Remove non-deterministic "generated" and "generatorVersion" fields from .dart_tool/package_config.json after flutter pub get, so the snapshot hash is stable across runs and all downstream test steps can be cached. Mount only .dart_tool/build as a mutable cache volume so the incremental build graph persists without polluting the deterministic snapshot. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>