TL;DR: an unofficial macOS desktop app for Slack that wraps the official Slack web client (app.slack.com) in Electron and applies patches on top of it. The guiding principle: behave exactly like the official Slack.app in core UX, then add extra features the official app does not have.
Everything is generated from a single build script,
slack-autocomplete-electron-app.sh, which writes the Electron app (main
process + preload), copies the pure logic module export-core.js, and packages
a signed arm64 .app.
The original itch: Slack's autocomplete no longer preselects the first result,
so muscle-memory @name<enter> mentions broke. The wrapper fixes that, and
over time grew a set of power features while keeping official-app behavior
everywhere else.
- Autocomplete fix: the first suggestion is auto-selected again (disabled the moment you use the mouse in the list)
- Channel export to JSON: full message history with threads, reactions (author lists backfilled), and resolved user names
- Channel list export: public/private/all membership as JSON or plain text
- Channel sections export/import: sidebar sections plus unsectioned channels to JSON, file embeds its own schema and editing instructions for hand- or LLM-editing, import is additive and previews a plan with Apply/Cancel before changing anything
- Last seen (presence) tracking: records when tracked users were last online by tapping the client's presence WebSocket and injects a watchlist of extra user ids into presence subscriptions. The "Last Seen" panel (File menu) is draggable/resizable and updates each section in place while open (rows and buttons are never rebuilt under the cursor) showing current subscriptions (unioned across all windows), per-user last-online sorted online-first, a transition log with resolved names, and an interactive watchlist editor with workspace name search (the watchlist file stays hand-editable; hot reload survives editor atomic saves, and a broken edit keeps the last good list and shows the parse error). Names paint in the background from a disk-persisted cache plus a bulk roster fetch, so the panel opens instantly. Presence state is reset on every launch (only timestamps persist), so "online now" is never claimed from stale pre-restart data. Presence is derived from live events only (throttled, no backfill); the data stays local.
- Reaction analytics CLI (
analyze-reactions.js) - Thread pop-out button in every thread header
- Esc closes attachment views; "Clear Cache (Keep Login)" menu item
- Workspace menu with Cmd+1..9 switching
The web client alone does not provide these; the wrapper implements them the
way the official desktop app does (see docs/official-slack-mimicry.md for
how that was reverse-engineered):
- Native notifications with inline reply from the banner, replace-by-tag
deduping, and an exact mention-count dock badge (
client.counts) - Huddles and calls: microphone/camera permissions, native screen-share picker
- "Open in new window" for channels and threads from Slack's own context menus, opening slim dedicated windows with a custom title-bar strip (traffic lights inside the UI, no native title bar)
- Near-instant pop-outs via a warm hidden window pool
- Downloads panel with progress, Open / Show in Finder, and a configurable downloads location (File menu)
- Official-style file handling: raw file links become tracked downloads, viewer pop-ups get real windows
- macOS split-screen tiling, hidden-inset title bar, standard window menu
- Cmd+K works immediately after launch: Slack's web client drops the shortcut
until its "user attention on chat" state settles (the desktop client is
exempt via its user agent), so when Slack ignores the key the preload asks
the main process for a trusted click on the top-nav search button
(decision logic in
cmdk-fallback-core.js)
./slack-autocomplete-electron-app.sh
open "$HOME/SlackAutocompleteElectron/dist/SlackAutocompleteElectron-darwin-arm64/SlackAutocompleteElectron.app"
The script installs dependencies, generates the app, and code-signs it with a
Developer identity from the local keychain when one exists (never committed;
CI builds stay ad-hoc signed). GitHub Actions builds an arm64 artifact on
every push and publishes a release with the zipped .app on v* tags.
Downloaded release builds need xattr -cr SlackAutocompleteElectron.app once
(ad-hoc signed, not notarized).
Tests: node --test (covers export-core, last-seen-core, cmdk-fallback-core,
and analyze-reactions)
- Unofficial and unaffiliated with Slack; personal-use tooling
- Some parity features hook Slack's web DOM (class names, data-qa attributes) and can degrade gracefully when Slack ships UI changes; the code favors layout-agnostic techniques where possible
- Huddle screen-share drawing and remote control are not available (they require Slack's private desktop bridge; see the mimicry notes)