feat(cloudflare): Auto-register Flue instrumentation in bundled workers - #24476
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Flue is registered, not patched — `instrument()` writes into module-scope state — so instrumenting it needs a reference to that module's own binding, and no channel payload carries one. On Node the user supplies it by calling `instrument()` themselves, which stays the only route there. In a bundled worker there is no `node_modules` to resolve one from, so it is supplied at build time instead. Two halves, mirroring how Mastra reaches a worker: - `flueIntegration()` registers the instrumentation when the `@flue/runtime` namespace is on the orchestrion marker, and no-ops when it is not. A `registrationOnly` orchestrion entry is what installs it on a bundler-only SDK: evaluating `@flue/runtime` registers the factory on the marker. That also keeps the integration reachable under `sideEffects: false`, which would otherwise let the bundler drop the module and the registration with it. - `@sentry/cloudflare/vite` splices a static `@flue/runtime` import into Sentry's own Flue integration module and exposes the namespace on `providedModules`. Two things the Mastra provider does not have to handle. `@flue/runtime` is ESM-only, so `createRequire().resolve()` throws `ERR_PACKAGE_PATH_NOT_EXPORTED` on it and the existence check goes through the ESM resolver. And the namespace is exposed through a getter rather than assigned: the snippet is prepended to Sentry's module, which the bundler may evaluate before `@flue/runtime` is initialized, so assigning it stores `undefined` — the key lands on `providedModules` with nothing behind it. An app that also calls `instrument()` itself is unaffected: its own registration wins and the integration swallows the resulting `InstrumentationAlreadyInstalledError`. Node is unchanged. `moduleInjectedTransforms` is wired into the bundler paths only, and Sentry stays external in a Flue node build, so neither half applies there and `flueIntegration()` installs as a no-op. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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RulaKhaled
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September 17, 2026 14:18
…ation The build-time presence check used `import.meta.resolve(spec, parentURL)`. The `parentURL` argument is ignored without `--experimental-import-meta-resolve`, so the check resolved from Sentry's own install rather than the app's, and it compiles to `undefined(...)` in this package's CJS build, where it threw and fell through to a `createRequire` fallback that always fails for an ESM-only package. Injection was therefore skipped outright on the CJS path and wherever Sentry is not installed beneath the app. It now resolves with `createRequire` from the Vite root and counts `ERR_PACKAGE_PATH_NOT_EXPORTED` as a hit: `@flue/runtime` publishes no `require` condition on any subpath, so that error means the package is present, while a missing one reports `MODULE_NOT_FOUND`. Also narrows the registration catch to `InstrumentationAlreadyInstalledError` so a changed `instrument()` contract surfaces instead of becoming a debug log, bounds the supported range at `<3.0.0`, drops the unused `flueModuleNames` export, and removes `flueIntegration()` from the default integrations — it has no binding to read on Node, where registering stays a manual `instrument(Sentry.createFlueInstrumentation())` call. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Reviewed by Cursor Bugbot for commit 97b7ed7. Configure here.
…try.init()` Core calls `integration.setup()` unguarded, and Cloudflare runs `Sentry.init()` inside the request wrapper, so rethrowing an unexpected `instrument()` failure would take down the handler — and every later request, since the client is never cached. A duplicate registration stays a debug log; anything else now warns that Flue spans will not be recorded, which keeps the failure visible without making it fatal. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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This is good :)
Breaking the import cycle with a getter is a good approach. Build-time presence detection avoids forcing @flue/runtime into every worker.
The only concern (which can be put off to a follow-up easily enough) is the overlap with Mastra, which is already drifting in a few spots (albeit pretty minor), so would probably be good to consolidate.
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| import { createRequire } from 'node:module'; | |||
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Main issue/comment I'd make for this PR: this file is nearly identical to the packages/cloudflare/src/vite/mastraObservability.ts file, except for the module specifier, the identifier, the target regex, the tolerated resolve error, and getter versus assignment.
Suggestion: extract one factory, eg createProvidedModulePlugin({ name, moduleName, identifier, targetId, lazy }), and let both call sites shrink to a few lines. That also gives one place to fix any other concerns for both packages.
Also, I notice that Mastra's plain catch { return; } works today only because @mastra/observability still publishes a require condition. If it goes ESM-only, that provider silently stops injecting, with the same symptom this branch just fixed for Flue. A shared check removes that potential future bug, and lets us improve both in one place.
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By the way, this can definitely be put off for a future PR, I just think we should probably get to it before there's a third one of these, and we start having a harder time deciding which drifting behavior is correct 😅
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will take it up on a follow up. you're right about the mastra half, it isn't hypothetical either, @mastra/observability@1.17.4 still ships a require condition, so mastraObservability.ts:48's bare catch { return; } works by luck, an esm only release turns injection off silently
fixed the flue side here and left mastra untouched so both land together with the rafactor
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| try { | ||
| createRequire(resolve(config.root, 'noop.js')).resolve(FLUE_MODULE); | ||
| } catch (error) { | ||
| if ((error as NodeJS.ErrnoException | undefined)?.code !== 'ERR_PACKAGE_PATH_NOT_EXPORTED') { | ||
| return; | ||
| } | ||
| } |
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Based on the comment above, it seems safer to detect module not found rather than "anything other than path not exported"?
Suggested change
| try { | |
| createRequire(resolve(config.root, 'noop.js')).resolve(FLUE_MODULE); | |
| } catch (error) { | |
| if ((error as NodeJS.ErrnoException | undefined)?.code !== 'ERR_PACKAGE_PATH_NOT_EXPORTED') { | |
| return; | |
| } | |
| } | |
| try { | |
| createRequire(resolve(config.root, 'noop.js')).resolve(FLUE_MODULE); | |
| } catch (error) { | |
| const code = (error as NodeJS.ErrnoException | undefined)?.code; | |
| if (code === 'MODULE_NOT_FOUND' || code === 'ERR_MODULE_NOT_FOUND') { | |
| return; | |
| } | |
| } |
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Oh, also, it'd be a bigger refactor, but I think if we have a rollup context, we can do await this.resolve(FLUE_MODULE, resolve(root, 'noop.js')) on it to get a more definitive answer, regardless of export type. That would drop createRequire, node:path and the error-code special case entirely.
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this.resolve() version is def nicer, I'll do it once with the refactor
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| try { | ||
| instrument(createFlueInstrumentation(options)); | ||
| } catch (error) { | ||
| // Never rethrow: `setup()` runs inside `Sentry.init()`, which core calls unguarded and | ||
| // Cloudflare calls per request, so throwing here would take down the request handler. | ||
| if ((error as Error | undefined)?.name === 'InstrumentationAlreadyInstalledError') { | ||
| DEBUG_BUILD && debug.log('[Flue] already instrumented by the app; skipping auto-registration'); | ||
| } else { | ||
| debug.warn('[Flue] auto-registration failed; Flue spans will not be recorded:', error); | ||
| } | ||
| } |
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In dev, a repeat instrument() under the same key doesn't throw, and instead disposes the previous registration. Sentry's dispose() (in packages/server-utils/src/ai/flue/index.ts) ends every tracked turn and tool span and clears all three maps.
Cloudflare calls Sentry.init() per request. With the default cacheClient: true the cached client short-circuits before setup() reruns, so this doesn't fire.
With cacheClient: false, or any path that bypasses the cache, setup() runs per request.
Under vite dev that means every request ends the in-flight turn and tool spans of every concurrent request, and the fresh registration starts with empty maps so those spans are then orphaned, and nothing throws or is logged.
Suggesgtion: guard the call with a module-scope flag, for example let registered = false; set after a successful instrument(). One registration per isolate is all the design wants, and the flag also avoids allocating two 1000-entry LRUMaps per request just to throw them away on the production path.
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Very nice. I guarded this on the binding rather than a bare boolean, so a fresh isolate still registers
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| transform(code: string, id: string): { code: string; map: ReturnType<MagicString['generateMap']> } | undefined { | ||
| if (!providerSnippet || !isFlueIntegrationModuleId(id)) return undefined; | ||
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| const ms = new MagicString(code); | ||
| ms.prepend(providerSnippet); | ||
| return { code: ms.toString(), map: ms.generateMap({ hires: true }) }; | ||
| }, |
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This is not idempotent, because the ms.prepend unconditionally adds the snippet.
If transform ever sees the same module twice in one environment, the output carries two import * as __SENTRY_FLUE_RUNTIME__ statements, which is a duplicate binding and a syntax error. Vite's per-environment module graphs make it unlikely, but it's a potential future hazard.
(Note: same thing in the Mastra plugin, probably another reason to consider consolidating them.)
Suggested change
| transform(code: string, id: string): { code: string; map: ReturnType<MagicString['generateMap']> } | undefined { | |
| if (!providerSnippet || !isFlueIntegrationModuleId(id)) return undefined; | |
| const ms = new MagicString(code); | |
| ms.prepend(providerSnippet); | |
| return { code: ms.toString(), map: ms.generateMap({ hires: true }) }; | |
| }, | |
| transform(code: string, id: string): { code: string; map: ReturnType<MagicString['generateMap']> } | undefined { | |
| if (!providerSnippet || !isFlueIntegrationModuleId(id) || code.includes(PROVIDER_IDENTIFIER)) { | |
| return undefined; | |
| } | |
| const ms = new MagicString(code); | |
| ms.prepend(providerSnippet); | |
| return { code: ms.toString(), map: ms.generateMap({ hires: true }) }; | |
| }, |
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I couldn't find a config where vite actually re-transforms its own output, but added it anyway
left the mastra copy as is so it lands with the factory
Cloudflare calls `Sentry.init()` per request. With `cacheClient: false` the cached client no longer short-circuits, so `setup()` reran and called `instrument()` again on every request. Flue only throws on a duplicate key when `!isDevMode()`, and `@flue/vite` generates the entry with `devMode: import.meta.env.DEV`. Under `vite dev` the repeat disposes the previous registration instead, and our `dispose()` ends every tracked turn and tool span, so each request killed the in-flight spans of every concurrent one with nothing thrown or logged. Keyed on the provided binding rather than a bare boolean, so a new isolate or a freshly provided namespace still registers. Set on the `InstrumentationAlreadyInstalledError` branch too: the app owns the key and we will never win it, so retrying only rebuilds two 1000-entry `LRUMap`s per request. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Review fixes, all in the Vite provider plugin. Treat only a module-not-found as absent. The old check skipped injection on any code other than `ERR_PACKAGE_PATH_NOT_EXPORTED`, so an installed package that failed to resolve some other way lost instrumentation silently. A malformed `package.json` resolves with `code === undefined` and hit exactly that. Injecting instead hands the failure to Vite, which reports it. Guard `transform` on the injected identifier. `ms.prepend` ran unconditionally, so a second pass over its own output would emit a duplicate `import * as` binding, which is a syntax error. Make the provider property enumerable, matching the Mastra plugin's plain assignment, so it survives a spread or `Object.keys`. Also re-export the `FlueOptions` type, which pairs with the `createFlueInstrumentation` this package already exports. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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`flueRuntime.ts` and `mastraObservability.ts` were near-identical, differing
only in the module specifier, the injected identifier, the target regex, how
they handled a failed resolve, and getter versus assignment. Both call sites are
now a few lines over a shared `createProvidedModulePlugin`.
Replace the `createRequire().resolve()` probe with the Rollup context's
`this.resolve()`, which answers with the same resolver and conditions the
injected import will use. That drops `createRequire`, `node:path` and the
error-code special case, and it fixes a latent bug on the Mastra side: its bare
`catch { return; }` worked only because `@mastra/observability` still publishes
a `require` condition, so an ESM-only release would have turned injection off
with no error and no log. The probe needs a plugin context, so it moves from
`configResolved` to `buildStart`. `configResolved` stays to capture the app
root.
Resolution runs per environment against a shared plugin instance, so the probe
stops once it finds the package and retries in the next environment otherwise.
Only the worker environment ever reaches `transform`, and it may not run first.
Mastra also picks up the two guards flue gained in #24476: `transform` is now
idempotent, and a resolver error injects rather than silently skipping.
Mastra keeps plain assignment. Switching it to flue's lazy getter is probably
right for the same reason flue needs one, but it is a behavior change and worth
deciding on its own.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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`flueRuntime.ts` and `mastraObservability.ts` were near-identical, differing
only in the module specifier, the injected identifier, the target regex, how
they handled a failed resolve, and getter versus assignment. Both call sites are
now a few lines over a shared `createProvidedModulePlugin`.
Replace the `createRequire().resolve()` probe with the Rollup context's
`this.resolve()`, which answers with the same resolver and conditions the
injected import will use. That drops `createRequire`, `node:path` and the
error-code special case, and it fixes a latent bug on the Mastra side: its bare
`catch { return; }` worked only because `@mastra/observability` still publishes
a `require` condition, so an ESM-only release would have turned injection off
with no error and no log. The probe needs a plugin context, so it moves from
`configResolved` to `buildStart`. `configResolved` stays to capture the app
root.
Resolution runs per environment against a shared plugin instance, so the probe
stops once it finds the package and retries in the next environment otherwise.
Only the worker environment ever reaches `transform`, and it may not run first.
Mastra also picks up the guards Flue gained in #24476: `transform` is
idempotent, a resolver error injects rather than silently skipping, and the
namespace now goes behind the same lazy getter. Assigning reads the binding at
injection time, so it stores `undefined` whenever the bundler evaluates Sentry's
module first. That hazard is not specific to Flue, so both providers use one
shape and the `lazy` option is gone.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Stacked on #24476 — review that first. A `flue init` Cloudflare app with no `instrument()` call anywhere: registration comes from the build, so any `gen_ai` span here is itself proof the auto-wiring worked. Covers AI spans, tool-error capture, a manual span nesting under its tool, and an orchestrion `dataloader` span in the agent's trace. Secrets go through `.dev.vars` rather than `--var` because Flue resolves the provider key inside `pi-ai` at runtime, leaving nothing for Vite to inline, and `vite preview` is what serves the worker with Flue's generated Durable Object config. Two Flue constraints the app works around, both commented in place: `agents` is imported by Flue's generated worker entry without being declared, so it only resolves under npm's hoisting and needs declaring for pnpm; and the `'use agent'` scan parses every source file as plain JavaScript, so generics and return types fail the build. _Worth a docs note_: the Sentry wrapper has to be re-exported as `cloudflare` from the agent module. Defining it elsewhere leaves the Durable Object unwrapped — the agent runs, turns settle, and nothing is traced. --------- Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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…24535) Follow-up to #24476, where @isaacs pointed out that `flueRuntime.ts` and `mastraObservability.ts` are near-identical and drifting. Both are now a few lines over a shared `createProvidedModulePlugin`, so the next provider is a config object rather than a third copy. The probe moves from `createRequire().resolve()` to the Rollup context's `this.resolve()`, which uses the same resolver and conditions as the injected import. That drops `createRequire`, `node:path` and the error-code special case, and fixes a latent Mastra bug: its bare `catch { return; }` only works because `@mastra/observability` still publishes a `require` condition, so an ESM-only release would have turned injection off silently, the same failure #24476 fixed for Flue. `this.resolve()` needs a plugin context, so the probe moves to `buildStart` and `configResolved` stays only to capture the app root. Resolution runs per environment against a shared instance, so it stops once the package is found and retries otherwise, since the worker environment may not run first. Mastra also picks up the guards Flue gained in #24476: `transform` is idempotent, a resolver error injects rather than skipping, and the namespace goes behind the same lazy getter. Assigning reads the binding at injection time and stores `undefined` if the bundler evaluates Sentry's module first, which is not Flue-specific, so there is one shape for both and no `lazy` option. `cloudflare-mastra` is the real check here: on workerd the injected binding is the only path `loadMastraObservability` can take, so a broken injection means no agent spans and a failing suite. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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Flue is registered, not patched —
instrument()writes into module-scope state — so instrumenting it needs a reference to that module's own binding, and no channel payload carries one. A bundled worker has nonode_modulesto resolve one from, so this supplies it at build time.@sentry/cloudflare/vitesplices a static@flue/runtimeimport into Sentry's own Flue integration module and exposes the namespace onprovidedModules;flueIntegration()reads it there and registers. AregistrationOnlyorchestrion entry installs the integration on a bundler-only SDK and keeps it reachable undersideEffects: false.@flue/runtimeis ESM-only, so the presence check resolves withcreateRequirefrom the Vite root and countsERR_PACKAGE_PATH_NOT_EXPORTEDas a hit — the package publishes norequirecondition on any subpath, while a genuinely missing one reportsMODULE_NOT_FOUND. The namespace is exposed through a getter rather than assigned, because the bundler may evaluate Sentry's module before@flue/runtimeis initialized.An app that also calls
instrument()itself is unaffected: its own registration wins, and only the resultingInstrumentationAlreadyInstalledErroris swallowed. On Node registering stays a manualinstrument(Sentry.createFlueInstrumentation())call —flueIntegration()is not among the default integrations there.Verified end to end in #24477.