diff --git a/packages/sdk-typescript/scripts/build.js b/packages/sdk-typescript/scripts/build.js
index 3aa346524e0..72a0923d755 100755
--- a/packages/sdk-typescript/scripts/build.js
+++ b/packages/sdk-typescript/scripts/build.js
@@ -87,7 +87,9 @@ const rootDir = join(__dirname, '..');
 // APIs merged in from main.
 // Bumped from 189KB to 190KB for historical branch sessions and transcript
 // branch-point projection merged with the upload and reasoning APIs.
-const MAX_DAEMON_BROWSER_BUNDLE_BYTES = 190 * 1024;
+// Bumped from 190KB to 191KB for the composer text-file attachment metadata
+// (#9180) on the local optimistic user transcript surface.
+const MAX_DAEMON_BROWSER_BUNDLE_BYTES = 191 * 1024;
 // The opt-in `daemon/transports` browser bundle legitimately ships the concrete
 // ACP transports (AcpHttpTransport/AcpWsTransport/AutoReconnect + negotiate), so
 // it's larger than the default barrel — but still budgeted so a future PR can't