# TDD Wave 5: Integration & API
**Date**: 2026-02-19
**Focus**: Forge agent integration, service API, event streaming
---
## Wave 5 Tests Summary
| 41 | CheckpointService creation | ✅ |
| 42 | Multi-session support | ✅ |
| 43 | Auto-checkpointing | ✅ |
| 44 | Service restore | ✅ |
| 45 | Checkpoint streaming/events | ✅ |
| 46 | API commands | ✅ |
| 47 | Background persistence | ✅ |
| 48 | Checkpoint annotations | ✅ |
| 49 | Concurrent sessions | ✅ |
| 50 | Service metrics & health | ✅ |
**Total**: 10 new tests, all passing (50/50 cumulative)
---
## Implementation Details
### New Module: `service.rs`
High-level service API for Forge integration:
```rust
pub struct CheckpointService {
storage: ThreadSafeStorage,
sessions: RwLock<HashMap<SessionId, SessionInfo>>,
subscribers: Mutex<HashMap<SessionId, Vec<Sender<CheckpointEvent>>>>,
annotations: RwLock<HashMap<CheckpointId, Vec<CheckpointAnnotation>>>,
running: RwLock<bool>,
}
```
### Service API
```rust
// Create service
let service = Arc::new(CheckpointService::new(storage));
// Create session
let session = service.create_session("my-session")?;
// Create checkpoint
let id = service.checkpoint(&session, "Description")?;
// Subscribe to events
let receiver = service.subscribe(&session)?;
// Execute commands
let result = service.execute(CheckpointCommand::List { session_id: session })?;
// Get metrics
let metrics = service.metrics()?;
```
### Event System
Real-time checkpoint events:
```rust
pub enum CheckpointEvent {
Created { checkpoint_id, session_id, timestamp },
Restored { checkpoint_id, session_id },
Deleted { checkpoint_id, session_id },
Compacted { session_id, remaining },
}
```
### Command Pattern
API commands for remote operation:
```rust
pub enum CheckpointCommand {
Create { session_id, message, tags },
List { session_id },
Restore { session_id, checkpoint_id },
Delete { checkpoint_id },
Compact { session_id, keep_recent },
}
```
### Auto-Checkpointing
Configurable automatic checkpoints:
```rust
pub struct AutoCheckpointConfig {
pub interval_seconds: u64,
pub on_error: bool,
pub on_tool_call: bool,
}
service.enable_auto_checkpoint(&session, AutoCheckpointConfig {
interval_seconds: 300,
on_error: true,
on_tool_call: false,
})?;
```
---
## Key Design Decisions
### 1. Session-Based Architecture
- Each debugging session has isolated checkpoints
- Sessions are identified by UUID
- Service manages multiple concurrent sessions
### 2. Event-Driven Notifications
- mpsc channels for event streaming
- Per-session subscriptions
- Best-effort delivery (no blocking)
### 3. Command Pattern for API
- All operations go through `CheckpointCommand`
- Consistent `CommandResult` types
- Easy to serialize for WebSocket/HTTP API
### 4. Annotations as Metadata
- Checkpoints can have notes/annotations
- Severity levels (Info, Warning, Critical)
- Stored separately from checkpoint data
---
## Code Metrics
| `src/service.rs` | ~450 | New |
| `tests/integration_tests.rs` | ~230 | New |
---
## Complete API Example
```rust
use forge_reasoning::*;
use std::sync::Arc;
#[tokio::main]
async fn main() -> Result<()> {
// Create service
let storage = ThreadSafeStorage::open("checkpoints.db")?;
let service = Arc::new(CheckpointService::new(storage));
// Create session
let session = service.create_session("debug-session")?;
// Subscribe to events
let mut receiver = service.subscribe(&session)?;
tokio::spawn(async move {
while let Ok(event) = receiver.recv() {
println!("Event: {:?}", event);
}
});
// Enable auto-checkpointing
service.enable_auto_checkpoint(&session, AutoCheckpointConfig {
interval_seconds: 300,
on_error: true,
on_tool_call: true,
})?;
// Manual checkpoint
let id = service.checkpoint(&session, "Important milestone")?;
// Annotate
service.annotate(&id, CheckpointAnnotation {
note: "This fixed the bug".to_string(),
severity: AnnotationSeverity::Critical,
timestamp: Utc::now(),
})?;
// List checkpoints
let cps = service.list_checkpoints(&session)?;
println!("Total: {}", cps.len());
// Metrics
let metrics = service.metrics()?;
println!("Active sessions: {}", metrics.active_sessions);
Ok(())
}
```
---
## Integration Points
### Forge Agent Loop
```rust
// In agent loop
if should_checkpoint(&state) {
let id = service.checkpoint(&session, "Auto-checkpoint")?;
}
// On error
if let Err(e) = operation() {
if config.on_error {
service.trigger_auto_checkpoint(&session, AutoTrigger::CodeModified)?;
}
}
```
### WebSocket API (Future)
```rust
// Client sends command
{
"command": "Create",
"session_id": "...",
"message": "Checkpoint from API",
"tags": ["api", "remote"]
}
// Server responds
{
"result": "Created",
"checkpoint_id": "..."
}
// Server streams events
{
"event": "Created",
"checkpoint_id": "...",
"timestamp": "2026-02-19T..."
}
```
---
## Project Complete!
| Wave 1 | Core creation | 10 | ~700 |
| Wave 2 | Query methods | 10 | ~1,000 |
| Wave 3 | Persistence | 10 | ~1,600 |
| Wave 4 | Thread safety | 10 | ~2,300 |
| Wave 5 | Integration | 10 | ~2,800 |
| **Total** | | **50** | **~2,800** |
---
## Running the Tests
```bash
cd /home/feanor/Projects/forge/forge-reasoning
cargo test
# Specific test suites
cargo test --test checkpoint_tests # Waves 1-3
cargo test --test thread_safety_tests # Wave 4
cargo test --test integration_tests # Wave 5
```
---
**TDD Complete - Temporal Checkpointing MVP Ready for Production!** ✅