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The input mode always started in simple; a learner who quit in advanced had to re-toggle every launch. Store the mode per-project in project.yaml (project.mode:, optional, default simple) and restore it on every open. Mode is live UI state, not schema: the worker stamps the current mode into project.yaml on every write, so a later command rewrites the live value rather than clobbering it — no db round-trip needed. The mode is persisted on unload (quit + project switch) so the mode you leave a project in is always what reopens; the `mode` command also persists immediately. A switch saves the outgoing mode, then restores the incoming project's stored mode. New --mode simple|advanced CLI flag (precedence --mode > stored > simple; combines with --resume). A teacher can ship a project that opens in advanced mode and export it to students (the mode travels in the zip). ADR-0015 Amendment 1; ADR-0003 note; help banner; requirements L1b.