refactor(chat): route browser chat through one runtime (P3 Slice-Zero Task 5) (#1172)

Co-authored-by: shaggy <[email protected]>

packages/types/src/chat/events.ts

@@ -6,6 +6,7 @@ import type {
   SlashCommandResultPayload,
   SystemReloadPayload,
 } from '../commands/index.js';
+import type { HarnessErrorCode, HarnessSelection, HarnessTurnState } from '../harness/index.js';
 
 export interface MessageAckPayload {
   conversationId: string;
@@ -107,8 +108,70 @@ export interface AbortPayload {
   conversationId: string;
 }
 
+/**
+ * The frozen P3 `turn:send` wire contract (Task Five; reused unchanged by Tasks 15 and 16).
+ * Accepts no attachments or authority-bearing fields in Slice Zero. Gateway validation
+ * requires a UUID conversation id, non-empty bounded content, a nested selection with exactly
+ * `harnessId`/`providerId`/`modelId` (each 1..255 chars), and a UUID-v4 idempotency key; it
+ * rejects unknown fields, top-level `provider`/`modelId`, malformed nesting, and empty values
+ * before any runtime dispatch.
+ */
+export interface HarnessTurnSendPayload {
+  readonly conversationId: string; // UUID; required before send
+  readonly content: string; // trimmed, 1..10_000 characters
+  readonly selection: HarnessSelection; // nested; exactly three ids
+  readonly idempotencyKey: string; // browser-generated UUID v4
+}
+
+/**
+ * The frozen `turn:ack` wire contract. Success echoes the accepted idempotency key and the
+ * exact requested selection tuple; failure carries only fixed/safe text and never a
+ * substituted effective selection or raw exception text.
+ */
+export type HarnessTurnAckPayload =
+  | {
+      readonly ok: true;
+      readonly conversationId: string;
+      readonly idempotencyKey: string;
+      readonly turnId: string;
+      readonly correlationId: string;
+      readonly state: HarnessTurnState;
+      readonly selection: HarnessSelection;
+    }
+  | {
+      readonly ok: false;
+      readonly conversationId?: string;
+      readonly idempotencyKey?: string;
+      readonly code: HarnessErrorCode | 'request_invalid' | 'runtime_unsupported';
+      readonly message: string; // fixed/safe text only
+      readonly retryable: boolean;
+      readonly correlationId: string;
+      /** Present only when a complete tuple was validated; always the requested tuple. */
+      readonly selection?: HarnessSelection;
+    };
+
+/**
+ * The frozen browser send-protocol advertisement (Task Five; server → client only).
+ *
+ * A conversation id or a harness selection never proves that the connected Gateway actually
+ * handles a given wire event, so after BetterAuth authenticates a browser Socket connection the
+ * Gateway advertises — exactly once, targeted to that socket — which send event the client may
+ * use. `legacy-message` in legacy mode, `unavailable` in `pi-rpc` (including test-ready Pi
+ * graphs); Task Five never advertises `turn-send` (its authenticated handler lands in Task 15).
+ * Capability is routing information, never authorization: every server handler still enforces
+ * authentication, ownership, DTO, mode, and runtime checks.
+ */
+export type ChatSendProtocol = 'legacy-message' | 'turn-send' | 'unavailable';
+
+export interface ChatSendCapabilityPayload {
+  readonly protocol: ChatSendProtocol;
+  /** Exact Socket.IO id for the authenticated browser connection this advertisement is bound to. */
+  readonly connectionId: string;
+}
+
 /** Socket.IO typed event map: server → client */
 export interface ServerToClientEvents {
+  'chat:send-capability': (payload: ChatSendCapabilityPayload) => void;
   'message:ack': (payload: MessageAckPayload) => void;
   'agent:start': (payload: AgentStartPayload) => void;
   'agent:end': (payload: AgentEndPayload) => void;
@@ -121,12 +184,14 @@ export interface ServerToClientEvents {
   'command:result': (payload: SlashCommandResultPayload) => void;
   'command:approval': (payload: SlashCommandApprovalResultPayload) => void;
   'system:reload': (payload: SystemReloadPayload) => void;
+  'turn:ack': (payload: HarnessTurnAckPayload) => void;
   error: (payload: ErrorPayload) => void;
 }
 
 /** Socket.IO typed event map: client → server */
 export interface ClientToServerEvents {
   message: (data: ChatMessagePayload) => void;
+  'turn:send': (data: HarnessTurnSendPayload) => void;
   'set:thinking': (data: SetThinkingPayload) => void;
   'command:execute': (data: SlashCommandPayload) => void;
   'command:approve': (data: SlashCommandPayload) => void;

packages/types/src/chat/index.ts

@@ -14,6 +14,10 @@ export type {
   AbortPayload,
   ErrorPayload,
   ChatMessagePayload,
+  HarnessTurnSendPayload,
+  HarnessTurnAckPayload,
+  ChatSendProtocol,
+  ChatSendCapabilityPayload,
   ServerToClientEvents,
   ClientToServerEvents,
 } from './events.js';