diff --git a/test/helpers/hermetic-env.ts b/test/helpers/hermetic-env.ts
index 4fb17e734..e1acd87f5 100644
--- a/test/helpers/hermetic-env.ts
+++ b/test/helpers/hermetic-env.ts
@@ -211,6 +211,15 @@ export function getHermeticDirs(): HermeticDirs {
       trustedDirs: [repoRoot()],
     });
     fs.writeFileSync(path.join(configDir, '.claude.json'), JSON.stringify(seed, null, 2));
+    // Seed one-time onboarding markers into the CHILD's GSTACK_HOME.
+    // bin/gstack-skill-start reads ${GSTACK_HOME:-$HOME/.gstack} (EOV7), so
+    // the operator-HOME seeding in e2e-helpers.ts no longer reaches hermetic
+    // children — without these, the emission layer fires lake-intro/telemetry
+    // prompts that burn turns and can stall PTY tests waiting on an answer.
+    // Tests that exercise onboarding itself override GSTACK_HOME per-test.
+    for (const f of ['.activated', '.completeness-intro-seen', '.telemetry-prompted', '.proactive-prompted', '.first-loop-tip-shown']) {
+      fs.writeFileSync(path.join(gstackHome, f), '');
+    }
   } catch (err) {
     try { fs.rmSync(runRoot, { recursive: true, force: true }); } catch { /* best-effort */ }
     throw err;