tanstackstart-react: server route parametrization never applies when the route tree is not at src/, and the matcher skips brace params and index routes #25067

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release (reproduced on 10.75.0; the same code ships in 11.4.0)

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/tanstackstart-react

SDK Version

10.75.0 and 11.4.0 (both inspected)

Framework Version

@tanstack/react-start 1.168.60, @tanstack/react-router 1.170.41, nitro 3.x as the Vite plugin

Link to Sentry event

No response (the report is about missing route parametrization, not an event)

Reproduction Example/SDK Setup

// vite.config.ts
plugins: [
  tanstackStart({ srcDirectory: "app" }), // route tree is generated at app/routeTree.gen.ts
  nitro(),
  react(),
  sentryTanstackStart({ telemetry: false, autoInstrumentMiddleware: false }),
]

// app/server.ts
import "./instrument.server";
import { isEnabled, wrapFetchWithSentry } from "@sentry/tanstackstart-react";
import handler, { createServerEntry } from "@tanstack/react-start/server-entry";
const entry = { fetch: (request: Request) => handler.fetch(request) };
export default createServerEntry(isEnabled() ? wrapFetchWithSentry(entry) : entry);

Routes in the generated tree include /groups/$groupId, /@{$groupSlug}, /@{$groupSlug}/covers/$coverId, /sitemap-{$page}.xml, and index routes such as /artists/.

Steps to Reproduce

The server-side route parametrization from #21147 does not apply to this app, for two reasons that are independent of the runtime (verified on Node):

1. The Vite plugin only reads src/routeTree.gen.ts.
vite/routePatterns.ts resolves path.resolve(root, "src/routeTree.gen.ts"). TanStack Start's srcDirectory option (or generatedRouteTree in tsr.config.json) moves that file, and the plugin silently falls back to []. I built the app and inspected the server chunk: the call is updateSpanWithRouteParametrization(method, url.pathname, []). There is no option on sentryTanstackStart to point at the file. A plugin placed before Sentry's that replaces __SENTRY_ROUTE_PATTERNS__ itself does embed all 79 patterns, so the generated file is available in time; only the path is wrong.

2. The runtime matcher does not follow TanStack's segment grammar.
server/routeParametrization.ts patternToRegex treats a segment as dynamic only when it startsWith("$"). With the correct 79-pattern list injected, Sentry's own matchUrlToRoutePattern returns:

• every affixed (brace) param route unmatched: /@some-group → null (pattern /@{$groupSlug}), /@some-group/covers/cover123 → null, /sitemap-3.xml → null (pattern /sitemap-{$page}.xml);
• every index route unmatched, because the URL's trailing slash is stripped but the pattern keeps it: /artists → null (pattern /artists/), /covers, /events, /groups, /showcase → null; and /groups/abc123/ → /groups/$groupId (the layout) instead of the index pattern /groups/$groupId/;
• plain $param routes work: /groups/abc123 → /groups/$groupId.

Optional segments ({-$x}) and splats ($) are not handled either, though this app has none.

Expected Result

• sentryTanstackStart reads the route tree from the configured srcDirectory / tsr.config.json, or accepts a routeTree path option.
• Matching follows TanStack's grammar (brace prefix/suffix params, optional segments, splats, index trailing slash), or delegates to the router's own getMatchedRoutes(pathname) so the SDK never has to re-implement it.

Actual Result

On Node, server transactions keep concrete URLs (GET /groups/abc123) for every app whose route tree is not at src/, and brace-param and index routes are never parametrized even when the pattern list is correct.

Related: #24839 covers the separate Bun/Deno runtime gaps (no http.server span on fetch-style entries such as Nitro's Vercel web entry), which I also see in production on Vercel's Bun runtime. This report is only about the two Node-reproducible defects above.