What is book_chapter.update_from_source?

A book-editing tool that updates a Markdown or LaTeX chapter so it matches changes in a separate source file.

Use it to incorporate source-file changes into a book chapter while preserving the target chapter's structure and style.

It avoids manually comparing the two files and uses the recorded Git version to identify what changed since the chapter was last generated.

book_chapter.update_from_source — Skill for Claude Code by gpsaggese

Install

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.

Any agent

npx skills add gpsaggese/helpers --skill book_chapter.update_from_source

Clone the repo

git clone --depth 1 https://github.com/gpsaggese/helpers

Made for: Claude Code.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/gpsaggese/helpers/book_chapter.update_from_source/github.svg)](https://agentmods.dev/skills/gpsaggese/helpers/book_chapter.update_from_source)

Your own site

<a href="https://agentmods.dev/skills/gpsaggese/helpers/book_chapter.update_from_source"><img src="https://agentmods.dev/badge/skills/gpsaggese/helpers/book_chapter.update_from_source/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/gpsaggese/helpers/book_chapter.update_from_source"><img src="https://agentmods.dev/badge/skills/gpsaggese/helpers/book_chapter.update_from_source.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 12 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,281 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00012	$0.01281
Opus 5.5	$0.00005	$0.00512
Sonnet 5.5	$0.00002	$0.00256
Haiku 4.5	$0.00001	$0.00128

Measured yesterday against content hash 60798e5e1176, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

book_chapter.update_from_source 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.

.claude/skills/book_chapter.update_from_source/SKILL.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Goal

Given a book content file <TARGET> (markdown or tex) and its source file <SOURCE>, find the changes in <SOURCE> and incorporate them into <TARGET>

Workflow

Read the Version Header

<SOURCE> has a header with the Git hash and timestamp of the material used to generate the current <TARGET>

E.g.,

% git_hash=<GIT_HASH>, timestamp=<TIMESTAMP>
% <SOURCE>

E.g.,

% git_hash=f15bc6b9, timestamp=2026-07-15 14:41:12 EDT
% book_springer/lectures_source/Lesson02.1_From_Data_Science_To_Decision_Science.txt

Get the diff of <SOURCE> since <GIT_HASH> once, up front, not per section:
```
> git diff <GIT_HASH> -- <SOURCE>
```

Incorporate Changes

Modify <TARGET> to reflect every change in <SOURCE> since <GIT_HASH>
Follow the style of <TARGET>, reading the matching .claude/skills/*.rules.md
<TARGET> may be a superset of <SOURCE>. A .typ chapter routinely adds headings, diagrams, or paragraphs that group or expand several flat .smd slides (see "Structural Hierarchy" in typst.rules.md)
- If <SOURCE> drops a heading or diagram that <TARGET> built on, keep the <TARGET> content, since it has no direct counterpart anymore
- Remove it only if the diff shows the underlying fact or example was changed or retracted, not merely reorganized out of the slide deck
Update the header at the top of <TARGET> to the new hash and timestamp:
```
// git_hash=<NEW_GIT_HASH> timestamp=<NEW_TIMESTAMP>
```

Compare Entire Flow

Make the flow of <TARGET> (typst, latex, or md) follow the flow of <SOURCE>

E.g., run extract_toc_from_txt.py on both files and compare

> extract_toc_from_txt.py -i msml610/lectures_source/Lesson03.3-Non_classical_logics.smd

> extract_toc_from_txt.py -i msml610/book/Lesson03.3-Non_classical_logics.typ

Ensure the flow of <TARGET> is consistent with <SOURCE>

Update Source-Line References

A .typ <TARGET> has a // From: <SOURCE>:<LINE> '<slide title>' comment above each section, pointing to the exact <SOURCE> line it was generated from
An edit above a slide shifts every later line number. After incorporating the changes, walk the // From: comments top to bottom and fix each <LINE> so it matches the slide's current position in <SOURCE>
- Find a slide by grepping <SOURCE> for its * or # title

Read the full file on GitHub · 100 lines

Changes

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 · 100 lines · 12 tokens per session scan A 60798e5e1176

Subscribe to this mod's changes

book_chapter.update_from_source is a skill published in the GitHub repository gpsaggese/helpers (158 stars, last pushed today), licensed Apache-2.0. It adds 12 tokens to every session and 1,281 once invoked, about $0.0000 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 2026-11-06.

Commits Git and workflow Writing and docs

book_chapter.update_from_source next to 6 skills from other repositories
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book_chapter.update_from_sourcegpsaggese/helpers	Skill	158	today	Apache-2.0	A	12	Claude Code
create-prprisma/orm	Skill	48k	today	Apache-2.0	A	48	Claude Code, Codex
git-commitThinkInAIXYZ/deepchat	Skill	6.4k	yesterday	Apache-2.0	A	15	Claude Code, Codex
repo-syncdavidondrej/skills	Skill	4.3k	yesterday	MIT	A	25	Claude Code, Codex
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