microsoft/amplifier-philosophy

Amplifier Philosophy: The Linux Kernel Metaphor

Core Principle: Mechanism Not Policy

If two teams might want different behavior, it belongs in a module, not the kernel.

The kernel provides mechanisms (mount, emit, dispatch). Modules provide policies (what to mount, when to emit, how to handle).

Architecture Patterns

Kernel (amplifier-core)

Keep it minimal and stable:

• Session management (session_create, mount, unmount)
• Event emission (emit)
• Hook registration
• Context access

Never add to kernel:

• Provider selection
• Tool routing
• Plan generation
• Default behaviors
• File I/O

Modules (Everything Else)

All capabilities as modules:

• Providers: LLM backends (Anthropic, OpenAI, Ollama)
• Tools: Capabilities (filesystem, bash, web)
• Orchestrators: Execution strategies
• Context Managers: State management
• Hooks: Lifecycle observers

Mount Point System

Think of modules as devices mounted at paths:

/mnt/providers/{name}  - LLM backends
/mnt/tools/{name}      - Agent capabilities
/mnt/hooks/{event}     - Lifecycle observers
/mnt/context           - Conversation state
/mnt/orchestrator      - Execution loop

Each mount point has a stable connector (Protocol interface).

Event-Driven Design

If it's important, emit an event:

• session:start, session:end
• prompt:submit, prompt:complete
• provider:request, provider:response
• tool:pre, tool:post
• context:pre_compact, context:post_compact

Hooks observe, never interfere:

• Logging hooks record events
• Approval hooks check permissions
• Cost tracking hooks monitor usage
• Failures in hooks never stop execution

Module Development Checklist

When creating a new module:

1. ✅ Implements Protocol only - No kernel internals
2. ✅ Emits canonical events - Observable lifecycle
3. ✅ Handles own failures - Never crash kernel
4. ✅ Configuration via mount() - No hard-coded defaults
5. ✅ Entry point registration - Discoverable

Decision Framework

Is This Kernel Work?

Ask: "Would every team use this the exact same way?"

• Yes → Might be kernel (rare)
• No → Definitely a module

Extract to Kernel?

Only after:

• Two real implementations exist
• Clear convergence on mechanism
• No opinion baked in

Prefer Regeneration

• Don't patch modules - Regenerate from spec
• Keep connectors stable - Module internals can change
• Update spec, rebuild module - Not line-by-line edits

Remember

Ruthless simplicity. If two designs solve it, pick the one with fewer moving parts and clearer failure modes.

Modules compete at edges. The kernel enables them, doesn't choose between them.

Observability is mandatory. If it's not in the logs, it didn't happen.