# walrust Roadmap
## Vision
**Simple, reliable SQLite backups to S3 with integrity verification.**
Core differentiators:
- LTX format with SHA256 verification
- Lower memory footprint than Litestream
- Built for production: verify, explain, webhook alerting
- Honest about what works (no vaporware)
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## Current Capabilities (v0.5.1)
**Core features that work:**
- `walrust watch` - Watch and sync multiple databases
- `walrust snapshot` - Take immediate snapshot
- `walrust restore` - Restore database from S3
- `walrust list` - List backups
- `walrust compact` - Clean up old snapshots with GFS retention
- `walrust replicate` - Poll-based read replica
- `walrust explain` - Configuration preview with cost estimation
- `walrust verify` - Backup integrity verification with exit codes
- LTX format with SHA256 verification
- Chained page checksums (O(changed pages) not O(entire DB))
- Point-in-time restore (by TXID or timestamp)
- Multi-database support
- Prometheus metrics + dashboard
- Webhook notifications (corruption, circuit breaker)
- Retry logic with circuit breaker
- Shadow WAL mode
- Constant RSS regardless of write throughput (~70MB for 50MB DB)
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## Future Considerations (v1.0+)
**Not planning yet, but might be useful:**
### Disk-Based Upload Queue
- Litestream-style disk caching
- Decoupled WAL encoding from S3 uploads
- Crash recovery
- Local cache for fast restore
### Push-Based Read Replicas
- Push-based replication (requires network)
- Lower latency than polling
### Additional Features
- Multi-region replication
- Encryption at rest
- Concurrent S3 uploads in uploader
**Philosophy:** Ship working features, not roadmaps. Only add features when users ask for them.
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## Completed Features (see CHANGELOG.md)
**v0.5.1:**
- Fixed RSS scaling linearly with write throughput (67MB→361MB) — now constant ~70MB
- Streaming `ChainHasher` for incremental checksum verification during LTX decode
- `read_frames_as_page_map()` — streaming WAL dedup (peak memory = unique pages)
- Shadow WAL streaming dedup, retry buffer sharing via `Arc<Vec<u8>>`
**v0.5.0:**
- Chained page checksums — eliminated full-DB read from sync hot path
- `wal_page_overlay` HashMap removed
- Page clone elimination in dedup and encode paths
**v0.4.0:**
- Split watch.rs (1856 lines) and restore.rs (1083 lines) into focused modules
- Wired periodic validation into watch_independent mode
- Wired cache cleanup (retention_duration, max_cache_size) into watch_independent
- Deleted dead watch modes (watch_simple, watch_config) and ~350 lines of dead code
- Removed all `#[ignore]` tests — 346 tests pass, 0 ignored
**v0.3.2:**
- `walrust explain` command with cost estimation
- `walrust verify` with exit codes, continuity checks, webhook integration
- Webhook notifications for corruption and circuit breaker events
- Published to crates.io
**v0.3.1:**
- Refactored sync.rs into focused modules
- Extracted litepages to separate repo
**v0.3.0 and earlier:**
- LTX format integration
- Point-in-time restore
- Multi-database support
- GFS retention policy
- Prometheus metrics
- Webhook notifications
- Retry logic with circuit breaker
- Shadow WAL mode
- Read replicas
- DST (Deterministic Simulation Testing)
- See CHANGELOG.md for full history
