diff --git a/server/__tests__/lane-runtime.test.js b/server/__tests__/lane-runtime.test.js
index b17e36c..e5820e7 100644
--- a/server/__tests__/lane-runtime.test.js
+++ b/server/__tests__/lane-runtime.test.js
@@ -29,7 +29,30 @@ const profileLib = require("../lib/lane-profile");
 const runtime = require("../lib/lane-runtime");
 const { isListening } = require("../lib/ports");
 
-after(() => fsMod.rmSync(SUITE_ROOT, { recursive: true, force: true }));
+/**
+ * Lanes whose boot hook actually spawned a detached process. `harness_spawn`
+ * children outlive the hook by design, so a test that throws before its own
+ * `downLane` — or never calls one — leaves a real server holding a real port
+ * AFTER the suite exits. The port pool is only ten wide per name, so ten such
+ * runs exhaust it and every later boot fails with EPORTBUSY: a leak in these
+ * tests reads as a failure in whichever test runs next.
+ */
+const bootedLanes = new Set();
+
+// One teardown, in this order on purpose: downLane reads the pid files under
+// LANES_ROOT, which lives inside SUITE_ROOT — removing the tree first would
+// leave nothing to kill the children with.
+after(async () => {
+  for (const id of bootedLanes) {
+    try {
+      const lane = lanesLib.getLane(id);
+      if (lane) await runtime.downLane(lane);
+    } catch {
+      /* already stopped, or torn down by the test itself */
+    }
+  }
+  fsMod.rmSync(SUITE_ROOT, { recursive: true, force: true });
+});
 
 let laneSeq = 0;
 /** A lane row backed by a real directory, so profile lookup and mkdir work. */
@@ -274,6 +297,7 @@ describe("lifecycle", () => {
     const lane = makeLane();
     serverProfile(lane, 19100);
 
+    bootedLanes.add(lane.id);
     const facts = await runtime.upLane(lanesLib.getLane(lane.id));
     assert.equal(facts.available, true);
     assert.equal(facts.up, true);
@@ -301,6 +325,7 @@ describe("lifecycle", () => {
     assert.equal(afterDown.up, false);
     assert.deepEqual(afterDown.services, []);
 
+    bootedLanes.delete(lane.id);
     slots.releaseSlot(lane.id);
   });
 
@@ -377,12 +402,22 @@ describe("upLane qc option", () => {
       ].join("\n"),
     });
 
+    bootedLanes.add(lane.id);
     await runtime.upLane(lanesLib.getLane(lane.id), { qc: true });
     const booted = lanesLib.getLane(lane.id);
     const markerPath = pathMod.join(booted.cwd, "qc-marker.txt");
     const marker = fsMod.readFileSync(markerPath, "utf8");
     assert.match(marker, /QC=from-qc/);
 
+    // Stop the stack BEFORE releasing the slot: downLane locates the pid file
+    // through the lane's slot directory, so a released slot orphans a running
+    // child with no way left to reach it. Asserting the port went quiet is what
+    // makes a broken teardown fail HERE instead of leaking a live server into
+    // the next run's port pool.
+    const bootedPort = booted.ports.web;
+    await runtime.downLane(lanesLib.getLane(lane.id));
+    assert.equal(await isListening(bootedPort), false, "boot hook's child outlived downLane");
+    bootedLanes.delete(lane.id);
     slots.releaseSlot(lane.id);
   });
 
@@ -408,12 +443,17 @@ describe("upLane qc option", () => {
       ].join("\n"),
     });
 
+    bootedLanes.add(lane.id);
     await runtime.upLane(lanesLib.getLane(lane.id));
     const booted = lanesLib.getLane(lane.id);
     const markerPath = pathMod.join(booted.cwd, "qc-marker-no-qc.txt");
     const marker = fsMod.readFileSync(markerPath, "utf8");
     assert.match(marker, /QC=not-set/);
 
+    const bootedPort = booted.ports.web;
+    await runtime.downLane(lanesLib.getLane(lane.id));
+    assert.equal(await isListening(bootedPort), false, "boot hook's child outlived downLane");
+    bootedLanes.delete(lane.id);
     slots.releaseSlot(lane.id);
   });
 });