Teach this on backtoschool.help: a class title that fits, walked up from the lecture to its collection

[ralyodio]

What broke

Clicking Teach this on backtoschool.help while a folder channel was live failed with:

Could not open a classroom: title is too long

A folder channel names its entry by the whole served path, and a course is deep (Coursera - Deep Learning Specialization/1. Neural Networks.../Week 1.../03_what-is-a-neural-network.mp4), so the title ran past the school's 160-character limit in live-events.ts. The school's own form already has maxlength="160", so the one-click flow was the only sender of an oversize title.

What changed

classTitle() in web/src/live-context.ts trims a title that does not fit by walking up from the file:

• the lecture (cleaned by liveTitle, so 03_what-is-a-neural-network.mp4 becomes what-is-a-neural-network) and the outermost folder (the collection) are always kept
• the folders between are filled back in from the lecture upward while they fit, so the nearest context survives first
• if even collection + lecture run over, the collection is cut at a word and the lecture stays whole
• a title with no path is cut at a word; a title that already fits is left alone

Example at 160: Coursera - Deep Learning Specialization › Neural Networks and Deep Learning Basics › what-is-a-neural-network-and-how-does-it-learn

teachOnSchool() in web/src/app.ts passes the share title through it before POSTing the class.

Verified

• bun test web/test: 109 pass (2 new tests for classTitle)
• web typecheck clean

🤖 Generated with Claude Code