RFC: Product session restore host API

Source PR: #71 · docs/rfcs/0016-product-session-restore.md · @replghost

Description

A product checkpoints its own session state into a reserved storage key and receives host lifecycle events, so it can flush before backgrounding, restart or force quit. The host owns storage, scheduling and retention; the product owns serialization.

Motivation

A host can reopen the product set but not the working context, so a product comes back to its start page with the draft, step or selection gone. No browser API serializes a live JS heap, so the state has to be semantic and product-written.

Requirements

• host_session_lifecycle_subscribe delivers the events; state bytes go through the existing local-storage methods.
• The reserved storage key is __truapi/session_restore/v1.
• The blob carries an envelope version, a product schema version, and a Json or Cbor state payload.
• Restore is best-effort with a cold-boot fallback, and state never reaches another product.

Tasks

• RFC document body
• Implementation — rust-core
• Implementation — hosts
  • dotli
  • Desktop
  • iOS
  • Android
  • host-cli

Start with docs/rfcs/0016-product-session-restore.md and Source PR #71. Compare the RFC requirements with the existing local-storage methods and host_session_lifecycle_subscribe API described by the issue. Done means the RFC body and the listed rust-core and host implementations are addressed, including dotli, Desktop, iOS, Android, and host-cli.