feat: Flathub support

.github/workflows/flatpak.yml

@@ -0,0 +1,163 @@
+name: Flatpak
+
+on:
+  push:
+    branches: [main]
+    paths: ['flatpak/**', 'src/**', 'package.json', 'package-lock.json', 'electron-builder.yml', '.github/workflows/flatpak.yml']
+  pull_request:
+    paths: ['flatpak/**', 'src/**', 'package.json', 'package-lock.json', 'electron-builder.yml', '.github/workflows/flatpak.yml']
+  workflow_dispatch:
+
+concurrency:
+  group: flatpak-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  MANIFEST: flatpak/com.andersonlaverde.slacky.yml
+  APP_ID: com.andersonlaverde.slacky
+
+jobs:
+  metadata:
+    name: Validate metadata
+    runs-on: ubuntu-24.04-arm
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Install validators
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends appstream desktop-file-utils
+
+      # --no-net keeps this to structural validation. The screenshot URL is
+      # checked separately below, because it is a Flathub submission
+      # requirement rather than something that blocks a build.
+      - name: Validate AppStream metainfo
+        run: appstreamcli validate --explain --no-net flatpak/${{ env.APP_ID }}.metainfo.xml
+
+      - name: Check screenshots resolve
+        run: |
+          urls=$(grep -oP '(?<=<image>)[^<]+' flatpak/${{ env.APP_ID }}.metainfo.xml)
+          missing=0
+          for url in $urls; do
+            if curl -sSfLI --max-time 30 "$url" >/dev/null 2>&1; then
+              echo "ok  $url"
+            else
+              echo "::warning file=flatpak/${{ env.APP_ID }}.metainfo.xml::Screenshot $url does not resolve. Flathub rejects submissions with unreachable screenshots."
+              missing=1
+            fi
+          done
+          if [ "$missing" = 1 ]; then
+            echo "Screenshots are still outstanding; see the checklist in flatpak/README.md."
+          fi
+
+      - name: Validate desktop entry
+        run: desktop-file-validate flatpak/${{ env.APP_ID }}.desktop
+
+  build:
+    name: Build flatpak (arm64)
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 90
+    steps:
+      - uses: actions/checkout@v7
+
+      # The build sandbox has no network, so every npm tarball and the Electron
+      # binary have to be declared as sources up front. See flatpak/README.md.
+      - name: Generate offline npm sources
+        run: |
+          python3 -m venv .venv
+          .venv/bin/pip install --quiet PyYAML \
+            'flatpak-node-generator @ git+https://github.com/flatpak/flatpak-builder-tools.git#subdirectory=node'
+          .venv/bin/flatpak-node-generator npm package-lock.json -o flatpak/generated-sources.json
+
+      # The committed manifest builds a published tag, which is what Flathub
+      # needs but would make CI test the last release instead of this commit.
+      # Swap that one source for the checked-out tree.
+      - name: Point the manifest at the checked-out tree
+        run: |
+          .venv/bin/python - <<'PY'
+          import sys, os, yaml
+          path = os.environ['MANIFEST']
+          with open(path) as f:
+              manifest = yaml.safe_load(f)
+          local = {'type': 'dir', 'path': '..',
+                   'skip': ['.git', '.venv', 'node_modules', 'dist', 'build-dir']}
+          swapped = 0
+          # Every module, not a hardcoded index: the app module is not
+          # necessarily first, and silently rewriting the wrong one means CI
+          # builds the last release instead of the commit under test.
+          for module in manifest['modules']:
+              sources = module.get('sources')
+              if not sources:
+                  continue
+              for i, source in enumerate(sources):
+                  if isinstance(source, dict) and source.get('type') == 'git':
+                      sources[i] = local
+                      swapped += 1
+          if swapped != 1:
+              sys.exit(f'expected exactly one git source to swap, found {swapped}')
+          with open(path, 'w') as f:
+              yaml.safe_dump(manifest, f, sort_keys=False)
+          PY
+          cat "$MANIFEST"
+
+      - name: Install flatpak-builder
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends flatpak flatpak-builder elfutils
+
+      # ~1.5 GB of runtimes, and dl.flathub.org times out often enough to
+      # matter. Exact key only: a half-restored ostree repo is worse than none,
+      # and the install step below repairs anything the cache got wrong.
+      - name: Cache flatpak runtimes
+        uses: actions/cache@v6
+        with:
+          path: ~/.local/share/flatpak
+          key: flatpak-runtimes-24.08-node24-electron2
+
+      - name: Install runtimes
+        run: |
+          # dl.flathub.org has served truncated objects and 503s for the Node
+          # SDK extension. Back off far enough to ride out a bad spell rather
+          # than hammering a CDN that is already unwell.
+          retry() {
+            attempts=4
+            delay=30
+            for attempt in $(seq $attempts); do
+              "$@" && return 0
+              if [ "$attempt" -eq "$attempts" ]; then
+                echo "::error::flathub failed $attempts times, giving up"
+                return 1
+              fi
+              echo "::warning::flathub attempt $attempt failed, retrying in ${delay}s"
+              sleep $delay
+              delay=$((delay * 2))
+            done
+          }
+          retry flatpak remote-add --user --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
+          retry flatpak install --user -y --noninteractive flathub \
+            org.freedesktop.Platform//24.08 \
+            org.freedesktop.Sdk//24.08 \
+            org.freedesktop.Sdk.Extension.node24//24.08 \
+            org.electronjs.Electron2.BaseApp//24.08
+
+      - name: Cache build downloads
+        uses: actions/cache@v6
+        with:
+          path: .flatpak-builder/downloads
+          key: flatpak-downloads-${{ hashFiles('package-lock.json') }}
+          restore-keys: flatpak-downloads-
+
+      - name: Build
+        run: |
+          flatpak-builder --user --force-clean --disable-rofiles-fuse \
+            --repo=repo build-dir "$MANIFEST"
+
+      - name: Bundle
+        run: |
+          flatpak build-bundle repo slacky.flatpak "$APP_ID" --runtime-repo=https://dl.flathub.org/repo/flathub.flatpakrepo
+
+      - uses: actions/upload-artifact@v7
+        with:
+          name: slacky-flatpak-arm64
+          path: slacky.flatpak
+          if-no-files-found: error

.gitignore

@@ -1,3 +1,10 @@
 node_modules/
 dist/*
 .DS_Store
+
+# flatpak build artifacts
+flatpak/generated-sources.json
+flatpak-node/
+flatpak-node-generator.py
+.flatpak-builder/
+build-dir/

electron-builder.yml

@@ -17,6 +17,9 @@ protocols:
 linux:
   category: Network
   synopsis: Slack client for Linux arm64 systems
+  # Pinned so the binary inside the unpacked build has a predictable name; the
+  # flatpak wrapper in flatpak/slacky.sh execs /app/main/slacky.
+  executableName: slacky
   target:
     - target: AppImage
       arch:

flatpak/README.md

@@ -0,0 +1,103 @@
+# Flatpak / Flathub packaging
+
+Files here build Slacky as a flatpak and prepare the Flathub submission for
+[#10](https://github.com/andirsun/Slacky/issues/10).
+
+| File | Purpose |
+| --- | --- |
+| `com.andersonlaverde.slacky.yml` | flatpak-builder manifest |
+| `com.andersonlaverde.slacky.metainfo.xml` | AppStream metadata (mandatory on Flathub) |
+| `com.andersonlaverde.slacky.desktop` | Desktop entry |
+| `slacky.sh` | Launcher, wraps the app in zypak |
+
+## Two things that are not obvious
+
+`electronDist` is passed explicitly because flatpak-node-generator writes the
+Electron zip flat into `$XDG_CACHE_HOME/electron`, while `@electron/get` looks
+for it under a `sha256`-of-the-URL subdirectory. The cached zip is therefore
+invisible to electron-builder, which then tries to reach github.com and fails
+in the network-less build sandbox. Unpacking it and passing `electronDist`
+sidesteps the cache layout entirely.
+
+`npm ci`, not `npm install`: install re-resolves the dependency tree and
+reaches for packages outside the lockfile, which are by definition absent from
+the generated offline sources (`ENOTCACHED`).
+
+## Why this does not use electron-builder's flatpak target
+
+electron-builder's `flatpak` target shells out to `flatpak-builder` itself. The
+first attempt at this manifest called `npm run pack -- --linux flatpak` from
+inside `build-commands`, which runs flatpak-builder inside a flatpak build — that
+is what wedged it. The manifest now runs `electron-builder --linux dir`, which
+only produces an unpacked tree, and the flatpak is assembled around that tree.
+
+## Prerequisites
+
+flatpak-builder does not run on macOS. Build on Linux; to produce the arm64
+package you need arm64 hardware or `qemu-user-static` binfmt emulation.
+
+```sh
+flatpak install -y flathub org.freedesktop.Platform//24.08 org.freedesktop.Sdk//24.08 \
+    org.freedesktop.Sdk.Extension.node24//24.08 org.electronjs.Electron2.BaseApp//24.08
+```
+
+## Generating `generated-sources.json`
+
+The build sandbox has no network, so every npm tarball and the Electron binary
+have to be declared as sources up front. That file is generated, not written by
+hand, and is not committed — regenerate it whenever `package-lock.json` changes:
+
+```sh
+# Needs network. Run from the repo root.
+pipx install 'git+https://github.com/flatpak/flatpak-builder-tools.git#subdirectory=node'
+flatpak-node-generator npm package-lock.json -o flatpak/generated-sources.json
+```
+
+The generator also emits `flatpak-node/electron-builder-arch-args.sh`, which the
+manifest sources so electron-builder targets the architecture being built.
+
+## CI
+
+`.github/workflows/flatpak.yml` builds this manifest on `ubuntu-24.04-arm` for
+every pull request that touches the app or the packaging, and uploads the
+resulting `slacky.flatpak` as a run artifact you can install with
+`flatpak install --user slacky.flatpak`. A separate job validates the AppStream
+and desktop metadata.
+
+CI generates `generated-sources.json` itself, and rewrites the manifest's `git`
+source to a `dir` source so it builds the commit under test rather than the last
+published tag. The committed manifest keeps the `git` source, which is what
+Flathub requires.
+
+## Building and running locally
+
+```sh
+flatpak-builder --user --install --force-clean build-dir \
+    flatpak/com.andersonlaverde.slacky.yml
+flatpak run com.andersonlaverde.slacky
+```
+
+## Before submitting to Flathub
+
+- [ ] **Add a real screenshot.** `com.andersonlaverde.slacky.metainfo.xml` points
+      at `build/screenshots/main-window.png`, which does not exist yet. Flathub
+      rejects submissions whose screenshot URLs do not resolve.
+- [ ] Validate the metadata:
+      ```sh
+      appstreamcli validate flatpak/com.andersonlaverde.slacky.metainfo.xml
+      desktop-file-validate flatpak/com.andersonlaverde.slacky.desktop
+      flatpak run --command=flatpak-builder-lint org.flatpak.Builder \
+          manifest flatpak/com.andersonlaverde.slacky.yml
+      ```
+- [ ] Confirm huddles work — mic, camera and screen share — since `--device=all`
+      is the permission most likely to be questioned in review.
+- [ ] Bump `tag:` and `commit:` in the manifest to the release being published,
+      and add a matching `<release>` entry to the metainfo.
+- [ ] Submit: open a pull request against
+      [flathub/flathub](https://github.com/flathub/flathub) on the `new-pr`
+      branch adding this manifest. Flathub then creates
+      `flathub/com.andersonlaverde.slacky`, and future releases are published by
+      updating the manifest in *that* repo, not this one.
+- [ ] Slacky bundles no Slack trademark assets beyond the app icon; double-check
+      the icon before submission, since Flathub review looks at third-party
+      branding.

flatpak/com.andersonlaverde.slacky.desktop

@@ -0,0 +1,12 @@
+[Desktop Entry]
+Type=Application
+Name=Slacky
+GenericName=Slack Client
+Comment=Slack client for Linux arm64 systems
+Exec=slacky %U
+Icon=com.andersonlaverde.slacky
+Terminal=false
+Categories=Network;InstantMessaging;
+Keywords=slack;chat;messaging;huddle;workspace;
+StartupWMClass=Slacky
+MimeType=x-scheme-handler/slack;

flatpak/com.andersonlaverde.slacky.metainfo.xml

@@ -0,0 +1,72 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<component type="desktop-application">
+  <id>com.andersonlaverde.slacky</id>
+
+  <name>Slacky</name>
+  <summary>Slack client for Linux arm64 systems</summary>
+
+  <metadata_license>CC0-1.0</metadata_license>
+  <project_license>MIT</project_license>
+
+  <developer id="com.andersonlaverde">
+    <name>Anderson Laverde</name>
+  </developer>
+
+  <description>
+    <p>
+      Slacky is a desktop Slack client for Linux machines running on arm64
+      hardware, where the official Slack desktop app is not available. It wraps
+      the Slack web client in a native window so it behaves like a normal
+      desktop application.
+    </p>
+    <p>Features:</p>
+    <ul>
+      <li>Sign in to several Slack workspaces and switch between them</li>
+      <li>Desktop notifications that focus the window when clicked</li>
+      <li>Huddles, including pop-out huddle windows</li>
+      <li>Google single sign-on completed inside the app</li>
+      <li>slack:// deep links open in Slacky rather than a browser</li>
+    </ul>
+  </description>
+
+  <launchable type="desktop-id">com.andersonlaverde.slacky.desktop</launchable>
+
+  <!--
+    TODO before submitting to Flathub: this screenshot URL has to resolve to a
+    real image. Flathub's review will reject the submission otherwise. Add a
+    PNG at the path below on the main branch, or point these at wherever the
+    screenshots end up living.
+  -->
+  <screenshots>
+    <screenshot type="default">
+      <image>https://raw.githubusercontent.com/andirsun/Slacky/main/build/screenshots/main-window.png</image>
+      <caption>The Slack workspace running in Slacky</caption>
+    </screenshot>
+  </screenshots>
+
+  <url type="homepage">https://github.com/andirsun/Slacky</url>
+  <url type="bugtracker">https://github.com/andirsun/Slacky/issues</url>
+  <url type="vcs-browser">https://github.com/andirsun/Slacky</url>
+
+  <!--
+    Slacky is a client for a third-party chat service, so users can exchange
+    arbitrary messages through it.
+  -->
+  <content_rating type="oars-1.1">
+    <content_attribute id="social-chat">intense</content_attribute>
+    <content_attribute id="social-audio">intense</content_attribute>
+  </content_rating>
+
+  <releases>
+    <release version="1.0.0" date="2026-08-24">
+      <description>
+        <p>
+          First stable release: multiple workspaces, native huddle pop-out
+          windows, in-app Google SSO, window focus on notification click, and
+          arm64 AppImage, deb and rpm packages.
+        </p>
+      </description>
+      <url>https://github.com/andirsun/Slacky/releases/tag/v1.0.0</url>
+    </release>
+  </releases>
+</component>