The Mac app for Muse Code

Hand Muse Wonder a fix, a feature or a refactor. Watch it work, steer it mid-turn, and review every change before it lands.

Download Thalia

Free for Apple Silicon Macs on macOS 27. Uses your own Muse Code plan.

The Thalia app icon: a pale blue wave beneath a peak, on a deep blue tile.

A Thalia chat while Muse works: the request, Working with 15 steps, a trace strip, five commands run with one failed, seven files read, and report.test.ts edited. The sidebar marks the chat Running. — **Fig. 1**A job in progress: Muse’s steps as they happen, with the edit it just made.

Give it the whole job

A bug you’ve been putting off

Describe what’s wrong or paste the error. Muse traces the cause, makes the fix and can run your tests. You read the diff before you keep it.

Review of src/report.ts, plus 14 minus 7: the first hunk in unified view, where the weekly total now splits a session at midnight into per-day segments. — **Fig. 2**A bug fix as Review shows it: the diff against where the project started.

A feature, planned first

Switch to Plan and Muse reads the project without changing it, then writes out the approach, the steps and how to check the work. Approve the plan and it builds it.

Muse’s note that the plan is ready for review, then Plan ready with Request Changes and Approve and Implement. The message box below is in Plan mode with Muse Wonder Full 1.0. — **Fig. 3**Plan ready: Request Changes, or Approve and Implement.

A change across many files

Renames, migrations, cleanups. Review lists every file Muse touched against where your project started, new files included, so nothing slips in unseen.

Review lists four changed files, report.ts, session.ts, summary.ts and report.test.ts, with their added and removed line counts beside the first file’s diff. — **Fig. 4**A change across four files, listed in Review beside the diff.

Muse Wonder, and every other model on your plan

The model picker shows what your Muse Code plan includes: Muse Wonder, and Muse Wonder Full on the plans that have it. Choose per chat or per project. The Effort menu only offers levels that model actually supports, so what you pick is what runs.

The top of the open model menu: Muse default, which is ticked, Muse Wonder 1.0, the runtime’s default, and Muse Wonder Full 1.0, each with its 1.0M context. — **Fig. 5**The model menu: Muse default, Muse Wonder and Muse Wonder Full.

Every job in its own chat

Start a chat with or without a project, and keep your work tidy with sidebar sections and project groups. If Muse is busy in another chat, your next draft waits until it’s free. Inside a job, Muse can hand parts to helper agents that run side by side, and you can follow each one. The Inbox gathers what’s waiting on you, from a command to allow to a plan to approve, next to what’s running and what just finished.

The sidebar: the demo-app project with six chats, one marked Waiting for you. — **Fig. 6**One project, one chat per job.

The Inbox: a command approval waiting on you and a plan awaiting approval with Review Plan, then three running items, a command and two helper agents, and a recently finished turn. — **Fig. 7**The Inbox: what is waiting on you, what is running, and what just finished.

Agents and Jobs: two helper agents, Helper 1 and Helper 2, both running, the second selected, with its live feed of completed steps below. — **Fig. 8**Two helper agents running side by side, with one followed live.

You decide what lands

Before a command runs

When a command needs your approval, you see the whole command, invisible characters included, before you allow it.

⌘Command↩Return Allow onceescEscape Deny

An approval card titled Muse wants to run a command, showing node --version as the current component and as the full command, with Allow once and Deny. The message box below it reads Steer Muse. — **Fig. 9**The approval card: the part Muse is about to run, then the full command, character for character.

The chat after approval: the request, then a line reading Allowed by you, bash, 4:19 PM. — **Fig. 10**The receipt. Every decision stays in the chat, with who made it and when.

Before a file changes

In Plan mode nothing is edited until you approve the plan.

Before you keep it

Approve the exact snapshot you reviewed. If a file changes afterwards, the approval no longer holds.

⇧Shift⌘Command↩Return Approve this snapshot

Unified diff of src/cli.ts against baseline ff5040d: one comment line added at the top, above three unchanged import lines. — **Fig. 11**The diff, at the size you’d read it in the app.

Changes panel: Snapshot 4b56b91, up to date, taken 4:30 PM against baseline ff5040d, one file, cli.ts plus one. — **Fig. 12**The snapshot, and the baseline it was taken against.

Saved snapshot 4b56b91. Reviewer Alex Rivera. Approved by Alex Rivera, Oct 19, 2026 at 4:30 PM. — **Fig. 13**Who approved which snapshot.

Mid-turn

Type a new instruction and Muse takes it without starting over, or stop the turn with ⌘Command.Period

After the fact

Roll back to a checkpoint, with a preview of which files come back first. Checkpoints help you undo; they aren’t a backup.

Restore this checkpoint? Seven files change; Thalia saves a Before restore checkpoint first. Restore 7 Files and Cancel. — **Fig. 14**Before a restore, a preview: which checkpoint, how many files, and what is left alone.

The Changes and History panel: one file, snapshot 4b56b91 approved, and a History list of seven checkpoints, the latest marked before turn, 4:31 PM. — **Fig. 15**The checkpoint list for a chat.

Made for the Mac

Written in Swift and SwiftUI for macOS 27. It opens in a moment even with a long chat history, and stays light while long replies stream. Keyboard first, with a command bar on ⌘CommandKK Connector keys you enter live in your Keychain. Open a pull request with the GitHub CLI, connect MCP servers with a browser sign-in, or talk the job through with voice mode. The app sends us no analytics and no telemetry.

Build and run your Xcode projects without leaving Thalia: follow the build log and console in the output dock, pick a scheme and press Run, and see SwiftUI previews and the Simulator beside your chat.

7 releases since 27 September

27 OctoberBuild and run Xcode projects beside your chat, start chats without a project, and organise your work in a much lighter, faster app.
23 OctoberThalia, redesigned: a calmer, faster window, Cmd-K to jump anywhere, an Inbox for what needs you, and a Review workspace built for shipping.
18 OctoberShell commands in the composer, workflow and helper-agent controls, clearer Muse Code usage, and safer permissions and recovery.
13 OctoberYour Muse Code plan’s models, including Muse Wonder, in the model picker; effort choices that match each model; smoother review and plan approval; and connector and voice fixes.
3 OctoberA safer, steadier Thalia: clearer plan and approval controls, files that reach Muse, and more reliable review, connectors and voice.
27 SeptemberA small patch so connector sign-in actually finishes.
27 SeptemberFor Apple Silicon Macs running macOS 27.

Read the changelog

A note from us

We built Thalia because we wanted to give Muse real work and still know exactly what it did. It’s an independent app, it’s free, and it gets better every week or two. If something is wrong or missing, tell us, and it will likely be in the next release.

Give Muse its next job

Download Thalia

Free for Apple Silicon Macs on macOS 27. Meta sets any Muse Code subscription or usage charges. Intel Macs are not supported, and Windows and Linux versions have not been announced.

Or with Homebrew:

brew install --cask mabry-ventures/tap/thalia