fix(app): eliminate session switch latency — deferRender, Suspense flash, instant rendering

packages/app/src/pages/session.tsx

@@ -320,7 +320,8 @@ export default function Page() {
   const messagesReady = createMemo(() => {
     const id = params.id
     if (!id) return true
-    return sync.data.message[id] !== undefined
+    // Ready when messages are loaded OR session exists in the list (render immediately with cached data)
+    return sync.data.message[id] !== undefined || sync.session.get(id) !== undefined
   })
   const historyMore = createMemo(() => {
     const id = params.id
@@ -386,7 +387,6 @@ export default function Page() {
     mobileTab: "session" as "session" | "changes",
     changes: "git" as ChangeMode,
     newSessionWorktree: "main",
-    deferRender: false,
   })
 
   const [followup, setFollowup] = persisted(
@@ -404,17 +404,6 @@ export default function Page() {
     }),
   )
 
-  createComputed((prev) => {
-    const key = sessionKey()
-    if (key !== prev) {
-      setStore("deferRender", true)
-      requestAnimationFrame(() => {
-        setTimeout(() => setStore("deferRender", false), 0)
-      })
-    }
-    return key
-  }, sessionKey())
-
   let reviewFrame: number | undefined
   let refreshFrame: number | undefined
   let refreshTimer: number | undefined
@@ -993,30 +982,28 @@ export default function Page() {
     loadingClass: string
     emptyClass: string
   }) => (
-    <Show when={!store.deferRender}>
-      <SessionReviewTab
-        title={changesTitle()}
-        empty={reviewEmpty(input)}
-        diffs={reviewDiffs}
-        view={view}
-        diffStyle={input.diffStyle}
-        onDiffStyleChange={input.onDiffStyleChange}
-        onScrollRef={(el) => setTree("reviewScroll", el)}
-        focusedFile={tree.activeDiff}
-        onLineComment={(comment) => addCommentToContext({ ...comment, origin: "review" })}
-        onLineCommentUpdate={updateCommentInContext}
-        onLineCommentDelete={removeCommentFromContext}
-        lineCommentActions={reviewCommentActions()}
-        commentMentions={{
-          items: file.searchFilesAndDirectories,
-        }}
-        comments={comments.all()}
-        focusedComment={comments.focus()}
-        onFocusedCommentChange={comments.setFocus}
-        onViewFile={openReviewFile}
-        classes={input.classes}
-      />
-    </Show>
+    <SessionReviewTab
+      title={changesTitle()}
+      empty={reviewEmpty(input)}
+      diffs={reviewDiffs}
+      view={view}
+      diffStyle={input.diffStyle}
+      onDiffStyleChange={input.onDiffStyleChange}
+      onScrollRef={(el) => setTree("reviewScroll", el)}
+      focusedFile={tree.activeDiff}
+      onLineComment={(comment) => addCommentToContext({ ...comment, origin: "review" })}
+      onLineCommentUpdate={updateCommentInContext}
+      onLineCommentDelete={removeCommentFromContext}
+      lineCommentActions={reviewCommentActions()}
+      commentMentions={{
+        items: file.searchFilesAndDirectories,
+      }}
+      comments={comments.all()}
+      focusedComment={comments.focus()}
+      onFocusedCommentChange={comments.setFocus}
+      onViewFile={openReviewFile}
+      classes={input.classes}
+    />
   )
 
   const reviewPanel = () => (
@@ -1658,7 +1645,7 @@ export default function Page() {
   const composerRegion = (placement: "dock" | "inline") => (
     <SessionComposerRegion
       state={composer}
-      ready={!store.deferRender && messagesReady()}
+      ready={messagesReady()}
       centered={placement === "dock" && centered()}
       placement={placement}
       inputRef={(el) => {
@@ -1710,7 +1697,6 @@ export default function Page() {
 
   return (
     <div class="relative size-full overflow-hidden flex flex-col">
-      {sessionSync() ?? ""}
       <SessionHeader />
       <div
         class="flex-1 min-h-0 flex flex-col md:flex-row "

packages/app/src/pages/session/composer/session-composer-region.tsx

@@ -101,18 +101,14 @@ export function SessionComposerRegion(props: {
   createEffect(() => {
     route.sessionKey()
     const ready = props.ready
-    const delay = 140
 
     clear()
     setStore("ready", false)
     if (!ready) return
 
     frame = requestAnimationFrame(() => {
       frame = undefined
-      timer = window.setTimeout(() => {
-        setStore("ready", true)
-        timer = undefined
-      }, delay)
+      setStore("ready", true)
     })
   })