simplex-chat/scripts/ci/desktop-linux

Desktop app CI on Linux

.github/workflows/desktop-linux.yml builds the desktop app from the branch on a GitHub runner (Ubuntu 24.04), runs its JVM tests (:common:desktopTest), and drives the app on a virtual display: onboarding to the chat list, then the chat list with the toolbar at the bottom (the default) and at the top. On request it also runs Claude Code driving the same path, a test backend, and the latest release as a baseline.

Running it

The workflow runs only when started by hand, on any branch, from the Actions tab or with gh workflow run: CI on GitHub's runners says how and lists the inputs.

Every run builds the core library, and the backend when it's asked for, from the branch's own Haskell code. It reuses an earlier build only when the sources are unchanged, as an artifact of the same branch named after a hash of its sources (30 days): for the core src/**, cabal.project, simplex-chat.cabal, PRIVACY.md and the build scripts, for the backend src/**, the CLI's and the directory's sources, cabal.project, simplex-chat.cabal and its build script. So a branch that changes core and app code together tests both. The workflow saves no Actions caches, which this repository evicts within hours and shares with build.yml.

Jobs

Job	Does	Time
plan	chooses the jobs, finds earlier core and backend builds	10 s
core	scripts/desktop/build-lib-linux.sh via build-core.sh	skipped when reused, about 24 min not
app	the app (:desktop:createDistributable), desktopTest with the snapshots, smoke-test.sh	about 12 min: build 4.5, desktopTest 0.7, smoke test 3.5
claude (opt-in)	after app passed: its distributable at the first screen, then Claude Code drives it	about 4 min, Claude 3
backend (opt-in)	build-backend.sh: simplex-chat, simplex-directory-service, and smp-server from the simplexmq commit cabal.project pins	about 30 min, skipped when reused
release (opt-in)	the latest release's .deb for this Ubuntu, onboarding only, to tell a branch's failure from the runner's	1.5 min

Queueing for a runner adds from under a minute to 20 minutes. Results are artifacts: desktop-smoke-test (numbered screenshots, the text OCR read from each, steps.log, checks.txt, app.log), desktop-test-report, desktop-snapshots (below), desktop-claude-test, and the backend's logs; desktop-app, the distributable for manual tests and the Claude job, is kept 14 days. The job summaries list the checks, the desktopTest results and the Claude usage.

Scripts

• ui: the UI driver. Compose for Desktop has no accessibility tree on Linux, so it finds text on screenshots by OCR (tesseract) and acts with xdotool on an Xvfb display. ui alone prints its commands: start (with app settings), shot, text, find, wait, click, right-click, click-text, scroll, type, key, avatar (a profile image's colour), ink (a text's height), do (several in a row), stop. screen-text.py, screen-colour.py and screen-ink.py are its helpers.
• smoke-test.sh <app dir> <out dir> [start|onboarding|setup|backend]: the scripted cases; the default is onboarding and both layouts. setup also creates a local group and makes the test SMP server the app's only names server; backend does that, connects to the seeded name, and checks both layouts.
• backend.sh start <tar.gz> <dir> / stop <dir>: the test backend, below.
• claude-test.sh, claude-test.md (the prompt), claude-scope (whether the prompt uses the test backend, and optionally the session's turns and budget), claude-guard.py, claude-usage.py: the Claude job.
• build-core.sh, install-core.sh, build-backend.sh, earlier-run.sh, release-app.sh, test-summary.py: builds, reuse and reports.

Snapshots

:common:desktopTest runs SnapshotTest (apps/multiplatform/common/src/desktopTest/kotlin/chat/simplex/app/SnapshotTest.kt). It renders each preview listed in previewScenes with Compose's ImageComposeScene, 402 dp wide at density 1, one pixel per dp, as tall as the preview's content up to 874 dp, so a preview that fills any height is 874 pixels tall. It renders the light and dark themes without a wallpaper, over the theme's background, and keeps the fourth frame, 3 s of frame time after the first. As the app does for its screens, the test provides an AppBarHandler (LocalAppBarHandler) and the window state (simplexWindowState, sized as the scene). Each preview is rendered at the default font size; the chat item previews (package views.chat.item) also at 1.4 and 1.5, the two largest values of the desktop app's font size setting.

everyPreviewIsRendered reads the Kotlin sources of commonMain and desktopMain without comments, and fails when a @Preview function is missing from both previewScenes and previewsCallingCore, or when either names a function absent from the sources; a scene is named <file>.<function>. previewsCallingCore lists the previews whose layouts validate names or descriptions with the core library (chatValidName, chatJsonLength), which the test JVM does not load, so they are not rendered. The previews of androidMain and of the Android app module are left out too, since they use Android APIs.

The test runs in UTC and en_US (the JVM's default TimeZone and Locale), and replaces the theme overrides with ones without a wallpaper. It sets the app's theme and font size for each render, and restores these settings and defaults when it finishes. Before each render it clears the terminal's items, which previews that send commands to the core add with the time they are sent, so that PreviewTerminalLayout shows an empty terminal. Previews show previewDate (ChatItemView.kt) in place of the current time.

The images go to SNAPSHOT_DIR, otherwise to apps/multiplatform/common/build/snapshots, as PNG files named <file>.<function>-<light|dark>-font-<100|140|150>.png, with index-desktop.json listing each file's scene, theme, font scale, and pixel width and height. The app job sets SNAPSHOT_DIR to snapshots/ of the artifact desktop-snapshots, then the step "Compare snapshots" runs scripts/ci/snapshots-compare.py with the references in apps/multiplatform/common/src/desktopTest/snapshots, as the iOS workflow does (iOS, "Snapshots"): a missing, extra or resized render, or a pixel beyond the tolerance, fails the step, and the diff images go to snapshots-diff/ of the same artifact.

scripts/ci/snapshots-remote.py desktop record|check [branch] starts desktop-linux.yml on a pushed branch, waits for the run and downloads snapshots/ and snapshots-diff/ of its desktop-snapshots: record replaces the PNG files in apps/multiplatform/common/src/desktopTest/snapshots with the run's renders, for review and commit; check prints the files that failed the run's comparison.

The test backend

backend.sh starts, on the runner, with CLI peers:

• a chat relay (--relay --headless) and a directory service on the preset servers;
• a group ci_group and a channel ci_channel with letter avatars as large as the apps make them (avatar), registered and approved by the admin ci_admin, and found by a new user who sends the directory "ci seed";
• an SMP server on 127.0.0.1:5223 whose [NAMES] section asks names-resolver.py, and a contact ci_contact whose address it resolves as seeded.testing, checked with a connect plan from another client.

It writes the directory's address to <dir>/directory-link and the SMP server's to <dir>/names-server. The app reaches the names server only with private routing set to unknown servers (ui start … NetworkSMPProxyMode=Unknown), since the preset proxies can't reach 127.0.0.1, and with the test server's receiving role off: a directory can't answer requests whose reply queue is on it.

The Claude job

It needs the GitHub environment app-sim-claude with the secret CLAUDE_CODE_OAUTH_TOKEN, a Claude subscription token. Which branches may use it is decided only by that environment's branch rule in the repository settings: on a branch the rule doesn't allow, a requested Claude run fails at the environment check. It runs once the app job has passed, on that job's distributable, one per branch at a time. The token goes only to the step that runs claude; claude-test.sh passes it to the claude process alone, and every ui call unsets it too. The job starts the test backend when claude-scope says backend: yes; a run that asks for Claude must then ask for the backend too, or the plan job fails. On master it says no, since this prompt doesn't use the backend. The job installs Claude Code at the version the iOS workflow pins too, and runs claude-haiku-5-5 with the turns and budget claude-scope sets (--max-turns 60 and --max-budget-usd 3 unless it sets max-turns: or max-budget-usd:) and the iOS sessions' other flags (--restricted, --permission-prompts none, --effort high); the job's time limit is 120 minutes. Its Bash runs only single ui commands (claude-guard.py, a PreToolUse hook: Claude Code runs read-only commands without asking in every permission mode). Before anything the session wrote is printed or uploaded, claude-test.sh checks it for the token; if it's there, the output, transcript, Claude Code's stderr and the guard log are deleted and the job fails. It passes when Claude's final message ends with CLAUDE-TEST: PASS; report.md, the transcript, the guard's log and claude-usage.json are in desktop-claude-test.

Cost

The runners are free for this public repository. A Claude run spends the subscription's usage limits, which interactive sessions share: Haiku 5.5 does this smoke path in 15 to 30 turns, 0.01 to 0.02 USD estimated at API prices (Claude Code's estimate, not a bill on a subscription).