diff --git a/scripts/tsdown-build.mjs b/scripts/tsdown-build.mjs
index 5faa9799dbb..871e89ddbf0 100644
--- a/scripts/tsdown-build.mjs
+++ b/scripts/tsdown-build.mjs
@@ -6,6 +6,23 @@ const logLevel = process.env.OPENCLAW_BUILD_VERBOSE ? "info" : "warn";
 const extraArgs = process.argv.slice(2);
 const INEFFECTIVE_DYNAMIC_IMPORT_RE = /\[INEFFECTIVE_DYNAMIC_IMPORT\]/;
 const UNRESOLVED_IMPORT_RE = /\[UNRESOLVED_IMPORT\]/;
+const ANSI_ESCAPE_RE = new RegExp(String.raw`\u001B\[[0-9;]*m`, "g");
+
+function findFatalUnresolvedImport(lines) {
+  for (const line of lines) {
+    if (!UNRESOLVED_IMPORT_RE.test(line)) {
+      continue;
+    }
+
+    const normalizedLine = line.replace(ANSI_ESCAPE_RE, "");
+    if (!normalizedLine.includes("extensions/")) {
+      return normalizedLine;
+    }
+  }
+
+  return null;
+}
+
 const result = spawnSync(
   "pnpm",
   ["exec", "tsdown", "--config-loader", "unrun", "--logLevel", logLevel, ...extraArgs],
@@ -32,10 +49,11 @@ if (result.status === 0 && INEFFECTIVE_DYNAMIC_IMPORT_RE.test(`${stdout}\n${stde
   process.exit(1);
 }
 
-if (result.status === 0 && UNRESOLVED_IMPORT_RE.test(`${stdout}\n${stderr}`)) {
-  console.error(
-    "Build emitted [UNRESOLVED_IMPORT]. Declare or bundle the missing dependency instead of silently externalizing it.",
-  );
+const fatalUnresolvedImport =
+  result.status === 0 ? findFatalUnresolvedImport(`${stdout}\n${stderr}`.split("\n")) : null;
+
+if (fatalUnresolvedImport) {
+  console.error(`Build emitted [UNRESOLVED_IMPORT] outside extensions: ${fatalUnresolvedImport}`);
   process.exit(1);
 }