From 7efbdd23cc7bc285243ca96464d73f63f454ac37 Mon Sep 17 00:00:00 2001
From: Tim <hello@timsmart.co>
Date: Wed, 3 Apr 2024 11:32:30 +1300
Subject: [PATCH] add unique identifier to Tracer.ParentSpan tag (#2459)

---
 .changeset/many-frogs-impress.md              |  5 ++++
 packages/effect/src/Channel.ts                |  4 ++--
 packages/effect/src/Effect.ts                 | 24 +++++++++----------
 packages/effect/src/Layer.ts                  | 12 +++++-----
 packages/effect/src/Stream.ts                 |  4 ++--
 packages/effect/src/Tracer.ts                 | 18 ++++++++++----
 packages/effect/src/internal/cause.ts         |  4 ++--
 packages/effect/src/internal/channel.ts       |  4 ++--
 packages/effect/src/internal/core-effect.ts   | 22 ++++++++---------
 packages/effect/src/internal/core.ts          |  2 +-
 packages/effect/src/internal/fiberRuntime.ts  |  6 ++---
 packages/effect/src/internal/layer.ts         |  8 +++----
 .../effect/src/internal/layer/circular.ts     |  4 ++--
 packages/effect/src/internal/stream.ts        |  4 ++--
 packages/effect/src/internal/tracer.ts        |  4 ++--
 packages/experimental/src/Machine.ts          |  4 ++--
 packages/opentelemetry/src/internal/tracer.ts | 10 ++++----
 17 files changed, 76 insertions(+), 63 deletions(-)
 create mode 100644 .changeset/many-frogs-impress.md

diff --git a/.changeset/many-frogs-impress.md b/.changeset/many-frogs-impress.md
new file mode 100644
index 0000000000..1cac94adea
--- /dev/null
+++ b/.changeset/many-frogs-impress.md
@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+add unique identifier to Tracer.ParentSpan tag
diff --git a/packages/effect/src/Channel.ts b/packages/effect/src/Channel.ts
index 3804c4230f..16091f0b0e 100644
--- a/packages/effect/src/Channel.ts
+++ b/packages/effect/src/Channel.ts
@@ -2107,7 +2107,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     } | undefined
@@ -2120,7 +2120,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     } | undefined
diff --git a/packages/effect/src/Effect.ts b/packages/effect/src/Effect.ts
index 85b654b90a..983172e17e 100644
--- a/packages/effect/src/Effect.ts
+++ b/packages/effect/src/Effect.ts
@@ -5126,7 +5126,7 @@ export const currentSpan: Effect<Tracer.Span, Cause.NoSuchElementException> = ef
  * @since 2.0.0
  * @category tracing
  */
-export const currentParentSpan: Effect<Tracer.ParentSpan, Cause.NoSuchElementException> = effect.currentParentSpan
+export const currentParentSpan: Effect<Tracer.AnySpan, Cause.NoSuchElementException> = effect.currentParentSpan
 
 /**
  * @since 2.0.0
@@ -5148,12 +5148,12 @@ export const spanLinks: Effect<Chunk.Chunk<Tracer.SpanLink>> = effect.spanLinks
  */
 export const linkSpans: {
   (
-    span: Tracer.ParentSpan,
+    span: Tracer.AnySpan,
     attributes?: Record<string, unknown>
   ): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, R>
   <A, E, R>(
     self: Effect<A, E, R>,
-    span: Tracer.ParentSpan,
+    span: Tracer.AnySpan,
     attributes?: Record<string, unknown>
   ): Effect<A, E, R>
 } = effect.linkSpans
@@ -5169,7 +5169,7 @@ export const makeSpan: (
   options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }
@@ -5190,7 +5190,7 @@ export const makeSpanScoped: (
   options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }
@@ -5213,7 +5213,7 @@ export const useSpan: {
     options: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     },
@@ -5233,7 +5233,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     } | undefined
@@ -5244,7 +5244,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     } | undefined
@@ -5265,7 +5265,7 @@ export const withSpanScoped: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     }
@@ -5276,7 +5276,7 @@ export const withSpanScoped: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     }
@@ -5290,8 +5290,8 @@ export const withSpanScoped: {
  * @category tracing
  */
 export const withParentSpan: {
-  (span: Tracer.ParentSpan): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, Tracer.ParentSpan>>
-  <A, E, R>(self: Effect<A, E, R>, span: Tracer.ParentSpan): Effect<A, E, Exclude<R, Tracer.ParentSpan>>
+  (span: Tracer.AnySpan): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, Tracer.ParentSpan>>
+  <A, E, R>(self: Effect<A, E, R>, span: Tracer.AnySpan): Effect<A, E, Exclude<R, Tracer.ParentSpan>>
 } = effect.withParentSpan
 
 // -------------------------------------------------------------------------------------
diff --git a/packages/effect/src/Layer.ts b/packages/effect/src/Layer.ts
index 0fc23b7139..b95a8317fe 100644
--- a/packages/effect/src/Layer.ts
+++ b/packages/effect/src/Layer.ts
@@ -896,7 +896,7 @@ export const setConfigProvider: (configProvider: ConfigProvider) => Layer<never>
  * @since 2.0.0
  * @category tracing
  */
-export const parentSpan: (span: Tracer.ParentSpan) => Layer<Tracer.ParentSpan> = circularLayer.parentSpan
+export const parentSpan: (span: Tracer.AnySpan) => Layer<Tracer.ParentSpan> = circularLayer.parentSpan
 
 /**
  * @since 2.0.0
@@ -962,7 +962,7 @@ export const span: (
   options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
     readonly onEnd?:
@@ -1018,7 +1018,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
       readonly onEnd?:
@@ -1032,7 +1032,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
       readonly onEnd?:
@@ -1047,8 +1047,8 @@ export const withSpan: {
  * @category tracing
  */
 export const withParentSpan: {
-  (span: Tracer.ParentSpan): <A, E, R>(self: Layer<A, E, R>) => Layer<A, E, Exclude<R, Tracer.ParentSpan>>
-  <A, E, R>(self: Layer<A, E, R>, span: Tracer.ParentSpan): Layer<A, E, Exclude<R, Tracer.ParentSpan>>
+  (span: Tracer.AnySpan): <A, E, R>(self: Layer<A, E, R>) => Layer<A, E, Exclude<R, Tracer.ParentSpan>>
+  <A, E, R>(self: Layer<A, E, R>, span: Tracer.AnySpan): Layer<A, E, Exclude<R, Tracer.ParentSpan>>
 } = internal.withParentSpan
 
 // -----------------------------------------------------------------------------
diff --git a/packages/effect/src/Stream.ts b/packages/effect/src/Stream.ts
index 80204e3472..5b8e41fc0f 100644
--- a/packages/effect/src/Stream.ts
+++ b/packages/effect/src/Stream.ts
@@ -4025,7 +4025,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     } | undefined
@@ -4036,7 +4036,7 @@ export const withSpan: {
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     } | undefined
diff --git a/packages/effect/src/Tracer.ts b/packages/effect/src/Tracer.ts
index 5a890f2d80..44d68b02a4 100644
--- a/packages/effect/src/Tracer.ts
+++ b/packages/effect/src/Tracer.ts
@@ -26,7 +26,7 @@ export interface Tracer {
   readonly [TracerTypeId]: TracerTypeId
   span(
     name: string,
-    parent: Option.Option<ParentSpan>,
+    parent: Option.Option<AnySpan>,
     context: Context.Context<never>,
     links: ReadonlyArray<SpanLink>,
     startTime: bigint
@@ -52,13 +52,21 @@ export type SpanStatus = {
  * @since 2.0.0
  * @category models
  */
-export type ParentSpan = Span | ExternalSpan
+export type AnySpan = Span | ExternalSpan
 
 /**
  * @since 2.0.0
  * @category tags
  */
-export const ParentSpan: Context.Tag<ParentSpan, ParentSpan> = internal.spanTag
+export interface ParentSpan {
+  readonly _: unique symbol
+}
+
+/**
+ * @since 2.0.0
+ * @category tags
+ */
+export const ParentSpan: Context.Tag<ParentSpan, AnySpan> = internal.spanTag
 
 /**
  * @since 2.0.0
@@ -81,7 +89,7 @@ export interface Span {
   readonly name: string
   readonly spanId: string
   readonly traceId: string
-  readonly parent: Option.Option<ParentSpan>
+  readonly parent: Option.Option<AnySpan>
   readonly context: Context.Context<never>
   readonly status: SpanStatus
   readonly attributes: ReadonlyMap<string, unknown>
@@ -98,7 +106,7 @@ export interface Span {
  */
 export interface SpanLink {
   readonly _tag: "SpanLink"
-  readonly span: ParentSpan
+  readonly span: AnySpan
   readonly attributes: Readonly<Record<string, unknown>>
 }
 
diff --git a/packages/effect/src/internal/cause.ts b/packages/effect/src/internal/cause.ts
index e11611e0fd..c2c23c3e23 100644
--- a/packages/effect/src/internal/cause.ts
+++ b/packages/effect/src/internal/cause.ts
@@ -12,7 +12,7 @@ import { pipeArguments } from "../Pipeable.js"
 import { hasProperty, isFunction } from "../Predicate.js"
 import type { Predicate, Refinement } from "../Predicate.js"
 import * as ReadonlyArray from "../ReadonlyArray.js"
-import type { ParentSpan, Span } from "../Tracer.js"
+import type { AnySpan, Span } from "../Tracer.js"
 import * as OpCodes from "./opCodes/cause.js"
 
 // -----------------------------------------------------------------------------
@@ -989,7 +989,7 @@ export const pretty = <E>(cause: Cause.Cause<E>): string => {
       message += `\r\n${filterStack(e.stack)}`
     }
     if (e.span) {
-      let current: Span | ParentSpan | undefined = e.span
+      let current: Span | AnySpan | undefined = e.span
       let i = 0
       while (current && current._tag === "Span" && i < 10) {
         message += `\r\n    at ${current.name}`
diff --git a/packages/effect/src/internal/channel.ts b/packages/effect/src/internal/channel.ts
index ab90f17949..33dada6d75 100644
--- a/packages/effect/src/internal/channel.ts
+++ b/packages/effect/src/internal/channel.ts
@@ -2316,7 +2316,7 @@ export const withSpan = dual<
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     }
@@ -2329,7 +2329,7 @@ export const withSpan = dual<
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     }
diff --git a/packages/effect/src/internal/core-effect.ts b/packages/effect/src/internal/core-effect.ts
index f065d0fa40..4001617546 100644
--- a/packages/effect/src/internal/core-effect.ts
+++ b/packages/effect/src/internal/core-effect.ts
@@ -1994,7 +1994,7 @@ export const annotateSpans = dual<
 )
 
 /** @internal */
-export const currentParentSpan: Effect.Effect<Tracer.ParentSpan, Cause.NoSuchElementException> = serviceOptional(
+export const currentParentSpan: Effect.Effect<Tracer.AnySpan, Cause.NoSuchElementException> = serviceOptional(
   internalTracer.spanTag
 )
 
@@ -2002,7 +2002,7 @@ export const currentParentSpan: Effect.Effect<Tracer.ParentSpan, Cause.NoSuchEle
 export const currentSpan: Effect.Effect<Tracer.Span, Cause.NoSuchElementException> = core.flatMap(
   core.context<never>(),
   (context) => {
-    const span = context.unsafeMap.get(internalTracer.spanTag.key) as Tracer.ParentSpan | undefined
+    const span = context.unsafeMap.get(internalTracer.spanTag.key) as Tracer.AnySpan | undefined
     return span !== undefined && span._tag === "Span"
       ? core.succeed(span)
       : core.fail(new core.NoSuchElementException())
@@ -2019,12 +2019,12 @@ export const currentTimeNanosTracing = core.fiberRefGetWith(
 /* @internal */
 export const linkSpans = dual<
   (
-    span: Tracer.ParentSpan,
+    span: Tracer.AnySpan,
     attributes?: Record<string, unknown>
   ) => <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A, E, R>,
   <A, E, R>(
     self: Effect.Effect<A, E, R>,
-    span: Tracer.ParentSpan,
+    span: Tracer.AnySpan,
     attributes?: Record<string, unknown>
   ) => Effect.Effect<A, E, R>
 >(
@@ -2049,7 +2049,7 @@ export const makeSpan = (
   options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }
@@ -2117,7 +2117,7 @@ export const useSpan: {
   <A, E, R>(name: string, options: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }, evaluate: (span: Tracer.Span) => Effect.Effect<A, E, R>): Effect.Effect<A, E, R>
@@ -2131,7 +2131,7 @@ export const useSpan: {
   const options: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   } | undefined = args.length === 1 ? undefined : args[0]
@@ -2153,9 +2153,9 @@ export const useSpan: {
 /** @internal */
 export const withParentSpan = dual<
   (
-    span: Tracer.ParentSpan
+    span: Tracer.AnySpan
   ) => <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan>>,
-  <A, E, R>(self: Effect.Effect<A, E, R>, span: Tracer.ParentSpan) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan>>
+  <A, E, R>(self: Effect.Effect<A, E, R>, span: Tracer.AnySpan) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan>>
 >(2, (self, span) => provideService(self, internalTracer.spanTag, span))
 
 /** @internal */
@@ -2163,14 +2163,14 @@ export const withSpan = dual<
   (name: string, options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }) => <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan>>,
   <A, E, R>(self: Effect.Effect<A, E, R>, name: string, options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan>>
diff --git a/packages/effect/src/internal/core.ts b/packages/effect/src/internal/core.ts
index 58b041cdc4..a99469f587 100644
--- a/packages/effect/src/internal/core.ts
+++ b/packages/effect/src/internal/core.ts
@@ -3084,7 +3084,7 @@ export const mapInputContext = dual<
 /** @internal */
 export const currentSpanFromFiber = <A, E>(fiber: Fiber.RuntimeFiber<A, E>): Option.Option<Tracer.Span> => {
   const span = fiber.getFiberRef(currentContext).unsafeMap.get(internalTracer.spanTag.key) as
-    | Tracer.ParentSpan
+    | Tracer.AnySpan
     | undefined
   return span !== undefined && span._tag === "Span" ? Option.some(span) : Option.none()
 }
diff --git a/packages/effect/src/internal/fiberRuntime.ts b/packages/effect/src/internal/fiberRuntime.ts
index 542d198967..187eb4e06e 100644
--- a/packages/effect/src/internal/fiberRuntime.ts
+++ b/packages/effect/src/internal/fiberRuntime.ts
@@ -3547,7 +3547,7 @@ export const makeSpanScoped = (
   options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }
@@ -3572,14 +3572,14 @@ export const withSpanScoped = dual<
   (name: string, options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }) => <A, E, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan> | Scope.Scope>,
   <A, E, R>(self: Effect.Effect<A, E, R>, name: string, options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
   }) => Effect.Effect<A, E, Exclude<R, Tracer.ParentSpan> | Scope.Scope>
diff --git a/packages/effect/src/internal/layer.ts b/packages/effect/src/internal/layer.ts
index 5e77688968..048bd10a01 100644
--- a/packages/effect/src/internal/layer.ts
+++ b/packages/effect/src/internal/layer.ts
@@ -1117,7 +1117,7 @@ export const withSpan = dual<
   (name: string, options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
     readonly onEnd?:
@@ -1127,7 +1127,7 @@ export const withSpan = dual<
   <A, E, R>(self: Layer.Layer<A, E, R>, name: string, options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
     readonly onEnd?:
@@ -1150,9 +1150,9 @@ export const withSpan = dual<
 /** @internal */
 export const withParentSpan = dual<
   (
-    span: Tracer.ParentSpan
+    span: Tracer.AnySpan
   ) => <A, E, R>(self: Layer.Layer<A, E, R>) => Layer.Layer<A, E, Exclude<R, Tracer.ParentSpan>>,
-  <A, E, R>(self: Layer.Layer<A, E, R>, span: Tracer.ParentSpan) => Layer.Layer<A, E, Exclude<R, Tracer.ParentSpan>>
+  <A, E, R>(self: Layer.Layer<A, E, R>, span: Tracer.AnySpan) => Layer.Layer<A, E, Exclude<R, Tracer.ParentSpan>>
 >(2, (self, span) => provide(self, succeedContext(Context.make(tracer.spanTag, span))))
 
 // circular with Effect
diff --git a/packages/effect/src/internal/layer/circular.ts b/packages/effect/src/internal/layer/circular.ts
index 4c710b8a82..0592a30309 100644
--- a/packages/effect/src/internal/layer/circular.ts
+++ b/packages/effect/src/internal/layer/circular.ts
@@ -185,7 +185,7 @@ export const setConfigProvider = (configProvider: ConfigProvider.ConfigProvider)
   layer.scopedDiscard(fiberRuntime.withConfigProviderScoped(configProvider))
 
 /** @internal */
-export const parentSpan = (span: Tracer.ParentSpan): Layer.Layer<Tracer.ParentSpan> =>
+export const parentSpan = (span: Tracer.AnySpan): Layer.Layer<Tracer.ParentSpan> =>
   layer.succeedContext(Context.make(tracer.spanTag, span))
 
 /** @internal */
@@ -194,7 +194,7 @@ export const span = (
   options?: {
     readonly attributes?: Record<string, unknown> | undefined
     readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-    readonly parent?: Tracer.ParentSpan | undefined
+    readonly parent?: Tracer.AnySpan | undefined
     readonly root?: boolean | undefined
     readonly context?: Context.Context<never> | undefined
     readonly onEnd?:
diff --git a/packages/effect/src/internal/stream.ts b/packages/effect/src/internal/stream.ts
index 788fee67e9..fef02fb41b 100644
--- a/packages/effect/src/internal/stream.ts
+++ b/packages/effect/src/internal/stream.ts
@@ -6803,7 +6803,7 @@ export const withSpan = dual<
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     }
@@ -6814,7 +6814,7 @@ export const withSpan = dual<
     options?: {
       readonly attributes?: Record<string, unknown> | undefined
       readonly links?: ReadonlyArray<Tracer.SpanLink> | undefined
-      readonly parent?: Tracer.ParentSpan | undefined
+      readonly parent?: Tracer.AnySpan | undefined
       readonly root?: boolean | undefined
       readonly context?: Context.Context<never> | undefined
     }
diff --git a/packages/effect/src/internal/tracer.ts b/packages/effect/src/internal/tracer.ts
index 268e9cee63..45e64ba7ce 100644
--- a/packages/effect/src/internal/tracer.ts
+++ b/packages/effect/src/internal/tracer.ts
@@ -19,7 +19,7 @@ export const make = (options: Omit<Tracer.Tracer, Tracer.TracerTypeId>): Tracer.
 export const tracerTag = Context.GenericTag<Tracer.Tracer>("effect/Tracer")
 
 /** @internal */
-export const spanTag = Context.GenericTag<Tracer.ParentSpan>("effect/ParentSpan")
+export const spanTag = Context.GenericTag<Tracer.ParentSpan, Tracer.AnySpan>("effect/ParentSpan")
 
 const randomHexString = (function() {
   const characters = "abcdef0123456789"
@@ -46,7 +46,7 @@ export class NativeSpan implements Tracer.Span {
 
   constructor(
     readonly name: string,
-    readonly parent: Option.Option<Tracer.ParentSpan>,
+    readonly parent: Option.Option<Tracer.AnySpan>,
     readonly context: Context.Context<never>,
     readonly links: ReadonlyArray<Tracer.SpanLink>,
     readonly startTime: bigint
diff --git a/packages/experimental/src/Machine.ts b/packages/experimental/src/Machine.ts
index 9f5fd87870..f05705c3be 100644
--- a/packages/experimental/src/Machine.ts
+++ b/packages/experimental/src/Machine.ts
@@ -492,7 +492,7 @@ export const boot = <
       readonly [
         Procedure.TaggedRequest.Any,
         Deferred.Deferred<any, any>,
-        Tracer.ParentSpan | undefined,
+        Tracer.AnySpan | undefined,
         addSpans: boolean
       ]
     >())
@@ -520,7 +520,7 @@ export const boot = <
         const context = FiberRefs.getOrDefault(fiberRefs, FiberRef.currentContext)
 
         const deferred = Deferred.unsafeMake<Request.Success<R>, Request.Error<R>>(fiber.id())
-        const span: Tracer.ParentSpan | undefined = context.unsafeMap.get(Tracer.ParentSpan.key)
+        const span: Tracer.AnySpan | undefined = context.unsafeMap.get(Tracer.ParentSpan.key)
         const addSpans = FiberRefs.getOrDefault(fiberRefs, currentTracingEnabled)
 
         return [request, deferred, span, addSpans] as const
diff --git a/packages/opentelemetry/src/internal/tracer.ts b/packages/opentelemetry/src/internal/tracer.ts
index 6ca75d09ed..a0485ee10d 100644
--- a/packages/opentelemetry/src/internal/tracer.ts
+++ b/packages/opentelemetry/src/internal/tracer.ts
@@ -27,7 +27,7 @@ export class OtelSpan implements EffectTracer.Span {
     contextApi: OtelApi.ContextAPI,
     tracer: OtelApi.Tracer,
     readonly name: string,
-    readonly parent: Option.Option<EffectTracer.ParentSpan>,
+    readonly parent: Option.Option<EffectTracer.AnySpan>,
     readonly context: Context.Context<never>,
     readonly links: ReadonlyArray<EffectTracer.SpanLink>,
     startTime: bigint
@@ -125,7 +125,7 @@ export const make = Effect.map(Tracer, (tracer) =>
     },
     context(execution, fiber) {
       const currentSpan = fiber.getFiberRef(FiberRef.currentContext).unsafeMap.get(EffectTracer.ParentSpan.key) as
-        | EffectTracer.ParentSpan
+        | EffectTracer.AnySpan
         | undefined
 
       if (currentSpan === undefined) {
@@ -238,14 +238,14 @@ const createTraceState = Option.liftThrowable(OtelApi.createTraceState)
 
 const populateContext = (
   otelContext: OtelApi.Context,
-  span: EffectTracer.ParentSpan,
+  span: EffectTracer.AnySpan,
   context?: Context.Context<never>
 ): OtelApi.Context =>
   span instanceof OtelSpan ?
     OtelApi.trace.setSpan(otelContext, span.span) :
     OtelApi.trace.setSpanContext(otelContext, makeSpanContext(span, context))
 
-const makeSpanContext = (span: EffectTracer.ParentSpan, context?: Context.Context<never>): OtelApi.SpanContext => ({
+const makeSpanContext = (span: EffectTracer.AnySpan, context?: Context.Context<never>): OtelApi.SpanContext => ({
   spanId: span.spanId,
   traceId: span.traceId,
   isRemote: span._tag === "ExternalSpan",
@@ -263,7 +263,7 @@ const makeSpanContext = (span: EffectTracer.ParentSpan, context?: Context.Contex
 })
 
 const extractTraceTag = <I, S>(
-  parent: EffectTracer.ParentSpan,
+  parent: EffectTracer.AnySpan,
   context: Context.Context<never>,
   tag: Context.Tag<I, S>
 ) =>