refactor(runtime-host): name the forwarding rule, not the durability class

isRuntimeSessionForwardedEvent / RuntimeSessionForwardedEvent describe what
the predicate decides — forward live to subscribers — now that the durable
steering_message belongs to it. Rename the client projectSessionEvent to
match its Host-side counterpart. Addresses review on #3316.

Author: me2seeks

packages/runtime-host/src/adapter/session-projector.ts

@@ -328,7 +328,7 @@ export class RuntimeHostSessionProjector {
       return emptyUpdate(events);
     }
     if (frame.kind === 'subscription.session_event') {
-      const event = projectToolEvent(frame);
+      const event = projectSessionEvent(frame);
       if (event) {
         if (event.type === 'steering_message') {
           if (this.#renderedSteeringMessageIds.has(event.messageId)) {
@@ -476,7 +476,7 @@ export function projectRuntimeHostInteractionRequest(
   return [];
 }
 
-function projectToolEvent(
+function projectSessionEvent(
   frame: Extract<SubscriptionFrame, { kind: 'subscription.session_event' }>,
 ): SessionEvent | undefined {
   const event = frame.event;

packages/runtime-host/src/server/root-turn-coordinator.ts

@@ -73,7 +73,7 @@ import type { ConnectionContext, TurnOperationHandlerMap } from './operation-dis
 import { RootAdmissionOwner } from './root-admission-owner.js';
 import { type SessionAdmissionLease, SessionAdmissionGate } from './session-admission-gate.js';
 import {
-  type RuntimeSessionTransientEvent,
+  type RuntimeSessionForwardedEvent,
   SessionContinuityCoordinator,
 } from './session-continuity-coordinator.js';
 import type {
@@ -2096,7 +2096,7 @@ export class RootTurnCoordinator implements HostedExecutionAuthority {
             // Presentation observers do not participate in execution authority.
           }
         }
-        if (isRuntimeSessionTransientEvent(event)) {
+        if (isRuntimeSessionForwardedEvent(event)) {
           await this.continuity.acceptRuntimeEvent(input.sessionId, active.runId, event);
         } else if (isInteractionAnswerAck(event)) {
           await this.continuity.refreshCanonical(input.sessionId);
@@ -2774,9 +2774,13 @@ function isStoppedInteractionAdmission(
   );
 }
 
-function isRuntimeSessionTransientEvent(
+// Membership answers one question: forward this event live to subscribers via
+// the continuity coordinator instead of letting the canonical refresh carry
+// it. Persistence is orthogonal — it happens upstream in the run's own event
+// stream, which is why the durable steering_message belongs here.
+function isRuntimeSessionForwardedEvent(
   event: SessionEvent,
-): event is RuntimeSessionTransientEvent {
+): event is RuntimeSessionForwardedEvent {
   return (
     event.type === 'text_delta' ||
     event.type === 'text_complete' ||

packages/runtime-host/src/server/session-continuity-coordinator.ts

@@ -61,7 +61,7 @@ const MAX_SUBSCRIBER_QUEUED_BYTES = 256 * 1024;
 
 export type { CanonicalSessionProjection } from './canonical-session-projection.js';
 
-export type RuntimeSessionTransientEvent = Extract<
+export type RuntimeSessionForwardedEvent = Extract<
   SessionEvent,
   {
     type:
@@ -96,7 +96,7 @@ interface SessionProjectionState {
    */
   toolResultPreviews: Map<
     string,
-    Extract<RuntimeSessionTransientEvent, { type: 'tool_result_preview' }>
+    Extract<RuntimeSessionForwardedEvent, { type: 'tool_result_preview' }>
   >;
   terminalPublicationFence?: TerminalPublicationFence;
 }
@@ -599,7 +599,7 @@ export class SessionContinuityCoordinator implements SessionContinuityService {
   async acceptRuntimeEvent(
     sessionId: string,
     runId: string,
-    event: RuntimeSessionTransientEvent,
+    event: RuntimeSessionForwardedEvent,
   ): Promise<void> {
     if (
       (event.type === 'text_delta' || event.type === 'thinking_delta') &&
@@ -1397,7 +1397,7 @@ export class SessionContinuityCoordinator implements SessionContinuityService {
     subscriber: Subscriber,
     sessionId: string,
     runId: string,
-    event: Extract<RuntimeSessionTransientEvent, { type: 'text_delta' | 'thinking_delta' }>,
+    event: Extract<RuntimeSessionForwardedEvent, { type: 'text_delta' | 'thinking_delta' }>,
     kind: SessionAssistantDelta['kind'],
     startOffset: number,
   ): void {
@@ -1841,7 +1841,7 @@ function jsonStringContentBytes(value: string): number {
 
 function projectSessionEvent(
   event: Exclude<
-    RuntimeSessionTransientEvent,
+    RuntimeSessionForwardedEvent,
     {
       type:
         | 'text_delta'