fix(runtime-fallback): carry delegated system and tools through bootstrap retry

When the first prompt fails before any durable user message persists,
runtime fallback retry was rebuilding the request from parts alone and
losing the delegated agent system prompt and tool gates. Now it threads
bootstrap.system and bootstrap.tools into the retry body alongside the
captured retry parts, so the retried prompt keeps the same scope as the
initial delegate launch.

src/hooks/runtime-fallback/auto-retry.ts

@@ -8,7 +8,7 @@ import { prepareFallback } from "./fallback-state"
 import { SessionCategoryRegistry } from "../../shared/session-category-registry"
 import { clearDelegatedChildSessionBootstrap } from "../../shared/delegated-child-session-bootstrap"
 import { buildRetryModelPayload } from "./retry-model-payload"
-import { getLastUserRetryParts } from "./last-user-retry-parts"
+import { getLastUserRetryPayload } from "./last-user-retry-parts"
 import { extractSessionMessages } from "./session-messages"
 import { resolveRegisteredAgentName } from "../../features/claude-code-session-state"
 import {
@@ -144,7 +144,8 @@ export function createAutoRetryHelpers(deps: HookDeps) {
         path: { id: sessionID },
         query: { directory: ctx.directory },
       })
-      const retryParts = getLastUserRetryParts(messagesResp, sessionID)
+      const retryPayload = getLastUserRetryPayload(messagesResp, sessionID)
+      const retryParts = retryPayload.retryParts
       if (retryParts.length > 0) {
         log(`[${HOOK_NAME}] Auto-retrying with fallback model (${source})`, {
           sessionID,
@@ -166,6 +167,8 @@ export function createAutoRetryHelpers(deps: HookDeps) {
             body: {
               ...(launchAgent ? { agent: launchAgent } : {}),
               ...retryModelPayload,
+              ...(retryPayload.system ? { system: retryPayload.system } : {}),
+              ...(retryPayload.tools ? { tools: retryPayload.tools } : {}),
               parts: retryParts,
             },
             query: { directory: ctx.directory },