diff --git a/packages/ai/src/route/executor.ts b/packages/ai/src/route/executor.ts
index 388fd4198ef..6786b9f2a22 100644
--- a/packages/ai/src/route/executor.ts
+++ b/packages/ai/src/route/executor.ts
@@ -1,4 +1,4 @@
-import { Cause, Context, Effect, Layer, Option, Schema } from "effect"
+import { Cause, Context, Effect, Layer, Option, Schema, Stream } from "effect"
 import {
   FetchHttpClient,
   Headers,
@@ -297,44 +297,88 @@ export const classifyHttpFailure = (input: {
   })
 }
 
-const toHttpError = (redactedNames: ReadonlyArray<string | RegExp>) => (error: unknown) => {
-  const transportError = (input: {
-    readonly message: string
-    readonly kind?: string | undefined
-    readonly request?: HttpClientRequest.HttpClientRequest | undefined
-  }) =>
+type HttpOperation = "request" | "read"
+
+const NativeTransportFailure = Schema.Struct({
+  message: Schema.String,
+  code: Schema.optionalKey(Schema.String),
+  cause: Schema.optionalKey(Schema.Unknown),
+})
+const decodeNativeTransportFailure = Schema.decodeUnknownOption(NativeTransportFailure)
+
+const nativeTransportFailure = (error: unknown) => {
+  const failure = Option.getOrUndefined(decodeNativeTransportFailure(error))
+  if (!failure) return undefined
+  if (failure.code !== undefined) return failure
+  const cause = Option.getOrUndefined(decodeNativeTransportFailure(failure.cause))
+  if (cause?.code !== undefined) return cause
+  return failure
+}
+
+const httpError = (input: {
+  readonly error: unknown
+  readonly request: HttpClientRequest.HttpClientRequest
+  readonly operation: HttpOperation
+  readonly redactedNames: ReadonlyArray<string | RegExp>
+}) => {
+  const request = HttpClientError.isHttpClientError(input.error) ? input.error.request : input.request
+  const transportError = (failure: { readonly message: string; readonly code?: string | undefined }) =>
     new AIError({
       module: "RequestExecutor",
-      method: "execute",
+      method: input.operation,
       reason: new TransportReason({
-        message: input.message,
-        kind: input.kind,
-        url: input.request ? redactUrl(input.request.url) : undefined,
-        http: input.request ? new HttpContext({ request: requestDetails(input.request, redactedNames) }) : undefined,
+        message: failure.message,
+        transport: "http",
+        operation: input.operation,
+        code: failure.code,
+        url: redactUrl(request.url),
+        http: new HttpContext({ request: requestDetails(request, input.redactedNames) }),
       }),
     })
 
-  if (Cause.isTimeoutError(error)) {
-    return transportError({ message: error.message, kind: "Timeout" })
-  }
-  if (!HttpClientError.isHttpClientError(error)) {
-    return transportError({ message: error instanceof Error ? error.message : "HTTP transport failed" })
-  }
-  const request = "request" in error ? error.request : undefined
-  if (error.reason._tag === "TransportError") {
+  const source =
+    HttpClientError.isHttpClientError(input.error) && "cause" in input.error.reason
+      ? input.error.reason.cause
+      : input.error
+  const native = nativeTransportFailure(source)
+  const code = native?.code
+  const raw = native?.message ?? (input.error instanceof Error ? input.error.message : undefined)
+  const detail = raw ? redactBody(raw, secretValues(request)) : undefined
+  const message = code && detail && !detail.includes(code) ? `${code}: ${detail}` : detail
+
+  if (Cause.isTimeoutError(input.error) || Cause.isTimeoutError(source))
+    return transportError({ message: message ?? "HTTP transport timed out", code: code ?? "Timeout" })
+  if (!HttpClientError.isHttpClientError(input.error))
+    return transportError({ message: message ?? "HTTP transport failed", code })
+  if (input.error.reason._tag === "TransportError") {
     return transportError({
-      message: error.reason.description ?? "HTTP transport failed",
-      kind: error.reason._tag,
-      request,
+      message: message ?? input.error.reason.description ?? "HTTP transport failed",
+      code: code ?? input.error.reason._tag,
     })
   }
   return transportError({
-    message: `HTTP transport failed: ${error.reason._tag}`,
-    kind: error.reason._tag,
-    request,
+    message: message ?? `HTTP transport failed: ${input.error.reason._tag}`,
+    code: code ?? input.error.reason._tag,
   })
 }
 
+export const stream = (
+  executor: Interface,
+  request: HttpClientRequest.HttpClientRequest,
+  middleware?: HttpMiddleware,
+): Stream.Stream<Uint8Array, AIError> =>
+  Stream.unwrap(
+    Effect.gen(function* () {
+      const redactedNames = yield* Headers.CurrentRedactedNames
+      const response = yield* executor.execute(request, middleware)
+      return response.stream.pipe(
+        Stream.mapError((error) =>
+          httpError({ error, request: response.request, operation: "read", redactedNames }),
+        ),
+      )
+    }),
+  )
+
 export const layer: Layer.Layer<Service, never, HttpClient.HttpClient> = Layer.effect(
   Service,
   Effect.gen(function* () {
@@ -343,15 +387,16 @@ export const layer: Layer.Layer<Service, never, HttpClient.HttpClient> = Layer.e
       Effect.gen(function* () {
         const redactedNames = yield* Headers.CurrentRedactedNames
         if (!middleware)
-          return yield* http
-            .execute(request)
-            .pipe(Effect.mapError(toHttpError(redactedNames)), Effect.flatMap(statusError(request, redactedNames)))
+          return yield* http.execute(request).pipe(
+            Effect.mapError((error) => httpError({ error, request, operation: "request", redactedNames })),
+            Effect.flatMap(statusError(request, redactedNames)),
+          )
 
         const response = yield* middleware(request, (input) =>
           http
             .execute(input)
             .pipe(Effect.mapError((cause) => (cause instanceof Error ? cause : new Error(String(cause))))),
-        ).pipe(Effect.mapError(toHttpError(redactedNames)))
+        ).pipe(Effect.mapError((error) => httpError({ error, request, operation: "request", redactedNames })))
         return yield* statusError(response.request, redactedNames)(response)
       })
     return Service.of({
diff --git a/packages/ai/src/route/transport/http.ts b/packages/ai/src/route/transport/http.ts
index 12482f39188..06cb2fa48cd 100644
--- a/packages/ai/src/route/transport/http.ts
+++ b/packages/ai/src/route/transport/http.ts
@@ -1,4 +1,4 @@
-import { Effect, Stream } from "effect"
+import { Effect } from "effect"
 import { Headers, HttpClientRequest } from "effect/unstable/http"
 import { Auth } from "../auth.js"
 import { render as renderEndpoint } from "../endpoint.js"
@@ -6,6 +6,7 @@ import { Framing } from "../framing.js"
 import type { HttpMiddleware, Transport, TransportPrepareInput } from "./index.js"
 import * as ProviderShared from "../../protocols/shared.js"
 import { mergeJsonRecords, type LLMRequest } from "../../schema/index.js"
+import { RequestExecutor } from "../executor.js"
 
 export type JsonRequestInput<Body> = TransportPrepareInput<Body>
 
@@ -86,26 +87,8 @@ export const httpJson = <Body, Frame>(input: HttpJsonInput<Body, Frame>): HttpJs
         middleware: prepareInput.middleware,
       }
     }),
-  frames: (prepared, request, runtime) =>
-    Stream.unwrap(
-      runtime.http
-        .execute(prepared.request, prepared.middleware)
-        .pipe(
-          Effect.map((response) =>
-            prepared.framing.frame(
-              response.stream.pipe(
-                Stream.mapError((error) =>
-                  ProviderShared.eventError(
-                    `${request.model.provider}/${request.model.route.id}`,
-                    `Failed to read ${request.model.provider}/${request.model.route.id} stream`,
-                    ProviderShared.errorText(error),
-                  ),
-                ),
-              ),
-            ),
-          ),
-        ),
-    ),
+  frames: (prepared, _request, runtime) =>
+    prepared.framing.frame(RequestExecutor.stream(runtime.http, prepared.request, prepared.middleware)),
 })
 
 export const sseJson = {
diff --git a/packages/ai/src/route/transport/websocket.ts b/packages/ai/src/route/transport/websocket.ts
index 0198deb5c63..b1d8854de1e 100644
--- a/packages/ai/src/route/transport/websocket.ts
+++ b/packages/ai/src/route/transport/websocket.ts
@@ -1,6 +1,6 @@
 import { Cause, Context, Effect, Layer, Queue, Stream } from "effect"
 import { Headers } from "effect/unstable/http"
-import { AIError, TransportReason } from "../../schema/index.js"
+import { AIError, TransportReason, type TransportOperation } from "../../schema/index.js"
 import * as HttpTransport from "./http.js"
 import type { Transport } from "./index.js"
 
@@ -29,12 +29,18 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/AI
 const transportError = (
   method: string,
   message: string,
-  input: { readonly url?: string; readonly kind?: string } = {},
+  input: { readonly operation: TransportOperation; readonly url?: string; readonly code?: string },
 ) =>
   new AIError({
     module: "WebSocketExecutor",
     method,
-    reason: new TransportReason({ message, url: input.url, kind: input.kind }),
+    reason: new TransportReason({
+      message,
+      transport: "websocket",
+      operation: input.operation,
+      url: input.url,
+      code: input.code,
+    }),
   })
 
 const eventMessage = (event: Event) => {
@@ -55,7 +61,8 @@ const waitOpen = (ws: globalThis.WebSocket, input: WebSocketRequest) => {
     return Effect.fail(
       transportError("open", `WebSocket closed before opening (state ${ws.readyState})`, {
         url: input.url,
-        kind: "open",
+        operation: "request",
+        code: "closed",
       }),
     )
   }
@@ -79,7 +86,10 @@ const waitOpen = (ws: globalThis.WebSocket, input: WebSocketRequest) => {
       cleanup()
       resume(
         Effect.fail(
-          transportError("open", `Failed to open WebSocket: ${eventMessage(event)}`, { url: input.url, kind: "open" }),
+          transportError("open", `Failed to open WebSocket: ${eventMessage(event)}`, {
+            url: input.url,
+            operation: "request",
+          }),
         ),
       )
     }
@@ -89,7 +99,8 @@ const waitOpen = (ws: globalThis.WebSocket, input: WebSocketRequest) => {
         Effect.fail(
           transportError("open", `WebSocket closed before opening with code ${event.code}`, {
             url: input.url,
-            kind: "open",
+            operation: "request",
+            code: String(event.code),
           }),
         ),
       )
@@ -118,7 +129,8 @@ const webSocketUrl = (value: string) =>
     catch: (error) =>
       transportError("prepare", error instanceof Error ? error.message : "Invalid WebSocket URL", {
         url: value,
-        kind: "websocket",
+        operation: "request",
+        code: "invalid-url",
       }),
   })
 
@@ -129,7 +141,7 @@ export const open = (input: WebSocketRequest) =>
     catch: (error) =>
       transportError("open", error instanceof Error ? error.message : "Failed to construct WebSocket", {
         url: input.url,
-        kind: "open",
+        operation: "request",
       }),
   }).pipe(Effect.flatMap((ws) => fromWebSocket(ws, input)))
 
@@ -150,7 +162,10 @@ export const fromWebSocket = (
       Queue.failCauseUnsafe(
         messages,
         Cause.fail(
-          transportError("message", "Unsupported WebSocket message payload", { url: input.url, kind: "message" }),
+          transportError("message", "Unsupported WebSocket message payload", {
+            url: input.url,
+            operation: "read",
+          }),
         ),
       )
     }
@@ -158,7 +173,10 @@ export const fromWebSocket = (
       Queue.failCauseUnsafe(
         messages,
         Cause.fail(
-          transportError("message", `WebSocket error: ${eventMessage(event)}`, { url: input.url, kind: "message" }),
+          transportError("message", `WebSocket error: ${eventMessage(event)}`, {
+            url: input.url,
+            operation: "read",
+          }),
         ),
       )
     }
@@ -167,7 +185,11 @@ export const fromWebSocket = (
       Queue.failCauseUnsafe(
         messages,
         Cause.fail(
-          transportError("message", `WebSocket closed with code ${event.code}`, { url: input.url, kind: "close" }),
+          transportError("message", `WebSocket closed with code ${event.code}`, {
+            url: input.url,
+            operation: "read",
+            code: String(event.code),
+          }),
         ),
       )
     }
@@ -188,7 +210,7 @@ export const fromWebSocket = (
           catch: (error) =>
             transportError("sendText", error instanceof Error ? error.message : "Failed to send WebSocket message", {
               url: input.url,
-              kind: "write",
+              operation: "write",
             }),
         }),
       messages: Stream.fromQueue(messages),
@@ -243,7 +265,8 @@ export const json = <Body, Message>(input: JsonInput<Body, Message>): JsonTransp
       return Stream.fail(
         transportError("json", "WebSocket JSON transport requires WebSocketExecutor.Service", {
           url: prepared.url,
-          kind: "websocket",
+          operation: "request",
+          code: "unavailable",
         }),
       )
     }
diff --git a/packages/ai/src/schema/errors.ts b/packages/ai/src/schema/errors.ts
index 0c201450fd9..d03f2f3cf7f 100644
--- a/packages/ai/src/schema/errors.ts
+++ b/packages/ai/src/schema/errors.ts
@@ -92,10 +92,18 @@ export class ProviderInternalReason extends Schema.Class<ProviderInternalReason>
   http: Schema.optional(HttpContext),
 }) {}
 
+export const TransportType = Schema.Literals(["http", "websocket"])
+export type TransportType = typeof TransportType.Type
+
+export const TransportOperation = Schema.Literals(["request", "read", "write"])
+export type TransportOperation = typeof TransportOperation.Type
+
 export class TransportReason extends Schema.Class<TransportReason>("AI.Error.Transport")({
   _tag: Schema.tag("Transport"),
   message: Schema.String,
-  kind: Schema.optional(Schema.String),
+  transport: TransportType,
+  operation: TransportOperation,
+  code: Schema.optional(Schema.String),
   url: Schema.optional(Schema.String),
   http: Schema.optional(HttpContext),
 }) {}
diff --git a/packages/ai/test/executor.test.ts b/packages/ai/test/executor.test.ts
index 1d3353e44b8..7a483bbbd4d 100644
--- a/packages/ai/test/executor.test.ts
+++ b/packages/ai/test/executor.test.ts
@@ -1,10 +1,10 @@
 import { describe, expect } from "bun:test"
-import { Effect, Layer, Ref } from "effect"
-import { Headers, HttpClient, HttpClientRequest, HttpClientResponse } from "effect/unstable/http"
+import { Effect, Layer, Ref, Stream } from "effect"
+import { Headers, HttpClient, HttpClientError, HttpClientRequest, HttpClientResponse } from "effect/unstable/http"
 import { LLM, AIError } from "../src/index.js"
 import { LLMClient, RequestExecutor } from "../src/route.js"
 import * as OpenAIChat from "../src/protocols/openai-chat.js"
-import { dynamicResponse } from "./lib/http.js"
+import { dynamicResponse, systemError } from "./lib/http.js"
 import { deltaChunk } from "./lib/openai-chunks.js"
 import { sseRaw } from "./lib/sse.js"
 import { it } from "./lib/effect.js"
@@ -67,6 +67,64 @@ const expectAIError = (error: unknown) => {
 const errorHttp = (error: AIError) => ("http" in error.reason ? error.reason.http : undefined)
 
 describe("RequestExecutor", () => {
+  it.effect("parses response body failures at the executor seam", () =>
+    Effect.gen(function* () {
+      const executor = yield* RequestExecutor.Service
+      const error = yield* RequestExecutor.stream(executor, secretRequest).pipe(Stream.runDrain, Effect.flip)
+
+      expectAIError(error)
+      expect(error.reason).toMatchObject({
+        _tag: "Transport",
+        message: "ECONNRESET: disconnected <redacted> <redacted>",
+        transport: "http",
+        operation: "read",
+        code: "ECONNRESET",
+        url: "https://provider.test/v1/chat?api_key=%3Credacted%3E&debug=1",
+      })
+    }).pipe(
+      Effect.provide(
+        responsesLayer([
+          new Response(
+            new ReadableStream({
+              start(controller) {
+                controller.error(systemError("ECONNRESET", "disconnected query-secret-123 header-secret-456"))
+              },
+            }),
+          ),
+        ]),
+      ),
+    ),
+  )
+
+  it.effect("unwraps native transport failure causes", () =>
+    Effect.gen(function* () {
+      const executor = yield* RequestExecutor.Service
+      const error = yield* RequestExecutor.stream(executor, secretRequest).pipe(Stream.runDrain, Effect.flip)
+
+      expectAIError(error)
+      expect(error.reason).toMatchObject({
+        _tag: "Transport",
+        message: "ECONNRESET: socket closed",
+        operation: "read",
+        code: "ECONNRESET",
+      })
+    }).pipe(
+      Effect.provide(
+        responsesLayer([
+          new Response(
+            new ReadableStream({
+              pull(controller) {
+                controller.error(
+                  new TypeError("fetch failed", { cause: systemError("ECONNRESET", "socket closed") }),
+                )
+              },
+            }),
+          ),
+        ]),
+      ),
+    ),
+  )
+
   it.effect("preserves middleware error messages", () =>
     Effect.gen(function* () {
       const executor = yield* RequestExecutor.Service
@@ -79,6 +137,48 @@ describe("RequestExecutor", () => {
     }).pipe(Effect.provide(responsesLayer([]))),
   )
 
+  it.effect("reports the request sent by middleware", () =>
+    Effect.gen(function* () {
+      const executor = yield* RequestExecutor.Service
+      const error = yield* executor
+        .execute(request, (original, handler) =>
+          handler(
+            original.pipe(
+              HttpClientRequest.setUrl("https://proxy.test/v1/chat?api_key=proxy-secret"),
+              HttpClientRequest.setHeader("authorization", "Bearer proxy-secret"),
+            ),
+          ),
+        )
+        .pipe(Effect.flip)
+
+      expectAIError(error)
+      expect(error.reason).toMatchObject({
+        _tag: "Transport",
+        message: "ECONNRESET: proxy disconnected <redacted>",
+        url: "https://proxy.test/v1/chat?api_key=%3Credacted%3E",
+        http: {
+          request: {
+            url: "https://proxy.test/v1/chat?api_key=%3Credacted%3E",
+            headers: { authorization: "<redacted>" },
+          },
+        },
+      })
+    }).pipe(
+      Effect.provide(
+        dynamicResponse((input) =>
+          Effect.fail(
+            new HttpClientError.HttpClientError({
+              reason: new HttpClientError.TransportError({
+                request: input.request,
+                cause: systemError("ECONNRESET", "proxy disconnected proxy-secret"),
+              }),
+            }),
+          ),
+        ),
+      ),
+    ),
+  )
+
   it.effect("classifies context overflow responses", () =>
     Effect.gen(function* () {
       const executor = yield* RequestExecutor.Service
diff --git a/packages/ai/test/lib/http.ts b/packages/ai/test/lib/http.ts
index e53794aa876..7c98d687ce4 100644
--- a/packages/ai/test/lib/http.ts
+++ b/packages/ai/test/lib/http.ts
@@ -1,5 +1,5 @@
 import { Effect, Layer, Ref } from "effect"
-import { HttpClient, HttpClientRequest, HttpClientResponse } from "effect/unstable/http"
+import { HttpClient, HttpClientError, HttpClientRequest, HttpClientResponse } from "effect/unstable/http"
 import { LLMClient, RequestExecutor, WebSocketExecutor } from "../../src/route.js"
 import type { Service as LLMClientService } from "../../src/route/client.js"
 import type { Service as RequestExecutorService } from "../../src/route/executor.js"
@@ -14,7 +14,9 @@ export type HandlerInput = {
   ) => HttpClientResponse.HttpClientResponse
 }
 
-export type Handler = (input: HandlerInput) => Effect.Effect<HttpClientResponse.HttpClientResponse>
+export type Handler = (
+  input: HandlerInput,
+) => Effect.Effect<HttpClientResponse.HttpClientResponse, HttpClientError.HttpClientError>
 
 const handlerLayer = (handler: Handler): Layer.Layer<HttpClient.HttpClient> =>
   Layer.succeed(
@@ -34,6 +36,12 @@ const handlerLayer = (handler: Handler): Layer.Layer<HttpClient.HttpClient> =>
 
 export type RuntimeEnv = RequestExecutorService | WebSocketExecutorService | LLMClientService
 
+export interface SystemError extends Error {
+  readonly code: string
+}
+
+export const systemError = (code: string, message: string): SystemError => Object.assign(new Error(message), { code })
+
 export const runtimeLayer = (layer: Layer.Layer<HttpClient.HttpClient>): Layer.Layer<RuntimeEnv> => {
   const requestExecutorLayer = RequestExecutor.layer.pipe(Layer.provide(layer))
   const deps = Layer.mergeAll(requestExecutorLayer, WebSocketExecutor.layer)
@@ -63,14 +71,20 @@ export const dynamicResponse = (handler: Handler) => runtimeLayer(handlerLayer(h
  * Layer that emits the supplied SSE chunks and then aborts mid-stream. Used to
  * exercise transport errors that surface during parsing.
  */
-export const truncatedStream = (chunks: ReadonlyArray<string>) =>
+export const truncatedStream = (chunks: ReadonlyArray<string>, error: Error = new Error("connection reset")) =>
   dynamicResponse((input) =>
     Effect.sync(() => {
       const encoder = new TextEncoder()
+      let index = 0
       const stream = new ReadableStream({
-        start(controller) {
-          for (const chunk of chunks) controller.enqueue(encoder.encode(chunk))
-          controller.error(new Error("connection reset"))
+        pull(controller) {
+          const chunk = chunks[index]
+          if (chunk !== undefined) {
+            index++
+            controller.enqueue(encoder.encode(chunk))
+            return
+          }
+          controller.error(error)
         },
       })
       return input.respond(stream, { headers: SSE_HEADERS })
diff --git a/packages/ai/test/provider/openai-chat.test.ts b/packages/ai/test/provider/openai-chat.test.ts
index 910e57d26a5..ea327aa1235 100644
--- a/packages/ai/test/provider/openai-chat.test.ts
+++ b/packages/ai/test/provider/openai-chat.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect } from "bun:test"
-import { Effect, Schema, Stream } from "effect"
+import { Effect, Ref, Schema, Stream } from "effect"
 import { HttpClientRequest } from "effect/unstable/http"
 import {
   HttpOptions,
@@ -22,7 +22,7 @@ import { ProviderShared } from "../../src/protocols/shared.js"
 import { Auth, LLMClient } from "../../src/route.js"
 import { compileRequest } from "../../src/route/client.js"
 import { it } from "../lib/effect.js"
-import { dynamicResponse, fixedResponse, truncatedStream } from "../lib/http.js"
+import { dynamicResponse, fixedResponse, systemError, truncatedStream } from "../lib/http.js"
 import { deltaChunk, usageChunk } from "../lib/openai-chunks.js"
 import { sseEvents } from "../lib/sse.js"
 
@@ -1221,12 +1221,44 @@ describe("OpenAI Chat route", () => {
 
   it.effect("surfaces transport errors that occur mid-stream", () =>
     Effect.gen(function* () {
-      const layer = truncatedStream([
-        `data: ${JSON.stringify(deltaChunk({ role: "assistant", content: "Hello" }))}\n\n`,
-      ])
-      const error = yield* LLMClient.generate(request).pipe(Effect.provide(layer), Effect.flip)
+      const layer = truncatedStream(
+        [`data: ${JSON.stringify(deltaChunk({ role: "assistant", content: "Hello" }))}\n\n`],
+        systemError("ECONNRESET", "socket closed unexpectedly"),
+      )
+      const events = yield* Ref.make<ReadonlyArray<LLMEvent>>([])
+      const error = yield* LLMClient.stream(request).pipe(
+        Stream.tap((event) => Ref.update(events, (current) => [...current, event])),
+        Stream.runDrain,
+        Effect.provide(layer),
+        Effect.flip,
+      )
 
-      expect(error.message).toContain("Failed to read openai/openai-chat stream")
+      expect((yield* Ref.get(events)).some((event) => event.type === "text-delta")).toBeTrue()
+      expect(error.reason).toMatchObject({
+        _tag: "Transport",
+        message: "ECONNRESET: socket closed unexpectedly",
+        transport: "http",
+        operation: "read",
+        code: "ECONNRESET",
+        url: "https://api.openai.test/v1/chat/completions",
+      })
+    }),
+  )
+
+  it.effect("surfaces transport errors before the first stream frame", () =>
+    Effect.gen(function* () {
+      const error = yield* LLMClient.generate(request).pipe(
+        Effect.provide(truncatedStream([], systemError("ECONNRESET", "socket closed before output"))),
+        Effect.flip,
+      )
+
+      expect(error.reason).toMatchObject({
+        _tag: "Transport",
+        message: "ECONNRESET: socket closed before output",
+        transport: "http",
+        operation: "read",
+        code: "ECONNRESET",
+      })
     }),
   )
 
diff --git a/packages/core/src/aisdk.ts b/packages/core/src/aisdk.ts
index 1234e1053b3..9652c16921a 100644
--- a/packages/core/src/aisdk.ts
+++ b/packages/core/src/aisdk.ts
@@ -763,7 +763,9 @@ function apiCallErrorReason(error: APICallError) {
   if (error.statusCode !== undefined || !error.isRetryable) return reason
   return new TransportReason({
     message: reason.message,
-    kind: error.name,
+    transport: "http",
+    operation: "request",
+    code: error.name,
     url: error.url,
     http: "http" in reason ? reason.http : undefined,
   })
diff --git a/packages/core/test/aisdk.test.ts b/packages/core/test/aisdk.test.ts
index 9decce67b81..a7620759448 100644
--- a/packages/core/test/aisdk.test.ts
+++ b/packages/core/test/aisdk.test.ts
@@ -49,7 +49,9 @@ const client = LLMClient.layer.pipe(
   Layer.provide(
     Layer.succeed(
       RequestExecutor.Service,
-      RequestExecutor.Service.of({ execute: () => Effect.die("Unexpected HTTP request") }),
+      RequestExecutor.Service.of({
+        execute: () => Effect.die("Unexpected HTTP request"),
+      }),
     ),
   ),
 )
@@ -542,7 +544,12 @@ it.effect("retries status-less AI SDK transport failures", () =>
         isRetryable: true,
       }),
     )
-    expect(error.reason).toMatchObject({ _tag: "Transport", kind: "AI_APICallError" })
+    expect(error.reason).toMatchObject({
+      _tag: "Transport",
+      transport: "http",
+      operation: "request",
+      code: "AI_APICallError",
+    })
     expect(SessionRunnerRetry.isRetryable(error)).toBeTrue()
     expect("http" in error.reason ? error.reason.http?.request.url : undefined).toBe("https://api.example.com/chat")
   }),
diff --git a/packages/core/test/session-error.test.ts b/packages/core/test/session-error.test.ts
index 625427d65cd..d0e14b8fa70 100644
--- a/packages/core/test/session-error.test.ts
+++ b/packages/core/test/session-error.test.ts
@@ -39,7 +39,9 @@ describe("toSessionError", () => {
     )
     expect(toSessionError(llm(new QuotaExceededReason({ message: "quota" }))).type).toBe("provider.quota")
     expect(toSessionError(llm(new ContentPolicyReason({ message: "blocked" }))).type).toBe("provider.content-filter")
-    expect(toSessionError(llm(new TransportReason({ message: "transport" }))).type).toBe("provider.transport")
+    expect(
+      toSessionError(llm(new TransportReason({ message: "transport", transport: "http", operation: "request" }))).type,
+    ).toBe("provider.transport")
     expect(toSessionError(llm(new ProviderInternalReason({ message: "internal", status: 500 }))).type).toBe(
       "provider.internal",
     )
@@ -111,7 +113,7 @@ describe("toSessionError", () => {
     const eligible = [
       llm(new RateLimitReason({ message: "rate" })),
       llm(new ProviderInternalReason({ message: "internal", status: 500 })),
-      llm(new TransportReason({ message: "transport" })),
+      llm(new TransportReason({ message: "transport", transport: "http", operation: "request" })),
     ]
     const ineligible = [
       llm(new AuthenticationReason({ message: "auth", kind: "invalid" })),
diff --git a/packages/core/test/session-execution.test.ts b/packages/core/test/session-execution.test.ts
index e71cd12ade8..e6a6d498d59 100644
--- a/packages/core/test/session-execution.test.ts
+++ b/packages/core/test/session-execution.test.ts
@@ -32,7 +32,7 @@ describe("SessionExecution lifecycle", () => {
           new AIError({
             module: "test",
             method: "stream",
-            reason: new TransportReason({ message: "Disconnected" }),
+            reason: new TransportReason({ message: "Disconnected", transport: "http", operation: "request" }),
           }),
         ),
       ),
diff --git a/packages/core/test/session-runner.test.ts b/packages/core/test/session-runner.test.ts
index fa068812bb6..5bfbedf4d6f 100644
--- a/packages/core/test/session-runner.test.ts
+++ b/packages/core/test/session-runner.test.ts
@@ -515,7 +515,11 @@ const providerUnavailable = () =>
   new AIError({
     module: "test",
     method: "stream",
-    reason: new TransportReason({ message: "Provider unavailable" }),
+    reason: new TransportReason({
+      message: "Provider unavailable",
+      transport: "http",
+      operation: "request",
+    }),
   })
 
 const incompleteStream = () =>