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dedash — Claude Code skill: strip em-dashes by context

A skill that finds em-dashes and the marks standing in for them in a scope you name, then picks punctuation that fits each clause.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓
npx skills add LilMGenius/paperthin --skill dedash -a claude-code
Open on GitHub

What dedash does

You hand it a scope: a passage, a field, a file, a selection, or a whole tree. The skill walks that scope looking for any mark doing an em-dash's job — setting off an aside, an appositive, an abrupt turn, or standing in for a missing conjunction. It judges by role in the sentence, not by codepoint. U+2014, the horizontal bar U+2015, and the two- and three-em dashes U+2E3A and U+2E3B all count. Hyphens, minus signs, and ranges like 1990–2020 or London–Paris stay.

Each replacement follows the grammatical role. A parenthetical aside gets commas or parentheses. An appositive gets a colon or comma. An abrupt turn gets a full stop, semicolon, or comma. Where the dash replaced a missing connective, the sentence is rewritten. No blanket sweep: the same glyph can need different punctuation in different clauses.

After editing, the skill re-reads every changed sentence and fixes awkward rhythm, doubled spaces, and lost connectors. Code, diffs, command output, identifiers, URLs, and paths are left alone. It reports how many dashes it found and changed. Edits run per occurrence with unicode-safe handling (PYTHONUTF8=1), because a blanket replace breaks meaning where context differs. If the scope holds no such dash, it reports a miss instead of touching nearby punctuation.

Genuinely ambiguous cases — a deliberate em-dash in stylized prose, say — surface as judgment calls rather than silent mutations. The scope stays exactly as you named it.

What it helps with

  • strip em-dashes from a finished draft
  • swap dashes for commas or parentheses per clause
  • catch U+2015 and U+2E3A look-alikes too
  • keep hyphens, minus signs, and ranges intact
  • re-read edited sentences for broken rhythm

Example prompts for the agent

  • remove the em-dashes in docs/intro.md
  • go through the selected passage and replace each dash with punctuation that fits
  • check src/ for marks doing an em-dash's job

How to install dedash

1Skills CLI (Vercel)

npx skills add LilMGenius/paperthin --skill dedash -a claude-code

2Manually: put the files in place

~/.claude/skills/dedash/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/dedash/

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about dedash

How do I install dedash in Claude?

Run npx skills add LilMGenius/paperthin --skill dedash -a claude-code. The skill lands at ~/.claude/skills/dedash/SKILL.md.

What does dedash do?

It finds marks acting as em-dashes inside the scope you name and replaces each one with the punctuation or wording its clause needs, chosen by grammatical role.

Which dashes count as em-dashes?

U+2014, the horizontal bar U+2015, and the two- and three-em dashes U+2E3A and U+2E3B. Hyphens, minus signs, and ranges such as 1-10 or London–Paris are left untouched.

Source text

SKILL.md · MIT
---
name: dedash
disable-model-invocation: true
description: "Remove em-dashes and the dashes standing in for them from a user-owned scope, reading each occurrence in context and choosing the punctuation or wording that fits."
---

Remove em-dashes and the dashes standing in for them from the scope the user names, one occurrence at a time, while leaving hyphens, ranges, and deliberate marks alone.

## Goal

Replace each em-dash that should not remain with the mark or wording its clause actually needs. Target any dash doing an em-dash's job, whatever its exact character: U+2014 and its longer or repurposed look-alikes all read the same on the page. The user owns the scope: a passage, field, file, selection, or tree. Do not widen it without asking.

## Workflow

1. **FIND**: Take the exact scope from the user and locate every dash doing an em-dash's job in it, judged by the role it plays in the sentence, not its codepoint: any mark that sets off an aside, an appositive, an abrupt turn, or a missing conjunction. The em-dash (U+2014) is the common one; the horizontal bar (U+2015) and the two- and three-em dashes (U+2E3A, U+2E3B) read the same and count. The en-dash (U+2013) is the boundary case: it counts when it joins clauses where an em-dash would fit, but stays when it spans a range's endpoints, numeric or not (`1990–2020`, the `London–Paris` route). A dash doing a non-em job (a hyphen, a minus, a range) stays. Surface anything genuinely ambiguous as a judgment call rather than changing it blindly.
2. **REPLACE per role**: Choose per occurrence by grammatical role:
   - *Parenthetical aside*: commas or parentheses when the dashed material can be lifted out of the sentence.
   - *Appositive*: a colon or comma when the dashed material renames, defines, or expands the noun before it.
   - *Abrupt turn*: a full stop, semicolon, or comma when the dash marks a pivot, interruption, or restart.
   - *False-conjunction break*: rewrite the sentence when the dash stands in for a missing "and", "but", "because", "so", or another real connective.
3. **LEAVE-ALONE**: Unless the user explicitly includes them and the context proves them wrong, leave untouched:
   - hyphenated compounds, minus signs, and negative numbers
   - ranges such as `1-10`, `1–10`, or `London–Paris`; a range dash is not an em-dash
   - code, diffs, command output, identifiers, serialized data, URLs, paths, anchors, and query strings
   - quoted or clearly deliberate em-dashes in stylized prose; these surface as judgment calls, never as blind mutations
4. **RE-READ**: Read every changed sentence in place. Fix awkward rhythm, dangling punctuation, doubled spaces, and connector loss introduced by the replacement. If the sentence now needs wording instead of punctuation, rewrite the smallest clause that solves it.
5. **REPORT**: State the scope checked, how many dashes were found and changed, which replacements were used by role, and anything left alone or surfaced as a judgment call.

## Rules

- Never do blanket replacement. The same glyph can require different punctuation in different clauses.
- Never replace an em-dash with a hyphen as the cleanup.
- Mutate with edit-safety: edit unicode-safe (`PYTHONUTF8=1`) and replace each dash per occurrence, never a blanket sweep; if the scope contains no such dash, report a MISS rather than changing nearby punctuation.
- Preserve the user's voice. This skill removes a mark where requested; it does not flatten style outside the user-owned scope.

## Verification

Before finishing, confirm:

1. The scope stayed exactly user-owned.
2. Every replacement was selected per occurrence by grammatical role.
3. Leave-alone cases stayed untouched or were reported as judgment calls.
4. The report includes counts and any judgment calls.

© LilMGenius · MIT · LilMGenius/paperthin

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