- Sanitize Content-Disposition filenames to prevent header injection (strip control chars, quotes, semicolons)
- Add CloudFront cookie refresh middleware so cookies are re-issued when expired
- Log errors in groupAttachments instead of silently swallowing them
- Move useFileUpload hook to shared/hooks/ per project architecture conventions
- Add uploadWithToast helper to deduplicate try/catch/toast pattern across 3 components
- Refactor ApiClient.uploadFile to reuse auth headers, 401 handling, and error parsing
- Allow empty MIME types client-side (let server sniff and decide)
- Constrain Image extension max-width in rich-text-editor to prevent layout overflow
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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