fix(runtime): recover once from output-free streams closed before completion

packages/core/src/events.ts

@@ -1208,6 +1208,7 @@ export type ProviderRetryReason =
   | 'provider_unavailable'
   | 'rate_limit'
   | 'timeout'
+  | 'incomplete_stream'
   | 'unknown';
 
 /**

packages/runtime-host/src/__tests__/protocol.test.ts

@@ -60,10 +60,34 @@ import {
   TURN_MESSAGE_QUOTE_TEXT_MAX_LENGTH,
   TURN_FAILURE_MESSAGE_MAX_BYTES,
   decodeMessageContent,
+  decodeTurnProviderRetry,
   TURN_SKILL_ID_MAX_COUNT,
   TURN_SKILL_ID_MAX_LENGTH,
 } from '../protocol/turn.js';
 
+test('decodes the protocol-incomplete stream retry reason', () => {
+  assert.deepEqual(
+    decodeTurnProviderRetry({
+      phase: 'scheduled',
+      attempt: 2,
+      maxAttempts: 2,
+      delayMs: 1_000,
+      reason: 'incomplete_stream',
+    }),
+    {
+      phase: 'scheduled',
+      attempt: 2,
+      maxAttempts: 2,
+      delayMs: 1_000,
+      reason: 'incomplete_stream',
+    },
+  );
+});
+
+test('publishes a new compatibility epoch for protocol-incomplete retry progress', () => {
+  assert.ok(RUNTIME_HOST_COMPATIBILITY_EPOCH > 109);
+});
+
 describe('Runtime Host bootstrap protocol', () => {
   test('accepts only authenticated-listener registration endpoints on IPv4 loopback', () => {
     const registration = {

packages/runtime-host/src/protocol/index.ts

@@ -100,7 +100,9 @@ export const RUNTIME_HOST_REGISTRATION_SCHEMA_VERSION = 1 as const;
 export const RUNTIME_HOST_PROTOCOL_VERSION = 0 as const;
 // Increment when the same protocol version no longer guarantees safe Client-Host
 // interoperability. Mismatches are rejected before domain commands are admitted.
-export const RUNTIME_HOST_COMPATIBILITY_EPOCH = 109 as const;
+export const RUNTIME_HOST_COMPATIBILITY_EPOCH = 110 as const;
+// 110: Turn provider-retry progress may carry the `incomplete_stream` reason;
+// older peers reject that closed-union value.
 // 109: accepted Client Capability invocations may carry one bounded nested form
 // Interaction request/result round trip.
 // 108: Session Interaction snapshots, forwarded Runtime events, and Agent Graph

packages/runtime-host/src/protocol/turn.ts

@@ -792,6 +792,7 @@ function requireProviderRetryReason(value: unknown): ProviderRetryReason {
     value === 'provider_unavailable' ||
     value === 'rate_limit' ||
     value === 'timeout' ||
+    value === 'incomplete_stream' ||
     value === 'unknown'
   ) {
     return value;