LilSQL v0.8.4_01 introduces a fully structured logging system and a deterministic undo engine, forming the foundation for safe state recovery and future redo support.

This release focuses on correctness, explicit behavior, and invariant safety, not user-facing convenience.

• Centralized, append-only command logging
• Each successful mutation produces a single immutable log entry
• Logs include:
  • command
  • database & table scope
  • action type
  • before / after snapshots (where applicable)
  • execution phase metadata
• Log format designed explicitly to support undo & future redo

• Deterministic undo for all mutating commands
• Undo restores engine state using logged snapshots, not recomputation
• Supports:
  • CREATE (database, table, rows)
  • DELETE (database, table, columns, rows)
  • UPDATE (database name, table name, column name, row values)
• Undo semantics are explicit and bounded
• Undo history collapses after execution (redo not yet implemented)

• Undo guarantees state consistency, not full data recovery
• Destructive operations follow force-style semantics
• Only data explicitly logged is recoverable
• Prevents “ghost undo” and timeline paradoxes

• Engine maintains an undo counter representing available undo steps
• Each successful mutation increments undo availability
• Executing undo resets undo history (redo planned for later builds)
• Prevents re-undoing already reverted operations

• Undo never depends on runtime state
• All recovery is log-driven
• Schema and row data are always restored to a valid state
• No partial or ambiguous restoration paths

• Recursive / force delete flags are planned but not implemented yet
• This release lays the groundwork for:
  • force delete (-f)
  • redo support
  • checkpointing
• Logging format is considered stable going forward

• v0.8.4 is split into incremental internal builds:
  • v0.8.4_01 — Logging & Undo foundation
  • v0.8.4_02 — Force delete semantics (planned)
  • v0.8.4_03 — Redo engine (planned)
• These builds collectively form the v0.8.4 milestone

This release is experimental but architecturally complete for its scope.
It prioritizes correctness and explicit behavior over convenience.