test(ios): run the native text probe on the main thread

Apply the minimal candidate from #6364 and cover recycled geometry in the native probe. Document that the probe does not reproduce mounted Fabric clipping.

Co-authored-by: Oxxx <103127477+omcdowell@users.noreply.github.com>

packages/app/e2e/mobile/native-text-reflow/README.md

@@ -0,0 +1,31 @@
+# Native iOS text geometry regression
+
+Run on the Namespace Mac with a fresh simulator development build. Use the PID
+returned by `xcrun simctl launch <your-task-simulator-UDID> sh.paseo.debug`.
+Attach only to your task's app, while no device replay is running:
+
+```sh
+PASEO_NATIVE_TEXT_REFLOW_PID=12345 \
+PASEO_NATIVE_TEXT_REFLOW_LOG=/Volumes/devbox/workspace/native-text-reflow.log \
+bash packages/app/e2e/mobile/native-text-reflow/ios.sh
+```
+
+The probe constructs the installed `RNUITextView`, fills its real UIKit text view,
+and resizes its content container from 500 to 240 and back to 500 points. It
+asserts the inner frame follows both widths and the same selection survives.
+It then recycles the view the way Fabric's pool does and remounts it 30 points
+wider and at the same size; the inner frame must still match the container.
+A zeroed frame on recycle comes back 30 or 0 points wide. This assertion checks
+the intermediate recycled geometry; it does not reproduce visible clipping in a
+mounted Fabric paragraph or exercise the subsequent `drawRect` call.
+It uses public UIView/UITextView operations, without mocking React Native.
+LLDB detaches after the probe. An assertion failure or evaluation error fails the
+shell command; the log distinguishes them.
+
+This covers native container resizing and selection retention. It does not cover
+Fabric event delivery, chat row height, reader anchoring, or the on-screen copy
+menu. Those require the real chat journey: read an older multiline response,
+open/close Explorer, resize/rotate, inspect complete paragraphs and bullets,
+retain expanded/collapsed details, and check a stationary reader's position.
+Accessibility exposes full text even when glyphs are clipped, so a text wait
+alone does not verify that journey.

packages/app/e2e/mobile/native-text-reflow/ios.py

@@ -0,0 +1,76 @@
+import lldb
+
+
+def __lldb_init_module(debugger, _internal_dict):
+    process = debugger.GetSelectedTarget().GetProcess()
+    main_threads = [thread for thread in process if thread.GetQueueName() == "com.apple.main-thread"]
+    if len(main_threads) != 1 or not process.SetSelectedThread(main_threads[0]):
+        raise RuntimeError("Could not select the UIKit main thread")
+    debugger.HandleCommand("expression -l objc++ -- @import UIKit")
+    frame = process.GetSelectedThread().GetSelectedFrame()
+    options = lldb.SBExpressionOptions()
+    options.SetLanguage(lldb.eLanguageTypeObjC_plus_plus)
+    is_main_thread = frame.EvaluateExpression("(BOOL)[NSThread isMainThread]", options)
+    if is_main_thread.GetError().Fail() or is_main_thread.GetValueAsUnsigned() != 1:
+        raise RuntimeError("Refusing to run UIKit probe outside the main thread")
+    result = frame.EvaluateExpression(
+        r'''({
+            UIView *host = (UIView *)[[NSClassFromString(@"RNUITextView") alloc] init];
+            auto hostFrame = host.frame;
+            hostFrame.size.width = 500;
+            hostFrame.size.height = 200;
+            host.frame = hostFrame;
+            UIView *container = (UIView *)[host performSelector:@selector(contentView)];
+            container.frame = host.bounds;
+            UITextView *text = nil;
+            for (UIView *child in host.subviews) {
+                if ([child isKindOfClass:UITextView.class]) text = (UITextView *)child;
+                for (UIView *nested in child.subviews) {
+                    if ([nested isKindOfClass:UITextView.class]) text = (UITextView *)nested;
+                }
+            }
+            text.frame = container.bounds;
+            text.font = [UIFont systemFontOfSize:16];
+            text.text = @"A realistic multiline paragraph must reflow when Explorer narrows the available chat width, then fill the restored width without replacing the text view or discarding a selection.";
+            auto range = text.selectedRange;
+            range.location = 12;
+            range.length = 9;
+            text.selectedRange = range;
+            auto frame = container.frame;
+            frame.size.width = 240;
+            container.frame = frame;
+            [container layoutIfNeeded];
+            CGFloat narrow = text.frame.size.width;
+            auto selection = text.selectedRange;
+            frame.size.width = 500;
+            container.frame = frame;
+            [container layoutIfNeeded];
+            CGFloat wide = text.frame.size.width;
+            auto keptSelection = text.selectedRange;
+            // Fabric recycles the view: the container keeps its size in the pool,
+            // and the next paragraph mounts it 30 points wider (a list-item paragraph
+            // reused by a full-width one) or at the same size.
+            [host performSelector:@selector(prepareForRecycle)];
+            frame.size.width = 530;
+            container.frame = frame;
+            [container layoutIfNeeded];
+            CGFloat reusedWider = text.frame.size.width;
+            [host performSelector:@selector(prepareForRecycle)];
+            container.frame = frame;
+            [container layoutIfNeeded];
+            CGFloat reusedSame = text.frame.size.width;
+            BOOL ok = text != nil && narrow == 240 && wide == 500 &&
+                reusedWider == 530 && reusedSame == 530 &&
+                selection.location == keptSelection.location &&
+                selection.length == keptSelection.length &&
+                selection.location == 12 && selection.length == 9;
+            [NSString stringWithFormat:@"NATIVE_REFLOW_%@ narrow=%.0f wide=%.0f recycled=%.0f,%.0f selection=%lu:%lu",
+                ok ? @"PASS" : @"FAIL", narrow, wide, reusedWider, reusedSame,
+                (unsigned long)keptSelection.location,
+                (unsigned long)keptSelection.length];
+        })''',
+        options,
+    )
+    if result.GetError().Fail():
+        raise RuntimeError(result.GetError().GetCString())
+    print(result.GetObjectDescription())

packages/app/e2e/mobile/native-text-reflow/ios.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+: "${PASEO_NATIVE_TEXT_REFLOW_PID:?Set the PID of your task-owned Paseo iOS simulator app}"
+: "${PASEO_NATIVE_TEXT_REFLOW_LOG:?Set the test output log path}"
+
+if [[ "$(ps -p "$PASEO_NATIVE_TEXT_REFLOW_PID" -o comm=)" != *PaseoDebug.app/PaseoDebug ]]; then
+  echo "Expected a running PaseoDebug simulator app" >&2
+  exit 1
+fi
+
+probe_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+xcrun lldb --batch -p "$PASEO_NATIVE_TEXT_REFLOW_PID" \
+  -o "command script import $probe_dir/ios.py" \
+  -o "process detach" -o quit > "$PASEO_NATIVE_TEXT_REFLOW_LOG" 2>&1
+
+grep '^NATIVE_REFLOW_' "$PASEO_NATIVE_TEXT_REFLOW_LOG"
+grep -q '^NATIVE_REFLOW_PASS narrow=240 wide=500 recycled=530,530 selection=12:9$' "$PASEO_NATIVE_TEXT_REFLOW_LOG"

patches/react-native-uitextview+2.2.0.patch

@@ -0,0 +1,88 @@
+diff --git a/node_modules/react-native-uitextview/ios/RNUITextView.mm b/node_modules/react-native-uitextview/ios/RNUITextView.mm
+index d0c31ed..d1605ea 100644
+--- a/node_modules/react-native-uitextview/ios/RNUITextView.mm
++++ b/node_modules/react-native-uitextview/ios/RNUITextView.mm
+@@ -22,6 +22,7 @@ using namespace facebook::react;
+   RNUITextViewShadowNode::ConcreteState::Shared _state;
+   UITapGestureRecognizer * _outsideTapRecognizer;
+   BOOL _suppressSelectionChange;
++  CGRect _lastTextLayoutFrame;
+ }
+ 
+ + (ComponentDescriptorProvider)componentDescriptorProvider
+@@ -47,7 +48,8 @@ using namespace facebook::react;
+     _textView.delegate = self;
+     // Must match RCTTextLayoutManager, which measures with usesFontLeading = NO.
+     _textView.layoutManager.usesFontLeading = NO;
+-    [self addSubview:_textView];
++    _textView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
++    [_view addSubview:_textView];
+ 
+     const auto longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self
+                                                                                           action:@selector(handleLongPressIfNecessary:)];
+@@ -91,19 +93,21 @@ using namespace facebook::react;
+   [super prepareForRecycle];
+   _state.reset();
+ 
+-  // Reset the frame to zero so that when it properly lays out on the next use
+-  _textView.frame = CGRectZero;
++  // Keep the text view on the content container's bounds. The container keeps
++  // its size while the view waits in the recycle pool, and autoresizing only
++  // applies the size delta on reuse, so a zeroed text view would come back as
++  // wide as that delta (zero, or a two-word column).
++  _textView.frame = _view.bounds;
+   _textView.attributedText = nil;
++  _lastTextLayoutFrame = CGRectZero;
+ }
+ 
+ - (void)layoutSubviews
+ {
+   [super layoutSubviews];
+-  // _textView's frame is assigned inside drawRect, which only fires when
+-  // state changes. Trigger a redraw whenever the host frame moves out from
+-  // under it (rotation, parent relayout) so the text view resizes and
+-  // onTextLayout re-fires with the new line wrapping.
+-  if (!CGRectEqualToRect(_textView.frame, _view.frame)) {
++  // Autoresizing updates UIKit immediately; report the new line layout when
++  // the content container's bounds change.
++  if (!CGRectEqualToRect(_lastTextLayoutFrame, _view.bounds)) {
+     [self setNeedsDisplay];
+   }
+ }
+@@ -124,10 +128,16 @@ using namespace facebook::react;
+   // entirely when nothing actually changed so a JS-side state update made in
+   // response to onSelectionChange doesn't deselect what the user is selecting.
+   const BOOL textChanged = ![_textView.attributedText isEqualToAttributedString:convertedAttrString];
+-  const BOOL frameChanged = !CGRectEqualToRect(_textView.frame, _view.frame);
+-  if (!textChanged && !frameChanged) {
++  const BOOL frameChanged = !CGRectEqualToRect(_textView.frame, _view.bounds);
++  const BOOL layoutChanged = !CGRectEqualToRect(_lastTextLayoutFrame, _view.bounds);
++  if (!textChanged && !frameChanged && !layoutChanged) {
+     return;
+   }
++  // Size the text view before handing it the text, so UIKit lays the text out
++  // at the container width instead of a stale width.
++  if (frameChanged) {
++    _textView.frame = _view.bounds;
++  }
+   if (textChanged) {
+     // Reassigning attributedText clears any active selection. Save it and
+     // restore after, while suppressing the synthetic textViewDidChangeSelection
+@@ -141,9 +151,6 @@ using namespace facebook::react;
+     }
+     _suppressSelectionChange = NO;
+   }
+-  if (frameChanged) {
+-    _textView.frame = _view.frame;
+-  }
+ 
+   __block std::vector<std::string> lines;
+   const int maxLines = props.numberOfLines;
+@@ -162,6 +169,7 @@ using namespace facebook::react;
+     }
+   }];
+ 
++  _lastTextLayoutFrame = _view.bounds;
+   if (_eventEmitter != nullptr) {
+     std::dynamic_pointer_cast<const facebook::react::RNUITextViewEventEmitter>(_eventEmitter)
+     ->onTextLayout(facebook::react::RNUITextViewEventEmitter::OnTextLayout{static_cast<int>(self.tag), lines});

scripts/postinstall-patches.mjs

@@ -12,6 +12,10 @@ const patchedPackages = [
     nodeModulesPath: "node_modules/react-native-markdown-display",
     patchPrefix: "react-native-markdown-display+",
   },
+  {
+    nodeModulesPath: "node_modules/react-native-uitextview",
+    patchPrefix: "react-native-uitextview+",
+  },
   // Remove after react-native-unistyles ships
   // https://github.com/jpudysz/react-native-unistyles/pull/1203.
   {