- Add `SanitizePromptText` stripping ~24 invisible Unicode codepoints
and collapsing excessive newlines
- Apply at write and read paths for defense-in-depth
- Frontend: warn in both prompt textareas when invisible characters
detected
- Explicit codepoint list (not blanket `unicode.Cf`) to avoid breaking
flag emoji
- 34 Go tests + idempotency meta-test, 11 TS unit tests, 4 Storybook
stories
> This PR was created with the help of Coder Agents, and was reviewed by my human.
Cian Johnston