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Description of the pull request

⚠️ Stacked on #2894 — review/merge that first. Base this diff against chore/flutter-3.44.0, not master.

🛑 BLOCKED — not mergeable as-is. 19 type errors remain, and every one of them is upstream. See Why it's blocked.

Flutter has split Material and Cupertino out of the framework into the flutter.dev-published material_ui and cupertino_ui packages — both v1.0.0, published 2026-08-12, the same day as Flutter 3.47 stable.

Both require flutter: >=3.44.0. That is exactly the floor #2894 raises, which is what makes this work possible now and why it is stacked rather than standalone.

What changed

• 409 import directives across 405 tracked files. package:flutter/material.dart → package:material_ui/material_ui.dart (403) and package:flutter/cupertino.dart → package:cupertino_ui/cupertino_ui.dart (6). Only the URI is replaced, so the three imports carrying show/hide clauses keep them. Verified up front that every occurrence is a plain import directive — there are no export directives and no doc/string references to either URI anywhere in the repo.
• Dependencies added to the 10 pubspecs that need them (material_ui ×10, cupertino_ui ×4), and both registered in melos.yaml's command.bootstrap.dependencies — the workspace's single version registry, where every shared dependency is pinned.
• directives_ordering reapplied via dart fix (188 files). Renaming the URIs moved them relative to their neighbours; the lint is enabled repo-wide, so this is a consequence of the rewrite, not unrelated churn.
• Localizations (step 2 of the official guide). GlobalMaterialLocalizations now comes from material_ui and GlobalCupertinoLocalizations from cupertino_ui; GlobalWidgetsLocalizations stays in flutter_localizations, which is still its home. The flutter_localizations import is narrowed with a show so its own GlobalMaterialLocalizations can't collide with material_ui's. The public barrel re-exports each from its new home — this is a public API change for stream_chat_localizations.

Why the migration is hand-rolled, not dart fix

The README says to run dart fix --apply --code=migrate_design_widgets. That does not work in Flutter 3.47. The transform ships in the SDK at fix_data/fix_material/fix_material.yaml, but it is a data-driven replacedBy keyed off the library being deprecated — and package:flutter/material.dart carries no @Deprecated annotation in 3.47. The transform's own comment reads TODO(Piinks): Link eventual deprecation PR. Against the real packages dart fix reports Nothing to fix! even with the lint enabled and the diagnostic firing 13×.

The rewrite reproduces that fix's output byte-for-byte, confirmed against a probe package where the fix does apply.

Why it's blocked

material_ui ships its own implementations, and Flutter 3.47's material.dart does not re-export them. So flutter/material's ThemeData / ThemeExtension / ColorScheme and material_ui's are unrelated types. Reproduced minimally:

error - The argument type 'ThemeData (where ThemeData is defined in .../flutter/lib/src/material/theme_data.dart)'
        can't be assigned to the parameter type 'ThemeData (where ThemeData is defined in .../material_ui-1.0.0/lib/src/theme_data.dart)'

The 19 remaining errors are all that collision, from two dependencies that haven't migrated:

stream_core_flutter must migrate first — it's ours, so that's a sequencing decision, not a wait. dynamic_color is third-party and only affects sample_app.

MaterialUiCompatibilityBridge does not rescue this. It is documented as an app-level tool for a modern app hosting legacy widgets; it bridges ThemeData/MaterialLocalizations at runtime and does nothing for compile-time signature mismatches, nor for the reverse case of a legacy app hosting a migrated SDK.

Consumer impact

For the same reason, this is breaking for every consumer of stream_chat_flutter: once our public API speaks material_ui types, an app still on package:flutter/material.dart gets the error above, and Theme.of(context) lookups won't resolve across the two universes at runtime. This needs a major version and coordination with the other Stream SDKs.

Testing

Goldens were not run or regenerated: the package doesn't compile until the blocker clears, and material_ui's widgets may rasterise differently, so the ~40-golden macOS baseline from #2894 needs re-checking once it does.

Follow-up

migrate_design_widgets is enabled in analysis_options.yaml, as the regression guard for this migration — without it a new package:flutter/material.dart import would pass CI and silently reintroduce the split.

This is safe at the 3.44 floor even though that analyzer doesn't recognise the rule. undefined_lint is reported against analysis_options.yaml itself, so it only surfaces when that file is inside the analysed directory. legacy_version_analyze runs cd packages/X/lib && dart analyze --fatal-infos ., which leaves the options file out of scope — verified exit 0 from lib/ versus exit 2 from the package root with the same unknown rule enabled. The main analyze job runs the latest stable, which knows the rule. It fires 0 times across all seven packages now that the migration is complete.

Screenshots / Videos

Not applicable — no intended visual change. Any pixel movement from material_ui's implementations is a finding, not an expectation.

🤖 Generated with Claude Code