fix(database): clamp pool bounds, guard redis probe, harden error page

Address review feedback on #744:
- clamp DATABASE_POOL_MAX to >= 1 and DATABASE_POOL_MIN to <= max so bad
  env values can not produce a pool that fails every acquire
- healthcheck redis probe checks client status before PING so commands are
  not queued indefinitely while redis is down (maxRetriesPerRequest is null)
- probe() clears its timeout timer once the check settles
- error.html shows only the status code, not the error message
- docs: correct SQLite default to kener.sqlite.db to match knexfile

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

knexfile.ts

@@ -25,9 +25,13 @@ const keepAliveEnabled = process.env.DATABASE_KEEPALIVE !== "false";
 //   ones that go stale and wedge the app until a manual restart
 // - 15s acquire/create timeouts: fail fast instead of hanging requests for
 //   knex's default 60s during a database outage
+// Tarn requires max >= 1 and min <= max; clamp so a bad env value can not
+// produce a pool that fails every acquire
+const poolMax = Math.max(1, intFromEnv("DATABASE_POOL_MAX", 10));
+const poolMin = Math.min(intFromEnv("DATABASE_POOL_MIN", 0), poolMax);
 const pool = {
-  min: intFromEnv("DATABASE_POOL_MIN", 0),
-  max: intFromEnv("DATABASE_POOL_MAX", 10),
+  min: poolMin,
+  max: poolMax,
   idleTimeoutMillis: intFromEnv("DATABASE_IDLE_TIMEOUT_MS", 30000),
   createTimeoutMillis: intFromEnv("DATABASE_CREATE_TIMEOUT_MS", 15000),
 };

scripts/main.ts

@@ -24,14 +24,19 @@ async function start() {
   // Caps a health probe at 2s so a wedged dependency can not hang the
   // endpoint. A probe is healthy unless it throws, times out, or resolves false.
   const probe = async (check: () => Promise<unknown>): Promise<boolean> => {
+    let timer: ReturnType<typeof setTimeout> | undefined;
     try {
       const result = await Promise.race([
         check(),
-        new Promise((_, reject) => setTimeout(() => reject(new Error("health probe timeout")), 2000)),
+        new Promise((_, reject) => {
+          timer = setTimeout(() => reject(new Error("health probe timeout")), 2000);
+        }),
       ]);
       return result !== false;
     } catch {
       return false;
+    } finally {
+      clearTimeout(timer);
     }
   };
 
@@ -39,7 +44,17 @@ async function start() {
   // not bounce the app while a dependency is down (a restart can not fix a
   // dead database); pass ?strict=1 to get 503 when any component is down.
   app.get(base + "/healthcheck", async (req: any, res: any) => {
-    const [dbOk, redisOk] = await Promise.all([probe(() => dbInstance.ping()), probe(() => redisConnection().ping())]);
+    const [dbOk, redisOk] = await Promise.all([
+      probe(() => dbInstance.ping()),
+      // Guard on status before PING: the shared ioredis client has
+      // maxRetriesPerRequest null, so commands sent while disconnected would
+      // queue forever and accumulate across healthcheck polls
+      probe(async () => {
+        const redis = redisConnection();
+        if (redis.status !== "ready") return false;
+        return await redis.ping();
+      }),
+    ]);
     const healthy = dbOk && redisOk;
     const strict = req.query.strict === "1";
     res.status(strict && !healthy ? 503 : 200).json({

src/error.html

@@ -67,7 +67,7 @@
       <h1>This status page is temporarily unavailable</h1>
       <p>We are having trouble serving this page right now. It usually resolves on its own.</p>
       <p>This page will retry automatically in 30 seconds.</p>
-      <div class="code">%sveltekit.status% · %sveltekit.error.message%</div>
+      <div class="code">%sveltekit.status%</div>
     </div>
   </body>
 </html>

src/routes/(docs)/docs/content/v4/setup/environment-variables.md

@@ -239,8 +239,8 @@ SMTP_SECURE=1
 ### Database Configuration {#database-configuration}
 
 | Variable                      | Description                                                  | Default                               |
-| :---------------------------- | :----------------------------------------------------------- | :----------------------------- |
-| `DATABASE_URL`                | Full database connection string                              | `sqlite://./database/kener.db` |
+| :---------------------------- | :----------------------------------------------------------- | :------------------------------------ |
+| `DATABASE_URL`                | Full database connection string                              | `sqlite://./database/kener.sqlite.db` |
 | `DATABASE_POOL_MIN`           | Minimum pool connections (PostgreSQL/MySQL)                  | `0`                                   |
 | `DATABASE_POOL_MAX`           | Maximum pool connections (PostgreSQL/MySQL)                  | `10`                                  |
 | `DATABASE_ACQUIRE_TIMEOUT_MS` | Wait for a free connection before failing (PostgreSQL/MySQL) | `15000`                               |
@@ -258,7 +258,7 @@ SMTP_SECURE=1
 
 ```bash
 # SQLite (default)
-DATABASE_URL=sqlite://./database/kener.db
+DATABASE_URL=sqlite://./database/kener.sqlite.db
 
 # PostgreSQL
 DATABASE_URL=postgresql://user:password@localhost:5432/kener
@@ -484,7 +484,7 @@ Create a `.env` file in the project root:
 ```bash
 # .env
 KENER_SECRET_KEY=dev-secret-key
-DATABASE_URL=sqlite://./database/kener.db
+DATABASE_URL=sqlite://./database/kener.sqlite.db
 
 # Custom variables
 API_KEY=test-key-123