---
title: DI and Lifecycle
description: How AI services are registered, resolved, and started through Vessel
deprecated: true
supersededBy: ['/docs/cortex', '/docs/shield', '/docs/sentinel', '/docs/weave', '/docs/nexus']
---

## Preferred DI Pattern

Use constructor registration and type-based resolution as your default style.

```go
// Register constructors
forge.ProvideConstructor(c, func(db *Database, logger forge.Logger) *UserService {
    return &UserService{db: db, logger: logger}
})
// Resolve by type (no string keys needed)
userService, err := forge.InjectType[*UserService](c)

eventBus, _ := vessel.InjectType[interfaces.EventBus](app.Container())
```

## AI Extension Constructor Graph

`ai.Extension.Register(app)` registers these constructors eagerly:

1. `aisdk.LLMManager`
2. `aisdk.StateStore`
3. `aisdk.VectorStore`
4. `*AgentFactory`
5. `*AgentManager`
6. Optional training services when `Training.Enabled` is true

## Alias Keys Used by AI Extension

- `forge.ai.llmManager`
- `forge.ai.sdk.llmManager`
- `forge.ai.sdk.stateStore`
- `forge.ai.sdk.vectorStore`
- `vectorStore` (legacy alias)
- `forge.ai.agentFactory`
- `forge.ai.agentManager`
- `forge.ai.training.modelTrainer`
- `forge.ai.training.dataManager`
- `forge.ai.training.pipelineManager`

## Resolution Helpers

Use these first in app code:

- `ai.GetLLMManager(c)` / `ai.MustGetLLMManager(c)`
- `ai.GetStateStore(c)` / `ai.MustGetStateStore(c)`
- `ai.GetVectorStore(c)` / `ai.MustGetVectorStore(c)`
- `ai.GetAgentFactory(c)` / `ai.MustGetAgentFactory(c)`
- `ai.GetAgentManager(c)` / `ai.MustGetAgentManager(c)`

Training helpers (only when enabled):

- `ai.GetModelTrainer(c)`
- `ai.GetDataManager(c)`
- `ai.GetPipelineManager(c)`

## Lifecycle Behavior

- `Register`: wires constructors and logs setup details.
- `Start`: marks extension started and increments metric `forge.ai.extension.started`.
- `Stop`: marks extension stopped and increments metric `forge.ai.extension.stopped`.
- `Health`: returns `nil`.

## Override Strategy

When you need custom implementations:

- register your own constructor before app start
- provide expected aliases for backward-compatible resolution
- keep type-based resolution for app code

This keeps your app code clean while remaining compatible with extension internals.