Review Flutter SDK golden changes

Keep the pixel comparator exact when upgrading Flutter. First prove a failure is fresh and that its master matches the current reference. Retained test/**/failures images can predate a successful reference update.

Flutter 3.47.2 compatibility review

The Studio baseline run on Flutter 3.47.2 and Dart 3.13.2 found nine existing fixtures failing in both Linux and blocked-text CI variants. The relevant rounded-border sources and fixtures were unchanged. Obers UI still resolved to git 990286c9; Alchemist remained 0.14.0. This was not a redesigned screen or a local Obers theme change.

CI now pins the same Flutter 3.47.2 renderer. The provenance test python tool/test/studio_sdk_baseline_test.py rejects a mismatched CI SDK, nonportable reference paths, changed accepted hashes or a nonzero comparator tolerance. Older renderer baselines are not claimed to match these references.

Two separately captured runs of each variant produced identical test PNG bytes. Every captured master matched its current reference SHA-256. Full Linux captures and isolated differences were inspected at native resolution. The differences were confined to the existing rounded border fringes; text, interiors and layout did not move. A signed-distance audit of the reviewed rounded rectangles found no changed pixel more than 3px from those borders. That geometric audit is not a comparison tolerance, an ignored region or a permission to accept future differences.

Native rounded-edge rasterization drift is the evidence-supported inference. An old/new engine rendering bisection was not executed, so no particular upstream renderer commit is attributed. Historical timeline captures from July were excluded: they used superseded masters and did not establish a current timeline regression.

Fixture	Linux changed pixels	CI changed pixels	Maximum channel delta	Reviewed geometry
wave2_text_scene	95	95	7	Rounded Box card border
gradient_editor	200	209	35	Stop strip and color field borders
spectrum_color_picker	264	404	34	Six palette swatch borders
inspector_shell	315	312	21	Code card and rounded badges
playground_idle	118	115	21	Code card and language badge
start_first_run	450	450	87	Tips and template card corners
start_returning	804	802	87	Recent glyph and template borders
start_samples_open	43	43	35	Unoccluded template corners
start_compact	46	46	85	Tips card top corners

Exact paths, dimensions, previous/accepted PNG hashes and audited geometry are recorded in tool/baselines/flutter_3_47_2_golden_migration.json. This report records an independently reviewed migration of exactly 18 existing references. Post-update verification passed twice without enabling reference updates: all eight package runs exited zero with fresh successful terminal JSON events, no JSON errors and unchanged accepted reference hashes. These runs covered the six exact files below and both Linux/CI variants. The complete repository gate subsequently passed twice with fresh external runtimes: formatting, fatal analysis, custom lint, 20 successful Flutter batch reports, four successful Dart package reports, 70 root-tool tests and all 11 required coverage targets above 97% per pass. Each report was independently checked for successful terminal JSON and absence of errors. Interrupted and disk-full retries were not counted. This accepts the pre-redesign Fluvie test baseline, not the local Obers tree or any redesigned application screen. Do not update a directory of unrelated goldens or change the comparator.

Reproduce the review

Run each exact file twice, once per variant, using a private temporary runtime and a fresh JSON reporter. Save each variant’s failure captures before the next variant overwrites the shared failure filenames.

TMPDIR='<owned runtime>' flutter test '<exact test file>' --tags golden \
  --plain-name 'variant: Linux' --file-reporter 'json:<fresh Linux report>'
TMPDIR='<owned runtime>' flutter test '<exact test file>' --tags golden \
  --plain-name 'variant: CI' --file-reporter 'json:<fresh CI report>'

The six files are packages/fluvie/test/serialization/goldens_wave2_test.dart, the editor’s goldens_gradient_editor_test.dart and goldens_spectrum_picker_test.dart, the gallery’s goldens_shell_test.dart and playground_golden_test.dart, and apps/slides/test/goldens_start_test.dart. Run from the owning package. A fresh completed failure report is the expected pre-migration result; it is not a passing gate.

After review, migrate only the individually accepted reference paths. Run the same exact files twice without updates, then run the complete repository gate. The Studio suite runner requires a fresh successful terminal JSON event as well as process exit zero before publishing merged coverage. A terminated Flutter process can return zero despite incomplete tests; that is not success.

This baseline review supplies no feature completion or 23-board Studio pixel parity claim. Those require separate screenshots and real feature journeys.

Where to next

Read the coverage policy and the release verification guide.