fix: support frozen intrinsics when adjusting Error.stackTraceLimit#2444
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tim-smart merged 1 commit intoJun 19, 2026
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In hardened/deterministic JavaScript environments (SES "frozen intrinsics", Temporal-style sandboxes), `Error` is frozen and `Error.stackTraceLimit` is read-only. Effect mutates `stackTraceLimit` in several internal spots to capture short/empty stack traces cheaply; under frozen intrinsics those assignments throw, breaking Effect entirely. Add an internal `internal/stackTraceLimit.ts` helper (mirroring Node's own guard) that detects writability once at module load and degrades `set` to a silent no-op when the property can't be modified. Replace the raw mutations across Context.ts, Layer.ts, LayerMap.ts, internal/effect.ts, internal/tracer.ts, HttpApiMiddleware.ts and RpcMiddleware.ts with guarded get/set calls, keeping `new Error()` inline at each call site so captured stack traces still point at the real caller. `unsafeSecureJsonParse` in unstable/ai/Tool.ts imports the same internal helper directly (it lives in the same package here, unlike `@effect/ai` upstream). Ports Effect-TS/effect#6279 to effect-smol. Original change stood up by @arlyon. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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This was referenced Jun 19, 2026
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effect-smol equivalent of Effect-TS/effect#6279 |
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Ports Effect-TS/effect#6279 to
effect-smol.Type
Description
In hardened/deterministic JavaScript environments (SES "frozen intrinsics", Temporal-style sandboxes),
Erroris frozen andError.stackTraceLimitis read-only. Effect mutatesstackTraceLimitin several internal spots to capture short or empty stack traces cheaply, using the pattern:In these environments the assignments throw, breaking Effect entirely.
This PR adds
packages/effect/src/internal/stackTraceLimit.ts, which checks writability once at module load (mirroring Node's internal guard) and exposesgetStackTraceLimit()/setStackTraceLimit()helpers wheresetis a silent no-op when the property can't be modified. All raw mutations are replaced with these guarded calls, withnew Error()kept inline at each call site so the captured stack trace still points at the real caller rather than the helper.Call sites updated:
Context.ts,Layer.ts,LayerMap.ts,internal/effect.ts(cause pretty-errors,Effect.fn),internal/tracer.ts,unstable/httpapi/HttpApiMiddleware.ts,unstable/rpc/RpcMiddleware.ts.Notes for review (vs. the upstream
effectPR)The
effect-smollayout differs fromEffect-TS/effect, so this is a port rather than a cherry-pick:internal/effect.ts, publicContext.ts/Layer.ts/LayerMap.ts) rather than split acrosscause/core-effect/runtime/layer/context; there is noMicro.ts.ErrorWithStackTraceLimitinterface and.tsimport extensions.unsafeSecureJsonParse(unstable/ai/Tool.ts) imports the internal helper directly instead of duplicating the guard, becauseailives in the same package here (unlike@effect/aiupstream).Behavior in normal (writable) environments is unchanged. A changeset and a dedicated test (
packages/effect/test/StackTraceLimit.test.ts, covering both the writable and frozen paths) are included; typecheck and lint pass and the affected suites (Cause, Tracer, Context, LayerMap, Effect) are green.Note
The original change was stood up by @arlyon. This description and PR were aided via Claude Code.