Comprehensive schema design for three critical foundational features:
1. Tree Forking Model (Issue #11)
- Add parent_tree_id, fork_reason, parent_updated_at to trees
- Self-referential relationship with orphaning on parent delete
- Update detection mechanism for "parent tree updated" notifications
2. Session Custom Steps Enhancement (Issues #4-#7 partial)
- Backward-compatible JSONB enhancement (no migration)
- Track step source (ad-hoc, library, forked-tree)
- Link to StepLibrary for usage analytics
- Support "save session as tree" reconstruction
3. Session Share Tokens (Issue #15)
- New session_shares table with token-based access
- New session_share_views table for detailed analytics
- Account-level policy: allow_public_shares
- Public vs account-only visibility with permission checks
All schema changes designed for backward compatibility and minimal
migration complexity. Establishes durable domain model that future
features depend on.
Migration plan: 022 (tree forking), 023 (session sharing)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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