Settles the undo/snapshot half (U1/U2) before implementation:
- every-mutation single-step undo (supersedes destructive-only model)
- hybrid whole-project snapshot (db backup API + yaml/csv copy),
reconciling ADR-0006 with ADR-0015's derived-db model
- persisted N=50 ring; redo discarded on new work
- batch ops (replay + future) record one undo step; import excluded
- --no-undo disable switch
Adds the implementation plan and updates README index, requirements
U1/U2, and CLAUDE.md in lockstep.
Captures up-front design decisions for RDBMS Playground:
stack (Rust + Ratatui + SQLite), input modes, project file
format, type vocabulary, undo snapshots and replay log,
sharing/export, and testing approach. ADR-0000 establishes
the ADR practice itself and mandates index upkeep alongside
any ADR change.
claude@clouddev1