diff --git a/sdk/tests/backlog-picker-flow.test.ts b/sdk/tests/backlog-picker-flow.test.ts
index af7ead69..0b938437 100644
--- a/sdk/tests/backlog-picker-flow.test.ts
+++ b/sdk/tests/backlog-picker-flow.test.ts
@@ -29,6 +29,13 @@ function run(command: string, cwd: string): string {
   return execFileSync('sh', ['-c', command], {
     cwd,
     encoding: 'utf8',
+    stdio: ['ignore', 'pipe', 'pipe'],
+    // Capture stderr instead of letting it through to ours. Several tests here
+    // assert that a step FAILS, and `execFileSync` otherwise echoes the child's
+    // stack trace into the suite's output -- so a passing run prints
+    // `ENOENT ... .relayflow/backlog-picker-entry.json` and looks broken.
+    // #156 was filed on exactly that appearance. The text is still available on
+    // the thrown error for a test that wants to assert on it.
     env: { ...process.env, RELAYFLOWS_SDK_DIST: join(__dirname, '..', 'dist') },
   });
 }
diff --git a/sdk/tests/work-package-consumer.test.ts b/sdk/tests/work-package-consumer.test.ts
index 46781a0b..aae51acf 100644
--- a/sdk/tests/work-package-consumer.test.ts
+++ b/sdk/tests/work-package-consumer.test.ts
@@ -77,7 +77,8 @@ describe('the Garden join: picker output feeds the consumer', () => {
     const flowPath = join(__dirname, '..', '..', 'testdata', 'backlog-picker.flow.yaml');
     const flow = load(readFileSync(flowPath, 'utf8')) as { steps: Array<{ id: string; command: string }> };
     const step = (id: string) => flow.steps.find((s) => s.id === id)!.command;
-    const run = (cmd: string, cwd: string) => execFileSync('sh', ['-c', cmd], { cwd, encoding: 'utf8', env: { ...process.env, RELAYFLOWS_SDK_DIST: join(__dirname, '..', 'dist') }, });
+    // stdio: stderr captured, not echoed -- see backlog-picker-flow.test.ts.
+    const run = (cmd: string, cwd: string) => execFileSync('sh', ['-c', cmd], { cwd, encoding: 'utf8', stdio: ['ignore', 'pipe', 'pipe'], env: { ...process.env, RELAYFLOWS_SDK_DIST: join(__dirname, '..', 'dist') }, });
 
     const dir = mkdtempSync(join(tmpdir(), 'garden-join-'));
     try {