Problem

A Greptile/Jihoon meeting prep in Slack rendered a whole sentence with a strikethrough through it. The struck span started at $3K and ended right before 2 , the tell.

The agent wrote two approximations using a leading tilde: ~$3K and ~2 (tilde = "approximately"). It did not write any strikethrough.

This is not a remark-gfm issue (that's the web app). Slack prep is built server-side by Cedar's own converter markdownToSlackRichText → parseInline, whose inline tokenizer deliberately supported single-tilde strikethrough (~strike~, Slack's native syntax). The two stray single tildes got paired, striking everything between them.

Fix

• Drop the single-tilde alternative from the inline regex , strikethrough now requires double tildes (~~strike~~); a lone ~ is left literal.
• Renumber the downstream capture-group references after removing the branch.
• Update comments to document why single-tilde strike is gone.

Single-tilde strike is vanishingly rare in agent output; single-tilde "approximately" (and ~/path, ~5%) is common , same tradeoff as remark-gfm's singleTilde: false.

Tests

• Replaced the stale "renders ~strike~" assertion with double-tilde-only.
• Added a regression test feeding ~$3K … ~2 that asserts nothing is struck and both literal ~$3K/~2 survive.

21/21 tests pass in markdown-to-slack-richtext.test.ts; edited file typechecks clean.

Scope note

The sister converter convertMarkdownToSlackMrkdwn (utils/slack-mrkdwn.ts) is untouched , it has no tilde rule and only produces the plain-text fallback string, not the visible rich_text blocks. That lower-traffic raw-mrkdwn path (fallback/overflow, slack-bot-chat replies) still relies on Slack's own single-tilde rendering; can be addressed separately if desired.

🤖 Generated with Claude Code

Greptile Summary

The PR prevents approximation markers such as ~$3K and ~2 from being paired as Slack strikethrough delimiters.

• Restricts rich-text strikethrough parsing to double-tilde Markdown syntax.
• Renumbers downstream tokenizer capture references consistently.
• Adds regression coverage ensuring single tildes remain literal and unstruck.

Confidence Score: 5/5

The PR appears safe to merge, with the intended double-tilde-only behavior covered by a focused regression test.

The tokenizer’s capture groups remain correctly aligned after removing the single-tilde branch, and no current caller-visible defect or repository-rule violation remains.

Important Files Changed

_{Reviews (1): Last reviewed commit: "fix(slack): don't strike single-tilde "a..." | Re-trigger Greptile}