Release v0.2.0

.claudeignore

@@ -0,0 +1,28 @@
+
+node_modules/
+vendor/
+.venv/
+venv/
+
+
+dist/
+build/
+out/
+target/
+
+
+.git/
+.svn/
+
+
+*.log
+*.pdf
+*.zip
+*.tar.gz
+*.mp4
+*.mp3
+
+
+.DS_Store
+*.pyc
+__pycache__/

.config/nextest.toml

@@ -0,0 +1,8 @@
+# Nextest configuration for d-engine
+
+[profile.default]
+
+# Force serial execution for tests that use /tmp/db
+[[profile.default.overrides]]
+filter = "test(tmp_db) | test(config_path_env)"
+threads-required = 'num-cpus'

.github/workflows/benchmark.yml

@@ -0,0 +1,83 @@
+name: Performance Benchmarks
+
+permissions:
+  contents: read
+
+# Run benchmarks on a schedule and manual trigger only
+on:
+  # Run weekly on Sunday at 2 AM UTC
+  schedule:
+    - cron: "0 2 * * 0"
+
+  # Allow manual triggering for on-demand performance testing
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: full
+
+jobs:
+  benchmark:
+    name: Run Performance Benchmarks
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0 # Full history for performance comparison
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y protobuf-compiler
+
+      - name: Cache Rust dependencies
+        uses: Swatinem/rust-cache@v2
+        with:
+          # Cache key includes benchmark to avoid interference with test cache
+          key: benchmark-${{ runner.os }}-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Run benchmarks
+        run: |
+          echo "========================================="
+          echo "Running d-engine Performance Benchmarks"
+          echo "========================================="
+          echo ""
+          echo "Performance Targets:"
+          echo "  • Without TTL: < 10ns overhead"
+          echo "  • With TTL passive check: < 50ns overhead"
+          echo "  • Piggyback cleanup: < 1ms"
+          echo ""
+
+          # Run benchmarks and save output
+          cargo bench --package d-engine-server 2>&1 | tee benchmark_output.txt
+
+          echo ""
+          echo "✅ Benchmarks completed successfully"
+
+      - name: Upload detailed results as artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: benchmark-results
+          path: |
+            target/criterion/
+            benchmark_output.txt
+          retention-days: 30
+
+      - name: Performance summary
+        run: |
+          echo "========================================="
+          echo "Performance Benchmark Summary"
+          echo "========================================="
+          echo ""
+          echo "📊 Benchmark results uploaded as artifacts"
+          echo ""
+          echo "To view detailed results:"
+          echo "  1. Download the artifact"
+          echo "  2. Open target/criterion/report/index.html in your browser"
+          echo ""
+          echo "✅ Performance monitoring complete"

.github/workflows/ci.yml

@@ -1,5 +1,8 @@
 name: CI
 
+permissions:
+  contents: read
+
 on:
   push:
   pull_request:
@@ -38,32 +41,32 @@ jobs:
     name: Test and Collect Coverage
     runs-on: ubuntu-latest
     needs: lint
+    permissions:
+      contents: read
+    env:
+      RUST_TOOLCHAIN: 1.88.0
+      CI: 1
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - name: Cache dependencies
-        uses: actions/cache@v4
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@master
         with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-            target
-          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-cargo-
+          toolchain: ${{ env.RUST_TOOLCHAIN }}
+          components: llvm-tools-preview
+
+      - name: Cache using Swatinem/rust-cache
+        uses: Swatinem/rust-cache@v2
 
       - name: Install Protobuf compiler
         run: sudo apt-get install -y protobuf-compiler
 
-      - name: Install cargo-llvm-cov
+      - name: Install cargo tools
         run: |
           cargo install cargo-llvm-cov --locked
-
-      - name: Install cargo-nextest
-        run: |
-          cargo install cargo-nextest --locked
+          cargo install cargo-nextest --version 0.9.114 --locked
 
       - name: Run tests with nextest and generate coverage
         run: |

.github/workflows/commit-message-check.yml

@@ -1,11 +1,16 @@
 name: Validate Commit Messages
 
+permissions:
+  contents: read
+
 on:
   pull_request:
 
 jobs:
   validate-commits:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
       - uses: actions/checkout@v3
         with:
@@ -16,16 +21,16 @@ jobs:
           BASE_SHA=${{ github.event.pull_request.base.sha }}
           HEAD_SHA=${{ github.event.pull_request.head.sha }}
 
-          ALLOWED_TYPES="feat|fix|refs|doc|perf|refactor|chore"
+          ALLOWED_TYPES="feat|fix|refs|doc|docs|perf|refactor|style|test|chore|ci|revert"
           SCOPE_PATTERN="([a-z][a-z0-9-]*)"
           TICKET_PATTERN="#[0-9]+:"
           FULL_PATTERN="^($ALLOWED_TYPES)(\($SCOPE_PATTERN\))? $TICKET_PATTERN.+$"
 
           # Validate the format of all new submissions
           for commit in $(git rev-list $BASE_SHA..$HEAD_SHA); do
             msg=$(git show -s --format=%s $commit)
-            
-            # skip merge 
+
+            # skip merge
             if [[ "$msg" =~ ^Merge ]]; then
               continue
             fi

.github/workflows/dependency-audit.yml

@@ -1,5 +1,8 @@
 name: Dependency Audit
 
+permissions:
+  contents: read
+
 on:
   push:
     branches: [main, develop]
@@ -12,6 +15,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
       - name: Install protoc
         run: sudo apt-get update && sudo apt-get install -y protobuf-compiler
 
@@ -26,7 +32,7 @@ jobs:
 
       - name: Audit dependencies
         run: |
-          cargo install cargo-deny
+          cargo install cargo-deny --locked
           cargo deny check all
 
       - name: Update dependencies

.gitignore

@@ -46,3 +46,6 @@ docker/monitoring/prometheus/data/
 lcov.info
 
 CONTEXT
+*.bak*
+.claudeignore
+safe-split-commits.sh

CHANGELOG.md

@@ -4,6 +4,93 @@ All notable changes to this project will be documented in this file.
 
 ---
 
+## [v0.2.0] - 2025-12-11 [✅ Released]
+
+### 🎯 Highlights for Developers
+
+#### Workspace Structure - Modular Dependencies
+
+**Problem**: v0.1.x pulled all dependencies even for client-only usage  
+**Solution**: Feature flags `client`/`server`/`full` - depend only on what you need
+
+```toml
+# Client-only (lightweight)
+d-engine = { version = "0.2", features = ["client"] }
+
+# Embedded server (full engine)
+d-engine = { version = "0.2", features = ["server"] }
+```
+
+**Impact**: Faster builds, smaller binaries
+
+#### TTL/Lease - Automatic Key Expiration
+
+**Use Case**: Distributed locks, session management, temporary state  
+**API**: `client.put_with_ttl("session:123", data, Duration::from_secs(60))`  
+**Feature**: Crash-safe (survives restart via absolute expiration time)
+
+#### Watch API - Real-Time Key Monitoring
+
+**Use Case**: Config change notifications, service discovery  
+**Example**:
+
+```rust,ignore
+let mut watcher = client.watch("config/").await?;
+while let Some(event) = watcher.next().await {
+    println!("Changed: {:?}", event);
+}
+```
+
+**Performance**: Lock-free, <0.1ms notification latency
+
+#### StandaloneServer - One-Line Deployment
+
+**Use Case**: Independent server process (production deployment)  
+**API**: `run(shutdown_rx)` uses env config, `run_with(config_path, shutdown_rx)` uses explicit config  
+**Benefit**: Blocks until shutdown, no manual lifecycle management
+
+#### EmbeddedEngine - In-Process Integration
+
+**Use Case**: Embed d-engine in your Rust application  
+**API**: `start()` uses env config, `start_with(config_path)` uses explicit config, `start_custom(...)` for advanced usage  
+**Benefit**: Zero gRPC overhead via LocalKvClient (<0.1ms latency)
+
+#### LocalKvClient - Zero-Overhead Embedded Access
+
+**When**: Your app and d-engine in same process  
+**Benefit**: Skip gRPC serialization, direct memory access (<0.1ms)  
+**Example**: See `examples/service-discovery-embedded/`
+
+---
+
+### 📚 New Examples
+
+- `examples/quick-start/` - 5-minute single-node setup
+- `examples/single-node-expansion/` - Dynamic 1→3 node scaling
+- `examples/service-discovery-embedded/` - LocalKvClient zero-overhead access
+- `examples/service-discovery-standalone/` - Watch API pattern
+
+---
+
+### ⚠️ Breaking Changes
+
+**File-based State Machine WAL Format**
+
+- WAL now uses absolute expiration time (not relative TTL)
+- **Action Required**: See [MIGRATION_GUIDE.md](./MIGRATION_GUIDE.md) if upgrading from v0.1.x
+- **New users**: No action needed
+
+---
+
+### 🚀 Performance & Quality
+
+- Watch API: Lock-free, tested with 1000+ concurrent watchers, <0.1ms notification latency
+- TTL cleanup: Lazy (read-time check) + Background (scheduled task), <1% CPU overhead
+- 1000+ new integration tests covering edge cases
+- Zero clippy warnings across entire codebase
+
+---
+
 ## [v0.1.4] - 2025-10-12 [✅ Released]
 
 ### Features