From 8fb77712233462e86b4b5ef192f08af82526df03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ullrich=20Sch=C3=A4fer?= <hi+github@ullrich.is>
Date: Tue, 24 Mar 2026 23:39:33 +0100
Subject: [PATCH] Add withDb() helper for graceful DB error handling
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Shared withDb() wrapper in @trails-cool/db catches database
connection errors and throws a 503 Response instead of crashing
the server. Re-throws React Router responses (redirects, data()).

Applied to Planner session routes — replaces manual try/catch.
Any route can use withDb(() => ...) for automatic 503 on DB failure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 apps/planner/app/routes/api.sessions.ts | 22 ++++++----------------
 apps/planner/app/routes/session.$id.tsx |  8 +++-----
 packages/db/src/index.ts                | 24 ++++++++++++++++++++++++
 3 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/apps/planner/app/routes/api.sessions.ts b/apps/planner/app/routes/api.sessions.ts
index 1827f7a..3778341 100644
--- a/apps/planner/app/routes/api.sessions.ts
+++ b/apps/planner/app/routes/api.sessions.ts
@@ -2,6 +2,7 @@ import { data } from "react-router";
 import type { Route } from "./+types/api.sessions";
 import { createSession, listSessions } from "~/lib/sessions";
 import { parseGpxAsync } from "@trails-cool/gpx";
+import { withDb } from "@trails-cool/db";
 
 export async function action({ request }: Route.ActionArgs) {
   if (request.method !== "POST") {
@@ -15,7 +16,7 @@ export async function action({ request }: Route.ActionArgs) {
     gpx?: string;
   };
 
-  try {
+  return withDb(async () => {
     const session = await createSession({ callbackUrl, callbackToken });
 
     let initialWaypoints: Array<{ lat: number; lon: number; name?: string }> | undefined;
@@ -29,26 +30,15 @@ export async function action({ request }: Route.ActionArgs) {
     }
 
     return data(
-      {
-        sessionId: session.id,
-        url: `/session/${session.id}`,
-        initialWaypoints,
-      },
+      { sessionId: session.id, url: `/session/${session.id}`, initialWaypoints },
       { status: 201 },
     );
-  } catch (e) {
-    return data(
-      { error: "Database unavailable", details: (e as Error).message },
-      { status: 503 },
-    );
-  }
+  });
 }
 
 export async function loader(_args: Route.LoaderArgs) {
-  try {
+  return withDb(async () => {
     const sessions = await listSessions();
     return data({ sessions });
-  } catch {
-    return data({ sessions: [], error: "Database unavailable" });
-  }
+  });
 }
diff --git a/apps/planner/app/routes/session.$id.tsx b/apps/planner/app/routes/session.$id.tsx
index 67b3043..2c630d7 100644
--- a/apps/planner/app/routes/session.$id.tsx
+++ b/apps/planner/app/routes/session.$id.tsx
@@ -2,6 +2,7 @@ import { useParams, useSearchParams } from "react-router";
 import type { Route } from "./+types/session.$id";
 import { getSession } from "~/lib/sessions";
 import { data } from "react-router";
+import { withDb } from "@trails-cool/db";
 import { ClientOnly } from "~/components/ClientOnly";
 import { lazy, Suspense } from "react";
 
@@ -14,7 +15,7 @@ export function meta(_args: Route.MetaArgs) {
 }
 
 export async function loader({ params }: Route.LoaderArgs) {
-  try {
+  return withDb(async () => {
     const session = await getSession(params.id);
     if (!session) {
       throw data({ error: "Session not found" }, { status: 404 });
@@ -24,10 +25,7 @@ export async function loader({ params }: Route.LoaderArgs) {
       callbackUrl: session.callbackUrl ?? null,
       callbackToken: session.callbackToken ?? null,
     });
-  } catch (e) {
-    if (e instanceof Response) throw e; // Re-throw data() responses
-    throw data({ error: "Database unavailable" }, { status: 503 });
-  }
+  });
 }
 
 export default function SessionPage({ loaderData }: Route.ComponentProps) {
diff --git a/packages/db/src/index.ts b/packages/db/src/index.ts
index b051bfd..0cd5ba6 100644
--- a/packages/db/src/index.ts
+++ b/packages/db/src/index.ts
@@ -14,4 +14,28 @@ export function createDb(connectionString?: string) {
 
 export type Database = ReturnType<typeof createDb>;
 
+/**
+ * Wraps a route handler (loader/action) to catch database errors
+ * and return a 503 Service Unavailable instead of crashing.
+ */
+export function withDb<T>(handler: () => Promise<T>): Promise<T> {
+  return handler().catch((error) => {
+    if (error instanceof Response) throw error; // Re-throw React Router responses (redirects, data())
+    const message = error instanceof Error ? error.message : "Unknown error";
+    if (
+      message.includes("connect") ||
+      message.includes("ECONNREFUSED") ||
+      message.includes("DrizzleQueryError") ||
+      message.includes("AggregateError") ||
+      message.includes("database")
+    ) {
+      throw new Response(JSON.stringify({ error: "Database unavailable" }), {
+        status: 503,
+        headers: { "Content-Type": "application/json" },
+      });
+    }
+    throw error;
+  });
+}
+
 export { plannerSchema, journalSchema };