feat: core domain types and rocksdb storage layer

[vieiralucas]

Summary

• Add core domain types: FilaError (with thiserror), Message, and QueueConfig with serde serialization
• Implement binary key encoding (storage::keys) with big-endian numerics and length-prefixed strings for correct lexicographic ordering in RocksDB
• Add Storage trait abstraction with WriteBatchOp for atomic multi-CF operations
• Implement RocksDbStorage with 5 column families (messages, leases, lease_expiry, queues, state)

Test plan

• 6 key encoding unit tests (lexicographic ordering, prefix matching, collision avoidance)
• 10 RocksDB integration tests (CRUD for all CFs, prefix scan, expired lease scan, atomic write batch, data persistence across reopen)
• cargo clippy -- -D warnings passes
• cargo fmt --check passes
• All 16 tests pass via cargo nextest run

---

Summary by cubic

Adds core domain types and a RocksDB storage layer with atomic batches and lexicographic key encoding for durable, ordered message persistence. Implements Story 1.3 requirements for queues, messages, leases, and expiry scans.

• New Features

  • StorageError with StorageResult; removed FilaError from core.
  • Message and QueueConfig with serde/serde_json; UUIDv7 message IDs.
  • Storage trait + WriteBatchOp; RocksDbStorage with CFs: messages, leases, lease_expiry, queues, state; atomic batches and durable reopen.
  • Binary key encoding (big-endian u64, length‑prefixed strings) with prefixes for queue and fairness scans; lease expiry keys enable efficient timeout scanning.

• Bug Fixes

  • Checked u16 cast for string length prefixes to avoid truncation in key encoding.

^{Written for commit 899b27b. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 13 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="crates/fila-core/src/storage/keys.rs">

<violation number="1" location="crates/fila-core/src/storage/keys.rs:16">
P1: Unsafe truncating cast `s.len() as u16` — strings longer than 65535 bytes silently produce a corrupted length prefix, leading to key collisions and data corruption. Use `u16::try_from(s.len()).expect("queue/fairness key exceeds 64 KiB")` (or return a `Result`) to fail loudly instead of silently corrupting keys.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}