Architecture

Architecture

Overall Flow 

Session (Event Sourcing) ──► fold / Projection ──► Prompt Assemble ──► Agent Turn/Step Loop
                                                                        │
                        Tool Waterfall (pre → execute → post → result) ◄─┘

Three Pillars

1. Event Sourcing

  • Session state is fully derived from an append-only event log
  • Every write appends one immutable event; the engine enforces ordering invariants (turn open/close pairing, tool call↔result matching)
  • At any moment the log can be replayed, forked, compacted, and persisted

2. Turn/Step Loop (Agent Loop)

  • Turn: one complete conversational round-trip (user message → Agent processing → end)
  • Step: a tool continuation within a Turn (the model requests a tool → execute → feed the result back to the model)
  • Cancellation, timeouts, and tracing are propagated layer by layer through ctx to both tools and the LLM

3. Tool Waterfall

  • A four-stage chain: pre → execute → post → result
  • Each stage is a pluggable middleware: approval, sandbox, token budget, and limits can all be mounted
  • Supports concurrency hardening such as object pools and read-only registries

Capability Seam

Every capability is a service definition + provider structure: replacing the provider changes the overall behavior, consistent with the official design.

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