diff --git a/sdk/package.json b/sdk/package.json
index bd4928809..5c465c8e1 100644
--- a/sdk/package.json
+++ b/sdk/package.json
@@ -25,7 +25,7 @@
     "typecheck": "tsc --noEmit && tsc -p tsconfig.type-tests.json",
     "typecheck:tests": "tsc -p tsconfig.tests.json",
     "test:prep": "( cd ../kernel && sh ../ops/cargo.sh build ) && ( [ ! -d ../testdata/preflight ] || find ../testdata/preflight -name '*-cli' -type f -exec chmod +x {} + )",
-    "test": "npm run test:prep && npm run typecheck && npm run build && npm run typecheck:tests && vitest run",
+    "test": "sh scripts/test.sh",
     "test:watch": "vitest"
   },
   "license": "UNLICENSED",
diff --git a/sdk/scripts/prune-test-build.mjs b/sdk/scripts/prune-test-build.mjs
new file mode 100644
index 000000000..c4d97ba40
--- /dev/null
+++ b/sdk/scripts/prune-test-build.mjs
@@ -0,0 +1,37 @@
+// Drop the build outputs a test run does not need, to keep the propagated
+// tree small in a cloud sandbox.
+//
+// Source maps only. Declaration files are deliberately NOT pruned: package.json
+// declares `"types": "./dist/index.d.ts"`, so deleting them would leave the
+// package's own declared type entry pointing at a file that `npm test` had just
+// removed. Nothing in this repo breaks today -- every current in-repo consumer
+// imports `.js` (`ops/probes/**`, `workflows/drive.yaml`,
+// `workflows/drive-cloud.yaml`, `testdata/backlog-picker.flow.yaml`), and
+// `surface` does not depend on the sdk -- but the next TypeScript consumer
+// would hit a failure whose cause is "someone ran the tests", which is not a
+// cost worth paying for the space. The file
+// count that actually matters is `kernel/target/debug` at ~4900 files (see
+// ops/cargo.sh); `dist` declarations are noise beside it.
+import { readdir, rm } from "node:fs/promises";
+import { resolve } from "node:path";
+
+const generatedDirectories = [resolve(import.meta.dirname, "../dist")];
+
+for (const directory of generatedDirectories) {
+  let entries;
+  try {
+    entries = await readdir(directory, { recursive: true, withFileTypes: true });
+  } catch (error) {
+    if (error.code === "ENOENT") continue;
+    throw error;
+  }
+
+  await Promise.all(
+    entries
+      .filter(
+        (entry) =>
+          entry.isFile() && entry.name.endsWith(".map"),
+      )
+      .map((entry) => rm(resolve(entry.parentPath, entry.name))),
+  );
+}
diff --git a/sdk/scripts/test.sh b/sdk/scripts/test.sh
new file mode 100644
index 000000000..e2b96de5c
--- /dev/null
+++ b/sdk/scripts/test.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+set -eu
+
+trap 'node scripts/prune-test-build.mjs' EXIT
+
+npm run test:prep
+npm run typecheck
+npm run build
+npm run typecheck:tests
+vitest run