diff --git a/.quixos-subtree-source.json b/.quixos-subtree-source.json
index d3b276e..3b8ebb3 100644
--- a/.quixos-subtree-source.json
+++ b/.quixos-subtree-source.json
@@ -1,7 +1,7 @@
 {
   "version": 1,
   "sourceRepo": "https://gitea-external.egads.tutti.syntaxblitz.net/quixos/quixos",
-  "sourceCommit": "57684c7548883dc4fc25dc8f943c7a43b3489fcf",
+  "sourceCommit": "806ea0e9f41340acf119b7374f5150ef5b378074",
   "sourcePath": "quixos-instance/quixos-nix-helpers",
   "exportName": "quixos-nix-helpers",
   "mirrorRemote": "https://gitea-external.egads.tutti.syntaxblitz.net/quixos/quixos-nix-helpers.git"
diff --git a/restricted-execution/service.mjs b/restricted-execution/service.mjs
index c8efc7d..3db0ade 100644
--- a/restricted-execution/service.mjs
+++ b/restricted-execution/service.mjs
@@ -148,6 +148,11 @@ export async function serveRestrictedRegistry(config, io = process) {
     engines = new Set(),
     idleEngines = [];
   const metrics = { starts: 0, reused: 0, completed: 0, peakRSSBytes: 0 };
+  const changed = () => {
+    try {
+      config.onChange?.();
+    } catch {}
+  };
   let buffered = Buffer.alloc(0),
     stopped = false,
     failure;
@@ -244,6 +249,7 @@ export async function serveRestrictedRegistry(config, io = process) {
           // physical memory remains the supervising process/cgroup's contract.
           if (rss <= 128 * 1024 * 1024) {
             idleEngines.push(engine);
+            engine.idleUntil = Date.now() + limits.engineIdleMs;
             engine.idleTimer = setTimeout(() => void destroyEngine(engine).catch(fail), limits.engineIdleMs);
           } else await destroyEngine(engine);
         } else await destroyEngine(engine);
@@ -300,6 +306,7 @@ export async function serveRestrictedRegistry(config, io = process) {
       } finally {
         engines.delete(engine);
         await engine.release?.();
+        changed();
       }
     })();
     return engine.destroying;
@@ -418,6 +425,7 @@ export async function serveRestrictedRegistry(config, io = process) {
       },
     );
     metrics.starts++;
+    changed();
     engine.exited = new Promise((resolve) => {
       engine.child.once("exit", resolve);
       engine.child.once("error", resolve);
@@ -462,6 +470,9 @@ export async function serveRestrictedRegistry(config, io = process) {
         executionMs: call.executionMs ?? null,
         totalMs: performance.now() - call.receivedAt,
       };
+      metrics.lastFailure =
+        reply.status === "failed" && /^[A-Z0-9_]{1,128}$/.test(reply.error?.code) ? reply.error.code : null;
+      changed();
       send(call.cancellationReply ?? reply);
       pump();
     })());
@@ -470,6 +481,7 @@ export async function serveRestrictedRegistry(config, io = process) {
     const { message } = call;
     call.startedAt = performance.now();
     active.set(message.invocation, call);
+    changed();
     const terminate = (code) => {
       if (!call.open) return;
       void finish(call, fixedError(code), {
@@ -687,6 +699,9 @@ export async function serveRestrictedRegistry(config, io = process) {
       queued: queued.length,
       engines: engines.size,
       idle: idleEngines.length,
+      idleDeadline: idleEngines.length
+        ? new Date(Math.min(...idleEngines.map((engine) => engine.idleUntil))).toISOString()
+        : null,
     }),
   };
 }
diff --git a/restricted-execution/service.test.mjs b/restricted-execution/service.test.mjs
index b6087b4..409f615 100644
--- a/restricted-execution/service.test.mjs
+++ b/restricted-execution/service.test.mjs
@@ -570,12 +570,25 @@ test("an expired frame token cannot borrow a later invocation's broker", async (
 });
 
 test("idle engines evict without a graph poll and restart with fresh state", async () => {
-  const f = await fixture(registry("return request.input;"), { engineIdleMs: 30 });
+  const updates = [];
+  const f = await fixture(registry("return request.input;"), {
+    engineIdleMs: 30,
+    onChange: () => updates.push(f.stats()),
+  });
   try {
     f.start("first");
     assert.equal((await f.receive()).output, "first");
     await new Promise((resolve) => setTimeout(resolve, 100));
     assert.equal(f.stats().engines, 0);
+    assert.ok(
+      updates.some((s) => s.active > 0),
+      "Inspectors observe active invocation admission",
+    );
+    assert.ok(
+      updates.some((s) => s.idle > 0 && s.idleDeadline),
+      "Idle eviction deadline is visible",
+    );
+    assert.equal(updates.at(-1).engines, 0, "Eviction pushes an update without a graph poll");
     f.start("second");
     assert.equal((await f.receive()).output, "second");
     assert.equal(f.stats().starts, 2);