* M9: collaboration: per-user undo, rejections, reconnect
Step 3 of docs/collab-protocol.md, the parts that don't need the transport:
- Per-user undo and redo (figcraft_collab::Client::{undo, redo}): each undoable batch is a step
(values before/after by target, nodes created/deleted). Others' batches ordered after the step
take its targets for good; creates invert to deletes (not when others built inside), deletes
re-create the subtree. An undo or redo waits for every earlier batch and is remade from the
confirmed state when it goes out; derived data follows as a follow-up batch.
- Rejections: refused batches leave the history (with an undo waiting on them) and queue a
Notice; the engine shows it through Session::message (the UI's toast).
- Offline queue and reconnect: Hello.resume {session, client_id, seq}; the server keeps a
bounded log and answers with the missed batches or a snapshot, plus what it did with the
client's batches (processed {last_batch, refused}); queued batches then go out.
Server::state / restore persist the session (client-id counter, log, session id).
- Presence carries editing_text {node, caret, selection}.
- Engine: documents in a live session (LiveDoc, Session::collab_*): commands, gestures and
groups sync as one step each; edit.undo / edit.redo route to the per-user history; remote
edits show under a gesture in progress. Outside a session snapshot undo is unchanged.
- Sim: dropped connections, undo/redo, and a checker that no undo reverts a change by someone
else its author had seen. New tests in undo_tests, reconnect_tests, collab_live_tests,
collab_undo_tests.
- CLAUDE.md / AGENTS.md: collab in the L2 layer list.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* M9: collaboration wording in the progress docs after per-user undo and reconnect
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
* M9: protocol doc: what the engine's live-session tests cover
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
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