2 min lesson
Cursor 3 ('Glass'): the agent window is the default surface
Answer this: "A developer wants a coding agent to run on every pull request to catch convention violations, with no editor window involved. Which Cursor surface fits and what keeps its behavior consistent with how the team's editor behaves?"
Step 1 of 2
Cursor 3 ('Glass'): the agent window is the default surfaceoutput to outcome
The framing that dates a candidate fastest: a year ago Cursor's core was three things - Tab, indexing and chat. The current product is an end-to-end SDLC control plane, and the most-recent top-level surface is Cursor 3An older release label for Cursor's multi-agent interface; current product guidance calls the active surface the Agents Window. Press Enter for the full definition. (called Glass, or the agent's window), shipped roughly a month before the 2026 workshops. It is one abstraction level above the editor: it shows every workspace across local and cloud environments, multiple repos and archived/active agents, and it was redesigned ground-up to manage many parallel agents rather than to edit one file. You can still toggle back to the classic editor view (file tree left, code center, terminal bottom, agent pane right). The design rationale is the line worth memorizing: as models improved, attention shifted from the model's output (the exact code) to its outcome.
The mode dropdown (Agent, Plan, Debug, Ask) changes the tools available to the same underlying model - not the model itself. Agent (default) does everything: writes code, runs the terminal, makes plans and to-dos. Plan researches the whole indexed codebase and outputs only an editable plan, making no edits until you switch to Agent. Debug adds instrumentation and walks you through reproduction. Ask is read-only Q&A over the codebase - a smaller toolset, output stays in chat - ideal for onboarding to a legacy codebase or for non-engineers. Saying "changing the mode changes the toolset, not the model" out loud is a fast credibility signal.
When asked what Cursor can do, don't list features. Open with the framing - "a year ago this was Tab, indexing and chat; now it's an SDLC control plane" - then draw the three layers and place each capability, then pick one scenario and walk the surface you'd choose. That structure shows you think in terms of jobs and surfaces, which is exactly how a DX Engineer reasons about what to teach.