The no-emdash lint rule was added in #24375 but only enforces on new code (added lines in the diff). There are ~1170 existing violations across the repo.

Scope

• Replace all Unicode emdash (U+2014) and endash (U+2013) characters with commas, semicolons, periods, or restructured sentences.
• Heaviest concentrations: coderd/x/chatd/, site/src/pages/AgentsPage/, docs/ai-coder/agents/, scripts/releaser/.
• Generated files (api/typesGenerated.ts) inherit from Go source doc comments; fix the Go source, then regenerate.
• Agent instruction files (AGENTS.md, site/AGENTS.md, .claude/docs/GO.md) contain emdash in the rule text and surrounding prose.

After cleanup

Simplify scripts/check_emdash.sh to scan all tracked files instead of parsing diffs. The script reduces from ~114 lines to ~15.

Refs #24375

🤖 Filed by Coder Agents on behalf of @mafredri.