Limrun Chat

A ChatGPT-style iOS chat app built with Bazel (rules_apple + rules_swift, bzlmod, Bazel 9) that a coding agent can build from any environment, including Linux, using Limrun's remote build execution (RBE). No local Xcode required.

The UI is a single SwiftUI module:

• //App:App: an ios_application with an asymmetric ChatGPT-style chat view: right-aligned user bubbles, full-width assistant text, a streaming typing indicator, and a morphing composer.
• The assistant is mocked: replies stream word-by-word from a canned AsyncStream (App/Sources/Chat/FakeAssistant.swift). There is no network and no API key. Swap in a real token source and the UI never changes.
• All colors come from asset Color Sets (light + dark), so theming is driven entirely by the asset catalog.

The swift_library globs Sources/**/*.swift, so adding or editing Swift files needs no BUILD.bazel change.

Setup

Get an API key from the Limrun Console:

export LIM_API_KEY=lim_....

Install the lim CLI:

npm install --global lim

The agent skill in .agents/skills/limrun-xcode-bazel documents the full lim xcode rbe workflow.

Build over Limrun RBE

From the workspace root, bring up the remote build stack:

lim xcode rbe

This targets/creates a remote Xcode instance, opens a tunnel, and writes a .limrun/ Bazel config. Keep it running. It prints the exact build command, which on Bazel 9 is:

bazelisk --digest_function=sha256 build --config=limrun //App:App

Run on a remote simulator

Attach a simulator (installs the last build immediately and returns a signed live-stream URL):

lim ios create --attach

Every successful --config=limrun build then auto-reinstalls and relaunches the app on the simulator. No local Xcode, no codesigning, the same build runs from Linux or macOS.