From 3cd60471fc662fee2b0e3777a6d2847f9cb8515b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 15:30:46 +0000
Subject: [PATCH 01/10] Initial plan


From 229eb6e02210d92c59747583fb7b628c1c7b7ff7 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 15:44:36 +0000
Subject: [PATCH 02/10] Add File type spector tests for body and multipart
 scenarios

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/specs/type/file/main.tsp  | 219 +++++++++++++
 .../http-specs/specs/type/file/mockapi.ts     | 291 ++++++++++++++++++
 2 files changed, 510 insertions(+)
 create mode 100644 packages/http-specs/specs/type/file/main.tsp
 create mode 100644 packages/http-specs/specs/type/file/mockapi.ts

diff --git a/packages/http-specs/specs/type/file/main.tsp b/packages/http-specs/specs/type/file/main.tsp
new file mode 100644
index 00000000000..786f426d3fb
--- /dev/null
+++ b/packages/http-specs/specs/type/file/main.tsp
@@ -0,0 +1,219 @@
+import "@typespec/http";
+import "@typespec/spector";
+
+using TypeSpec.Http;
+using Spector;
+
+@doc("Test for File type usage in request and response bodies")
+@scenarioService("/type/file")
+namespace Type.File;
+
+// Define custom File types for testing
+model PngImageFile extends TypeSpec.Http.File {
+  contentType: "image/png";
+}
+
+model ImageFile extends TypeSpec.Http.File {
+  contentType: "image/png" | "image/jpeg";
+}
+
+/**
+ * Test File as request and response body with specific content type
+ */
+@route("/body")
+namespace Body {
+  @scenario
+  @scenarioDoc("""
+    Test File type as request body with specific content type.
+    Expected request:
+    - Content-Type header: image/png
+    - Body: binary content matching packages/http-specs/assets/image.png
+    """)
+  @post
+  @route("/request/specific-content-type")
+  op uploadFileSpecificContentType(@bodyRoot file: PngImageFile): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type as response body with specific content type.
+    Expected response:
+    - Content-Type header: image/png
+    - Body: binary content matching packages/http-specs/assets/image.png
+    """)
+  @get
+  @route("/response/specific-content-type")
+  op downloadFileSpecificContentType(): PngImageFile;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type as request body with multiple allowed content types (image/png or image/jpeg).
+    Client should send image/png.
+    Expected request:
+    - Content-Type header: image/png
+    - Body: binary content matching packages/http-specs/assets/image.png
+    """)
+  @post
+  @route("/request/multiple-content-types")
+  op uploadFileMultipleContentTypes(@bodyRoot file: ImageFile): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type as response body with multiple allowed content types.
+    Service will return image/png.
+    Expected response:
+    - Content-Type header: image/png
+    - Body: binary content matching packages/http-specs/assets/image.png
+    """)
+  @get
+  @route("/response/multiple-content-types")
+  op downloadFileMultipleContentTypes(): ImageFile;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type as request body with unspecified content type (defaults to application/octet-stream).
+    Expected request:
+    - Content-Type header: application/octet-stream (or not specified)
+    - Body: binary content matching packages/http-specs/assets/image.png
+    """)
+  @post
+  @route("/request/default-content-type")
+  op uploadFileDefaultContentType(@bodyRoot file: TypeSpec.Http.File): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type as response body with unspecified content type (defaults to application/octet-stream).
+    Expected response:
+    - Content-Type header: application/octet-stream
+    - Body: binary content matching packages/http-specs/assets/image.png
+    """)
+  @get
+  @route("/response/default-content-type")
+  op downloadFileDefaultContentType(): TypeSpec.Http.File;
+}
+
+/**
+ * Test File in multipart form data scenarios
+ */
+@route("/multipart")
+namespace MultiPart {
+  model FileWithSpecificContentType extends TypeSpec.Http.File {
+    filename: string;
+    contentType: "image/png";
+  }
+
+  model FileWithMultipleContentTypes extends TypeSpec.Http.File {
+    filename: string;
+    contentType: "image/png" | "image/jpeg";
+  }
+
+  model FileWithRequiredMetadata extends TypeSpec.Http.File {
+    filename: string;
+    contentType: string;
+  }
+
+  @scenario
+  @scenarioDoc("""
+    Test File type in multipart form data with specific content type.
+    Expected request:
+    ```
+    POST /multipart/specific-content-type HTTP/1.1
+    Content-Type: multipart/form-data; boundary=abcde12345
+    
+    --abcde12345
+    Content-Disposition: form-data; name="file"; filename="image.png"
+    Content-Type: image/png
+    
+    {…file content of image.png…}
+    --abcde12345--
+    ```
+    """)
+  @post
+  @route("/specific-content-type")
+  op uploadFileSpecificContentType(
+    @header contentType: "multipart/form-data",
+    @multipartBody body: {
+      file: HttpPart<FileWithSpecificContentType>;
+    },
+  ): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type in multipart form data with multiple allowed content types.
+    Client should send image/png.
+    Expected request:
+    ```
+    POST /multipart/multiple-content-types HTTP/1.1
+    Content-Type: multipart/form-data; boundary=abcde12345
+    
+    --abcde12345
+    Content-Disposition: form-data; name="file"; filename="image.png"
+    Content-Type: image/png
+    
+    {…file content of image.png…}
+    --abcde12345--
+    ```
+    """)
+  @post
+  @route("/multiple-content-types")
+  op uploadFileMultipleContentTypes(
+    @header contentType: "multipart/form-data",
+    @multipartBody body: {
+      file: HttpPart<FileWithMultipleContentTypes>;
+    },
+  ): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type in multipart form data with required content type metadata.
+    Expected request:
+    ```
+    POST /multipart/required-content-type HTTP/1.1
+    Content-Type: multipart/form-data; boundary=abcde12345
+    
+    --abcde12345
+    Content-Disposition: form-data; name="file"; filename="image.png"
+    Content-Type: application/octet-stream
+    
+    {…file content of image.png…}
+    --abcde12345--
+    ```
+    """)
+  @post
+  @route("/required-content-type")
+  op uploadFileRequiredContentType(
+    @header contentType: "multipart/form-data",
+    @multipartBody body: {
+      file: HttpPart<FileWithRequiredMetadata>;
+    },
+  ): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test multiple File instances in multipart form data.
+    Expected request:
+    ```
+    POST /multipart/file-array HTTP/1.1
+    Content-Type: multipart/form-data; boundary=abcde12345
+    
+    --abcde12345
+    Content-Disposition: form-data; name="files"; filename="image1.png"
+    Content-Type: image/png
+    
+    {…file content of image.png…}
+    --abcde12345
+    Content-Disposition: form-data; name="files"; filename="image2.png"
+    Content-Type: image/png
+    
+    {…file content of image.png…}
+    --abcde12345--
+    ```
+    """)
+  @post
+  @route("/file-array")
+  op uploadFileArray(
+    @header contentType: "multipart/form-data",
+    @multipartBody body: {
+      files: HttpPart<FileWithSpecificContentType>[];
+    },
+  ): NoContentResponse;
+}
diff --git a/packages/http-specs/specs/type/file/mockapi.ts b/packages/http-specs/specs/type/file/mockapi.ts
new file mode 100644
index 00000000000..b1d5c889a2d
--- /dev/null
+++ b/packages/http-specs/specs/type/file/mockapi.ts
@@ -0,0 +1,291 @@
+import {
+  MockRequest,
+  passOnSuccess,
+  ScenarioMockApi,
+  ValidationError,
+} from "@typespec/spec-api";
+import { pngFile } from "../../helper.js";
+
+export const Scenarios: Record<string, ScenarioMockApi> = {};
+
+// Helper function to check file content
+function checkFileContent(req: MockRequest, expectedFile: Buffer) {
+  req.expect.rawBodyEquals(expectedFile);
+}
+
+// Helper function to check file in multipart
+function checkMultipartFile(
+  req: MockRequest,
+  file: Record<string, any>,
+  expectedContent: Buffer,
+  expectedContentType: string,
+  expectedFileName?: string,
+) {
+  req.expect.deepEqual(file.mimetype, expectedContentType);
+  req.expect.deepEqual(file.buffer, expectedContent);
+  if (expectedFileName) {
+    req.expect.deepEqual(file.originalname, expectedFileName);
+  }
+}
+
+// Body tests - Request with specific content type
+Scenarios.Type_File_Body_uploadFileSpecificContentType = passOnSuccess({
+  uri: "/type/file/body/request/specific-content-type",
+  method: "post",
+  request: {
+    body: {
+      contentType: "image/png",
+      rawContent: pngFile,
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    req.expect.containsHeader("content-type", "image/png");
+    checkFileContent(req, pngFile);
+    return { status: 204 };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Body tests - Response with specific content type
+Scenarios.Type_File_Body_downloadFileSpecificContentType = passOnSuccess({
+  uri: "/type/file/body/response/specific-content-type",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      contentType: "image/png",
+      rawContent: pngFile,
+    },
+  },
+  handler(req: MockRequest) {
+    return {
+      status: 200,
+      body: {
+        contentType: "image/png",
+        rawContent: pngFile,
+      },
+    };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Body tests - Request with multiple content types
+Scenarios.Type_File_Body_uploadFileMultipleContentTypes = passOnSuccess({
+  uri: "/type/file/body/request/multiple-content-types",
+  method: "post",
+  request: {
+    body: {
+      contentType: "image/png",
+      rawContent: pngFile,
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    // Client should send image/png (one of the allowed types)
+    const contentType = req.headers["content-type"];
+    if (contentType !== "image/png" && contentType !== "image/jpeg") {
+      throw new ValidationError(
+        "Expected content-type to be image/png or image/jpeg",
+        "image/png or image/jpeg",
+        contentType,
+      );
+    }
+    checkFileContent(req, pngFile);
+    return { status: 204 };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Body tests - Response with multiple content types
+Scenarios.Type_File_Body_downloadFileMultipleContentTypes = passOnSuccess({
+  uri: "/type/file/body/response/multiple-content-types",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      contentType: "image/png",
+      rawContent: pngFile,
+    },
+  },
+  handler(req: MockRequest) {
+    // Server returns image/png (one of the allowed types)
+    return {
+      status: 200,
+      body: {
+        contentType: "image/png",
+        rawContent: pngFile,
+      },
+    };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Body tests - Request with default content type
+Scenarios.Type_File_Body_uploadFileDefaultContentType = passOnSuccess({
+  uri: "/type/file/body/request/default-content-type",
+  method: "post",
+  request: {
+    body: {
+      contentType: "application/octet-stream",
+      rawContent: pngFile,
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    // Content-Type should be application/octet-stream or not specified
+    const contentType = req.headers["content-type"];
+    if (contentType && contentType !== "application/octet-stream") {
+      throw new ValidationError(
+        "Expected content-type to be application/octet-stream or not specified",
+        "application/octet-stream",
+        contentType,
+      );
+    }
+    checkFileContent(req, pngFile);
+    return { status: 204 };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Body tests - Response with default content type
+Scenarios.Type_File_Body_downloadFileDefaultContentType = passOnSuccess({
+  uri: "/type/file/body/response/default-content-type",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      contentType: "application/octet-stream",
+      rawContent: pngFile,
+    },
+  },
+  handler(req: MockRequest) {
+    return {
+      status: 200,
+      body: {
+        contentType: "application/octet-stream",
+        rawContent: pngFile,
+      },
+    };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Multipart tests - Specific content type
+Scenarios.Type_File_MultiPart_uploadFileSpecificContentType = passOnSuccess({
+  uri: "/type/file/multipart/specific-content-type",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 1) {
+      const file = req.files[0];
+      req.expect.deepEqual(file.fieldname, "file");
+      checkMultipartFile(req, file, pngFile, "image/png", "image.png");
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly one file", "1 file", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
+
+// Multipart tests - Multiple content types
+Scenarios.Type_File_MultiPart_uploadFileMultipleContentTypes = passOnSuccess({
+  uri: "/type/file/multipart/multiple-content-types",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 1) {
+      const file = req.files[0];
+      req.expect.deepEqual(file.fieldname, "file");
+      // Client should send image/png (one of the allowed types)
+      if (file.mimetype !== "image/png" && file.mimetype !== "image/jpeg") {
+        throw new ValidationError(
+          "Expected mimetype to be image/png or image/jpeg",
+          "image/png or image/jpeg",
+          file.mimetype,
+        );
+      }
+      req.expect.deepEqual(file.buffer, pngFile);
+      req.expect.deepEqual(file.originalname, "image.png");
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly one file", "1 file", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
+
+// Multipart tests - Required content type
+Scenarios.Type_File_MultiPart_uploadFileRequiredContentType = passOnSuccess({
+  uri: "/type/file/multipart/required-content-type",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 1) {
+      const file = req.files[0];
+      req.expect.deepEqual(file.fieldname, "file");
+      checkMultipartFile(req, file, pngFile, "application/octet-stream", "image.png");
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly one file", "1 file", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
+
+// Multipart tests - File array
+Scenarios.Type_File_MultiPart_uploadFileArray = passOnSuccess({
+  uri: "/type/file/multipart/file-array",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 2) {
+      for (const file of req.files) {
+        req.expect.deepEqual(file.fieldname, "files");
+        checkMultipartFile(req, file, pngFile, "image/png");
+      }
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly two files", "2 files", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});

From 3721792e147ac6fc3d073e070705eb0f24abfacf Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 15:51:43 +0000
Subject: [PATCH 03/10] Add comment explaining TypeSpec.Http.File usage and
 address code review

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/specs/type/file/main.tsp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/http-specs/specs/type/file/main.tsp b/packages/http-specs/specs/type/file/main.tsp
index 786f426d3fb..70b29440539 100644
--- a/packages/http-specs/specs/type/file/main.tsp
+++ b/packages/http-specs/specs/type/file/main.tsp
@@ -1,13 +1,16 @@
 import "@typespec/http";
 import "@typespec/spector";
 
-using TypeSpec.Http;
+using Http;
 using Spector;
 
 @doc("Test for File type usage in request and response bodies")
 @scenarioService("/type/file")
 namespace Type.File;
 
+// Note: Using TypeSpec.Http.File fully qualified because "File" in the namespace name
+// would shadow the File type from the Http namespace.
+
 // Define custom File types for testing
 model PngImageFile extends TypeSpec.Http.File {
   contentType: "image/png";

From 361156f92cc9f9147750415d69fed087a774bcce Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 16:18:09 +0000
Subject: [PATCH 04/10] Address PR feedback: use inline File syntax and move
 multipart tests to multipart spec

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/spec-summary.md           | 144 +++++++++++++++++
 .../specs/payload/multipart/main.tsp          | 124 ++++++++++++++
 .../specs/payload/multipart/mockapi.ts        | 122 ++++++++++++++
 packages/http-specs/specs/type/file/main.tsp  | 153 +-----------------
 .../http-specs/specs/type/file/mockapi.ts     | 125 --------------
 .../specs/type/file/test-inline.tsp           |   8 +
 6 files changed, 406 insertions(+), 270 deletions(-)
 create mode 100644 packages/http-specs/specs/type/file/test-inline.tsp

diff --git a/packages/http-specs/spec-summary.md b/packages/http-specs/spec-summary.md
index a25c9665dbe..7d445b29ea3 100644
--- a/packages/http-specs/spec-summary.md
+++ b/packages/http-specs/spec-summary.md
@@ -2050,6 +2050,88 @@ Content-Type: image/jpg
 --abcde12345--
 ```
 
+### Payload_MultiPart_FormData_File_uploadFileArray
+
+- Endpoint: `post /multipart/form-data/file/file-array`
+
+Test multiple File instances in multipart form data.
+Expected request:
+
+```
+POST /multipart/file/file-array HTTP/1.1
+Content-Type: multipart/form-data; boundary=abcde12345
+
+--abcde12345
+Content-Disposition: form-data; name="files"; filename="image1.png"
+Content-Type: image/png
+
+{…file content of image.png…}
+--abcde12345
+Content-Disposition: form-data; name="files"; filename="image2.png"
+Content-Type: image/png
+
+{…file content of image.png…}
+--abcde12345--
+```
+
+### Payload_MultiPart_FormData_File_uploadFileMultipleContentTypes
+
+- Endpoint: `post /multipart/form-data/file/multiple-content-types`
+
+Test File type in multipart form data with multiple allowed content types.
+Client should send image/png.
+Expected request:
+
+```
+POST /multipart/file/multiple-content-types HTTP/1.1
+Content-Type: multipart/form-data; boundary=abcde12345
+
+--abcde12345
+Content-Disposition: form-data; name="file"; filename="image.png"
+Content-Type: image/png
+
+{…file content of image.png…}
+--abcde12345--
+```
+
+### Payload_MultiPart_FormData_File_uploadFileRequiredContentType
+
+- Endpoint: `post /multipart/form-data/file/required-content-type`
+
+Test File type in multipart form data with required content type metadata.
+Expected request:
+
+```
+POST /multipart/file/required-content-type HTTP/1.1
+Content-Type: multipart/form-data; boundary=abcde12345
+
+--abcde12345
+Content-Disposition: form-data; name="file"; filename="image.png"
+Content-Type: application/octet-stream
+
+{…file content of image.png…}
+--abcde12345--
+```
+
+### Payload_MultiPart_FormData_File_uploadFileSpecificContentType
+
+- Endpoint: `post /multipart/form-data/file/specific-content-type`
+
+Test File type in multipart form data with specific content type.
+Expected request:
+
+```
+POST /multipart/file/specific-content-type HTTP/1.1
+Content-Type: multipart/form-data; boundary=abcde12345
+
+--abcde12345
+Content-Disposition: form-data; name="file"; filename="image.png"
+Content-Type: image/png
+
+{…file content of image.png…}
+--abcde12345--
+```
+
 ### Payload_MultiPart_FormData_fileArrayAndBasic
 
 - Endpoint: `post /multipart/form-data/complex-parts`
@@ -5210,6 +5292,68 @@ Expect to send a known value. Mock api expect to receive 'Monday'
 
 Expect to handle an unknown value. Mock api expect to receive 'Weekend'
 
+### Type_File_Body_downloadFileDefaultContentType
+
+- Endpoint: `get /type/file/body/response/default-content-type`
+
+Test File type as response body with unspecified content type (defaults to application/octet-stream).
+Expected response:
+
+- Content-Type header: application/octet-stream
+- Body: binary content matching packages/http-specs/assets/image.png
+
+### Type_File_Body_downloadFileMultipleContentTypes
+
+- Endpoint: `get /type/file/body/response/multiple-content-types`
+
+Test File type as response body with multiple allowed content types.
+Service will return image/png.
+Expected response:
+
+- Content-Type header: image/png
+- Body: binary content matching packages/http-specs/assets/image.png
+
+### Type_File_Body_downloadFileSpecificContentType
+
+- Endpoint: `get /type/file/body/response/specific-content-type`
+
+Test File type as response body with specific content type.
+Expected response:
+
+- Content-Type header: image/png
+- Body: binary content matching packages/http-specs/assets/image.png
+
+### Type_File_Body_uploadFileDefaultContentType
+
+- Endpoint: `post /type/file/body/request/default-content-type`
+
+Test File type as request body with unspecified content type (defaults to application/octet-stream).
+Expected request:
+
+- Content-Type header: application/octet-stream (or not specified)
+- Body: binary content matching packages/http-specs/assets/image.png
+
+### Type_File_Body_uploadFileMultipleContentTypes
+
+- Endpoint: `post /type/file/body/request/multiple-content-types`
+
+Test File type as request body with multiple allowed content types (image/png or image/jpeg).
+Client should send image/png.
+Expected request:
+
+- Content-Type header: image/png
+- Body: binary content matching packages/http-specs/assets/image.png
+
+### Type_File_Body_uploadFileSpecificContentType
+
+- Endpoint: `post /type/file/body/request/specific-content-type`
+
+Test File type as request body with specific content type.
+Expected request:
+
+- Content-Type header: image/png
+- Body: binary content matching packages/http-specs/assets/image.png
+
 ### Type_Model_Empty_getEmpty
 
 - Endpoint: `get /type/model/empty/alone`
diff --git a/packages/http-specs/specs/payload/multipart/main.tsp b/packages/http-specs/specs/payload/multipart/main.tsp
index 87a8f46f6c3..ea8eee08dc0 100644
--- a/packages/http-specs/specs/payload/multipart/main.tsp
+++ b/packages/http-specs/specs/payload/multipart/main.tsp
@@ -608,4 +608,128 @@ namespace FormData {
       ): NoContentResponse;
     }
   }
+
+  @route("/file")
+  namespace File {
+    model FileWithSpecificContentType extends TypeSpec.Http.File {
+      filename: string;
+      contentType: "image/png";
+    }
+
+    model FileWithMultipleContentTypes extends TypeSpec.Http.File {
+      filename: string;
+      contentType: "image/png" | "image/jpeg";
+    }
+
+    model FileWithRequiredMetadata extends TypeSpec.Http.File {
+      filename: string;
+      contentType: string;
+    }
+
+    @scenario
+    @scenarioDoc("""
+      Test File type in multipart form data with specific content type.
+      Expected request:
+      ```
+      POST /multipart/form-data/file/specific-content-type HTTP/1.1
+      Content-Type: multipart/form-data; boundary=abcde12345
+      
+      --abcde12345
+      Content-Disposition: form-data; name="file"; filename="image.png"
+      Content-Type: image/png
+      
+      {…file content of image.png…}
+      --abcde12345--
+      ```
+      """)
+    @post
+    @route("/specific-content-type")
+    op uploadFileSpecificContentType(
+      @header contentType: "multipart/form-data",
+      @multipartBody body: {
+        file: HttpPart<FileWithSpecificContentType>;
+      },
+    ): NoContentResponse;
+
+    @scenario
+    @scenarioDoc("""
+      Test File type in multipart form data with multiple allowed content types.
+      Client should send image/png.
+      Expected request:
+      ```
+      POST /multipart/form-data/file/multiple-content-types HTTP/1.1
+      Content-Type: multipart/form-data; boundary=abcde12345
+      
+      --abcde12345
+      Content-Disposition: form-data; name="file"; filename="image.png"
+      Content-Type: image/png
+      
+      {…file content of image.png…}
+      --abcde12345--
+      ```
+      """)
+    @post
+    @route("/multiple-content-types")
+    op uploadFileMultipleContentTypes(
+      @header contentType: "multipart/form-data",
+      @multipartBody body: {
+        file: HttpPart<FileWithMultipleContentTypes>;
+      },
+    ): NoContentResponse;
+
+    @scenario
+    @scenarioDoc("""
+      Test File type in multipart form data with required content type metadata.
+      Expected request:
+      ```
+      POST /multipart/form-data/file/required-content-type HTTP/1.1
+      Content-Type: multipart/form-data; boundary=abcde12345
+      
+      --abcde12345
+      Content-Disposition: form-data; name="file"; filename="image.png"
+      Content-Type: application/octet-stream
+      
+      {…file content of image.png…}
+      --abcde12345--
+      ```
+      """)
+    @post
+    @route("/required-content-type")
+    op uploadFileRequiredContentType(
+      @header contentType: "multipart/form-data",
+      @multipartBody body: {
+        file: HttpPart<FileWithRequiredMetadata>;
+      },
+    ): NoContentResponse;
+
+    @scenario
+    @scenarioDoc("""
+      Test multiple File instances in multipart form data.
+      Expected request:
+      ```
+      POST /multipart/form-data/file/file-array HTTP/1.1
+      Content-Type: multipart/form-data; boundary=abcde12345
+      
+      --abcde12345
+      Content-Disposition: form-data; name="files"; filename="image1.png"
+      Content-Type: image/png
+      
+      {…file content of image.png…}
+      --abcde12345
+      Content-Disposition: form-data; name="files"; filename="image2.png"
+      Content-Type: image/png
+      
+      {…file content of image.png…}
+      --abcde12345--
+      ```
+      """)
+    @post
+    @route("/file-array")
+    op uploadFileArray(
+      @header contentType: "multipart/form-data",
+      @multipartBody body: {
+        files: HttpPart<FileWithSpecificContentType>[];
+      },
+    ): NoContentResponse;
+  }
 }
diff --git a/packages/http-specs/specs/payload/multipart/mockapi.ts b/packages/http-specs/specs/payload/multipart/mockapi.ts
index 4c190ff8ad9..ee7f42e6cb6 100644
--- a/packages/http-specs/specs/payload/multipart/mockapi.ts
+++ b/packages/http-specs/specs/payload/multipart/mockapi.ts
@@ -414,3 +414,125 @@ Scenarios.Payload_MultiPart_FormData_HttpParts_NonString_float = passOnSuccess({
   handler: (req: MockRequest) => createHandler(req, [checkFloat]),
   kind: "MockApiDefinition",
 });
+
+// Helper function to check file in multipart for File type tests
+function checkMultipartFile(
+  req: MockRequest,
+  file: Record<string, any>,
+  expectedContent: Buffer,
+  expectedContentType: string,
+  fieldName: string = "file",
+  expectedFileName?: string,
+) {
+  req.expect.deepEqual(file.fieldname, fieldName);
+  req.expect.deepEqual(file.mimetype, expectedContentType);
+  req.expect.deepEqual(file.buffer, expectedContent);
+  if (expectedFileName) {
+    req.expect.deepEqual(file.originalname, expectedFileName);
+  }
+}
+
+// Multipart File type tests
+Scenarios.Payload_MultiPart_FormData_File_uploadFileSpecificContentType = passOnSuccess({
+  uri: "/multipart/form-data/file/specific-content-type",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 1) {
+      const file = req.files[0];
+      checkMultipartFile(req, file, pngFile, "image/png", "file", "image.png");
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly one file", "1 file", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Payload_MultiPart_FormData_File_uploadFileMultipleContentTypes = passOnSuccess({
+  uri: "/multipart/form-data/file/multiple-content-types",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 1) {
+      const file = req.files[0];
+      // Client should send image/png (one of the allowed types)
+      if (file.mimetype !== "image/png" && file.mimetype !== "image/jpeg") {
+        throw new ValidationError(
+          "Expected mimetype to be image/png or image/jpeg",
+          "image/png or image/jpeg",
+          file.mimetype,
+        );
+      }
+      req.expect.deepEqual(file.fieldname, "file");
+      req.expect.deepEqual(file.buffer, pngFile);
+      req.expect.deepEqual(file.originalname, "image.png");
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly one file", "1 file", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Payload_MultiPart_FormData_File_uploadFileRequiredContentType = passOnSuccess({
+  uri: "/multipart/form-data/file/required-content-type",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 1) {
+      const file = req.files[0];
+      checkMultipartFile(req, file, pngFile, "application/octet-stream", "file", "image.png");
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly one file", "1 file", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
+
+Scenarios.Payload_MultiPart_FormData_File_uploadFileArray = passOnSuccess({
+  uri: "/multipart/form-data/file/file-array",
+  method: "post",
+  request: {
+    headers: {
+      "content-type": "multipart/form-data",
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    if (req.files instanceof Array && req.files.length === 2) {
+      for (const file of req.files) {
+        req.expect.deepEqual(file.fieldname, "files");
+        checkMultipartFile(req, file, pngFile, "image/png", "files");
+      }
+      return { status: 204 };
+    } else {
+      throw new ValidationError("Expected exactly two files", "2 files", req.files);
+    }
+  },
+  kind: "MockApiDefinition",
+});
diff --git a/packages/http-specs/specs/type/file/main.tsp b/packages/http-specs/specs/type/file/main.tsp
index 70b29440539..4631b10c086 100644
--- a/packages/http-specs/specs/type/file/main.tsp
+++ b/packages/http-specs/specs/type/file/main.tsp
@@ -8,18 +8,6 @@ using Spector;
 @scenarioService("/type/file")
 namespace Type.File;
 
-// Note: Using TypeSpec.Http.File fully qualified because "File" in the namespace name
-// would shadow the File type from the Http namespace.
-
-// Define custom File types for testing
-model PngImageFile extends TypeSpec.Http.File {
-  contentType: "image/png";
-}
-
-model ImageFile extends TypeSpec.Http.File {
-  contentType: "image/png" | "image/jpeg";
-}
-
 /**
  * Test File as request and response body with specific content type
  */
@@ -34,7 +22,7 @@ namespace Body {
     """)
   @post
   @route("/request/specific-content-type")
-  op uploadFileSpecificContentType(@bodyRoot file: PngImageFile): NoContentResponse;
+  op uploadFileSpecificContentType(@bodyRoot file: Http.File<"image/png">): NoContentResponse;
 
   @scenario
   @scenarioDoc("""
@@ -45,7 +33,7 @@ namespace Body {
     """)
   @get
   @route("/response/specific-content-type")
-  op downloadFileSpecificContentType(): PngImageFile;
+  op downloadFileSpecificContentType(): Http.File<"image/png">;
 
   @scenario
   @scenarioDoc("""
@@ -57,7 +45,9 @@ namespace Body {
     """)
   @post
   @route("/request/multiple-content-types")
-  op uploadFileMultipleContentTypes(@bodyRoot file: ImageFile): NoContentResponse;
+  op uploadFileMultipleContentTypes(
+    @bodyRoot file: Http.File<"image/png" | "image/jpeg">,
+  ): NoContentResponse;
 
   @scenario
   @scenarioDoc("""
@@ -69,7 +59,7 @@ namespace Body {
     """)
   @get
   @route("/response/multiple-content-types")
-  op downloadFileMultipleContentTypes(): ImageFile;
+  op downloadFileMultipleContentTypes(): Http.File<"image/png" | "image/jpeg">;
 
   @scenario
   @scenarioDoc("""
@@ -80,7 +70,7 @@ namespace Body {
     """)
   @post
   @route("/request/default-content-type")
-  op uploadFileDefaultContentType(@bodyRoot file: TypeSpec.Http.File): NoContentResponse;
+  op uploadFileDefaultContentType(@bodyRoot file: Http.File): NoContentResponse;
 
   @scenario
   @scenarioDoc("""
@@ -91,132 +81,5 @@ namespace Body {
     """)
   @get
   @route("/response/default-content-type")
-  op downloadFileDefaultContentType(): TypeSpec.Http.File;
-}
-
-/**
- * Test File in multipart form data scenarios
- */
-@route("/multipart")
-namespace MultiPart {
-  model FileWithSpecificContentType extends TypeSpec.Http.File {
-    filename: string;
-    contentType: "image/png";
-  }
-
-  model FileWithMultipleContentTypes extends TypeSpec.Http.File {
-    filename: string;
-    contentType: "image/png" | "image/jpeg";
-  }
-
-  model FileWithRequiredMetadata extends TypeSpec.Http.File {
-    filename: string;
-    contentType: string;
-  }
-
-  @scenario
-  @scenarioDoc("""
-    Test File type in multipart form data with specific content type.
-    Expected request:
-    ```
-    POST /multipart/specific-content-type HTTP/1.1
-    Content-Type: multipart/form-data; boundary=abcde12345
-    
-    --abcde12345
-    Content-Disposition: form-data; name="file"; filename="image.png"
-    Content-Type: image/png
-    
-    {…file content of image.png…}
-    --abcde12345--
-    ```
-    """)
-  @post
-  @route("/specific-content-type")
-  op uploadFileSpecificContentType(
-    @header contentType: "multipart/form-data",
-    @multipartBody body: {
-      file: HttpPart<FileWithSpecificContentType>;
-    },
-  ): NoContentResponse;
-
-  @scenario
-  @scenarioDoc("""
-    Test File type in multipart form data with multiple allowed content types.
-    Client should send image/png.
-    Expected request:
-    ```
-    POST /multipart/multiple-content-types HTTP/1.1
-    Content-Type: multipart/form-data; boundary=abcde12345
-    
-    --abcde12345
-    Content-Disposition: form-data; name="file"; filename="image.png"
-    Content-Type: image/png
-    
-    {…file content of image.png…}
-    --abcde12345--
-    ```
-    """)
-  @post
-  @route("/multiple-content-types")
-  op uploadFileMultipleContentTypes(
-    @header contentType: "multipart/form-data",
-    @multipartBody body: {
-      file: HttpPart<FileWithMultipleContentTypes>;
-    },
-  ): NoContentResponse;
-
-  @scenario
-  @scenarioDoc("""
-    Test File type in multipart form data with required content type metadata.
-    Expected request:
-    ```
-    POST /multipart/required-content-type HTTP/1.1
-    Content-Type: multipart/form-data; boundary=abcde12345
-    
-    --abcde12345
-    Content-Disposition: form-data; name="file"; filename="image.png"
-    Content-Type: application/octet-stream
-    
-    {…file content of image.png…}
-    --abcde12345--
-    ```
-    """)
-  @post
-  @route("/required-content-type")
-  op uploadFileRequiredContentType(
-    @header contentType: "multipart/form-data",
-    @multipartBody body: {
-      file: HttpPart<FileWithRequiredMetadata>;
-    },
-  ): NoContentResponse;
-
-  @scenario
-  @scenarioDoc("""
-    Test multiple File instances in multipart form data.
-    Expected request:
-    ```
-    POST /multipart/file-array HTTP/1.1
-    Content-Type: multipart/form-data; boundary=abcde12345
-    
-    --abcde12345
-    Content-Disposition: form-data; name="files"; filename="image1.png"
-    Content-Type: image/png
-    
-    {…file content of image.png…}
-    --abcde12345
-    Content-Disposition: form-data; name="files"; filename="image2.png"
-    Content-Type: image/png
-    
-    {…file content of image.png…}
-    --abcde12345--
-    ```
-    """)
-  @post
-  @route("/file-array")
-  op uploadFileArray(
-    @header contentType: "multipart/form-data",
-    @multipartBody body: {
-      files: HttpPart<FileWithSpecificContentType>[];
-    },
-  ): NoContentResponse;
+  op downloadFileDefaultContentType(): Http.File;
 }
diff --git a/packages/http-specs/specs/type/file/mockapi.ts b/packages/http-specs/specs/type/file/mockapi.ts
index b1d5c889a2d..fcc260b1c9c 100644
--- a/packages/http-specs/specs/type/file/mockapi.ts
+++ b/packages/http-specs/specs/type/file/mockapi.ts
@@ -13,21 +13,6 @@ function checkFileContent(req: MockRequest, expectedFile: Buffer) {
   req.expect.rawBodyEquals(expectedFile);
 }
 
-// Helper function to check file in multipart
-function checkMultipartFile(
-  req: MockRequest,
-  file: Record<string, any>,
-  expectedContent: Buffer,
-  expectedContentType: string,
-  expectedFileName?: string,
-) {
-  req.expect.deepEqual(file.mimetype, expectedContentType);
-  req.expect.deepEqual(file.buffer, expectedContent);
-  if (expectedFileName) {
-    req.expect.deepEqual(file.originalname, expectedFileName);
-  }
-}
-
 // Body tests - Request with specific content type
 Scenarios.Type_File_Body_uploadFileSpecificContentType = passOnSuccess({
   uri: "/type/file/body/request/specific-content-type",
@@ -179,113 +164,3 @@ Scenarios.Type_File_Body_downloadFileDefaultContentType = passOnSuccess({
   },
   kind: "MockApiDefinition",
 });
-
-// Multipart tests - Specific content type
-Scenarios.Type_File_MultiPart_uploadFileSpecificContentType = passOnSuccess({
-  uri: "/type/file/multipart/specific-content-type",
-  method: "post",
-  request: {
-    headers: {
-      "content-type": "multipart/form-data",
-    },
-  },
-  response: {
-    status: 204,
-  },
-  handler(req: MockRequest) {
-    if (req.files instanceof Array && req.files.length === 1) {
-      const file = req.files[0];
-      req.expect.deepEqual(file.fieldname, "file");
-      checkMultipartFile(req, file, pngFile, "image/png", "image.png");
-      return { status: 204 };
-    } else {
-      throw new ValidationError("Expected exactly one file", "1 file", req.files);
-    }
-  },
-  kind: "MockApiDefinition",
-});
-
-// Multipart tests - Multiple content types
-Scenarios.Type_File_MultiPart_uploadFileMultipleContentTypes = passOnSuccess({
-  uri: "/type/file/multipart/multiple-content-types",
-  method: "post",
-  request: {
-    headers: {
-      "content-type": "multipart/form-data",
-    },
-  },
-  response: {
-    status: 204,
-  },
-  handler(req: MockRequest) {
-    if (req.files instanceof Array && req.files.length === 1) {
-      const file = req.files[0];
-      req.expect.deepEqual(file.fieldname, "file");
-      // Client should send image/png (one of the allowed types)
-      if (file.mimetype !== "image/png" && file.mimetype !== "image/jpeg") {
-        throw new ValidationError(
-          "Expected mimetype to be image/png or image/jpeg",
-          "image/png or image/jpeg",
-          file.mimetype,
-        );
-      }
-      req.expect.deepEqual(file.buffer, pngFile);
-      req.expect.deepEqual(file.originalname, "image.png");
-      return { status: 204 };
-    } else {
-      throw new ValidationError("Expected exactly one file", "1 file", req.files);
-    }
-  },
-  kind: "MockApiDefinition",
-});
-
-// Multipart tests - Required content type
-Scenarios.Type_File_MultiPart_uploadFileRequiredContentType = passOnSuccess({
-  uri: "/type/file/multipart/required-content-type",
-  method: "post",
-  request: {
-    headers: {
-      "content-type": "multipart/form-data",
-    },
-  },
-  response: {
-    status: 204,
-  },
-  handler(req: MockRequest) {
-    if (req.files instanceof Array && req.files.length === 1) {
-      const file = req.files[0];
-      req.expect.deepEqual(file.fieldname, "file");
-      checkMultipartFile(req, file, pngFile, "application/octet-stream", "image.png");
-      return { status: 204 };
-    } else {
-      throw new ValidationError("Expected exactly one file", "1 file", req.files);
-    }
-  },
-  kind: "MockApiDefinition",
-});
-
-// Multipart tests - File array
-Scenarios.Type_File_MultiPart_uploadFileArray = passOnSuccess({
-  uri: "/type/file/multipart/file-array",
-  method: "post",
-  request: {
-    headers: {
-      "content-type": "multipart/form-data",
-    },
-  },
-  response: {
-    status: 204,
-  },
-  handler(req: MockRequest) {
-    if (req.files instanceof Array && req.files.length === 2) {
-      for (const file of req.files) {
-        req.expect.deepEqual(file.fieldname, "files");
-        checkMultipartFile(req, file, pngFile, "image/png");
-      }
-      return { status: 204 };
-    } else {
-      throw new ValidationError("Expected exactly two files", "2 files", req.files);
-    }
-  },
-  kind: "MockApiDefinition",
-});
diff --git a/packages/http-specs/specs/type/file/test-inline.tsp b/packages/http-specs/specs/type/file/test-inline.tsp
new file mode 100644
index 00000000000..d79977fd36d
--- /dev/null
+++ b/packages/http-specs/specs/type/file/test-inline.tsp
@@ -0,0 +1,8 @@
+import "@typespec/http";
+
+using Http;
+
+namespace Test.FileInline;
+
+@post
+op upload(@bodyRoot file: Http.File<"image/png">): void;

From a69b9f8cbb327e2edebd075815ca2c8e56d6b889 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 16:18:34 +0000
Subject: [PATCH 05/10] Remove accidentally committed test file

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/specs/type/file/test-inline.tsp | 8 --------
 1 file changed, 8 deletions(-)
 delete mode 100644 packages/http-specs/specs/type/file/test-inline.tsp

diff --git a/packages/http-specs/specs/type/file/test-inline.tsp b/packages/http-specs/specs/type/file/test-inline.tsp
deleted file mode 100644
index d79977fd36d..00000000000
--- a/packages/http-specs/specs/type/file/test-inline.tsp
+++ /dev/null
@@ -1,8 +0,0 @@
-import "@typespec/http";
-
-using Http;
-
-namespace Test.FileInline;
-
-@post
-op upload(@bodyRoot file: Http.File<"image/png">): void;

From 107bfbd35181d665228a163c0eb138d63938e860 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 16:35:40 +0000
Subject: [PATCH 06/10] Address feedback: use inline File type, rename to
 FileWithRequiredFilename, remove FileWithRequiredMetadata

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 .../specs/payload/multipart/main.tsp          | 53 +++----------------
 .../specs/payload/multipart/mockapi.ts        | 39 ++------------
 2 files changed, 11 insertions(+), 81 deletions(-)

diff --git a/packages/http-specs/specs/payload/multipart/main.tsp b/packages/http-specs/specs/payload/multipart/main.tsp
index ea8eee08dc0..062a8b12e00 100644
--- a/packages/http-specs/specs/payload/multipart/main.tsp
+++ b/packages/http-specs/specs/payload/multipart/main.tsp
@@ -611,19 +611,8 @@ namespace FormData {
 
   @route("/file")
   namespace File {
-    model FileWithSpecificContentType extends TypeSpec.Http.File {
+    model FileWithRequiredFilename extends TypeSpec.Http.File<"image/png"> {
       filename: string;
-      contentType: "image/png";
-    }
-
-    model FileWithMultipleContentTypes extends TypeSpec.Http.File {
-      filename: string;
-      contentType: "image/png" | "image/jpeg";
-    }
-
-    model FileWithRequiredMetadata extends TypeSpec.Http.File {
-      filename: string;
-      contentType: string;
     }
 
     @scenario
@@ -647,17 +636,16 @@ namespace FormData {
     op uploadFileSpecificContentType(
       @header contentType: "multipart/form-data",
       @multipartBody body: {
-        file: HttpPart<FileWithSpecificContentType>;
+        file: HttpPart<TypeSpec.Http.File<"image/png">>;
       },
     ): NoContentResponse;
 
     @scenario
     @scenarioDoc("""
-      Test File type in multipart form data with multiple allowed content types.
-      Client should send image/png.
+      Test File type in multipart form data with required filename.
       Expected request:
       ```
-      POST /multipart/form-data/file/multiple-content-types HTTP/1.1
+      POST /multipart/form-data/file/required-filename HTTP/1.1
       Content-Type: multipart/form-data; boundary=abcde12345
       
       --abcde12345
@@ -669,36 +657,11 @@ namespace FormData {
       ```
       """)
     @post
-    @route("/multiple-content-types")
-    op uploadFileMultipleContentTypes(
-      @header contentType: "multipart/form-data",
-      @multipartBody body: {
-        file: HttpPart<FileWithMultipleContentTypes>;
-      },
-    ): NoContentResponse;
-
-    @scenario
-    @scenarioDoc("""
-      Test File type in multipart form data with required content type metadata.
-      Expected request:
-      ```
-      POST /multipart/form-data/file/required-content-type HTTP/1.1
-      Content-Type: multipart/form-data; boundary=abcde12345
-      
-      --abcde12345
-      Content-Disposition: form-data; name="file"; filename="image.png"
-      Content-Type: application/octet-stream
-      
-      {…file content of image.png…}
-      --abcde12345--
-      ```
-      """)
-    @post
-    @route("/required-content-type")
-    op uploadFileRequiredContentType(
+    @route("/required-filename")
+    op uploadFileRequiredFilename(
       @header contentType: "multipart/form-data",
       @multipartBody body: {
-        file: HttpPart<FileWithRequiredMetadata>;
+        file: HttpPart<FileWithRequiredFilename>;
       },
     ): NoContentResponse;
 
@@ -728,7 +691,7 @@ namespace FormData {
     op uploadFileArray(
       @header contentType: "multipart/form-data",
       @multipartBody body: {
-        files: HttpPart<FileWithSpecificContentType>[];
+        files: HttpPart<TypeSpec.Http.File<"image/png">>[];
       },
     ): NoContentResponse;
   }
diff --git a/packages/http-specs/specs/payload/multipart/mockapi.ts b/packages/http-specs/specs/payload/multipart/mockapi.ts
index ee7f42e6cb6..3ac7dbda70a 100644
--- a/packages/http-specs/specs/payload/multipart/mockapi.ts
+++ b/packages/http-specs/specs/payload/multipart/mockapi.ts
@@ -456,8 +456,8 @@ Scenarios.Payload_MultiPart_FormData_File_uploadFileSpecificContentType = passOn
   kind: "MockApiDefinition",
 });
 
-Scenarios.Payload_MultiPart_FormData_File_uploadFileMultipleContentTypes = passOnSuccess({
-  uri: "/multipart/form-data/file/multiple-content-types",
+Scenarios.Payload_MultiPart_FormData_File_uploadFileRequiredFilename = passOnSuccess({
+  uri: "/multipart/form-data/file/required-filename",
   method: "post",
   request: {
     headers: {
@@ -470,40 +470,7 @@ Scenarios.Payload_MultiPart_FormData_File_uploadFileMultipleContentTypes = passO
   handler(req: MockRequest) {
     if (req.files instanceof Array && req.files.length === 1) {
       const file = req.files[0];
-      // Client should send image/png (one of the allowed types)
-      if (file.mimetype !== "image/png" && file.mimetype !== "image/jpeg") {
-        throw new ValidationError(
-          "Expected mimetype to be image/png or image/jpeg",
-          "image/png or image/jpeg",
-          file.mimetype,
-        );
-      }
-      req.expect.deepEqual(file.fieldname, "file");
-      req.expect.deepEqual(file.buffer, pngFile);
-      req.expect.deepEqual(file.originalname, "image.png");
-      return { status: 204 };
-    } else {
-      throw new ValidationError("Expected exactly one file", "1 file", req.files);
-    }
-  },
-  kind: "MockApiDefinition",
-});
-
-Scenarios.Payload_MultiPart_FormData_File_uploadFileRequiredContentType = passOnSuccess({
-  uri: "/multipart/form-data/file/required-content-type",
-  method: "post",
-  request: {
-    headers: {
-      "content-type": "multipart/form-data",
-    },
-  },
-  response: {
-    status: 204,
-  },
-  handler(req: MockRequest) {
-    if (req.files instanceof Array && req.files.length === 1) {
-      const file = req.files[0];
-      checkMultipartFile(req, file, pngFile, "application/octet-stream", "file", "image.png");
+      checkMultipartFile(req, file, pngFile, "image/png", "file", "image.png");
       return { status: 204 };
     } else {
       throw new ValidationError("Expected exactly one file", "1 file", req.files);

From aa7271116d581df165677e453a915dfe732e379f Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 16:48:42 +0000
Subject: [PATCH 07/10] Add tests for File with application/json content type

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/spec-summary.md           | 52 +++++++++----------
 packages/http-specs/specs/type/file/main.tsp  | 22 ++++++++
 .../http-specs/specs/type/file/mockapi.ts     | 45 ++++++++++++++++
 3 files changed, 93 insertions(+), 26 deletions(-)

diff --git a/packages/http-specs/spec-summary.md b/packages/http-specs/spec-summary.md
index 7d445b29ea3..1a74bf9766b 100644
--- a/packages/http-specs/spec-summary.md
+++ b/packages/http-specs/spec-summary.md
@@ -2058,7 +2058,7 @@ Test multiple File instances in multipart form data.
 Expected request:
 
 ```
-POST /multipart/file/file-array HTTP/1.1
+POST /multipart/form-data/file/file-array HTTP/1.1
 Content-Type: multipart/form-data; boundary=abcde12345
 
 --abcde12345
@@ -2074,16 +2074,15 @@ Content-Type: image/png
 --abcde12345--
 ```
 
-### Payload_MultiPart_FormData_File_uploadFileMultipleContentTypes
+### Payload_MultiPart_FormData_File_uploadFileRequiredFilename
 
-- Endpoint: `post /multipart/form-data/file/multiple-content-types`
+- Endpoint: `post /multipart/form-data/file/required-filename`
 
-Test File type in multipart form data with multiple allowed content types.
-Client should send image/png.
+Test File type in multipart form data with required filename.
 Expected request:
 
 ```
-POST /multipart/file/multiple-content-types HTTP/1.1
+POST /multipart/form-data/file/required-filename HTTP/1.1
 Content-Type: multipart/form-data; boundary=abcde12345
 
 --abcde12345
@@ -2094,25 +2093,6 @@ Content-Type: image/png
 --abcde12345--
 ```
 
-### Payload_MultiPart_FormData_File_uploadFileRequiredContentType
-
-- Endpoint: `post /multipart/form-data/file/required-content-type`
-
-Test File type in multipart form data with required content type metadata.
-Expected request:
-
-```
-POST /multipart/file/required-content-type HTTP/1.1
-Content-Type: multipart/form-data; boundary=abcde12345
-
---abcde12345
-Content-Disposition: form-data; name="file"; filename="image.png"
-Content-Type: application/octet-stream
-
-{…file content of image.png…}
---abcde12345--
-```
-
 ### Payload_MultiPart_FormData_File_uploadFileSpecificContentType
 
 - Endpoint: `post /multipart/form-data/file/specific-content-type`
@@ -2121,7 +2101,7 @@ Test File type in multipart form data with specific content type.
 Expected request:
 
 ```
-POST /multipart/file/specific-content-type HTTP/1.1
+POST /multipart/form-data/file/specific-content-type HTTP/1.1
 Content-Type: multipart/form-data; boundary=abcde12345
 
 --abcde12345
@@ -5302,6 +5282,16 @@ Expected response:
 - Content-Type header: application/octet-stream
 - Body: binary content matching packages/http-specs/assets/image.png
 
+### Type_File_Body_downloadFileJsonContentType
+
+- Endpoint: `get /type/file/body/response/json-content-type`
+
+Test File type as response body with JSON content type.
+Expected response:
+
+- Content-Type header: application/json
+- Body: JSON content with file data
+
 ### Type_File_Body_downloadFileMultipleContentTypes
 
 - Endpoint: `get /type/file/body/response/multiple-content-types`
@@ -5333,6 +5323,16 @@ Expected request:
 - Content-Type header: application/octet-stream (or not specified)
 - Body: binary content matching packages/http-specs/assets/image.png
 
+### Type_File_Body_uploadFileJsonContentType
+
+- Endpoint: `post /type/file/body/request/json-content-type`
+
+Test File type as request body with JSON content type.
+Expected request:
+
+- Content-Type header: application/json
+- Body: JSON content with file data
+
 ### Type_File_Body_uploadFileMultipleContentTypes
 
 - Endpoint: `post /type/file/body/request/multiple-content-types`
diff --git a/packages/http-specs/specs/type/file/main.tsp b/packages/http-specs/specs/type/file/main.tsp
index 4631b10c086..ae445eb9c98 100644
--- a/packages/http-specs/specs/type/file/main.tsp
+++ b/packages/http-specs/specs/type/file/main.tsp
@@ -24,6 +24,28 @@ namespace Body {
   @route("/request/specific-content-type")
   op uploadFileSpecificContentType(@bodyRoot file: Http.File<"image/png">): NoContentResponse;
 
+  @scenario
+  @scenarioDoc("""
+    Test File type as request body with JSON content type.
+    Expected request:
+    - Content-Type header: application/json
+    - Body: JSON content with file data
+    """)
+  @post
+  @route("/request/json-content-type")
+  op uploadFileJsonContentType(@bodyRoot file: Http.File<"application/json">): NoContentResponse;
+
+  @scenario
+  @scenarioDoc("""
+    Test File type as response body with JSON content type.
+    Expected response:
+    - Content-Type header: application/json
+    - Body: JSON content with file data
+    """)
+  @get
+  @route("/response/json-content-type")
+  op downloadFileJsonContentType(): Http.File<"application/json">;
+
   @scenario
   @scenarioDoc("""
     Test File type as response body with specific content type.
diff --git a/packages/http-specs/specs/type/file/mockapi.ts b/packages/http-specs/specs/type/file/mockapi.ts
index fcc260b1c9c..42fb499aaf7 100644
--- a/packages/http-specs/specs/type/file/mockapi.ts
+++ b/packages/http-specs/specs/type/file/mockapi.ts
@@ -34,6 +34,51 @@ Scenarios.Type_File_Body_uploadFileSpecificContentType = passOnSuccess({
   kind: "MockApiDefinition",
 });
 
+// Body tests - Request with JSON content type
+Scenarios.Type_File_Body_uploadFileJsonContentType = passOnSuccess({
+  uri: "/type/file/body/request/json-content-type",
+  method: "post",
+  request: {
+    body: {
+      contentType: "application/json",
+      rawContent: JSON.stringify({ message: "test file content" }),
+    },
+  },
+  response: {
+    status: 204,
+  },
+  handler(req: MockRequest) {
+    req.expect.containsHeader("content-type", "application/json");
+    req.expect.rawBodyEquals(JSON.stringify({ message: "test file content" }));
+    return { status: 204 };
+  },
+  kind: "MockApiDefinition",
+});
+
+// Body tests - Response with JSON content type
+Scenarios.Type_File_Body_downloadFileJsonContentType = passOnSuccess({
+  uri: "/type/file/body/response/json-content-type",
+  method: "get",
+  request: {},
+  response: {
+    status: 200,
+    body: {
+      contentType: "application/json",
+      rawContent: JSON.stringify({ message: "test file content" }),
+    },
+  },
+  handler(req: MockRequest) {
+    return {
+      status: 200,
+      body: {
+        contentType: "application/json",
+        rawContent: JSON.stringify({ message: "test file content" }),
+      },
+    };
+  },
+  kind: "MockApiDefinition",
+});
+
 // Body tests - Response with specific content type
 Scenarios.Type_File_Body_downloadFileSpecificContentType = passOnSuccess({
   uri: "/type/file/body/response/specific-content-type",

From 0994f42868417b445e915f5cb08bd1fc15c0f17c Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 17:57:01 +0000
Subject: [PATCH 08/10] Fix default content type tests to expect image/png
 instead of application/octet-stream

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/spec-summary.md            | 10 ++++++----
 packages/http-specs/specs/type/file/main.tsp   | 10 ++++++----
 packages/http-specs/specs/type/file/mockapi.ts | 18 ++++++------------
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/packages/http-specs/spec-summary.md b/packages/http-specs/spec-summary.md
index 1a74bf9766b..32c198bfff1 100644
--- a/packages/http-specs/spec-summary.md
+++ b/packages/http-specs/spec-summary.md
@@ -5276,10 +5276,11 @@ Expect to handle an unknown value. Mock api expect to receive 'Weekend'
 
 - Endpoint: `get /type/file/body/response/default-content-type`
 
-Test File type as response body with unspecified content type (defaults to application/octet-stream).
+Test File type as response body with unspecified content type.
+The File type accepts any content type. For testing, server will return image/png.
 Expected response:
 
-- Content-Type header: application/octet-stream
+- Content-Type header: image/png
 - Body: binary content matching packages/http-specs/assets/image.png
 
 ### Type_File_Body_downloadFileJsonContentType
@@ -5317,10 +5318,11 @@ Expected response:
 
 - Endpoint: `post /type/file/body/request/default-content-type`
 
-Test File type as request body with unspecified content type (defaults to application/octet-stream).
+Test File type as request body with unspecified content type.
+The File type accepts any content type. For testing, sender will use image/png.
 Expected request:
 
-- Content-Type header: application/octet-stream (or not specified)
+- Content-Type header: image/png
 - Body: binary content matching packages/http-specs/assets/image.png
 
 ### Type_File_Body_uploadFileJsonContentType
diff --git a/packages/http-specs/specs/type/file/main.tsp b/packages/http-specs/specs/type/file/main.tsp
index ae445eb9c98..a977b8e6a47 100644
--- a/packages/http-specs/specs/type/file/main.tsp
+++ b/packages/http-specs/specs/type/file/main.tsp
@@ -85,9 +85,10 @@ namespace Body {
 
   @scenario
   @scenarioDoc("""
-    Test File type as request body with unspecified content type (defaults to application/octet-stream).
+    Test File type as request body with unspecified content type.
+    The File type accepts any content type. For testing, sender will use image/png.
     Expected request:
-    - Content-Type header: application/octet-stream (or not specified)
+    - Content-Type header: image/png
     - Body: binary content matching packages/http-specs/assets/image.png
     """)
   @post
@@ -96,9 +97,10 @@ namespace Body {
 
   @scenario
   @scenarioDoc("""
-    Test File type as response body with unspecified content type (defaults to application/octet-stream).
+    Test File type as response body with unspecified content type.
+    The File type accepts any content type. For testing, server will return image/png.
     Expected response:
-    - Content-Type header: application/octet-stream
+    - Content-Type header: image/png
     - Body: binary content matching packages/http-specs/assets/image.png
     """)
   @get
diff --git a/packages/http-specs/specs/type/file/mockapi.ts b/packages/http-specs/specs/type/file/mockapi.ts
index 42fb499aaf7..6d3c8d9b6d8 100644
--- a/packages/http-specs/specs/type/file/mockapi.ts
+++ b/packages/http-specs/specs/type/file/mockapi.ts
@@ -163,7 +163,7 @@ Scenarios.Type_File_Body_uploadFileDefaultContentType = passOnSuccess({
   method: "post",
   request: {
     body: {
-      contentType: "application/octet-stream",
+      contentType: "image/png",
       rawContent: pngFile,
     },
   },
@@ -171,15 +171,8 @@ Scenarios.Type_File_Body_uploadFileDefaultContentType = passOnSuccess({
     status: 204,
   },
   handler(req: MockRequest) {
-    // Content-Type should be application/octet-stream or not specified
-    const contentType = req.headers["content-type"];
-    if (contentType && contentType !== "application/octet-stream") {
-      throw new ValidationError(
-        "Expected content-type to be application/octet-stream or not specified",
-        "application/octet-stream",
-        contentType,
-      );
-    }
+    // File type accepts any content type, but for testing we expect image/png
+    req.expect.containsHeader("content-type", "image/png");
     checkFileContent(req, pngFile);
     return { status: 204 };
   },
@@ -194,15 +187,16 @@ Scenarios.Type_File_Body_downloadFileDefaultContentType = passOnSuccess({
   response: {
     status: 200,
     body: {
-      contentType: "application/octet-stream",
+      contentType: "image/png",
       rawContent: pngFile,
     },
   },
   handler(req: MockRequest) {
+    // File type accepts any content type, but for testing we return image/png
     return {
       status: 200,
       body: {
-        contentType: "application/octet-stream",
+        contentType: "image/png",
         rawContent: pngFile,
       },
     };

From 651bc95ef62a413ed3641a9d5a53f68b1f0ff1a5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 18:50:33 +0000
Subject: [PATCH 09/10] Run pnpm format to fix code formatting

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 packages/http-specs/specs/type/file/mockapi.ts | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/packages/http-specs/specs/type/file/mockapi.ts b/packages/http-specs/specs/type/file/mockapi.ts
index 6d3c8d9b6d8..41e6be7ef1d 100644
--- a/packages/http-specs/specs/type/file/mockapi.ts
+++ b/packages/http-specs/specs/type/file/mockapi.ts
@@ -1,9 +1,4 @@
-import {
-  MockRequest,
-  passOnSuccess,
-  ScenarioMockApi,
-  ValidationError,
-} from "@typespec/spec-api";
+import { MockRequest, passOnSuccess, ScenarioMockApi, ValidationError } from "@typespec/spec-api";
 import { pngFile } from "../../helper.js";
 
 export const Scenarios: Record<string, ScenarioMockApi> = {};

From 4d4afdabef3fed9b2d5f017a61e34286970bbff2 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 29 Jan 2026 19:05:04 +0000
Subject: [PATCH 10/10] Add changelog entry for File type spector tests

Co-authored-by: timotheeguerin <1031227+timotheeguerin@users.noreply.github.com>
---
 ...add-spector-test-file-content-type-2026-0-29-19-4-24.md | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 .chronus/changes/copilot-add-spector-test-file-content-type-2026-0-29-19-4-24.md

diff --git a/.chronus/changes/copilot-add-spector-test-file-content-type-2026-0-29-19-4-24.md b/.chronus/changes/copilot-add-spector-test-file-content-type-2026-0-29-19-4-24.md
new file mode 100644
index 00000000000..c62fc041965
--- /dev/null
+++ b/.chronus/changes/copilot-add-spector-test-file-content-type-2026-0-29-19-4-24.md
@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@typespec/http-specs"
+---
+
+Add Spector tests for File type with various content types (body and multipart)
\ No newline at end of file