fix(desktop): keep window title in sync with cluster context switches

[eliran-ops]

What

Register an OnContextSwitch callback in the desktop app's startup() so the OS window title re-renders whenever the user switches kubeconfig contexts via the in-page cluster selector.

• cmd/desktop/app.go: extract formatWindowTitle(contextName), add injectable setWindowTitle field, register an OnContextSwitch callback that calls updateWindowTitle(newContext).
• cmd/desktop/main.go: use the new helper for the initial title (was duplicated inline).
• cmd/desktop/app_test.go: regression coverage for formatWindowTitle, the update sequence (initial → switch → disconnect), and the nil-ctx guard before startup.

Why

The Wails window title was set exactly once in domReady and never refreshed. After switching contexts in-app, the OS titlebar kept pointing at the cluster Radar booted with (commonly prod) while the in-page selector and the data layer were on the new cluster — a state mismatch that's especially dangerous in a fleet UI: one of those moments where you click "Delete" thinking you're in dev. Hooking into the existing k8s.OnContextSwitch notification (already used by the SSE broadcaster at internal/server/sse.go:235) means the title now derives from the same source of truth as the data layer.

Where to start reading

• cmd/desktop/app.go:57-69 — the new OnContextSwitch registration in startup().
• cmd/desktop/app.go:43-55 — formatWindowTitle + updateWindowTitle.

Risky vs mechanical

• Risky-ish: the registration in startup(). The callback fires from another goroutine after PerformContextSwitch completes; safe because (a) a.ctx is written before the registration call in the same goroutine, and (b) OnContextSwitch synchronizes via contextSwitchMu (Lock on register / RLock on dispatch), giving happens-before to the callback.
• Mechanical: formatWindowTitle extraction + the inline domReady/main.go cleanup.

Not included

• Browser/standalone build: nothing in the web frontend currently sets document.title dynamically, so there's nothing to fix there. If we ever start setting it, hook the existing context_changed SSE event the broadcaster already emits.
• Destructive-action confirmations re-displaying the cluster name: separate hardening pass, would touch a lot of UI surface.

Made with Cursor

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Note

Low Risk
Low risk: desktop-only window title updates and new context-name parsing helpers; main behavior change is registering an additional OnContextSwitch callback and should not affect cluster operations beyond UI labeling.

Overview
Keeps the desktop OS window title continuously in sync with kubeconfig context changes by registering a k8s.OnContextSwitch callback during DesktopApp.startup() and routing all title updates through a new updateWindowTitle helper.

Extracts formatWindowTitle to centralize title rendering, including shortening provider-specific context strings via new clusterShortName parsing (GKE/EKS ARN/eksctl/AKS) so the title matches the in-app cluster selector.

Adds unit tests covering title formatting, successive context switches (including disconnect/empty context), and a nil-ctx guard via an injectable setWindowTitle function; main.go now uses formatWindowTitle for the initial Wails Title.

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