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docs/content/stories/epic3/3.1-module-system-interface.md

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+# Story 3.1: Module System Interface and Registry
+
+## Metadata
+- **Story ID**: 3.1
+- **Title**: Module System Interface and Registry
+- **Epic**: 3 - Module Framework
+- **Status**: Pending
+- **Priority**: High
+- **Estimated Time**: 5-6 hours
+- **Dependencies**: 1.1, 2.3
+
+## Goal
+Design and implement the complete module system interface with registration, dependency resolution, and lifecycle management.
+
+## Description
+This story creates the foundation of the module system by defining the module interface, manifest structure, and registry. The system must support module registration, dependency validation, and lifecycle hooks.
+
+## Deliverables
+
+### 1. Module Interface (`pkg/module/module.go`)
+- `IModule` interface with:
+  - `Name() string` - Module name
+  - `Version() string` - Module version
+  - `Dependencies() []string` - Module dependencies
+  - `Init() fx.Option` - FX options for module initialization
+  - `Migrations() []func(*ent.Client) error` - Database migrations
+  - Optional lifecycle hooks: `OnStart(ctx context.Context) error`
+  - Optional lifecycle hooks: `OnStop(ctx context.Context) error`
+
+### 2. Module Manifest (`pkg/module/manifest.go`)
+- `Manifest` struct with:
+  - Name, Version, Dependencies
+  - Permissions list
+  - Routes definition
+- `module.yaml` schema definition
+- Manifest parsing and validation
+
+### 3. Module Registry (`internal/registry/registry.go`)
+- Thread-safe module map
+- `Register(m IModule)` function
+- `All() []IModule` function
+- `Get(name string) (IModule, error)` function
+- Dependency validation (check dependencies are satisfied)
+- Duplicate name detection
+- Version compatibility checking
+- Dependency cycle detection
+
+## Implementation Steps
+
+1. **Create Module Interface**
+   - Create `pkg/module/module.go`
+   - Define IModule interface
+   - Add lifecycle hooks
+
+2. **Create Module Manifest**
+   - Create `pkg/module/manifest.go`
+   - Define Manifest struct
+   - Define module.yaml schema
+
+3. **Create Module Registry**
+   - Create `internal/registry/registry.go`
+   - Implement thread-safe registry
+   - Add validation logic
+
+4. **Test Registration**
+   - Test module registration
+   - Test dependency validation
+   - Test duplicate detection
+
+## Acceptance Criteria
+- [ ] Modules can register via `registry.Register()`
+- [ ] Registry validates dependencies
+- [ ] Registry prevents duplicate registrations
+- [ ] Module interface is extensible
+- [ ] Dependency cycles are detected
+- [ ] Version compatibility is checked
+
+## Related ADRs
+- [ADR-0021: Module Loading Strategy](../../adr/0021-module-loading-strategy.md)
+
+## Files to Create/Modify
+- `pkg/module/module.go` - Module interface
+- `pkg/module/manifest.go` - Module manifest
+- `internal/registry/registry.go` - Module registry
+