When viewing an archived agent, display a callout in place of the input
area that matches the message input styling. The Unarchive button calls
refreshAgent which auto-unarchives server-side.
Replace greedy agents Map subscription with a Zustand selector that
derives workspace agent visibility (ID sets only) with custom equality,
so the workspace screen only re-renders when agents are added, removed,
or archived — not on every status/activity update.
Fix tab pruning to check against all known agents (including archived)
instead of only active agents, so archived agent tabs survive
reconciliation. Remove the auto-unarchive effect that called
refreshAgent() as a workaround. Hide input area for archived agents.
useHostRuntimeSession returned the full HostRuntimeSnapshot, causing
every consumer to rerender on any internal state change (probe cycles,
client generation bumps). Replace with targeted hooks that return
primitives/stable references so useSyncExternalStore skips rerenders
when the subscribed value hasn't actually changed.
New hooks: useHostRuntimeClient, useHostRuntimeConnectionStatus,
useHostRuntimeLastError, useHostRuntimeAgentDirectoryStatus,
useHostRuntimeIsDirectoryLoading. Existing useHostRuntimeIsConnected
already followed this pattern.
useHostRuntimeSnapshot kept only for settings-screen where probe
data is legitimately needed.
Replace hardcoded renderContent() switch and per-kind descriptor logic
with a registry-based panel interface. Each panel type (agent, draft,
terminal, file) now self-registers with its component, useDescriptor
hook, and optional confirmClose. Panels access workspace context via
usePaneContext() instead of prop drilling. This prepares the workspace
screen for split pane support.