harden: remove debug /echo endpoint; widen LN health probe timeout

Remove the unauthenticated POST /echo route — a request-body reflector with
no place in production; it served only to echo attacker probe payloads.

Raise the health-check listener-backlog probe timeout from 5s to 15s. The
waitanyinvoice probe normally returns in ~1s but can intermittently take ~8s
while lightningd is briefly busy; the 5s cap turned those transient spikes
into health-check failures (and, at 3 consecutive, an unnecessary process
exit / container restart). 15s absorbs the busy spikes while a genuinely
wedged RPC still fails the check.

Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01DKkev76U4YRnRAqM6jqbae

2 files changed, 1 insertions, 6 deletions

diff --git a/index.ts b/index.ts
index 328c453f..9ce509c2 100644
--- a/index.ts
+++ b/index.ts
@@ -198,11 +198,6 @@ app.get("/replay/:index", (req, res) => {
   res.send({});
 });
 
-app.post("/echo", (req, res) => {
-  console.log("echo", req.body);
-  res.send(req.body);
-});
-
 const host: string = process.env["HOST"] || "0.0.0.0";
 const port: number = Number.parseInt(process.env["PORT"]) || 3119;
 
diff --git a/lib/health.ts b/lib/health.ts
index bb05b0db..96d15030 100644
--- a/lib/health.ts
+++ b/lib/health.ts
@@ -93,7 +93,7 @@ async function checkLightningHealth(): Promise<boolean> {
     try {
       const waiting = await withTimeout(
         ln.waitanyinvoice(payIndex, 1),
-        5_000,
+        15_000,
         "listener backlog probe",
       );
       if (Number(waiting?.pay_index) > payIndex) {