fix(terminal): detect shell tab visibility via MutationObserver

Shell is always mounted inside a display:none parent when the app
loads on a different tab. Added MutationObserver on the wrapper to
detect when the shell tab becomes visible and initialize/fit all
pending terminals at that moment. Removed attempt limit so retries
continue until the tab is actually shown.

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

web/src/components/Shell.jsx

@@ -425,15 +425,36 @@ export default function Shell({ api }) {
     }
   }, [])
 
+  const initPendingTabs = useCallback(() => {
+    for (const tab of tabsRef.current._tabList || []) {
+      if (!tabsRef.current[tab.id]) {
+        const container = document.getElementById(`terminal-${tab.id}`)
+        if (container && container.offsetHeight > 0) {
+          initTerminal(tab.id, tab)
+        }
+      }
+    }
+    requestAnimationFrame(() => {
+      for (const tab of tabsRef.current._tabList || []) {
+        const entry = tabsRef.current[tab.id]
+        if (entry) entry.fitAddon.fit()
+      }
+    })
+  }, [initTerminal])
+
+  useEffect(() => {
+    tabsRef.current._tabList = tabs
+  }, [tabs])
+
   useEffect(() => {
     let cancelled = false
     const pending = []
 
     const tryInitTab = (tab, attempt) => {
-      if (cancelled || attempt > 30) return
+      if (cancelled) return
       const shellCol = document.querySelector('.shell-terminal-col')
       if (!shellCol || shellCol.offsetParent === null) {
-        pending.push(setTimeout(() => tryInitTab(tab, attempt + 1), 150))
+        pending.push(setTimeout(() => tryInitTab(tab, attempt + 1), 200))
         return
       }
       const container = document.getElementById(`terminal-${tab.id}`)
@@ -461,11 +482,23 @@ export default function Shell({ api }) {
       }
     }
 
+    const wrapper = document.querySelector('.shell-layout')?.parentElement
+    let observer
+    if (wrapper) {
+      observer = new MutationObserver(() => {
+        if (!wrapper.classList.contains('tab-hidden') && wrapper.offsetParent !== null) {
+          initPendingTabs()
+        }
+      })
+      observer.observe(wrapper, { attributes: true, attributeFilter: ['class'] })
+    }
+
     return () => {
       cancelled = true
       pending.forEach(clearTimeout)
+      observer?.disconnect()
     }
-  }, [tabs, initTerminal])
+  }, [tabs, initTerminal, initPendingTabs])
 
   useEffect(() => {
     const entry = tabsRef.current[activeTab]
@@ -480,6 +513,8 @@ export default function Shell({ api }) {
 
   useEffect(() => {
     const iv = setInterval(() => {
+      const wrapper = document.querySelector('.shell-layout')?.parentElement
+      if (wrapper && wrapper.classList.contains('tab-hidden')) return
       const entry = tabsRef.current[activeTabRef.current]
       if (entry) {
         entry.fitAddon.fit()