Problem activity feeds, live presence, and Vim mode

This release is about seeing other people on the site — what they're solving, what they just shared, and reacting to it.

Activity on every problem

The Discussions tab is now an Activity feed. Alongside discussion posts, it shows recently shared solutions — who solved it, in what language, how fast — and you can drop a 🔥 on a solution or comment on it right under the code. Filter by All, Posts, or Solutions.

See where your people are

A new Following band on the dashboard shows live what the people you follow are doing: solving a problem, in a study group, or in a collab session — and when they were last active if they're away. The activity strip below it also now scrolls back through your full history instead of capping at three rows.

The editor learns your keybindings

• Vim and Emacs modes, selectable from editor settings and persisted.
• Hotkeys: Ctrl/Cmd+' runs the samples, Ctrl/Cmd+Enter submits.
• Ctrl/Cmd+Z undoes your last stroke while draw mode is on.
• Right-click → Paste finally pastes.

Re-run the case that beat you

Viewing a past failed submission now lets you pin its failed case straight into the Run flow — editable copy if it fits, re-check by id if it's oversized — so you can iterate against exactly what broke.

Study group scoring, fixed properly

Scores could go negative on long sessions (solving more problems could lower your score). The rule is rebuilt: harder problems are worth more, your score is the sum of distinct problems solved, and the leaderboard actually ranks by score. The session timer also no longer drifts when your clock is off.

Plus: garbled punctuation across problem descriptions is repaired, shared-solution views lost their double scrollbar, and dashboard stream thumbnails stay fresh.