Goal

Provide an app-friendly helper for model download/cache UX so Flutter examples and downstream apps do not need to hand-roll progress/cancel/retry state machines.

Motivation

Large GGUF downloads need clear UI states: resolving, cache check, downloading, verifying, promoting, ready, failed, cancelled. The low-level cache manager exposes the primitives; a higher-level helper could make correct app UX easier.

Possible shape

• ModelDownloadTask or ModelDownloadController
• progress stream/value notifier
• cancel/retry support
• current stage enum
• final resolved cache entry/path
• safe error messages with URL redaction

Acceptance criteria

• Decide whether this belongs in package API, example utility code, or a separate Flutter helper.
• Demonstrate usage in example/chat_app.
• Cover cancel/retry/failure states in tests.
• Keep low-level DefaultModelDownloadManager usable without Flutter dependencies.