See every Claude Code session you're running as one live tree, a flock.

Hello, and welcome to Flock.

The aim of this project is a better environment for AI-related workflow. When you're running many agents, the hard part stops being the code — the work becomes the bookkeeping.

Flock puts all of it in the sidebar as a tree, to keep track of everything. From there, sessions fork and branch out. Around that sits a variety of nice-to-have features: notifications for finished sessions, sessions grouped under user-defined projects and their directories, LLM account management, temporary chats, and much more.

What it does

A tree of sessions, not a list. See which session was forked from which. Use the UI or native in-session /fork.
Attention routing. A dot at the right edge of the row: amber means working, red means finished. It's that easy.
A notifications bell. The latest finished sessions, unseen first, each with its project and age. Click one to jump there. Dismiss a single entry, or mark all read at once. Plus a per-session mute that puts the bell to rest.
Session age. The time on a row is how long since you last prompted that session.
Worktrees keep their sessions. Running one agent per git worktree is how parallel work actually gets done. A session started in a linked checkout of a project's repository is filed under that project wherever the checkout sits on disk, with nothing to configure.
Branch rows, if you turn them on. lineage.git.branches — off — gives each of a project's checkouts a colour-coded row, with New Worktree…, Remove Worktree, where each checkout stands against its upstream (↑2 ↓1, and * for uncommitted work), and, with lineage.git.pullRequests on as well, a pull-request chip per branch. It is off because it is a lot of rows in a sidebar that has to stay readable, not because it is unfinished. See Branches and worktrees are parked.
Use several accounts. A row per subscription, whether it's a work plan, a personal plan, or an API key. Each account shows its current usage. An account also keeps its own config directory, so you only need to sign in once per account. New sessions are routed automatically, and a session is then pinned to its account.
Project workspaces. Scope a window to one project. Switching saves the tab layout you leave and restores the target's. With tmux installed, other projects' sessions keep running while hidden and reattach instantly; without it they close and resume from transcript. Unsaved editors are never touched.
Orchestration verbs. New, fork, fork and compact, rename in place, close, close with summary. New Project, new session and fork are one click at the top of the sidebar, and the last two ask no question: + starts a session in the project you are working in, and fork branches off the conversation you are looking at. A gear beside them holds the housekeeping and the closed-sessions filter.
Temporary chats. The chat button on a project row opens a scratch conversation about that project. Right-click the project and Old Chats… for the list of past chats.
Subprojects: lanes of work, or directories. A project is scoped to one directory. Add Subproject makes a named lane in a directory — so ~/magma-cs-mcp can hold "the server rewrite" and "the CS tooling" as two rows, which nothing on disk could tell apart — or takes on another directory, which gets a row of its own labelled by its basename. Worktree sessions are filed under the directory that owns the repository, so nothing lands in a project-wide leftover row. A project that has never made a lane draws exactly the rows it always did.
Open and close projects. A project you are not working on this month doesn't have to be deleted to get out of the way: Close Project takes it out of the tree and changes nothing else. The $(folder-opened) button at the top of the view lists every closed project.
Nothing is lost. Closing a tab does not remove its row. It's dimmed and stays one click from resuming. Only Delete removes a row, and that is also undoable.
It works with the Claude you already run. The session list is machine-wide, so claude typed into the bottom panel, or a conversation started by the official Claude Code extension, is in the tree too — with its age, its status dot and its place in the fork tree. Click one and Flock reveals the terminal it is already running in rather than opening a second copy. Rows Flock does not own say elsewhere and are never offered a verb that would lie about them. Full table →

Requirements

tmux. See below. Install it before you start.
The claude CLI on your PATH, or lineage.claudeBinary set to its full path.
VS Code 1.94 or newer. Also runs in Cursor, Windsurf and VSCodium. Flock uses no proposed APIs.
A trusted workspace. Restricted Mode blocks terminal creation, which Flock needs.

Install tmux

You need tmux. Flock runs your sessions inside it, and that is what lets a session keep working while you look at something else.

brew install tmux          # macOS
sudo apt install tmux      # Debian / Ubuntu
sudo dnf install tmux      # Fedora
sudo pacman -S tmux        # Arch

Check it worked with tmux -V. That is all you have to do. Flock looks for tmux on your PATH every time it starts a session, so there is no reload and no setting to turn on.

Flock uses its own private server, tmux -L lineage. You will never see it. No status bar, no prefix key, and your own tmux sessions and config are left alone. tmux ls will not even list Flock's.

Skip it and Flock still runs, but switching projects closes the other project's sessions instead of hiding them. They come back when you switch back, resumed from their transcripts. Anything a session was in the middle of is gone.

Windows does not get this, sorry. Sessions there always close and resume. Other platforms →

Known limits

Branches and worktrees are parked

The branch block — a row per checkout, the worktree verbs, the per-branch colours, the pull-request chip — is off behind lineage.git.branches, and it is off because of the sidebar rather than because of the code. A repository with six checkouts is six rows before the first session, and a sidebar is 250px wide.

Nothing about it is unfinished: it reads real worktrees, git worktree add and git worktree remove still confirm and still show the command first, and the rules are covered by the same tests they always were. Turn the setting on to get all of it back, including its menus.

Worktree MEMBERSHIP is not part of the switch. A session started in a linked checkout is filed under the project that owns the repository whether the rows are drawn or not — turning a view option off must never move somebody's sessions.

There is a preview of the answer to the row-count problem. lineage.preview.directoryModel hangs the branch rows off a directory rather than off the project and lists every local branch of that directory's repository — with only the directory's own checkout and the branches something is running on outside a Branches (N) fold that is shut by default. A repository with a hundred and eighty branches then costs one row, which is what makes showing all of them possible at all. It needs lineage.git.branches too, draws in the inline sidebar, and is off by default while the promotion policy earns its keep. Details →

Workspaces claim each other's sessions

A workspace switch decides which sessions belong to the project it is switching to by asking whether their directory sits inside one of the project's directories. The sidebar asks a different question — which project's directory is the longest match — and the two disagree whenever one project's directory contains another's.

When they disagree, both projects' saved layouts can name the same session, so switching between them brings the same tabs back under either one. If your projects do not nest, you will not see it. If they do, the workaround today is to leave workspace mode (Settings → Switch Workspace… → Leave Workspace Mode) or to turn lineage.workspaces.enabled off.

This is a known bug with a known fix — membership in a switch should be matchProject's answer, the same one the tree renders — and it is not fixed in this release.

Documentation

Settings — all 32, with defaults.
Reference — how it works, projects, subprojects, notifications, workspaces, close vs delete, naming, the sidebar rendering modes, and what you get alongside the Claude Code extension.

Privacy

Nothing leaves your machine unless you turn on one setting, named below. Flock reads the local session roster and local transcript files, and writes only to its own extension storage — plus, if you explicitly opt in, the hooks plugin directory and ~/.lineage/events.ndjson.

Your repositories are read on a timer and changed only when you ask. By itself Flock runs git worktree list --porcelain and git status --porcelain=v2 --branch, both reads, both cached. New Worktree… and Remove Worktree run git worktree add and git worktree remove — after a confirmation that shows you the exact command, and a second one before anything uncommitted is deleted.

lineage.git.pullRequests is the one thing in Flock that reaches the network, and it is off by default. With it on, Flock shells out to the gh CLI that you installed and signed in yourself: gh pr list while the Sessions view is visible, at most once every five minutes per repository, and gh pr create --web when you ask for it. Flock makes no HTTP requests of its own, bundles no API client, and never sees or stores a token. If gh is missing, not signed in, or the repository has no GitHub remote, the rows render exactly as they do with the setting off — one line in the Flock output channel, no dialog.

Development

npm install
npm run typecheck   # tsc --noEmit, source and tests
npm test            # vitest run
npm run compile     # esbuild bundle -> dist/extension.js
npm run watch       # rebuild on change

Press F5 to open an Extension Development Host with Flock loaded. There are no runtime dependencies — the extension is Node builtins plus the vscode API, bundled into a single file by esbuild. See CONTRIBUTING.md for the rest.

Credits

Provider logos under media/providers/ are the official brand marks, with paths taken from Simple Icons (icon data released under CC0 1.0). The marks themselves remain the trademarks of their respective owners.

License

MIT. See LICENSE.

Not affiliated with, endorsed by, or sponsored by Anthropic, OpenAI or Google. "Claude" and "Claude Code" are trademarks of Anthropic, PBC; "OpenAI" and "Codex" of OpenAI, L.L.C.; "Gemini" of Google LLC. Their names and logos appear here only to identify which tool a session runs — nominative use — and each remains the property of its owner. This is an independent, community-built tool.