Four small things, one interesting design gap
The backlog had four issues tagged XS or S. I batched them onto one branch to clear them in a session.
The spec-only fix
The grouped-view spec (#173) described setting hidden on transitionend during collapse animation, but didn’t guard against the user re-expanding mid-collapse. CSS reverses the transition, transitionend fires at the expanded position, and the unguarded handler hides a fully visible section. The row-detail-expansion spec had already solved this with two guards — a property filter (max-height vs the shorter opacity transition) and a state guard (.collapsing class still present). Applied the same pattern. No code change — grouped-view isn’t built yet.
The fire-and-forget that shouldn’t have been
The reconnection gap work (#174) was more interesting than expected. EventConnection already parsed the server’s gaps array from the ListenAck response — topics where the server couldn’t fully replay missed events. But the reconnect path was fire-and-forget: sendListen() was called in ws.onopen without registering a pending entry, so the ack (and its gaps) were discarded on arrival.
The fix reuses the existing pending map mechanism. Instead of creating a new callback path, the reconnect listen registers a pending entry whose resolve function calls setStatus('connected', { gaps }) instead of resolving a Promise. The connected status is now deferred until the ack arrives — which is the correct semantics. “Connected” should mean “subscriptions restored and ready to receive events,” not just “WebSocket open.”
EventStream.onReconnect gains a gaps: string[] parameter. Consumers can now distinguish a clean reconnect from one with data holes and show a stale-data UX if needed.
Cursor persistence
The cursor persistence work (#175) was straightforward once #174 landed. A new cursorStorage option on EventConnectionOptions accepts a Storage instance. On construction, persisted cursors seed topicSeqs; on each seq update, they’re written back. Page reloads reconnect with a since map instead of requesting a full snapshot. Storage key is URL-scoped (pages-ec:<url>), cleaned on unlisten and removed on close. Corrupted storage is silently ignored.
The action button that already existed
The action button issue (#138) described a component that didn’t exist — but PagesActionButton was already implemented in pages-viz with tests, pages-action-request dispatch, and runtime integration. The actual gap was narrower: missing ghost and outline variants, no disabled property, no loading spinner. Added all three. The architectural question — whether this should be a Lit component in pages-primitives instead of a vanilla component in pages-viz — is real but separate from the functional gap.