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 agentmods add skills/valsteen/write-code-by-hand/replace-linenpx skills add valsteen/write-code-by-hand --skill replace-linegit clone --depth 1 https://github.com/valsteen/write-code-by-handWhat 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 | $0.00046 | $0.00190 |
| Opus 5 | $0.00023 | $0.00095 |
| Sonnet 5 | $0.00009 | $0.00038 |
| Haiku 4.5 | $0.00005 | $0.00019 |
Grade A, and why
replace-line 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.
What it actually says
Replace Line
Replace one line with exactly the text supplied by the user.
Operational framing: perform single-line change control. No adjacent optimism.
Required Inputs
- Target file.
- Exact line number.
- Exact replacement text.
If any input is missing, ask for it.
Rules
- Replace only the specified line.
- Preserve the provided replacement exactly.
- Do not adjust surrounding lines.
- Do not choose a replacement from intent.
- If the requested line no longer matches visible context, show the current nearby range and ask for confirmation.
Output
Confirm:
Replaced <path>:<line> with the exact provided text.
What ships with it
1 file 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.
- yesterday First seen · 36 lines · 46 tokens per session scan A 6cb888b58f02
replace-line is a skill published in the GitHub repository valsteen/write-code-by-hand (5 stars, last pushed 2mo ago), licensed MIT. It adds 46 tokens to every session and 190 once invoked, about $0.0002 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 2026-08-31.
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