diff --git a/apps/server/src/orchestration-v2/testkit/ClaudeReplayFixtures.integration.test.ts b/apps/server/src/orchestration-v2/testkit/ClaudeReplayFixtures.integration.test.ts
index d7913f78a29e..79710bb0c57b 100644
--- a/apps/server/src/orchestration-v2/testkit/ClaudeReplayFixtures.integration.test.ts
+++ b/apps/server/src/orchestration-v2/testkit/ClaudeReplayFixtures.integration.test.ts
@@ -2,7 +2,6 @@ import * as NodeServices from "@effect/platform-node/NodeServices";
 import { assert, describe, it } from "@effect/vitest";
 import type { ProviderReplayTranscript } from "@t3tools/contracts";
 import * as Effect from "effect/Effect";
-import * as FileSystem from "effect/FileSystem";
 
 import { classifyClaudeNativeTool } from "../Adapters/ClaudeAdapterV2.ts";
 import {
@@ -27,12 +26,10 @@ import {
   THREAD_MERGE_BACK_SOURCE_MARKER,
 } from "./fixtures/shared.ts";
 import { checkpointWorkspace } from "./ReplayFixtureWorkspace.ts";
-import { decodeProviderReplayNdjson } from "./ReplayTranscriptNdjson.ts";
+import { readProviderReplayTranscript } from "./ReplayTranscriptNdjson.ts";
 
 const readTranscript = Effect.fn("readClaudeReplayFixture")(function* (file: URL) {
-  const fs = yield* FileSystem.FileSystem;
-  const text = yield* fs.readFileString(decodeURIComponent(file.pathname));
-  return yield* decodeProviderReplayNdjson(text);
+  return yield* readProviderReplayTranscript(file);
 }, Effect.provide(NodeServices.layer));
 
 function claudeFixture(name: string) {
diff --git a/apps/server/src/orchestration-v2/testkit/CodexReplayFixtures.integration.test.ts b/apps/server/src/orchestration-v2/testkit/CodexReplayFixtures.integration.test.ts
index ecc7e14aaeda..9643dabec756 100644
--- a/apps/server/src/orchestration-v2/testkit/CodexReplayFixtures.integration.test.ts
+++ b/apps/server/src/orchestration-v2/testkit/CodexReplayFixtures.integration.test.ts
@@ -3,7 +3,6 @@ import * as NodeServices from "@effect/platform-node/NodeServices";
 import type { ProviderReplayTranscript } from "@t3tools/contracts";
 import * as CodexReplay from "effect-codex-app-server/replay";
 import * as Effect from "effect/Effect";
-import * as FileSystem from "effect/FileSystem";
 import * as Schema from "effect/Schema";
 
 import { ORCHESTRATOR_REPLAY_FIXTURES } from "./fixtures/index.ts";
@@ -19,7 +18,7 @@ import {
   THREAD_MERGE_BACK_SIBLINGS_SOURCE_MARKER,
   THREAD_MERGE_BACK_SOURCE_MARKER,
 } from "./fixtures/shared.ts";
-import { decodeProviderReplayNdjson } from "./ReplayTranscriptNdjson.ts";
+import { readProviderReplayTranscript } from "./ReplayTranscriptNdjson.ts";
 
 const PROVIDER_THREAD_RESUME_FIRST_FINAL = "provider thread resume fixture first turn complete";
 const PROVIDER_THREAD_RESUME_SECOND_FINAL = "provider thread resume fixture second turn complete";
@@ -327,9 +326,7 @@ const decodeCodexTranscript = Schema.decodeUnknownEffect(
   CodexReplay.CodexAppServerReplayTranscript,
 );
 const readTranscript = Effect.fn("readCodexReplayFixture")(function* (file: URL) {
-  const fs = yield* FileSystem.FileSystem;
-  const text = yield* fs.readFileString(decodeURIComponent(file.pathname));
-  return yield* decodeProviderReplayNdjson(text);
+  return yield* readProviderReplayTranscript(file);
 }, Effect.provide(NodeServices.layer));
 
 function labels(
diff --git a/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.contract.test.ts b/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.contract.test.ts
index 6021642ee97f..749e219beb8e 100644
--- a/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.contract.test.ts
+++ b/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.contract.test.ts
@@ -2,7 +2,6 @@ import { assert, describe, it } from "@effect/vitest";
 import * as NodeServices from "@effect/platform-node/NodeServices";
 import { OrchestrationV2Command, ProviderDriverKind, ProviderInstanceId } from "@t3tools/contracts";
 import * as Effect from "effect/Effect";
-import * as FileSystem from "effect/FileSystem";
 import * as Schema from "effect/Schema";
 
 import { IdAllocatorV2, layer as idAllocatorLayer } from "../IdAllocator.ts";
@@ -13,13 +12,11 @@ import {
   materializeFixtureInput,
   type OrchestratorFixtureInput,
 } from "./fixtures/shared.ts";
-import { decodeProviderReplayNdjson } from "./ReplayTranscriptNdjson.ts";
+import { readProviderReplayTranscript } from "./ReplayTranscriptNdjson.ts";
 
 const decodeCommand = Schema.decodeUnknownEffect(OrchestrationV2Command);
 const readTranscript = Effect.fn("readOrchestratorReplayContractTranscript")(function* (file: URL) {
-  const fs = yield* FileSystem.FileSystem;
-  const text = yield* fs.readFileString(decodeURIComponent(file.pathname));
-  return yield* decodeProviderReplayNdjson(text);
+  return yield* readProviderReplayTranscript(file);
 }, Effect.provide(NodeServices.layer));
 
 function assertUnique(values: ReadonlyArray<string>, label: string) {
diff --git a/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.integration.test.ts b/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.integration.test.ts
index ffed1f80dd62..d4fe4a98e2a8 100644
--- a/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.integration.test.ts
+++ b/apps/server/src/orchestration-v2/testkit/OrchestratorReplayFixtures.integration.test.ts
@@ -2,7 +2,6 @@ import * as NodeServices from "@effect/platform-node/NodeServices";
 import { assert, describe, it } from "@effect/vitest";
 import type { OrchestrationV2DomainEvent, ProviderReplayTranscript } from "@t3tools/contracts";
 import * as Effect from "effect/Effect";
-import * as FileSystem from "effect/FileSystem";
 
 import { ClaudeOrchestratorReplayHarness } from "../Adapters/ClaudeAdapterV2.testkit.ts";
 import { CodexOrchestratorReplayHarness } from "../Adapters/CodexAdapterV2.testkit.ts";
@@ -25,15 +24,13 @@ import {
 } from "./ProviderReplayHarness.ts";
 import { checkpointWorkspace } from "./ReplayFixtureWorkspace.ts";
 import {
-  decodeProviderReplayNdjson,
   materializeReplayTranscriptRuntimeInstructions,
   materializeReplayTranscriptWorkspace,
+  readProviderReplayTranscript,
 } from "./ReplayTranscriptNdjson.ts";
 
 const readTranscript = Effect.fn("readOrchestratorReplayTranscript")(function* (file: URL) {
-  const fs = yield* FileSystem.FileSystem;
-  const text = yield* fs.readFileString(decodeURIComponent(file.pathname));
-  return yield* decodeProviderReplayNdjson(text);
+  return yield* readProviderReplayTranscript(file);
 }, Effect.provide(NodeServices.layer));
 
 function normalizeTestError(cause: unknown): Error {
diff --git a/apps/server/src/orchestration-v2/testkit/OrchestratorReplayRecovery.integration.test.ts b/apps/server/src/orchestration-v2/testkit/OrchestratorReplayRecovery.integration.test.ts
index 0fc4bf124c8f..316735feaa1e 100644
--- a/apps/server/src/orchestration-v2/testkit/OrchestratorReplayRecovery.integration.test.ts
+++ b/apps/server/src/orchestration-v2/testkit/OrchestratorReplayRecovery.integration.test.ts
@@ -42,9 +42,9 @@ import {
 import { runOrchestratorV2ProviderReplayScenario } from "./ProviderReplayHarness.ts";
 import { checkpointWorkspace } from "./ReplayFixtureWorkspace.ts";
 import {
-  decodeProviderReplayNdjson,
   materializeReplayTranscriptRuntimeInstructions,
   materializeReplayTranscriptWorkspace,
+  readProviderReplayTranscript,
 } from "./ReplayTranscriptNdjson.ts";
 
 const FIRST_FINAL = "provider thread resume fixture first turn complete";
@@ -54,9 +54,7 @@ const decodeCodexTranscript = Schema.decodeUnknownEffect(
   CodexReplay.CodexAppServerReplayTranscript,
 );
 const readRawTranscript = Effect.fn("readRecoveryTranscript")(function* (file: URL) {
-  const fs = yield* FileSystem.FileSystem;
-  const text = yield* fs.readFileString(decodeURIComponent(file.pathname));
-  return yield* decodeProviderReplayNdjson(text);
+  return yield* readProviderReplayTranscript(file);
 });
 const readCodexTranscript = Effect.fn("readCodexRecoveryTranscript")(function* (workspace: string) {
   const transcript = yield* readRawTranscript(
diff --git a/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.test.ts b/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.test.ts
index d494f18b7f8a..8217ebb9a4cc 100644
--- a/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.test.ts
+++ b/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.test.ts
@@ -1,11 +1,16 @@
 import { ProviderReplayNdjsonParseError } from "./ReplayTranscriptNdjson.ts";
+import * as NodePath from "@effect/platform-node/NodePath";
+import * as NodeServices from "@effect/platform-node/NodeServices";
 import { assert, describe, it } from "@effect/vitest";
 import * as Effect from "effect/Effect";
+import * as FileSystem from "effect/FileSystem";
+import * as Path from "effect/Path";
 import * as Schema from "effect/Schema";
 
 import {
   decodeProviderReplayNdjson,
   materializeReplayTranscriptWorkspace,
+  readProviderReplayTranscript,
 } from "./ReplayTranscriptNdjson.ts";
 
 const encodeParseError = Schema.encodeUnknownEffect(ProviderReplayNdjsonParseError);
@@ -96,3 +101,75 @@ describe("decodeProviderReplayNdjson", () => {
     }),
   );
 });
+
+const FILE_URL_TRANSCRIPT = `{"type":"transcript_start","provider":"codex","protocol":"codex.app-server","version":"0.120.0","scenario":"file-url-read"}
+{"type":"runtime_exit","status":"success"}
+`;
+
+it.layer(NodeServices.layer)("readProviderReplayTranscript", (it) => {
+  it.effect("loads a transcript behind a file URL containing an encoded space", () =>
+    Effect.gen(function* () {
+      const fs = yield* FileSystem.FileSystem;
+      const path = yield* Path.Path;
+      const dir = yield* fs.makeTempDirectoryScoped({ prefix: "t3 replay fixture " });
+      const filePath = path.join(dir, "transcript.ndjson");
+      yield* fs.writeFileString(filePath, FILE_URL_TRANSCRIPT);
+
+      const fileUrl = yield* path.toFileUrl(filePath);
+      assert.isTrue(fileUrl.pathname.includes("%20"));
+
+      const transcript = yield* readProviderReplayTranscript(fileUrl);
+      assert.equal(transcript.scenario, "file-url-read");
+    }),
+  );
+
+  it.effect("passes drive-letter and UNC file URLs through the Windows path service", () =>
+    Effect.gen(function* () {
+      const fs = yield* FileSystem.FileSystem;
+      const requestedPaths: Array<string> = [];
+      const recordingFs = FileSystem.FileSystem.of({
+        ...fs,
+        readFileString: (filePath: string) => {
+          requestedPaths.push(filePath);
+          return Effect.succeed(FILE_URL_TRANSCRIPT);
+        },
+      });
+      const readAsWindows = (file: URL) =>
+        readProviderReplayTranscript(file).pipe(
+          Effect.provideService(FileSystem.FileSystem, recordingFs),
+          Effect.provide(NodePath.layerWin32),
+        );
+
+      const driveLetter = yield* readAsWindows(
+        new URL("file:///C:/Users/dev/t3%20worktree/transcript.ndjson"),
+      );
+      const unc = yield* readAsWindows(new URL("file://fileserver/shared/transcript.ndjson"));
+
+      assert.equal(driveLetter.scenario, "file-url-read");
+      assert.equal(unc.scenario, "file-url-read");
+      assert.deepEqual(requestedPaths, [
+        "C:\\Users\\dev\\t3 worktree\\transcript.ndjson",
+        "\\\\fileserver\\shared\\transcript.ndjson",
+      ]);
+    }),
+  );
+
+  it.effect("rejects non-file URLs instead of decoding their pathname", () =>
+    Effect.gen(function* () {
+      const fs = yield* FileSystem.FileSystem;
+      const recordingFs = FileSystem.FileSystem.of({
+        ...fs,
+        readFileString: () => Effect.succeed(FILE_URL_TRANSCRIPT),
+      });
+      const error = yield* readProviderReplayTranscript(
+        new URL("https://example.com/transcript.ndjson"),
+      ).pipe(
+        Effect.provideService(FileSystem.FileSystem, recordingFs),
+        Effect.provide(NodePath.layerPosix),
+        Effect.flip,
+      );
+
+      assert.equal(error._tag, "BadArgument");
+    }),
+  );
+});
diff --git a/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.ts b/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.ts
index 1031e8ba04a8..1b62ca0f126e 100644
--- a/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.ts
+++ b/apps/server/src/orchestration-v2/testkit/ReplayTranscriptNdjson.ts
@@ -6,6 +6,8 @@ import {
   type ProviderReplayTranscriptHeader,
 } from "@t3tools/contracts";
 import * as Effect from "effect/Effect";
+import * as FileSystem from "effect/FileSystem";
+import * as Path from "effect/Path";
 import * as Schema from "effect/Schema";
 
 import { buildRuntimeInstructions } from "../../provider/RuntimeInstructions.ts";
@@ -230,3 +232,17 @@ export function decodeProviderReplayNdjson(
     });
   });
 }
+
+/**
+ * Reads a provider replay transcript from a `file:` URL and decodes it.
+ * Conversion goes through the `Path` service so drive-letter and UNC fixture
+ * URLs resolve to native paths on Windows instead of `/C:/...` pathname strings.
+ */
+export const readProviderReplayTranscript = Effect.fn("readProviderReplayTranscript")(function* (
+  file: URL,
+) {
+  const fs = yield* FileSystem.FileSystem;
+  const path = yield* Path.Path;
+  const text = yield* fs.readFileString(yield* path.fromFileUrl(file));
+  return yield* decodeProviderReplayNdjson(text);
+});