ZapMachine/kanban/tasks/017-make-session-folder-names-unique-stop-suppressing.md

id	title	status	priority	created	updated	started	completed	tags	claimed_by	claimed_at	class
17	Make session folder names unique, stop suppressing mkdir errors	done	medium	2026-07-17T03:57:50.884126062+02:00	2026-07-19T19:06:58.837663313+02:00	2026-07-19T19:06:58.839287746+02:00	2026-07-19T19:06:58.839287746+02:00	session	rain-raven	2026-07-19T19:06:58.837663313+02:00	standard

From framework review (docs/framework_review.md), P1-5. ZAP_MOMENT = date('Y-m-d-H_i_s') has second resolution. Two submissions in the same second collide on mkdir — suppressed with @, returns null folder, silently breaks all downstream operations. Fix: append random suffix to folder name, drop @, add recursive flag.