Summary

• Add agent:delegate:start and agent:delegate:end events to @agentskit/core
• Add createSharedContext() to @agentskit/runtime with read-only view for child agents
• Auto-generate synthetic ToolDefinition per delegate, injected into parent's tool list
• Wire delegation into ReAct loop: regular tools run sequentially, delegates run in parallel via Promise.all
• Recursive delegation with configurable maxDelegationDepth (default 3)
• RuntimeConfig.delegates provides default registry, RunOptions.delegates overrides per-run
• Child agent failures propagate as failed tool calls — parent LLM decides recovery

Test plan

• 7 shared context unit tests pass
• 3 buildDelegateTools unit tests pass
• 8 delegation integration tests pass (single child, parallel, events, errors, shared context, depth limit, override)
• 20 existing runner tests pass with no regressions
• pnpm build succeeds across all packages
• pnpm --filter @agentskit/runtime lint passes
• pnpm --filter @agentskit/core lint passes

Closes #12