Happier: a self-hostable, end-to-end encrypted client for Codex, Claude Code and OpenCode

The gap Happier fills between a local agent and a second screen

AI coding agents such as Codex, Claude Code and OpenCode run on your machine and hold their state in a terminal process. That is fine until you leave the desk. The session keeps running, but you cannot see it, steer it, or answer a prompt it is waiting on. Happier is a cross-device companion client aimed at exactly that moment: the README describes running sessions locally and then continuing or controlling them remotely from a phone, web UI or desktop app "without losing context."

The intended user is a developer who already uses one of these CLIs daily, not someone looking for a new agent. Happier does not replace the model or the agent loop; it sits around it. The README frames the switch as a substitution: where you would type `claude`, you type `happier`; where you would type `codex`, you type `happier codex`. That framing tells you a lot about scope. If you have no local agent installed, Happier has nothing to wrap.

How the local agent, the CLI wrapper and the encrypted bridge fit together

The repository is a Yarn monorepo with separate workspaces for the UI, server, CLI, website and docs, plus shared packages including `privacy-kit`, `protocol`, `transfers`, `agents` and `connection-supervisor`. The build script compiles `privacy-kit` and `@happier-dev/protocol` first, which is consistent with encryption and message framing being foundational rather than bolted on at the app layer.

The mechanism, as the README describes it, is a wrapper process. You launch an agent through `happier` instead of directly, and Happier acts as "a secure bridge between your local development environment and your other devices." Sessions can be browsed, followed live, or taken over: the README says you can open an existing Codex, Claude or OpenCode session on your machine, follow a session started outside the app in real time, or import it with continuity. Forking uses provider-native support where it exists (the README names OpenCode and Codex) and falls back to "Happier Replay" for any other provider. Handoff between machines keeps the same session ID and changes which machine is active.

The `connection-supervisor` package name suggests connection lifecycle is treated as its own concern, which matters for a client that must survive a phone losing signal mid-session. The README does not document the reconnect protocol, so treat that as an area to inspect in the source rather than something the docs promise.

Installing the CLI and running your first wrapped session

The README gives an installer script for macOS and Linux, a PowerShell equivalent for Windows, and an npm package for people who prefer that lane. The installer is the documented default; npm is described as the alternative "if you specifically want the npm package instead of the installer-managed lanes."

curl -fsSL https://happier.dev/install | bash

On Windows the README uses `iwr` piped into `iex`:

npm install -g @happier-dev/cli

After install, authenticate. The README recommends a mobile-first first run so the account and secret key are stored on the phone.

happier auth login

Then start an agent through the wrapper. The README's examples map each provider to a subcommand:

happier codex
happier opencode
happier gemini

What you should see is the agent running as usual, with the session registered so it appears in the app. The README also documents `happier attach` for reconnecting a terminal to a session started from the app, in either direction. If you open the terminal-connect link while logged out, the README states Happier routes you through sign in or account creation and then returns you to terminal approval.

Where Happier is the wrong tool

The README states plainly that Happier is in alpha preview and "might be buggy here and there." That is the first constraint. A tool that mediates access to your working directory and your agent credentials is not a neutral place for preview-quality code, and the README offers no stability guarantees.

There is a second, sharper limitation. Happier assumes you can run an agent locally on a machine you control. Everything the README describes, from session import to machine handoff, depends on a local process and a project directory. If your team standardises on a hosted agent platform with no local CLI, or if your organisation forbids running agent processes on developer laptops, Happier has no entry point.

The provider list also outruns the documentation. The README names Claude Code, Codex, OpenCode, Gemini, GitHub Copilot, Kiro, Pi, Kilo, Kimi, Qwen, Augment and "any custom ACP-compatible CLI." But the worked examples cover only a handful, and the README does not document rollback, nor what happens to an in-flight session when the bridge drops. The Android client is in private beta through a Google Group and a Play testing link, and the README points to a preview APK rather than a stable release channel.

Happier versus Happy, the project it forked from

The README is unusually direct about lineage. The authors were contributors to Happy, the project at slopus/happy, and say they used it daily before deciding their own needs "required faster iteration that we could not comfortably explore within the main project." Happier is therefore a fork in spirit and in code, built to move faster than upstream.

That is the real difference in approach, and it cuts both ways. A faster-moving fork can ship features upstream will not, and the README's emphasis on session handoff, Claude teams and a voice agent reads like a list of things the authors wanted sooner. The cost is that you are choosing a smaller project over one with a longer track record, and the README's own framing ("we loved and still love Happy") acknowledges the debt rather than arguing superiority. If you want the more conservative option, evaluate Happy on the same criteria. If you specifically want the features Happier lists and cannot get them upstream, the fork is the reason to pick it.

Licence, maintenance and what an upgrade actually costs

Happier is MIT licensed, which is permissive and imposes few obligations beyond preserving the notice. The repository also contains a `LICENCE` file at the top level alongside `CONTRIBUTING.md` and `DESIGN.md`; read the file rather than the GitHub label if licence terms matter to your legal review. Nothing here is legal advice.

The last push to the default branch `dev` was on 2026-09-10, ten days before this writing, and the most recent release listed is `ui-web-v0.2.12-dev.319` from the same day. The version string is worth reading carefully: it carries a `-dev.` suffix, and the release list also includes `ui-web-dev` and `ui-mobile-dev` bundles. This is a project publishing development builds, not tagged stable versions, which matches the README's alpha-preview description.

Upgrade cost follows from that. There is no documented migration path between releases, and the README does not describe how sessions, keys or paired devices survive a CLI upgrade. Because the CLI is installer-managed by default, the practical upgrade path is the install script again, with `npm install -g @happier-dev/cli` as the alternative lane. Self-hosting adds its own burden: the repository ships a `Dockerfile` and a `docker/` directory, and the Dockerfile installs a build toolchain and Python because some workspace dependencies "may not have prebuilt binaries for all architectures," so expect real build time on non-x86 hosts.

Collaboration, agents and the parts the README only sketches

Two features deserve separate scrutiny because they change what the tool is. First, collaborative sessions: the README says you can share a live session with teammates or via view-only public links, and add friends by username in the app. A view-only public link to a live coding session is a meaningful exposure surface, and the README does not describe link expiry or revocation. Second, the Agents panel: the README describes launching parallel review, plan or delegate runs, creating and managing Claude teams, messaging individual teammates and monitoring subagents.

The voice assistant is described in terms the README is careful about: "a real AI colleague, not just speech-to-text," backed by the same action system as the UI and CLI, monitoring running sessions and switching focus between them. The repository includes `packages/audio-stream-native` and `packages/sherpa-native`, which is consistent with on-device audio work, though the README does not document the speech stack. The sentence describing voice capabilities is truncated in the README as provided, so the full behaviour is not something this article can state.

Editorial conclusion

Adopt Happier if you already run Codex, Claude Code or OpenCode locally and want to keep a session alive while you move between terminal, browser and phone, and you accept alpha-preview software with a provider list broader than its documented edge cases. Do not adopt it as a hosted team platform or as a replacement for the agents themselves, because it is a client and a bridge, not a model runner. Verify first that `happier auth login` stores your account and secret key on the mobile device you intend to use, and that the session-handoff path works for the provider you actually run, since the README documents handoff and forking without a worked example for every provider.

Frequently asked questions

Official sources

1. happier-dev/happier on GitHub
2. License: MIT
3. Project website
4. README
5. Releases