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ref(core)!: Split browser/server-only exports out of the default entrypoint - #23762

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ref(core)!: Split browser/server-only exports out of the default entrypoint#23762
mydea wants to merge 5 commits into
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@mydea mydea commented Aug 31, 2026

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Splits the browser- and server-only exports out of @sentry/core's default entrypoint. @sentry/core now exposes only isomorphic code, and the @sentry/core/browser and @sentry/core/server entrypoints now contain only their platform-specific exports instead of also re-exporting the shared surface on top.

Previously the default entrypoint re-exported everything (via shared-exports.ts), and both /browser and /server re-exported that shared surface plus their platform extras. That meant importing anything from @sentry/core could drag server-only code (http server/client instrumentation, ANR, postgres/sql helpers, …) into browser bundles, and the platform entrypoints were never cleanly separable.

After this change:

  • @sentry/core — isomorphic exports only (the former shared-exports.ts, inlined into index.ts).
  • @sentry/core/browser — browser-only exports, e.g. the guarded startSpan/startInactiveSpan variants that install spanStreamingIntegration.
  • @sentry/core/server — server-only exports: ServerRuntimeClient, ServerRuntimeOptions, trpcMiddleware, wrapMcpServerWithSentry, the http client/server subscription APIs, flushIfServerless, loadModule, node stack-trace helpers, postgres/sql instrumentation, and more.

Consumer packages were updated to import platform-specific symbols from the matching entrypoint rather than from @sentry/core.

Root cause of the guarded-span split: the browser SDK's init() deliberately omits spanStreamingIntegration — referencing it would keep the whole span-streaming graph in every bundle, including error-only ones. Because the plain and guarded span-start APIs share their names, importing the plain variant in browser code compiles fine but produces spans that are then never sent. The new no-unguarded-span-apis lint rule is the only thing that catches this, and enforces that browser-facing code imports the span-start APIs from @sentry/core/browser.

Decisions

  • The three entrypoints are kept disjoint rather than having /browser and /server re-export the isomorphic surface. Consumers import isomorphic code from @sentry/core and platform code from the matching subpath — this is what makes the separation meaningful for tree-shaking and bundle size.
  • Marked breaking (!): symbols previously reachable from @sentry/core (e.g. trpcMiddleware, wrapMcpServerWithSentry) now live under @sentry/core/server.

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Comment thread packages/browser/src/index.ts
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size-limit report 📦

Path Size % Change Change
@sentry/browser 28.56 kB - -
@sentry/browser - with treeshaking flags 26.92 kB - -
@sentry/browser - with treeshaking flags tracing without tracing 26.82 kB - -
@sentry/browser (incl. Tracing) 48.75 kB - -
@sentry/browser (incl. Tracing + Span Streaming) 48.76 kB - -
@sentry/browser (incl. Tracing, Profiling) 51.68 kB - -
@sentry/browser (incl. Tracing, Replay) 88.23 kB - -
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags 77.63 kB - -
@sentry/browser (incl. Tracing, Replay with Canvas) 92.93 kB - -
@sentry/browser (incl. Tracing, Replay, Feedback) 105.85 kB - -
@sentry/browser (incl. Feedback) 46.05 kB - -
@sentry/browser (incl. sendFeedback) 33.62 kB - -
@sentry/browser (incl. FeedbackAsync) 38.73 kB - -
@sentry/browser (incl. Metrics) 29.51 kB - -
@sentry/browser (incl. Logs) 29.8 kB - -
@sentry/browser (incl. Metrics & Logs) 30.43 kB - -
@sentry/react 30.3 kB - -
@sentry/react (incl. Tracing) 50.94 kB - -
@sentry/vue 35.73 kB - -
@sentry/vue (incl. Tracing) 51.02 kB - -
@sentry/svelte 28.59 kB - -
CDN Bundle 30.35 kB - -
CDN Bundle (incl. Tracing) 49.38 kB - -
CDN Bundle (incl. Logs, Metrics) 32.58 kB - -
CDN Bundle (incl. Tracing, Logs, Metrics) 51.25 kB - -
CDN Bundle (incl. Replay, Logs, Metrics) 73.17 kB - -
CDN Bundle (incl. Tracing, Replay) 86.86 kB - -
CDN Bundle (incl. Tracing, Replay, Logs, Metrics) 88.73 kB - -
CDN Bundle (incl. Tracing, Replay, Feedback) 92.8 kB - -
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) 94.64 kB - -
CDN Bundle - uncompressed 89.95 kB - -
CDN Bundle (incl. Tracing) - uncompressed 147.2 kB - -
CDN Bundle (incl. Logs, Metrics) - uncompressed 96.24 kB - -
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed 152.89 kB - -
CDN Bundle (incl. Replay, Logs, Metrics) - uncompressed 225.41 kB - -
CDN Bundle (incl. Tracing, Replay) - uncompressed 266.69 kB - -
CDN Bundle (incl. Tracing, Replay, Logs, Metrics) - uncompressed 272.37 kB - -
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed 280.4 kB - -
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed 286.06 kB - -
@sentry/nextjs (client) 53.56 kB - -
@sentry/sveltekit (client) 49.19 kB - -
@sentry/core/server 40.64 kB -38.12% -25.03 kB 🔽
@sentry/core/browser 13.42 kB -74.12% -38.44 kB 🔽
@sentry/node 123.75 kB +0.01% +6 B 🔺
@sentry/node/import (ESM hook with diagnostics-channel injection) 85.32 kB -0.25% -213 B 🔽
@sentry/node - without tracing 88.02 kB +0.02% +10 B 🔺
@sentry/node - without channel injection 103.16 kB -0.01% -1 B 🔽
@sentry/aws-serverless 96.41 kB +0.02% +11 B 🔺
@sentry/cloudflare (withSentry) - minified 201.04 kB - -
@sentry/cloudflare (withSentry) 500.26 kB - -

View base workflow run

mydea and others added 2 commits August 31, 2026 14:03
…ypoint

`@sentry/core` now exposes only isomorphic code. The `/browser` and `/server`
entrypoints contain only their platform-specific exports instead of also
re-exporting the full shared surface, and consumer packages import
platform-specific symbols from the matching entrypoint.

A `no-unguarded-span-apis` lint rule enforces that browser-facing code imports
the span-start APIs from `@sentry/core/browser` (the guarded variant), never
from `@sentry/core`/`@sentry/core/server`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Point browser-facing tests at `@sentry/core` for isomorphic symbols (keeping
only the guarded span-start APIs on `@sentry/core/browser`), and point
server-facing tests at `@sentry/core/server` for the moved server-only symbols
(`flushIfServerless`, `loadModule`, `isNodeEnv`, `vercelWaitUntil`,
`nodeStackLineParser`, `trpcMiddleware`, `ServerRuntimeClient`, ...) so mocks and
spies intercept the same binding the source imports.

Update `core`'s `exports.test.ts` to the disjoint entrypoint contract: the root
entry serves the plain span-start APIs and `spanStreamingIntegration`, the
browser entry serves the guarded span-start variants, and the server entry
re-exports neither (server code imports the isomorphic APIs from the root entry).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
@mydea
mydea force-pushed the fn/split-core-exports branch from e32bdf9 to e787ccb Compare August 31, 2026 12:35
mydea and others added 3 commits August 31, 2026 14:40
The postgres/postgresjs tracing scenarios imported `uuid4` from
`@sentry/core/server`, which only serves server-specific exports and does not
provide `uuid4` — the ESM import crashed each scenario at load. `uuid4` is
isomorphic and lives on the root `@sentry/core` entry.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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