diff --git a/lib/engine/director.ts b/lib/engine/director.ts
index 8a2b029..aeb5e6c 100644
--- a/lib/engine/director.ts
+++ b/lib/engine/director.ts
@@ -13,6 +13,7 @@ import type {
   Session,
   StoryState,
   StoryStatePatch,
+  StreamRouterResult,
   WriterScenePlan,
 } from "@infiplot/types";
 import type { CharacterCard } from "./agents/characterDesigner";
@@ -259,6 +260,25 @@ export async function directScene(
       resolvePlan(extracted);
     }
     return result;
+  }).catch((err): StreamRouterResult => {
+    // routeTaggedStream rejected (stream read / network failure) BEFORE onPlan
+    // fired. Without this, planPromise would never settle and `await
+    // planPromise` below would hang the whole request FOREVER. Settle the plan
+    // with a minimal fallback and resolve routing to a degraded result so the
+    // pipeline produces a playable fallback scene (graceful degradation) rather
+    // than hanging or hard-crashing.
+    console.warn("[directScene] routeTaggedStream rejected, degrading:", err);
+    if (!planSettled) {
+      planSettled = true;
+      resolvePlan(minimalFallbackPlan());
+    }
+    return {
+      plan: undefined,
+      beats: [],
+      choices: undefined,
+      rawStorySegment: undefined,
+      degraded: true,
+    };
   });
 
   // ── Step 2 — await plan (settles at </plan> close — EARLY) ────────
diff --git a/lib/engine/prompts/registry.ts b/lib/engine/prompts/registry.ts
index 2063270..e62983e 100644
--- a/lib/engine/prompts/registry.ts
+++ b/lib/engine/prompts/registry.ts
@@ -27,7 +27,11 @@ export const WRITER_SEGMENTS: PromptSegment[] = [
   WRITER_FORMAT,
 ];
 
-if (process.env.NODE_ENV === "development") {
+// Validate unique segment IDs in ALL environments (not just development).
+// A duplicate ID — e.g. introduced by a bad merge — would otherwise silently
+// shadow a segment in production. This runs once at module load; the cost is
+// negligible. Throwing fast surfaces the misconfiguration at startup.
+{
   const ids = WRITER_SEGMENTS.map((s) => s.id);
   const seen = new Set<string>();
   for (const id of ids) {