logger.py: batch-checkpoint refactor (see app.py commit for details)

key-pool rotation: per-session OpenAI key assignment from OPENAI_KEY_01..10 (core/logger.py)

Session-recovery propagated from socratic: hidden gr.Textbox (#recovery-payload) + Gradio .then(js=...) chains write/clear localStorage; on_submit_initial / on_end_session yield JSON events on their CONFIRM yields. RECOVERY_HEAD adds modal styling + window.__SOC_RECOVERY helpers; storage key no_ai_session_v1; touch-observer adapted (no chat input — watches chatbot clicks + arg_input edits). on_recover_session rebuilds chatbot as [case_display, user_arg, INTRO_MESSAGE, perfect_answer.text] (mirrors on_submit_initial yield 2) and re-activates the 60s snapshot_timer. SessionLogger.from_dict restores dominant_framework (no_ai's logger lacks argument_submitted_at, so that field is skipped).

UI parity with socratic/socratic-frame: (1) hide Gradio Chatbot top chrome via show_label=False + CSS for share/clear/delete/trash; (2) strip the '# Case: ...' H1 from the initial chatbot message via display-only CASE_TEXT_DISPLAY; (3) hide the left yellow feedback-hint column (guide-col visible=False) so chatbot expands left, and drop the bottom-row mirror column to keep action buttons aligned under right-col.

Format walkthrough_started_at + argument_submitted_at as ISO 8601 in payload

Add walkthrough_started_at field to logger (top of payload, preserved across start_session)

Deploy: no_ai control bot — chapters TOC + essay logging