diff --git a/packages/api/src/agents/activityPhases/runtime.spec.ts b/packages/api/src/agents/activityPhases/runtime.spec.ts
index 9e21e1c07e..fe9490a78d 100644
--- a/packages/api/src/agents/activityPhases/runtime.spec.ts
+++ b/packages/api/src/agents/activityPhases/runtime.spec.ts
@@ -24,7 +24,7 @@ const batch = (id: string): PostToolBatchHookInput =>
     ],
   }) as PostToolBatchHookInput;
 
-const substantialText = (prefix: string): string => `${prefix} ${'x'.repeat(241)}`;
+const substantialText = (prefix: string): string => `${prefix} ${'x'.repeat(201)}`;
 
 async function flushDetached(): Promise<void> {
   for (let i = 0; i < 4; i += 1) {
@@ -96,7 +96,7 @@ describe('createActivityPhaseWiring', () => {
       GraphEvents.ON_MESSAGE_DELTA,
       {
         id: 'final-step',
-        delta: { content: { type: ContentTypes.TEXT, text: 'A'.repeat(241) } },
+        delta: { content: { type: ContentTypes.TEXT, text: 'A'.repeat(201) } },
       },
       undefined,
       undefined,
diff --git a/packages/api/src/agents/activityPhases/runtime.ts b/packages/api/src/agents/activityPhases/runtime.ts
index 01577c9707..c0a1ec5dd0 100644
--- a/packages/api/src/agents/activityPhases/runtime.ts
+++ b/packages/api/src/agents/activityPhases/runtime.ts
@@ -110,7 +110,7 @@ const MIN_ACTIVITIES = 2;
 const MAX_CONTEXT_ITEMS = 6;
 const MAX_EXCERPT_CHARS = 600;
 const REASONING_ANCHOR_CHARS = 80;
-const SUBSTANTIAL_TEXT_CHARS = 240;
+const SUBSTANTIAL_TEXT_CHARS = 200;
 const OUTPUT_CHAR_LIMIT = 160;
 const PHASE_TIMEOUT_MS = 12_000;
 /** Twelve enter the SDK prompt; one extra preserves its omitted-activity row. */