JetBrains 2026.3 Ships Air Natively: Run Claude Agent, Codex, Copilot, Junie in-IDE; BYO Subscriptions Locally; Junie Lite Free

Core Background & Industry Pain Points

Builders often juggle terminal agents, desktop apps, and the IDE—split subscriptions, hard-to-review diffs, and colliding parallel tasks. JetBrains moved Air in IDEs into EAP in October; with the 2026.3 stable wave in November 2026, Air ships as a built-in agentic layer—not another closed model vendor, but a way to wire the Claude / Codex / Copilot subscriptions you already pay for into IDE review, tests, and refactors.

Architecture Highlights & Internals

Air detects agents already installed and extends via the ACP registry. Claude Agent can sign in with a Claude subscription in the terminal or a full-screen IDE tab; other agents run in chat or terminal, and you can switch subscriptions or API keys mid-session. Agents can use IDE symbol search, rename refactoring, inspections, and run configurations; IntelliJ IDEA and CLion also expose the debugger. Parallel work uses Git worktrees; MCP servers and Skills can be configured once and reused. Official docs note worktrees isolate working trees, not security sandboxes.

Authoritative Benchmarks & Measured Scores

JetBrains did not publish a unified SWE-bench-style board for Air; this item invents no scores. Product claims: Air ships with all JetBrains IDEs in 2026.3; Junie Lite is free with a JetBrains Account; local sessions need no JetBrains AI plan; cloud Air Teams / longer handoffs need JetBrains AI (mobile Teams called out around Nov 15). Choose based on your existing subscriptions and ACP agent list rather than waiting for a single official ranking.

Developer Hands-on Guide

Upgrade to IntelliJ IDEA / CLion / PyCharm 2026.3 via Toolbox or the site, or start at jetbrains.com/air/ides. Connect Claude / Codex / Copilot first, then add ACP agents as needed; use line comments and per-file rollback to review agent edits. Embedded teams should read CLion 2026.3 notes on hard-fault agent debugging and CMake setup help. If you still use AI Assistant, JetBrains says Skills/MCP/ACP credentials and regular chat history migrate (chat-mode history does not).