From a996e5185089508ed80bb15f888a611d81f8b5f0 Mon Sep 17 00:00:00 2001
From: Lars Janssen <125481620+larsjtx@users.noreply.github.com>
Date: Mon, 11 May 2026 08:46:30 +0200
Subject: [PATCH] Avoid stack overflow when rendering text with many attributed
 runs

The reduce in TextBuilder built the result via Text("\(partialResult)\(text)"),
wrapping every attributed run in a LocalizedStringKey-backed Text.
At render time, SwiftUI's LocalizedStringKey.resolve walks the chain
and recurses ~8 stack frames per nesting level, overflowing the
main-thread stack for content that produces a few hundred runs
(e.g. emoji-dense notes where each emoji forms its own run).

Switch to Text + Text concatenation, which produces concat storage
that resolves linearly.

Fixes #56
---
 Sources/Textual/Internal/TextFragment/TextBuilder.swift | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Sources/Textual/Internal/TextFragment/TextBuilder.swift b/Sources/Textual/Internal/TextFragment/TextBuilder.swift
index 1910ba2d..87e0b4e8 100644
--- a/Sources/Textual/Internal/TextFragment/TextBuilder.swift
+++ b/Sources/Textual/Internal/TextFragment/TextBuilder.swift
@@ -96,9 +96,12 @@ extension Text {
       return text
     }
 
-    self = textValues.reduce(Text(verbatim: "")) { partialResult, text in
-      Text("\(partialResult)\(text)")
-    }
+    // Concatenate via `Text + Text` rather than `Text("\(partialResult)\(text)")`.
+    // The interpolation form produces a `LocalizedStringKey`-backed `Text` at every
+    // reduce step; resolving the resulting N-deep chain recurses ~8 stack frames per
+    // level during SwiftUI's render pass and overflows the main-thread stack for
+    // content that produces a few hundred attributed runs (e.g. emoji-dense notes).
+    self = textValues.reduce(Text(verbatim: ""), +)
   }
 
   private init(placeholderSize size: CGSize) {