mobile: fix rn 82 build on xcode 26.5

apps/mobile/ios/Podfile

@@ -5,6 +5,8 @@ require Pod::Executable.execute_command('node', ['-p',
     {paths: [process.argv[1]]},
   )', __dir__]).strip
 
+require_relative 'scripts/patch_fmt_consteval'
+
 platform :ios, min_ios_version_supported
 prepare_react_native_project!
 
@@ -66,6 +68,10 @@ post_install do |installer|
       :mac_catalyst_enabled => false,
       # :ccache_enabled => true
     )
+
+  # Keep fmt buildable on Xcode >= 26.2. See ios/scripts/patch_fmt_consteval.rb.
+  PatchFmtConsteval.apply!(installer.sandbox.root)
+
   installer.pods_project.targets.each do |target|
   target.build_configurations.each do |config|
       config.build_settings['APPLICATION_EXTENSION_API_ONLY'] = 'NO'

apps/mobile/ios/Podfile.lock

@@ -4092,6 +4092,6 @@ SPEC CHECKSUMS:
   toolbar-android: c426ed5bd3dcccfed20fd79533efc0d1ae0ef018
   Yoga: 689c8e04277f3ad631e60fe2a08e41d411daf8eb
 
-PODFILE CHECKSUM: 3fe13efa8356dcc061862bfa9f453dcd12ede70a
+PODFILE CHECKSUM: 30b2045c0f4fc91402a43a9e2a872af803f2d6c3
 
 COCOAPODS: 1.16.2

apps/mobile/ios/scripts/patch_fmt_consteval.rb

@@ -0,0 +1,77 @@
+# Xcode >= 26.2 rejects fmt's compile-time format-string check with
+#
+#   call to consteval function 'fmt::fstring<...>::fstring<char[N]>' is not a
+#   constant expression
+#
+# React Native 0.81/0.82 vendor fmt 11.0.2, which hits this. It is an upstream
+# incompatibility (reproducible in a stock RN app), but left alone it makes those
+# RN versions permanently un-buildable on a modern Xcode.
+#
+# fmt's own escape hatch is FMT_USE_CONSTEVAL: 0 downgrades the format-string
+# check from compile-time to run-time. fmt 11.0.2 does not guard its detection
+# block with #ifndef, so we cannot simply predefine the macro -- and doing it
+# through the build settings is worse anyway:
+#
+#   * a command-line GCC_PREPROCESSOR_DEFINITIONS outranks every per-target
+#     value, silently dropping COCOAPODS=1, RCT_METRO_PORT, ...
+#   * a second `post_install` block in the Podfile REPLACES React Native's own.
+#
+# So we patch the header itself, right after fmt has made up its mind and before
+# the first use of the macro. Idempotent, and safe to run on every pod install.
+
+module PatchFmtConsteval
+  MARKER = 'NOTESNOOK_FMT_CONSTEVAL_PATCH'.freeze
+
+  # The line that first consumes the macro; our override goes immediately above
+  # it, i.e. after the whole detection cascade.
+  ANCHOR = "#if FMT_USE_CONSTEVAL\n".freeze
+
+  OVERRIDE = <<~PATCH.freeze
+    // #{MARKER}: Xcode >= 26.2 rejects fmt's consteval format-string check
+    // (see ios/scripts/patch_fmt_consteval.rb). Applied automatically by
+    // `pod install`; downgrades the check to run-time.
+    #undef FMT_USE_CONSTEVAL
+    #define FMT_USE_CONSTEVAL 0
+  PATCH
+
+  # pods_root: the Pods directory (installer.sandbox.root).
+  def self.apply!(pods_root)
+    header = File.join(pods_root.to_s, 'fmt', 'include', 'fmt', 'base.h')
+
+    unless File.exist?(header)
+      Pod::UI.warn "fmt: #{header} not found, skipping consteval patch."
+      return
+    end
+
+    contents = File.read(header)
+
+    if contents.include?(MARKER)
+      Pod::UI.puts 'fmt: consteval patch already applied.'
+      return
+    end
+
+    index = contents.index(ANCHOR)
+    if index.nil?
+      Pod::UI.warn 'fmt: could not find `#if FMT_USE_CONSTEVAL` in base.h; ' \
+                   'the consteval patch was NOT applied. If this fmt version ' \
+                   'still uses a consteval format-string check, builds on ' \
+                   'Xcode >= 26.2 will fail -- update ' \
+                   'ios/scripts/patch_fmt_consteval.rb.'
+      return
+    end
+
+    contents.insert(index, OVERRIDE)
+
+    # CocoaPods checks pod sources out read-only (0444), so make the header
+    # writable for the write and restore the original mode afterwards.
+    mode = File.stat(header).mode & 0o7777
+    begin
+      File.chmod(mode | 0o200, header)
+      File.write(header, contents)
+    ensure
+      File.chmod(mode, header)
+    end
+
+    Pod::UI.puts 'fmt: patched base.h to set FMT_USE_CONSTEVAL=0 (Xcode >= 26.2 compatibility).'
+  end
+end