Start a session

Tell the agent what to do from the start page, from a project, or from Slack, and choose its repositories, model, permission mode, and who can find the session.

3 minutes

A session is one task for the agent, from your first message to a merged pull request. You can start one from the start page, from a project, or from Slack, and the box that takes your task is the same in the first two.

Start from New

Open New

Choose New at the top of the sidebar. The page greets you and puts the cursor in the box. On a phone, New is the middle tab, and the box sits at the bottom of the screen.
Say what the agent should do

Describe the change in the box, or paste an error. You can attach files with the paperclip or draw a diagram. Until you type, the box’s placeholder sums up how the session will run, from its start to the merge.
Choose a project, if it belongs to one

The project button in the box puts the session in a project, so it gets that project’s repositories and defaults. See Projects.
Choose Start session

The agent reads your message as soon as it starts. The session opens on its own page, where you follow the work.

The box starts with the choices most sessions need. More, under the box, opens the rest, and Less folds it away again. On a phone, the + in the box opens Add to this session, which holds the files, the project, and everything More holds.

What you can choose

Setting	Where it is	What it does
Repositories	More › Repositories	The repositories the agent works in. The picker lists what your connected code hosts offer, with Suggested first, and you can pick several.
Base branch	Set base branches, under the repository picker	The branch the agent starts a repository from. Leave it alone and each repository uses its default branch.
Model and effort	The model button in the box’s footer	The model, how hard it thinks (Low to Max), and Per phase, which runs planning, executing, or review on a model of its own.
Permission mode	More › How it runs	The mode the session starts in, from Manual to Bypass, and whether it waits for you when it needs an answer. See Autonomy.
After the pull request	More › How it runs › Once the PR is open	How far Evergreen takes the pull request by itself. See Pull requests.
What it carries	More › Session	Which of your instructions, plugins, memory, hooks, and agents from Settings the session uses. The change is for this session only.
Visibility	More › Session	Public or Private, described below. Once the session is private, the choice moves into the box, beside the project.
Coordination	More › Session	Whether the agent messages agents in other sessions on the same code, so they split the work. It’s described below.
Spending limit	More › Session	The session stops once its cost reaches the amount you set. Its branch and pull requests stay.

Repositories and base branches

You can leave Choose repositories (optional) empty. The agent then looks for the right repositories and asks you to confirm them before it clones anything. When you do pick repositories, choose Set base branches to start one from a branch other than its default. Type to filter the branch list, or name a branch the list doesn’t show. Clear branches puts every repository back on its default.

A repository marked Archived is there for context. The agent can read it but can’t push to it or open a pull request there.

Model and effort

Open the model button and pick a row. Model lists the models your workspace offers, and Effort sets how much the agent thinks, from Low (minimal thinking for the fastest answers) to Max (the most thinking the model supports). Per phase is off until you set a phase, and its Clear button resets them all. For what each model offers, see Models.

Permission mode

The first chip under How it runs is the mode the session starts in.

Manual asks before every edit and command.
Accept edits makes edits without asking, and commands ask first.
Plan reads and plans, changes nothing, then presents a plan for you to approve.
Auto runs on its own while a classifier checks each action.
Bypass runs without any checks.

The second chip, When it needs an answer, is Waits for you or Carries on without you. If your organization’s admins turned Auto or Bypass off, the menu still lists the mode but you can’t pick it. You can switch modes at any time while the session runs. Autonomy explains each mode in more detail.

If you leave these alone, a session starts in your project’s default mode, if it has one. Otherwise it uses your own default from Settings › Defaults, or the last mode you picked if you turned on Remember my last mode there. With none of these set, it starts in Auto and waits for you.

Who can find the session

The Who can find this session choice has two answers.

Everyone at Acme, with your organization’s name, makes the session Public. It shows in their session lists, and only collaborators can message the agent, answer its questions, and approve plans.
Only people you add makes it Private. It stays out of session lists, and only people with access can open it, such as the people you add and the people on its project. A link alone doesn’t open it.

A session starts public, except in a project that’s visible to its team or private. There it starts private unless you choose Everyone at Acme, so the session reaches the same people as its project. When where you start may surprise you, a sentence under the box says who can find the session and why, for example “Only people you add ▾ can find this session, because Payments is private.” Its first words are the choice itself, so you can change it right there. The sentence also speaks up when your last few sessions in an open project were private, when most of your recent sessions were private, and in a fork of a private session, which stays private.

While a new session is private, its choice sits in the box beside the project and names who will be able to read it.

In a list, only a private session is marked, with a lock before its title. A public session has no mark. You can change it later under Visibility on the session’s Details tab, or in its Share dialog, where General access reads “Everyone at Acme ▾ can open this session” or “Only people you add ▾ can open this session”. Work together covers adding people and who can open a private session.

Coordination

Coordination is a beta, and you only see the Coordination chip if it’s turned on for you. It starts on Coordinates. When two coordinating sessions work on the same code, Evergreen connects them, and their agents message each other to split the work and keep off each other’s changes. This includes your own sessions, so when you split a change across several sessions, their agents talk it through. A public session pairs only with public sessions, and a private one only with private sessions that the same people can open. Choose On its own and the agent doesn’t message agents in other sessions. You can change it later under Coordination on the session’s Details tab.

Tip

Pick Plan for a task you haven’t done before. A plan takes a minute to read and is the cheapest place to change direction.

Start from a project

Open a project from Projects. Its page has the same box at the top, which reads Start a session in and the project’s name until you type. A session started here belongs to the project and begins with the project’s settings: its repositories when you name none, its default permission mode if it sets one, its merge policy, and its minimum testing level. You can still change any of them for the one session.

Start from Slack

Once your workspace has connected Slack, you can start a session without leaving it. Slack covers the connection.

Type /evergreen and choose Start a session. A form opens with the task, the repositories, the model, and Mode. More options adds the base branch, a project, thinking, When the agent needs you, validation, visibility, and what the session carries.
Type /evergreen start followed by your task to start at once with your defaults.
Choose Send to Evergreen from the menu on any message to open the form with that message as the task.
Mention @Evergreen in a channel, or message the bot directly, and name the repository in your request. Evergreen starts a session and replies with a link. You can record a voice note instead of typing, as Slack explains.

Files can’t be attached in Slack’s form. Drop them into the session’s conversation after it opens.

The session talks to you in a new private channel by default, or in the thread where you asked. You choose under Settings › Defaults, in the Slack group, with Conversations. The same group has Start every session in Slack, which gives a session started on the web a Slack conversation right away.

What happens next

The agent writes a plan, or starts work, depending on the session’s permission mode. When it needs you, the session shows a card, and Plans and asks explains how to answer it from the web, Slack, or your phone.

Last updated October 19, 2026