docs: development

packages/client/AGENTS.md

@@ -54,6 +54,12 @@ Non-negotiables across the layers:
 - **Notifier publication discipline**: `notifyNow` is only the direct echo of a user gesture; structural updates use microtask-batched `markDirty`, while visible streaming chunks use cumulative `markFrameDirty`. See `runtime/src/client/sessions/notifier.ts`.
 - **The web layer is pure presentation.** Nothing that is "how to draw" (tool-card views, queue states) enters the session log; the host computes such data per frame or pushes it live, and replay recomputes it — falling back to the generic form when it can't. A new *model-visible* input still requires a session event (repo-wide rule).
 
+## Conversation Node discipline
+
+- A Chat business feature registers one `ConversationNodeDefinition` and its keyed `conversation.chat.node` renderer; do not add its event switch or fold to `Session`, `SessionManager`, or a central built-in dispatcher. Follow the [Conversation Node cookbook](../../docs/cookbook/adding-a-conversation-node.md).
+- `match(event)` reads only the current event. Every event in a multi-event Context carries or independently derives the same stable business id; `update` folds one Match into State and remains deterministically replayable by log `seq`.
+- The append hot path and renderers never scan the full event window, Contexts, or Chat Nodes. Accumulate in State, publish same-Turn/Step facts through `buildLocationData()`, and consume final Node data or constrained Location hooks.
+
 ## Directory regime (plugin packages)
 
 One UI feature = one plugin package (`src/client/` browser half). A multi-domain package splits by future package boundaries — ui-conversation is the exemplar: `contract/` (the only shared face), domain directories that never import a sibling domain, and `apply.ts` as the single cross-domain assembly point; `scripts/verify-client-domain-graph.ts` enforces the levels. Registration goes through `slots.register` in `apply` — never module-level side effects.