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Term

Tab completion

Inline code suggestion that appears as ghost text and accepts on Tab. The original AI-assist UX, popularised by GitHub Copilot in 2021. Distinct from chat, edit, and agent modes which involve multi-turn interaction.

Background

Tab completion is the lowest-friction AI surface in coding tools. The model predicts the next several tokens or lines and renders them as inline ghost text; pressing Tab accepts. Latency must stay under ~300 ms for the UX to feel natural, which constrains model size — providers run distilled or smaller specialist models for this surface. As agentic modes mature, tab completion remains the most-used feature by line count across all AI coding tools.