Semantic Line Breaks

Semantic Line Breaks

This page explains how dotclaude puts each sentence on its own line. It covers the sembr slice, which rewrites the text that Claude writes to a file or to a command. It is for a contributor who edits the sembr slice or who checks a rewrite.

dotclaude puts each sentence of the text that Claude writes on its own line. The sembr slice does this before the call runs. So the fix costs no model token. The code is in src/plugins/dotclaude/slices/sembr/. The rationale is in Decisions.

Why a Program and Not a Rule

• A semantic line break puts each sentence on its own line. The rendered output does not change. A diff shows which sentence changed.
• Claude joins sentences on one line in files and commits. CLAUDE.md asks for one sentence on each line.
• A rule in prose did not hold. So a program fixes the text. The check phase of the guard slice is described in Guards.
• The hook rewrites the input of the call. It never rewrites the file after the write. A rewrite after the write can make the next Edit fail with File has been modified since read. This is an inference from the bundle text, and it was not run.

Where It Runs

slice.ts declares one tool.call handler with the filter Write, Edit, and Bash. The phase is rewrite, so the handler runs before the check phase of the guard slice. adapters/mod.ts dispatches on the tool name.

Tool	Rule	Function
Write	Rewrites content of a Markdown file.	writeInput
Edit	Fixes old_string when it crosses a sentence end, and rewrites new_string.	editInput, repairEdit, rewriteEdit
Bash	Rewrites the quoted heredoc of git commit and gh pr create.	commandInput, rewriteCommand

The rules are pure functions in domain/rewrite.ts. They import only domain/split.ts and the kernel.

Which Files Change

isMarkdown in src/kernel/text.ts checks the path. It is true for a path that ends in .md or .mdx, in any letter case. A file of another type passes through with no change.

The Formatter

sembr in domain/split.ts is pure string code with no import. It only splits lines, and it never joins them. So an existing break stays, and a second run gives the same text.

• It splits after ., !, or ? when a space and a new sentence follow. The next sentence must start with a capital letter, a backtick, a quote, an opening bracket, an asterisk, or an underscore.
• It does not split after the abbreviations in the ABBREVIATIONS set, such as e.g. and i.e.. A missed split is better than a wrong split.
• It leaves unchanged the code spans, the link targets, the URLs, the fenced blocks, the <pre> and <code> blocks, and the math blocks. It also leaves unchanged the headings, the table rows, the link definitions, the HTML lines, and the horizontal rules.
• It keeps the list marker and the quote prefix of a split line.

Edit

• adapters/mod.ts checks the file with $.fs.exists first. A file that does not exist makes the handler return null. The Edit then runs as written.
• repairEdit runs when old_string is not in the file as written, and its split form is in the file. The handler then splits both strings and calls next.
• rewriteEdit changes new_string only when the edit starts and ends at line bounds of the file. A fragment of a line, a table row, and a span of inline code stay unchanged. rewriteEdit skips an edit with replace_all.

Bash

rewriteCommand acts only on the quoted heredoc forms:

• git commit -m "$(cat <<'EOF', which changes the message.
• gh pr create --body "$(cat <<'EOF', which changes the body.

For any other form (-m "...", -F, --body-file, or an unquoted heredoc), the command stays unchanged. The rewrite keeps the first line of a commit message, which is the subject. It keeps the last paragraph when each of its lines is a trailer, such as Co-Authored-By:. When an output line would equal the heredoc delimiter, the command stays unchanged.

Failure

A rule that throws is a defect. The handler lets the error reach Claude Code. Claude Code logs the error, skips the hook, and runs the call as written. The hook does not decide the permission, so the normal permission flow stays. A write still asks for approval. gh pr create still asks before it publishes.

The hook prints no additionalContext and no systemMessage. So the rewrite adds no token to the model context.

Chat

dotclaude does not rewrite the chat reply. A probe of a session.append handler showed that the handler changed the stored rows and the shown text. The handler also fired once for each content block of a reply. The rewrite also changed the result text of claude -p --output-format json.

Related Pages

• Guards: the checks that run after this rewrite.
• Prompt-Surface: the text that the plugin adds to the prompt.