a Go daemon core for proactive policy checks, timeout, throttling, single-flight, strict response validation, and feature-only persistence
TypeScript contracts for daemon snapshots and refresh results
Electron startup admission, forced-updater lease, restricted IPC, preload API, shared React UI, and i18n resources
deterministic development policy/updater scenarios and a loopback mock server

Tutti integrates the Go core in tuttid; TSH integrates it in desktopd. Electron talks only to its authenticated local daemon and never calls the public policy endpoint directly.

Hosts may show their business UI before awaiting startup admission. When the startup result requires an upgrade, the Electron controller keeps the business window visible and presents the forced-upgrade window as its modal child. A slow policy check therefore does not create a blank startup, while a resolved block prevents further interaction with the parent business window.

Daemon API

The product daemon exposes:

GET /v1/desktop-update-admission — current snapshot, no remote side effect
GET /v1/desktop-update-admission/startup — waits for the proactive initial check
POST /v1/desktop-update-admission/refresh — sends a foreground or retry lifecycle trigger

The daemon owns the 3-second startup timeout, 10-second foreground timeout, 30-minute foreground interval, request single-flight, and fail-open result. Resolved policy checks and invalid responses enter the foreground throttle window. Failed-open transport and timeout checks remain immediately eligible so a restored network can recover admission. Electron owns lifecycle signals, foreground recovery retries, and presentation.

Development scenarios

Packaged applications ignore all development variables. Invalid enabled development configuration fails startup.

Client identity and updater fields:

Variable	Meaning
`DESKTOP_UPDATE_ADMISSION_DEV`	Enables an unpackaged development scenario.
`DESKTOP_UPDATE_ADMISSION_CURRENT_VERSION`	One current version injected into both daemon admission and updater.
`DESKTOP_UPDATE_ADMISSION_LATEST_VERSION`	Updater target for available/downloaded outcomes.
`DESKTOP_UPDATE_ADMISSION_UPDATER`	`available`, `downloaded`, `unavailable`, `error`, or `targetBelowMinimum`.
`DESKTOP_UPDATE_ADMISSION_DOWNLOAD`	`success` or `error`.
`DESKTOP_UPDATE_ADMISSION_INSTALL`	`simulated` or `error`; neither invokes the production installer.
`DESKTOP_UPDATE_ADMISSION_TRANSPORT`	`in-process` (default) or `loopback`.
`DESKTOP_UPDATE_ADMISSION_MOCK_SERVER_URL`	Exact `http://127.0.0.1:<port>` origin used by the daemon in loopback mode.

Daemon-owned in-process policy fields:

Variable	Meaning
`DESKTOP_UPDATE_ADMISSION_MINIMUM_VERSION`	Default minimum for policy steps that require one.
`DESKTOP_UPDATE_ADMISSION_POLICY`	One policy outcome.
`DESKTOP_UPDATE_ADMISSION_POLICY_SEQUENCE`	Per-request sequence such as `upgradeRequired@1.1.0,minimumNotConfigured`.
`DESKTOP_UPDATE_ADMISSION_SCENARIO`	Named coordinated policy/updater scenario.
`DESKTOP_UPDATE_ADMISSION_FEATURE_KEYS`	Comma-separated feature keys returned by the in-process policy checker.
`DESKTOP_UPDATE_ADMISSION_FOREGROUND_INTERVAL_MS`	Daemon foreground interval override; integer at least 100.

The shortest in-process forced-upgrade scenario is:

DESKTOP_UPDATE_ADMISSION_DEV=1 \
DESKTOP_UPDATE_ADMISSION_CURRENT_VERSION=1.0.0 \
DESKTOP_UPDATE_ADMISSION_POLICY=upgradeRequired \
DESKTOP_UPDATE_ADMISSION_MINIMUM_VERSION=1.1.0 \
DESKTOP_UPDATE_ADMISSION_LATEST_VERSION=1.2.0 \
DESKTOP_UPDATE_ADMISSION_UPDATER=available

Named scenarios:

startup-force-success
startup-policy-timeout
startup-updater-unavailable
startup-target-below-minimum
startup-download-error
retry-policy-released
foreground-upgrade-required

For a complete HTTP test, start the server in a separate process containing all server-owned policy fields:

DESKTOP_UPDATE_ADMISSION_DEV=1 \
DESKTOP_UPDATE_ADMISSION_POLICY=upgradeRequired \
DESKTOP_UPDATE_ADMISSION_MINIMUM_VERSION=1.4.0 \
DESKTOP_UPDATE_ADMISSION_FEATURE_KEYS=workspace.example \
DESKTOP_UPDATE_ADMISSION_MOCK_SERVER_PORT=43210 \
pnpm exec desktop-update-admission-mock-server

Then start the client without policy fields:

DESKTOP_UPDATE_ADMISSION_DEV=1 \
DESKTOP_UPDATE_ADMISSION_CURRENT_VERSION=1.0.0 \
DESKTOP_UPDATE_ADMISSION_TRANSPORT=loopback \
DESKTOP_UPDATE_ADMISSION_MOCK_SERVER_URL=http://127.0.0.1:43210

Add DESKTOP_UPDATE_ADMISSION_UPDATER=available and a DESKTOP_UPDATE_ADMISSION_LATEST_VERSION to the client process to exercise the forced updater. Policy variables in a loopback client are rejected, preventing a second policy authority.

Feature availability

A valid featureAvailability.keys envelope replaces the daemon's exact-identity cache. Missing or invalid feature data retains the prior cache without changing a valid admission decision. The cache stores only identity, feature keys, policy revision, and fetch time; it never stores a minimum version or admission decision. The daemon always serializes keys as a JSON array, including [] when no feature keys are available.

Electron keeps only an in-memory projection for trusted renderer IPC:

const snapshot = await desktopApi.featureAvailability.getSnapshot();
const enabled = await desktopApi.featureAvailability.isSupported(
  "workspace.exampleFeature"
);

Renderer code does not read environment variables or access daemon cache files.