Parent PRD

#2

What to build

Evolve @agentskit/core to serve as the foundation for the entire v3 ecosystem. This means:

• Upgrade ToolDefinition: enforce schema: JSONSchema7 type, add optional init()/dispose() lifecycle methods, allow execute to return AsyncIterable<unknown>, add optional tags/category for discovery
• Add SkillDefinition: name, description, systemPrompt, optional examples, tools (tool name hints), delegates (other skill names), temperature, onActivate hook
• Add VectorMemory: store(docs), search(query, options), delete(ids) — separate from ChatMemory
• Add AgentEvent: Union type for lifecycle events (llm:start, llm:end, tool:start, tool:end, memory:load, agent:step, error, etc.)
• Add Observer: { name: string, on: (event: AgentEvent) => void | Promise<void> }
• Add EvalSuite / EvalResult: Minimal contract types for evaluation
• Extract shared primitives: Pull executeToolCall, consumeStream, buildMessage out of ChatController into standalone exported functions so both ChatController and the future AgentRunner can use them
• Emit AgentEvent from ChatController at appropriate lifecycle points

Core must remain zero external dependencies and under 10 KB gzipped.

Acceptance criteria

• ToolDefinition updated with JSONSchema7 type, lifecycle methods, AsyncIterable support, discovery metadata
• SkillDefinition interface exported from core
• VectorMemory interface exported from core (separate from ChatMemory)
• AgentEvent union type exported from core
• Observer interface exported from core
• EvalSuite and EvalResult types exported from core
• Shared primitives (executeToolCall, consumeStream, buildMessage) exported as standalone functions
• ChatController refactored to use shared primitives internally
• ChatController emits AgentEvents
• Zero external dependencies maintained
• Bundle stays under 10 KB gzipped
• All existing tests still pass
• TypeScript strict mode, no any

Blocked by

None — can start immediately

User stories addressed

• User story 4 (swap providers)
• User story 6 (custom tools with simple contract)
• User story 7 (JSON Schema for tool params)
• User story 25 (observability optional)
• User story 35 (custom memory backends with clear contract)