Session View Animation

Nucleic-Session: A8FFA1A6-443F-444A-A735-C53958D7E570
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Views/Transcript/MarkdownText.swift

@@ -258,4 +258,35 @@ struct MarkdownText: View {
         inlineCache.setObject(InlineBox(parsed), forKey: key)
         return parsed
     }
+
+    // MARK: - Pre-warming
+
+    /// Populate the block and inline caches for `markdown` ahead of layout. `AttributedString(markdown:)`
+    /// is the dominant per-row cost when a long transcript first lays out, and the eager `VStack`
+    /// runs it for every prose line synchronously — right as the session is pushed and the tab bar
+    /// is sliding away, which is what makes the load-in jitter. Calling this off the main thread
+    /// (see `TranscriptList`) does that parsing in the background so the first layout hits ready
+    /// results instead.
+    ///
+    /// Safe to call from any thread and redundantly: the caches are `NSCache` (thread-safe) and
+    /// keyed only by the source string (independent of `bodySize`), so a warm value equals what
+    /// the main thread would compute, and a repeat call is a cheap cache hit. Cooperatively
+    /// cancellable — a huge transcript's warm loop bails the moment its owning task is cancelled.
+    static func prewarm(_ markdown: String) {
+        for block in parse(markdown) {          // also warms the block cache
+            if Task.isCancelled { return }
+            switch block {
+            case .code:
+                break  // a code block renders via `Text(code)` — no inline parse to warm
+            case .text(let text):
+                for raw in text.components(separatedBy: "\n") {
+                    if let content = classify(raw).inlineContent { _ = attributedInline(content) }
+                }
+            case .table(let rows):
+                for row in rows where !Task.isCancelled {
+                    for cell in row { _ = attributedInline(cell) }
+                }
+            }
+        }
+    }
 }