Run JetBrains Junie in a tab

Agents: junie · On: phone, desktop

A tab can run Junie, JetBrains' coding agent CLI (junie). Fezu drives it over the CLI's ACP mode, so its answers, edits, plans and approvals show in the same transcript as the other agents.

Why you would use it

You use Junie with a JetBrains AI subscription, or with your own model key, and want to run it from the phone with the same controls you use on the other agents' tabs. Without either, you can still run Junie's free model in one-shot runs. This page lists what Junie does in a tab and what it does not.

How to use it

Install the CLI if the workstation does not have it. See install-an-agent.
Log in. Junie runs on a JetBrains account with a JetBrains AI subscription, or on a model key in the workstation's environment. See Logging in below.
Pick Junie in a tab's agent menu (#agentpick, under the message box), then a model in the model menu (#modelpick).
Set the effort on the same menu: low, medium, high or xhigh, as the model offers them.

The agent menu with Junie in its list after Copilot, with its mark.

Logging in

A JetBrains account. Tap Log in on Junie's row in the agents card, or send /login in a Junie tab. The card shows 1. Open the link and approve. and the link. Sign in to your JetBrains account there. The page then ends on a localhost address that does not load on your phone. The card says 2. The page ends on a localhost address that does not load. Copy that whole address and paste it here. Paste it into the field (Paste the address from the page that did not load) and tap Submit. The workstation checks the address and hands it to Junie. Junie gives up on a login after 5 minutes, so finish within that time.
A model key. A JUNIE_API_KEY (made on junie.jetbrains.com/cli), or a key for one provider, in the workstation's Fezu environment file counts as logged in. The provider keys Junie reads are JUNIE_OPENAI_API_KEY, JUNIE_ANTHROPIC_API_KEY, JUNIE_GOOGLE_API_KEY, JUNIE_GROK_API_KEY, JUNIE_META_API_KEY and JUNIE_OPENROUTER_API_KEY. The agents card names the key it found, never its value.

A JetBrains account without a JetBrains AI subscription logs in, but Junie then refuses every message in a full session. With How Junie runs on Auto (the default), Fezu then moves the tab to one-shot runs on Junie's free model; see One-shot runs. With it on Full session (ACP) the tab shows:

No active JetBrains AI subscription found. Junie needs a JetBrains AI subscription for this account, or a model key in the box's env (JUNIE_API_KEY or a provider key); see /login.

One-shot runs

A one-shot run sends each message to Junie as a run of its own, and the next message carries on the same Junie session. It is the only way to reach Junie's free model (Junie Lite): JetBrains turns that model off in a full session, so an account with no JetBrains AI subscription can use Junie only this way.

Open the cog's Agents card and tap Junie's row.
Pick how Junie runs in How Junie runs (#agent-run-junie):
- Auto: a full session while your account can run one. When a message fails because the account has no subscription, the workstation remembers it and new Junie tabs open on one-shot runs. A model key in the workstation's environment keeps Auto on a full session.
- Full session (ACP): always a full session, with every Junie feature this page lists.
- One-shot runs: always one-shot runs.
A tab on one-shot runs shows Junie's default model in the model menu (#modelpick), with the efforts low, medium and high. Without a model key that is the free model.

On Auto, a tab at Full whose message fails for lack of a subscription moves on its own and sends the same message again. The transcript shows:

Junie has no plan on this account: switched to one-shot runs on Junie's free model

A tab in Plan does not switch: its message fails with Junie has no plan on this account, and one-shot runs have no Plan; turn Plan off to run on Junie's free model, and nothing is sent again.

A tab at Ask or Auto stays where it is, and its message fails with:

Junie's free model runs only at Full, with no approvals; set the tab to Full to use it.

The workstation forgets that the account has no subscription when you log in to Junie again, and when you change How Junie runs. The setting is kept on each workstation and is not synced to your other workstations.

What a one-shot tab does:

Full only. Junie asks nothing in a one-shot run, so Full is the only level. A tab moved to one-shot runs at Ask or Auto keeps its level and shows Ask is not available on oneshot:default; set the tab to Full to use it (or Auto); its messages fail until you set it to Full.
Steps, not live text. Each step Junie finishes shows as a card when it finishes, and the reply shows when the run ends. Nothing streams in between.
Edits. The files Junie changed show as diffs when the run ends.
Stop. Stop ends the run at once.
Queue. A message you send while a run works waits for the run to end.
Resume after a restart. The next message carries on the same session.
Context. Junie keeps the whole session, step output included, and the context meter shows its size after each run. The free model's window is 262,144 tokens, below the default auto compact mark of 270k, so set a lower mark with /autocompact if you want Fezu to compact a long tab.
/compact. Fezu ends Junie's session, and your next message starts a new one with the transcript in front of it. See auto-compact.
A new session on a switch. A tab that moves between a full session and one-shot runs starts a new Junie session, so Junie does not see the messages from before the switch.

What works

Models. The model menu lists Junie's mixes (Normal, Hard, Frontier), the JetBrains AI models, the models of a provider key with the provider in brackets, such as Claude Haiku 5.5 (OpenRouter), and local Ollama models.
Steering. A message you send while a turn runs joins that turn. See queue-or-steer.
Stop. Stop ends the running turn. See stop-a-running-turn.
Resume after a restart. The tab picks its Junie session up again when Fezu restarts. See resume-after-a-restart.
Adopting a session. A Junie session on the workstation is listed on the resume screen by its title. Adopting it opens a tab with the session's conversation in it. See resume-a-session-from-disk.
/compact. Fezu sends Junie its /compress command. Junie answers Context will be compressed before the next task and compacts at the start of your next message, which shows a context compacted row.
Approvals. Below Full, a request from Junie shows as a card with Allow and Deny. After a Deny Junie carries on without that command and says so. See permission-levels.
Plan. Plan turns on Junie's plan mode. Junie's plan shows as the plan card; tap Build on it to turn Plan off and let Junie build. While it builds, its steps show in the plan strip.
Reasoning. Junie narrates its steps as it works. Those lines show as the tab's thinking rows; its answer shows as the reply.
Images. Images you attach go to Junie with the message.
Context meter. The tab's context figure follows the size Junie reports.

The levels

Fezu	What Junie does
Ask	Edits files without asking. Asks before it runs a command. Each request is a card.
Auto	Runs the commands Junie judges safe. Asks before the rest.
Full	Asks nothing.
Plan (flag)	Junie's plan mode, on any level. It reads and plans, and asks before any command.
Full, on one-shot runs	Asks nothing. The only level a one-shot run has; there is no Plan.

What you see

An effort the model does not offer is refused with model <model> does not support effort <effort>; supported: <efforts>.
Without a login the agents card shows not logged in and Log in.
A pasted address that is not the one Junie's login sent you to is refused with That is not the address Junie's login sent you to. Copy the whole address from the page that did not load.

Options and settings

Setting	Default	What it changes
`JUNIE_BIN` (environment variable on the workstation)	unset	The path to the `junie` binary. It wins over every other place Fezu looks.
`JUNIE_HOME` (environment variable on the workstation)	`~/.junie`	Where Junie keeps its sessions and logs. Fezu reads both there.
Update every hour, `agentUpdate.junie`	off	Runs Junie's installer once an hour when no Junie tab works. See update-agents-automatically.
How Junie runs, `agentRun.junie`	`Auto`	A full session, one-shot runs on Junie's free model, or Auto, which picks. Kept on each workstation. See One-shot runs.

Limits and known gaps

A subscription or a key is required. See Logging in.
A model or effort change restarts the process on the same session.
Building a plan writes a file into your project. Junie keeps the plan it builds in .junie/plans/<name>.md in the tab's folder.
A message sent just as a command starts can leave one extra card for that command marked interrupted: Junie drops the call and runs it again.
No fork, no side questions, no /mcp, no rewind. These are not offered on a Junie tab yet.
No usage meter. Junie reports no account quota here, so the usage meters have no Junie row. The context meter still works.
Junie cannot ask you a question. It asks in its reply instead.
One-shot runs have no approvals, no Plan, no steering, no attachments, no fork, no side questions and no live model switch. A message with an attachment fails with Attachments are not available in one-shot runs. Plan is refused with Plan is not available in one-shot runs.
One-shot runs do not stream. A step shows only once Junie finishes it, and the reply only at the end of the run.
After a Stop, the next one-shot message may finish the stopped task first. Junie picks the stopped task up again and reports on it, and the new message may go unanswered. Send it again.
A one-shot run that ends without a reply fails the turn with the last message or error line Junie printed, or junie exited code=<code> signal=<signal> without a result.
Adoption imports the last 400 items of the session at most. The agent still has the whole session.
Binary lookup. On Linux and macOS Fezu uses JUNIE_BIN if it is set, then junie on PATH, then ~/.local/bin/junie. If none exists the tab fails with junie is not installed (looked on PATH and in <folder>). On Windows it uses JUNIE_BIN, then junie on Path, and fails with junie is not installed (looked on Path).

the-three-agents: the agents and what each one can do
copilot: GitHub Copilot, the other agent on the same ACP core
permission-levels: the levels and Plan
switch-the-model: the model and effort menu
resume-a-session-from-disk: finding and adopting sessions
install-an-agent: installing the CLI from the phone
log-in-to-an-agent: logging in from the phone