Lab references deep-link to article sections or external sources, show linked cards with study links, and educators can attach cards and article targets. Grouped panel layout. Migration i2d3e4f5a607. 57 backend and 93 frontend tests pass.
Add Orthobullets-inspired numbered-answer UI, explicit study response confirmation, response statistics, review navigation, safe calculator, keyboard controls and sourced educator lab references. Persist attempt mode to prevent query-flag exam disclosure. Combined deployed-image backend suite (22), frontend suite (48), build and synthetic desktop/mobile browser checks pass. PostgreSQL round-trip and independent review remain release gates; no production deployment.
