sync"><img src="https://agentmods.dev/badge/skills/ondrej-svec/heart-of-gold-toolkit/harness-sync/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/ondrej-svec/heart-of-gold-toolkit/harness-sync"><img src="https://agentmods.dev/badge/skills/ondrej-svec/heart-of-gold-toolkit/harness-sync.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 | $0.00109 | $0.01789 |
| Opus 5 | $0.00055 | $0.00894 |
| Sonnet 5 | $0.00022 | $0.00358 |
| Haiku 4.5 | $0.00011 | $0.00179 |
Grade A, and why
harness-sync 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 12d 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 — 196 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Harness Sync
Move a working Claude Code harness to a second machine, and keep the two from drifting apart afterwards.
Distinct from its siblings: marvin:harness-up writes doctrine into a target
repo (AGENTS.md, docs taxonomy). marvin:scaffold installs dependencies and
configs. This skill replicates the harness itself — ~/.claude.
Boundaries
This skill MAY: clone or pull the user's config repo, read local config,
run claude plugin install commands, run the harness validator, report drift.
This skill MAY NOT: push to any remote, commit on the user's behalf, write
credentials, overwrite an existing ~/.claude without explicit confirmation,
or copy machine-local state (logs, auto memory, plugin caches, tokens).
Common Rationalizations
| Shortcut | Why It Fails | The Cost |
|---|---|---|
"Just rsync the whole ~/.claude" |
Carries credentials, logs, plugin caches and per-machine auto memory | Tokens leak onto a second machine; caches for the wrong architecture |
| "Clone over the existing config, it's probably the same" | It usually is not, and the delta is invisible after the fact | Local-only skills and hooks destroyed with no record |
| "Config is tracked, so the machines match" | Plugins install out-of-band; a tracked settings.json can name marketplaces that were never added here | Skills silently missing, hooks referencing plugins that aren't installed |
| "Skip validation, the repo was fine on the other machine" | Absolute paths, missing binaries and unexecutable scripts are all machine-specific | A harness that looks installed and silently no-ops |
Phase 0: Detect Mode
Entry: Skill invoked, optionally with check, install, or drift.
Resolve the mode:
| Signal | Mode |
|---|---|
| Argument given | Use it |
~/.claude/.git absent |
install — nothing here yet |
~/.claude/.git present, argument absent |
check |
If install and ~/.claude already contains un-tracked local work, stop and
ask via AskUserQuestion before touching anything.
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.
- 12d ago First seen · 196 lines · 109 tokens per session scan A 6958ffd603b4
harness-sync is a skill published in the GitHub repository ondrej-svec/heart-of-gold-toolkit (19 stars, last pushed 23d ago), licensed MIT. It adds 109 tokens to every session and 1,789 once invoked, about $0.0005 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 2026-08-30.
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