fix(webapp): collapse Prisma P1001 errors into a single Sentry issue

DB outages currently produce hundreds of distinct Sentry issues — one per
call site — which buries other alerts. Add a beforeSend rule that detects
err.code === "P1001" (KnownRequestError when a connection drops mid-query)
or err.errorCode === "P1001" (InitializationError when the client fails to
connect at startup) and assigns a stable fingerprint plus a db_unreachable
tag so all P1001 events collapse into one issue regardless of stack trace.

The rule list is extensible — additional fan-out errors can be added with
one entry.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: d-cs

.server-changes/webapp-sentry-fingerprint-p1001.md

@@ -0,0 +1,6 @@
+---
+area: webapp
+type: improvement
+---
+
+Group Prisma P1001 ("Can't reach database server") errors into a single Sentry issue via a `beforeSend` fingerprint rule, so DB outages no longer fan out into hundreds of distinct issues that bury other alerts. Adds a small extensible rule table for future collapsing rules.

apps/webapp/sentry.server.ts

@@ -1,6 +1,25 @@
 import * as Sentry from "@sentry/remix";
 import { addOtelTraceContextToEvent } from "./app/utils/sentryTraceContext.server";
 
+// Rules for collapsing high-volume errors into a single Sentry issue.
+// Without this, e.g. a DB outage produces hundreds of distinct issues —
+// one per stack trace — which buries other alerts. Add a new rule here
+// when you spot another error that fans out across call sites. Keep
+// predicates cheap (string compare, not regex over stack traces).
+const FINGERPRINT_RULES: Array<{
+  match: (err: { code?: unknown; errorCode?: unknown; name?: unknown }) => boolean;
+  fingerprint: string;
+  tags?: Record<string, string>;
+}> = [
+  {
+    // Prisma surfaces P1001 on `code` for KnownRequestError (mid-query connection drop)
+    // and `errorCode` for InitializationError (client failed to connect at startup).
+    match: (err) => err.code === "P1001" || err.errorCode === "P1001",
+    fingerprint: "prisma-p1001-db-unreachable",
+    tags: { db_unreachable: "true" },
+  },
+];
+
 if (process.env.SENTRY_DSN) {
   console.log("🔭 Initializing Sentry");
 
@@ -29,6 +48,20 @@ if (process.env.SENTRY_DSN) {
     // and stay visible.
     ignoreErrors: ["queryRoute() call aborted", /^ServiceValidationError(?::|$)/],
     includeLocalVariables: false,
+
+    beforeSend(event, hint) {
+      const err = hint.originalException as
+        | { code?: unknown; errorCode?: unknown; name?: unknown }
+        | undefined;
+      if (!err) return event;
+
+      const rule = FINGERPRINT_RULES.find((r) => r.match(err));
+      if (!rule) return event;
+
+      event.fingerprint = [rule.fingerprint];
+      if (rule.tags) event.tags = { ...event.tags, ...rule.tags };
+      return event;
+    },
   });
 
   Sentry.addEventProcessor(addOtelTraceContextToEvent);