Two reasons the back button was unreliable:
1. The very first history entry (the URL the user landed on) had
state: null because handleInitialRoute() called navigate(path,
false), and the pushState branch only ran when addToHistory=true.
When the user later pushState'd forward and then hit back, the
popstate handler's guard "e.state && e.state.route" was false on
the initial entry, so it silently did nothing — back appeared
broken. Now navigate() replaceState's the current entry whenever
addToHistory=false, so the initial entry (and any back-compat
URL rewrite) always carries its route. The popstate handler also
now falls back to window.location when state.route is missing,
so third-party history manipulation can't break us.
2. Open SSE streams (LiveSystem, taskEventBus, services-manager log
tails) block the browser's back-forward cache. Without BFCache,
back has to fully re-mount the page instead of restoring it
instantly the way Amazon/GitHub feel. Now pagehide closes every
live bus we own, and pageshow(persisted=true) reopens them when
the page is restored from BFCache. Log tails aren't auto-resumed
— Resume overlay handles that if the user comes back to a
services tab.
Public surface added: LiveSystem.pause()/resume() and
ServicesManager.pauseStreams(). TaskEventBus already had stop()/
start(). The legacy-URL rewrite in handleAppDetail also now
replaceState's with { route: canonical } instead of {} so the
stamp is consistent across all internal history updates.
Signed-off-by: librelad <librelad@digitalangels.vip>
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