CLAUDE.md: add ~100-line source file length convention

[d-morrison]

Summary

Adds a single File Structure guideline to CLAUDE.md:

• Aim to keep source files under ~100 lines; split longer files into named subfiles

Why

A review on #843 requested (1) decomposing the 462-line _sec_double_integrals.qmd into focused subfiles, and (2) recording the ~100-line size convention in CLAUDE.md.

The decomposition is handled in #843. This convention change is kept in its own dedicated PR per the CLAUDE.md rule that "Workflow / .github / CI / infra changes go in their own dedicated PRs — never mix them with book-content PRs."

Scope

One-line documentation change to CLAUDE.md; no .qmd/.R/content touched, so no render/lint/spell run is required.

https://claude.ai/code/session_01NQSLJmjMN22RpwpgJ6Lw6u

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Generated by Claude Code

[claude]

Claude finished @d-morrison's task in 48s —— View job

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Code Review

• Gather context
• Review the change
• Post findings

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Overall verdict: The change is correct and achieves its stated goal cleanly. Two minor clarity suggestions below.

CLAUDE.md line 39 (new line):

- Aim to keep source files under ~100 lines; split longer files into named subfiles

Finding 1 — Scope ambiguity: "source files" is unqualified, but the surrounding bullets are all .qmd-specific, and the split mechanism (_subfiles/) is a .qmd-only concept. It's not clear whether this convention is also intended for .R files in R/. A 100-line cap would be unusually tight for R package code. Consider scoping it explicitly: Aim to keep .qmd source files under ~100 lines; split longer files into named subfiles.

Finding 2 — "named subfiles" is slightly vague: The project already has a well-established _subfiles/ directory for this purpose. Saying split longer files into \_subfiles/`` (using the actual directory name) ties the convention to the project's existing structure and removes any ambiguity about where the splits should go.

Both are non-blocking suggestions. The change as written is still accurate and useful.

[claude]

Claude finished @d-morrison's task in 1m 44s —— View job

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Code Review

• Gather context
• Review the change
• Post findings

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Overall verdict: The change is correct, cleanly scoped, and ready to merge. Both findings from the prior review have been resolved by commit 29ceaa0.

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CLAUDE.md, line 39 (added):

- Aim to keep `.qmd` source files under ~100 lines; split longer files into named subfiles in `_subfiles/`

Prior findings — now resolved:

• Scope ambiguity — .qmd is now explicitly qualified. ✓
• "named subfiles" is vague — _subfiles/ is now named in the line. ✓

One non-blocking suggestion — bullet ordering:

The File Structure section currently reads:

- Subfiles (`_subfiles/`) must NOT begin with a section heading…
- Link to `.qmd` source files, not rendered `.html` files
- Aim to keep `.qmd` source files under ~100 lines; split longer files into named subfiles in `_subfiles/`
- `_extensions/` is vendored third-party code…

The new bullet references _subfiles/, so placing it directly after the existing _subfiles/ heading rule (bullet 1) would group all _subfiles/-related guidance together. As-is the ordering is fine — this is cosmetic only and does not block merge.

Fix ordering →

[claude]

Claude finished @d-morrison's task in 1m 45s —— View job

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Code Review

• Gather context
• Review the change
• Post findings

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Overall verdict: The change is correct, minimal, and achieves its stated goal. The PR is already merged. No blocking issues found.

The change — CLAUDE.md, line 39:

- Aim to keep `.qmd` source files under ~100 lines; split longer files into named subfiles in `_subfiles/`

Findings:

No blocking issues. One non-blocking cosmetic note:

Bullet ordering (cosmetic): The File Structure section now reads:

1. Subfiles (`_subfiles/`) must NOT begin with a section heading…
2. Link to `.qmd` source files, not rendered `.html` files
3. Aim to keep `.qmd` source files under ~100 lines; split longer files into named subfiles in `_subfiles/`  ← new
4. `_extensions/` is vendored third-party code…

Bullets 1 and 3 both reference _subfiles/. Moving bullet 3 to position 2 would group all _subfiles/-related guidance together. This is purely cosmetic — the current ordering is clear and accurate as-is.

Fix ordering →

Note: No inline review comment tool was available in this session, so findings are posted here rather than as line-level PR comments.