For the curious

Under the hood

Don’t read about how CoolDesk works. Poke it. Every toy below runs the app’s real rules with its real numbers.

Your tabs, history, files and time tracking stay on your computer. Nothing in this picture talks to a CoolDesk server.

01 · Extension ⇄ app

One jump, three deliveries

The app and the extension talk over a WebSocket on 127.0.0.1. Chrome naps idle extensions, so there’s a once-a-second HTTP poll as backup. Belt, braces, and a gate so the browser doesn’t act three times.

Try it · jump to a tab

Desktop app · SpotlightBrowser · extension

WebSocket push

HTTP poll (1 s)

Sync socket

Nothing sent yet

The same tab within 10 s counts as already handled.

src/background/bridge.js src/services/jumpGuard.js src-tauri/src/sidecar/server.rs

02 · Extension

The new tab has a guest list

It tracks time only on the tab you’re looking at, pauses when you go idle, and keeps everything in IndexedDB. Custom widgets run in a sandbox with no browser APIs. And it can only call seven hosts.

Try it · can the new tab call this?

A website the new tab tries to reach

Blocked. It isn’t on the list, so the browser refuses the connection.

Enforced by the browser through the page’s content security policy, not by our code.

manifest.json src/background/activity.js pages/widget-sandbox.html

03 · Spotlight

Search is a ladder, not a black box

No embeddings, no magic. Eight rules from exact match down to “letters in order”. Type something and watch which rung each app lands on.

Try it · the real scoring

Visual Studio
85 · acronym
Visual Studio Code
82 · acronym start
Vercel Dashboard
55 · letters in order

Each result takes the score of the first rule it passes.

src/services/searchService.js

04 · What comes first

Yesterday matters more than last week

Usage counts half as much every 3 days, and it’s log-scaled so 5 hours vs 3 barely differs but 20 minutes vs none does. Drag the sliders.

Try it · how much an item counts

Used for 120 min…this many days ago: 2

63%

of that time still counts

4.34

ranking score

Score = ln(1 + minutes × 0.5^(days ÷ 3)) + 2 if it’s open now.

src/services/itemRankingService.js

05 · Apps

Ten asks, one scan

Opening Spotlight makes several parts of the UI ask for your apps at the same moment. A lock lets one of them scan; the rest wait and share the answer.

Try it · 10 parts of the UI ask at once

#10

total scans: 0

Click again within 10 s: nobody scans at all.

src-tauri/src/lib.rs src-tauri/src/matcher.rs

06 · Your day

Open isn’t used

Every 30 seconds the app checks three things: what’s focused, when you last touched the keyboard or mouse, and what’s making sound. Flip them.

Try it · one sample every 30 s (sped up)

Last keypress or click: 20s ago

This sample

Active time, full credit

0m 00s

active

0m 00s

media

0m 00s

passive

Samples taken: 0

src-tauri/src/sidecar/sampler.rs

07 · Files

A download is five events pretending to be one

The file manager watches the folder you’re in. It waits for things to go quiet for 300 ms before refreshing, so you see one update, not five.

Try it · a file lands in Downloads

0 mscreate report.pdf.crdownload
120 mswrite +2 MB
240 mswrite +2 MB
360 mswrite +1 MB
480 msrename → report.pdf
780 ms✓ file list refreshes once

refreshes without settling

refreshes with it

Every event restarts a 300 ms timer; the list refreshes when it runs out.

src-tauri/src/dir_watch.rs src-tauri/src/folder_index.rs

08 · Data

Boring sync, on purpose

Plain JSON on your disk, IndexedDB in the browser. Records merge by id, the newest edit wins, and URLs are normalised first so www and a trailing slash don’t make duplicates.

Try it · the same note, edited in two places

In the browser extension

https://www.github.com/acme/app/

“Ship v2 Friday”

edited 10:02

In the desktop app

github.com/acme/app

“Ship v2 Monday”

edited 10:41

src-tauri/src/sidecar/sync.rs

09 · macOS

The hack Apple didn’t document

Apple’s public API can’t put a window over another app’s fullscreen Space. So, like Alfred, Raycast and yabai, CoolDesk uses the private CGS API in SkyLight.framework.

Try it · press Alt+K over a fullscreen app

VS Code · fullscreen Space

> my-app

Desktop 1

Spotlight joins the Space you’re looking at, right on top of VS Code.

src-tauri/src/dock/cgs.rs

10 · AI

The agent can look, not touch

The AI agent reads your CoolDesk data through a read-only MCP endpoint. It can propose changes; only you can apply them.

Try it · ask the agent

Which of my tabs belong to the launch?

→ tools/call list_tabs (read-only)
← 23 tabs

These 5 look like the launch: Product Hunt draft, landing page, Stripe, analytics and the changelog.

proposed: add 5 links to “Launch”

Nothing changes until you press it.

src-tauri/src/sidecar/mcp.rs

11 · Cheat sheet

Every cache, from 300 ms to forever-ish

Each one exists for a reason. Usually that reason is “something was asking too often”.

Every cache · log scale

Folder change events
300 msA download is create → grow → rename; re-list once.
Apps list
10 sMany parts of the UI ask at once; one scan answers all.
Jump-to-tab deliveries
10 sThree channels may deliver the same jump.
Browsing activity reads
30 sThe new tab reads it often.
Projects with dev servers
60 sThe Local tab polls; the disk walk needn’t.
Usage scores for ranking
5 minRead on every keystroke.
Latest release (this site)
5 minKeeps spikes off GitHub’s 60 req/h.
App categories, shell PATH
sessionLooked up once per app / per launch.

0.1 s1 s10 s1 min1 h

Hover a row for why it exists.

src-tauri/src/lib.rs src/background/activity.js server.mjs

Still curious?

CoolDesk is open source. Everything above is in the repo, comments and all.

Read the code on GitHub