# Implementation Plan: Core Distributed Architecture (Phase 1)

**Branch**: `001-distributed-core` | **Date**: 2025-11-30 | **Spec**: [specs/001-distributed-core/spec.md](specs/001-distributed-core/spec.md)
**Input**: Feature specification from `/specs/001-distributed-core/spec.md`

**Note**: This template is filled in by the `/speckit.plan` command. See `.specify/templates/commands/plan.md` for the execution workflow.

## Summary

Implement the foundational architecture for FlareDB, a distributed key-value store with CAS support. This includes setting up a Rust Cargo Workspace with 5 crates (`rdb-proto`, `rdb-storage`, `rdb-server`, `rdb-pd`, `rdb-client`), defining gRPC interfaces, implementing a RocksDB-based local storage engine, and verifying basic client-server interaction.

## Technical Context

**Language/Version**: Rust (Latest Stable)
**Primary Dependencies**:
- `tonic` (gRPC)
- `prost` (Protobuf)
- `rocksdb` (Storage Engine)
- `tokio` (Async Runtime)
- `clap` (CLI)
**Storage**: RocksDB (embedded via crate)
**Testing**: `cargo test` (Unit), `cargo nextest` (Optional), Custom Integration Scripts
**Target Platform**: Linux (x86_64), managed via Nix Flake
**Project Type**: Rust Cargo Workspace (Monorepo) with Nix environment
**Performance Goals**: Low-latency CAS operations (local storage baseline)
**Constraints**: Single-node verification for Phase 1, but architecture must support distributed extension.
**Scale/Scope**: 5 crates, ~2000 LOC estimate.

## Constitution Check

*GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.*

- **I. Reliability & Testing**:
  - Plan includes unit tests for `rdb-storage` (SC-002).
  - Plan includes integration verification (SC-003).
  - Compliant.
- **II. Agility & Evolution**:
  - Architecture uses standard crates (`tonic`, `rocksdb`) to avoid reinventing wheels.
  - Monorepo structure allows easy refactoring across crates.
  - Compliant.
- **III. Simplicity & Readability**:
  - Separation of concerns: Proto vs Storage vs Server vs PD vs Client.
  - Clear interfaces defined in `rdb-proto`.
  - Compliant.

## Project Structure

### Documentation (this feature)

```text
specs/001-distributed-core/
├── plan.md              # This file (/speckit.plan command output)
├── research.md          # Phase 0 output (/speckit.plan command)
├── data-model.md        # Phase 1 output (/speckit.plan command)
├── quickstart.md        # Phase 1 output (/speckit.plan command)
├── contracts/           # Phase 1 output (/speckit.plan command)
└── tasks.md             # Phase 2 output (/speckit.tasks command - NOT created by /speckit.plan)
```

### Source Code (repository root)

```text
flake.nix                 # Nix development environment definition
flake.lock                # Lockfile for Nix dependencies
Cargo.toml                # Workspace definition
rdb-proto/
├── Cargo.toml
├── build.rs
└── src/                  # Generated protos
rdb-storage/
├── Cargo.toml
└── src/                  # RocksDB wrapper, CAS logic
rdb-server/
├── Cargo.toml
└── src/                  # gRPC Server, Handlers
rdb-pd/
├── Cargo.toml
└── src/                  # Placement Driver (TSO)
rdb-client/
├── Cargo.toml
└── src/                  # Smart SDK
rdb-cli/                  # (Optional for Phase 1, but good to have)
├── Cargo.toml
└── src/
```

**Structure Decision**: Standard Rust Workspace layout to ensure modularity and separation of concerns as per the architecture design.

## Complexity Tracking

> **Fill ONLY if Constitution Check has violations that must be justified**

| Violation | Why Needed | Simpler Alternative Rejected Because |
|-----------|------------|-------------------------------------|
| N/A | | |