flutter

pubspec_overrides.yaml is a file next to pubspec.yaml that pub reads on top of it, limited to dependency_overrides, resolution and workspace. It replaces the whole dependency_overrides section, applies workspace-wide, and is left out of published archives. What it does, when to use it in a monorepo, and every edge case, verified on Dart 3.12.2.

Replace the deprecated textScaleFactor on MediaQueryData, Text, RichText and TextPainter with TextScaler. What dart fix rewrites (3 of 9 call sites in our sample), why its output can quietly undo Android 14 nonlinear font scaling, how to cap text size with clamp and withClampedTextScaling, and the equality and test gotchas. Measured on Flutter 3.44.8 with Dart 3.12.2.

A tested, file-by-file conversion of a Flutter app's settings.gradle, build.gradle and app/build.gradle to Kotlin DSL on Flutter 3.44.8, AGP 9.0.1 and Gradle 9.1.0, with the real compiler errors each naive rename produces and the exact fix for signing configs, flavors, minifyEnabled and kotlinOptions.

Use shared_preferences (SharedPreferencesWithCache) for a handful of flat flags and a JSON file in getApplicationSupportDirectory for a structured settings object. Covers the atomic-write pattern, the concurrent-save race, the Documents-folder trap on Windows and Linux, web support, and measured write costs on Flutter 3.44.8.

flutter upgrade aborts if git status in the SDK folder prints anything. Inspect it, restore pubspec.lock or git stash -u, and use --force only as a last resort.

Anything you compile into a Flutter web build, including --dart-define values, ships to the browser in plain text. The only safe pattern is a small backend proxy that holds the key, authenticates the user, pins the model, and streams the Responses API SSE back. Full Dart shelf proxy and Flutter client, tested with Flutter 3.44, Dart 3.12, and http 1.6.

Lock one Flutter route to landscape or portrait with SystemChrome.setPreferredOrientations without breaking the rest of the app: a stack-based lock that survives pushReplacement and restores on pop, why the empty list is the wrong reset, why iPad multitasking and Android 16 large screens ignore the lock, and what UIRequiresFullScreen means after iPadOS 26 and the iOS 27 SDK. Tested on Flutter 3.47.8 with Dart 3.13.7 and Xcode 27.1.

Calling remove inside a for-in loop or forEach throws ConcurrentModificationError. Use removeWhere for in-place filtering, build a new list with where or a collection-for, or loop backwards by index. Verified on Dart 3.13.7, with a benchmark of why removeAt in a loop is the slow option.

Put a discriminator field in the JSON, switch on it in a factory on the sealed base, and switch on the subtype to write it back. Three working versions on Dart 3.13.7: hand-written pattern matching, json_serializable 6.15.2, and Freezed 4.0.3 with unionKey and fallbackUnion, plus the gotchas each one hides.

depend_on_referenced_packages fires when a file imports or exports a package that is not listed in your own pubspec.yaml, even if it resolves through another dependency. Here is exactly what the rule checks on Dart 3.12.2 and Flutter 3.44.8, why transitive imports are a real bug, and how to fix each variant.