diff --git a/doc/SPEC-implementation.md b/doc/SPEC-implementation.md
index 5c5af615..ce94ec6a 100644
--- a/doc/SPEC-implementation.md
+++ b/doc/SPEC-implementation.md
@@ -392,6 +392,12 @@ Operational policy:
   - `issue_id` uuid fk not null
   - `asset_id` uuid fk not null
   - `issue_comment_id` uuid fk null
+- V1 attachment serving contract:
+  - Default upload allowlist includes common images, PDF, plain text/markdown/JSON/CSV/HTML, ZIP, and video artifacts (`video/mp4`, `video/webm`, `video/quicktime`).
+  - Attachment reads are company-scoped and expose stable path metadata: `contentPath`/`openPath` for inline-safe viewing and `downloadPath` for forced download.
+  - Inline-safe responses use `Content-Disposition: inline`; unsafe types and explicit download requests use `attachment`.
+  - Video attachments are inline-safe and support single `Range: bytes=start-end` requests with `206`, `Content-Range`, and `Accept-Ranges: bytes` for browser playback/seeking.
+- Attachment-backed artifact work products use `type: "artifact"`, `provider: "paperclip"`, and metadata with `attachmentId`, `contentType`, `byteSize`, `contentPath`, `openPath`, `downloadPath`, and optional `originalFilename`.
 
 ## 7.15 `documents` + `document_revisions` + `issue_documents`
 
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index ab8cf59a..51e7f20d 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -411,6 +411,7 @@ export type {
   DocumentTextProjection,
   DocumentTextRange,
   UpdateDocumentAnnotationThreadRequest,
+  AttachmentArtifactWorkProductMetadata,
   Issue,
   IssueAssigneeAdapterOverrides,
   IssueBlockerAttention,
@@ -921,6 +922,7 @@ export {
   createIssueAttachmentMetadataSchema,
   createIssueWorkProductSchema,
   updateIssueWorkProductSchema,
+  attachmentArtifactWorkProductMetadataSchema,
   issueWorkProductTypeSchema,
   issueWorkProductStatusSchema,
   issueWorkProductReviewStateSchema,
diff --git a/packages/shared/src/types/index.ts b/packages/shared/src/types/index.ts
index 8da1aba1..e3c80954 100644
--- a/packages/shared/src/types/index.ts
+++ b/packages/shared/src/types/index.ts
@@ -172,6 +172,7 @@ export type {
   IssueWorkProductProvider,
   IssueWorkProductStatus,
   IssueWorkProductReviewState,
+  AttachmentArtifactWorkProductMetadata,
 } from "./work-product.js";
 export type {
   Issue,
diff --git a/packages/shared/src/types/issue.ts b/packages/shared/src/types/issue.ts
index 9637d977..46ef3010 100644
--- a/packages/shared/src/types/issue.ts
+++ b/packages/shared/src/types/issue.ts
@@ -845,4 +845,6 @@ export interface IssueAttachment {
   createdAt: Date;
   updatedAt: Date;
   contentPath: string;
+  openPath?: string;
+  downloadPath?: string;
 }
diff --git a/packages/shared/src/types/work-product.ts b/packages/shared/src/types/work-product.ts
index 297a2463..21ad3675 100644
--- a/packages/shared/src/types/work-product.ts
+++ b/packages/shared/src/types/work-product.ts
@@ -53,3 +53,13 @@ export interface IssueWorkProduct {
   createdAt: Date;
   updatedAt: Date;
 }
+
+export interface AttachmentArtifactWorkProductMetadata {
+  attachmentId: string;
+  contentType: string;
+  byteSize: number;
+  contentPath: string;
+  openPath: string;
+  downloadPath: string;
+  originalFilename?: string | null;
+}
diff --git a/packages/shared/src/validators/index.ts b/packages/shared/src/validators/index.ts
index fb4838cf..c424e711 100644
--- a/packages/shared/src/validators/index.ts
+++ b/packages/shared/src/validators/index.ts
@@ -282,6 +282,7 @@ export {
 export {
   createIssueWorkProductSchema,
   updateIssueWorkProductSchema,
+  attachmentArtifactWorkProductMetadataSchema,
   issueWorkProductTypeSchema,
   issueWorkProductStatusSchema,
   issueWorkProductReviewStateSchema,
diff --git a/packages/shared/src/validators/work-product.test.ts b/packages/shared/src/validators/work-product.test.ts
new file mode 100644
index 00000000..214a9637
--- /dev/null
+++ b/packages/shared/src/validators/work-product.test.ts
@@ -0,0 +1,19 @@
+import { describe, expect, it } from "vitest";
+import { attachmentArtifactWorkProductMetadataSchema } from "./work-product.js";
+
+describe("attachmentArtifactWorkProductMetadataSchema", () => {
+  it("accepts the attachment-backed artifact metadata contract", () => {
+    const parsed = attachmentArtifactWorkProductMetadataSchema.parse({
+      attachmentId: "11111111-1111-4111-8111-111111111111",
+      contentType: "video/mp4",
+      byteSize: 1234,
+      contentPath: "/api/attachments/11111111-1111-4111-8111-111111111111/content",
+      openPath: "/api/attachments/11111111-1111-4111-8111-111111111111/content",
+      downloadPath: "/api/attachments/11111111-1111-4111-8111-111111111111/content?download=1",
+      originalFilename: "demo.mp4",
+    });
+
+    expect(parsed.contentType).toBe("video/mp4");
+    expect(parsed.downloadPath).toContain("download=1");
+  });
+});
diff --git a/packages/shared/src/validators/work-product.ts b/packages/shared/src/validators/work-product.ts
index b068b9c9..ca8d3852 100644
--- a/packages/shared/src/validators/work-product.ts
+++ b/packages/shared/src/validators/work-product.ts
@@ -29,6 +29,18 @@ export const issueWorkProductReviewStateSchema = z.enum([
   "changes_requested",
 ]);
 
+export const attachmentArtifactWorkProductMetadataSchema = z.object({
+  attachmentId: z.string().uuid(),
+  contentType: z.string().min(1),
+  byteSize: z.number().int().nonnegative(),
+  contentPath: z.string().min(1),
+  openPath: z.string().min(1),
+  downloadPath: z.string().min(1),
+  originalFilename: z.string().optional().nullable(),
+});
+
+export type AttachmentArtifactWorkProductMetadata = z.infer<typeof attachmentArtifactWorkProductMetadataSchema>;
+
 export const createIssueWorkProductSchema = z.object({
   projectId: z.string().uuid().optional().nullable(),
   executionWorkspaceId: z.string().uuid().optional().nullable(),
diff --git a/server/src/__tests__/attachment-types.test.ts b/server/src/__tests__/attachment-types.test.ts
index 7dfc34d2..a1508cf0 100644
--- a/server/src/__tests__/attachment-types.test.ts
+++ b/server/src/__tests__/attachment-types.test.ts
@@ -112,7 +112,7 @@ describe("normalizeContentType", () => {
 
 describe("isInlineAttachmentContentType", () => {
   it("allows the configured inline-safe types", () => {
-    for (const contentType of ["image/png", "image/svg+xml", "application/pdf", "text/plain"]) {
+    for (const contentType of ["image/png", "image/svg+xml", "application/pdf", "text/plain", "video/mp4"]) {
       expect(isInlineAttachmentContentType(contentType)).toBe(true);
     }
   });
diff --git a/server/src/__tests__/issue-attachment-routes.test.ts b/server/src/__tests__/issue-attachment-routes.test.ts
index 1dd2b988..04f93a68 100644
--- a/server/src/__tests__/issue-attachment-routes.test.ts
+++ b/server/src/__tests__/issue-attachment-routes.test.ts
@@ -113,7 +113,7 @@ type TestStorageService = StorageService & {
   };
 };
 
-function createStorageService(): TestStorageService {
+function createStorageService(body = Buffer.from("test")): TestStorageService {
   const calls: TestStorageService["__calls"] = {};
   return {
     provider: "local_disk",
@@ -130,15 +130,15 @@ function createStorageService(): TestStorageService {
       };
     },
     getObject: vi.fn(async () => ({
-      stream: Readable.from(Buffer.from("test")),
-      contentLength: 4,
+      stream: Readable.from(body),
+      contentLength: body.length,
     })),
     headObject: vi.fn(),
     deleteObject: vi.fn(),
   };
 }
 
-async function createApp(storage: StorageService) {
+async function createApp(storage: StorageService, options?: { companyIds?: string[]; source?: string }) {
   const [{ errorHandler }, { issueRoutes }] = await Promise.all([
     vi.importActual<typeof import("../middleware/index.js")>("../middleware/index.js"),
     vi.importActual<typeof import("../routes/issues.js")>("../routes/issues.js"),
@@ -148,8 +148,8 @@ async function createApp(storage: StorageService) {
     (req as any).actor = {
       type: "board",
       userId: "local-board",
-      companyIds: ["company-1"],
-      source: "local_implicit",
+      companyIds: options?.companyIds ?? ["company-1"],
+      source: options?.source ?? "local_implicit",
       isInstanceAdmin: false,
     };
     next();
@@ -254,6 +254,52 @@ describe("issue attachment routes", () => {
     expect(res.body.contentType).toBe("application/zip");
   });
 
+  it("accepts default video uploads for issue attachments", async () => {
+    const storage = createStorageService();
+    mockIssueService.getById.mockResolvedValue({
+      id: "11111111-1111-4111-8111-111111111111",
+      companyId: "company-1",
+      identifier: "PAP-1",
+    });
+    mockIssueService.createAttachment.mockResolvedValue(makeAttachment("video/mp4", "clip.mp4"));
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .post("/api/companies/company-1/issues/11111111-1111-4111-8111-111111111111/attachments")
+      .attach("file", Buffer.from("mp4"), { filename: "clip.mp4", contentType: "video/mp4" });
+
+    expect(res.status).toBe(201);
+    expect(storage.__calls.putFile).toMatchObject({
+      contentType: "video/mp4",
+      originalFilename: "clip.mp4",
+    });
+    expect(res.body).toMatchObject({
+      contentType: "video/mp4",
+      contentPath: "/api/attachments/attachment-1/content",
+      openPath: "/api/attachments/attachment-1/content",
+      downloadPath: "/api/attachments/attachment-1/content?download=1",
+    });
+  });
+
+  it("rejects unsupported upload content types before storing the file", async () => {
+    const storage = createStorageService();
+    mockIssueService.getById.mockResolvedValue({
+      id: "11111111-1111-4111-8111-111111111111",
+      companyId: "company-1",
+      identifier: "PAP-1",
+    });
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .post("/api/companies/company-1/issues/11111111-1111-4111-8111-111111111111/attachments")
+      .attach("file", Buffer.from("exe"), { filename: "payload.exe", contentType: "application/x-msdownload" });
+
+    expect(res.status).toBe(422);
+    expect(res.body.error).toBe("Unsupported attachment content type: application/x-msdownload");
+    expect(storage.__calls.putFile).toBeUndefined();
+    expect(mockIssueService.createAttachment).not.toHaveBeenCalled();
+  });
+
   it("enforces the process-level issue attachment limit even when the company limit allows more", async () => {
     const storage = createStorageService();
     mockIssueService.getById.mockResolvedValue({
@@ -326,4 +372,61 @@ describe("issue attachment routes", () => {
       'inline; filename="preview.png"',
     ]).toContain(res.headers["content-disposition"]);
   });
+
+  it("serves video attachments inline with byte-range support", async () => {
+    const storage = createStorageService(Buffer.from("abcdef"));
+    mockIssueService.getAttachmentById.mockResolvedValue({
+      ...makeAttachment("video/mp4", "clip.mp4"),
+      byteSize: 6,
+    });
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .get("/api/attachments/attachment-1/content")
+      .set("Range", "bytes=1-3");
+
+    expect(res.status).toBe(206);
+    expect(res.headers["content-type"]).toContain("video/mp4");
+    expect(res.headers["accept-ranges"]).toBe("bytes");
+    expect(res.headers["content-range"]).toBe("bytes 1-3/6");
+    expect(res.headers["content-length"]).toBe("3");
+    expect(res.headers["content-disposition"]).toBe('inline; filename="clip.mp4"');
+    expect(Buffer.from(res.body).toString("utf8")).toBe("bcd");
+  });
+
+  it("forces video downloads when the download path is requested", async () => {
+    const storage = createStorageService();
+    mockIssueService.getAttachmentById.mockResolvedValue(makeAttachment("video/webm", "clip.webm"));
+
+    const app = await createApp(storage);
+    const res = await request(app).get("/api/attachments/attachment-1/content?download=1");
+
+    expect(res.status).toBe(200);
+    expect(res.headers["content-disposition"]).toBe('attachment; filename="clip.webm"');
+  });
+
+  it("rejects invalid byte ranges without streaming the object", async () => {
+    const storage = createStorageService();
+    mockIssueService.getAttachmentById.mockResolvedValue(makeAttachment("video/mp4", "clip.mp4"));
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .get("/api/attachments/attachment-1/content")
+      .set("Range", "bytes=99-100");
+
+    expect(res.status).toBe(416);
+    expect(res.headers["content-range"]).toBe("bytes */4");
+    expect(storage.getObject).not.toHaveBeenCalled();
+  });
+
+  it("rejects cross-company attachment content reads", async () => {
+    const storage = createStorageService();
+    mockIssueService.getAttachmentById.mockResolvedValue(makeAttachment("video/mp4", "clip.mp4"));
+
+    const app = await createApp(storage, { companyIds: ["company-2"], source: "session" });
+    const res = await request(app).get("/api/attachments/attachment-1/content");
+
+    expect(res.status).toBe(403);
+    expect(storage.getObject).not.toHaveBeenCalled();
+  });
 });
diff --git a/server/src/attachment-types.ts b/server/src/attachment-types.ts
index 23ad3f76..4784ef82 100644
--- a/server/src/attachment-types.ts
+++ b/server/src/attachment-types.ts
@@ -1,7 +1,7 @@
 /**
  * Shared attachment content-type configuration.
  *
- * By default a curated set of image/document/text types are allowed. Set the
+ * By default a curated set of image/document/text/media types are allowed. Set the
  * `PAPERCLIP_ALLOWED_ATTACHMENT_TYPES` environment variable to a
  * comma-separated list of MIME types or wildcard patterns to expand the
  * allowed set for routes that use this allowlist.
@@ -26,11 +26,15 @@ export const DEFAULT_ALLOWED_TYPES: readonly string[] = [
   "image/webp",
   "image/gif",
   "application/pdf",
+  "application/zip",
   "text/markdown",
   "text/plain",
   "application/json",
   "text/csv",
   "text/html",
+  "video/mp4",
+  "video/webm",
+  "video/quicktime",
 ];
 
 export const DEFAULT_ATTACHMENT_CONTENT_TYPE = "application/octet-stream";
@@ -42,6 +46,9 @@ export const INLINE_ATTACHMENT_TYPES: readonly string[] = [
   "text/markdown",
   "application/json",
   "text/csv",
+  "video/mp4",
+  "video/webm",
+  "video/quicktime",
 ];
 
 /**
diff --git a/server/src/routes/issues.ts b/server/src/routes/issues.ts
index b2f2d872..6f1c6a23 100644
--- a/server/src/routes/issues.ts
+++ b/server/src/routes/issues.ts
@@ -1,4 +1,5 @@
 import { randomUUID } from "node:crypto";
+import { Transform } from "node:stream";
 import { Router, type Request, type Response } from "express";
 import multer from "multer";
 import { z } from "zod";
@@ -91,6 +92,7 @@ import {
 import { shouldWakeAssigneeOnCheckout } from "./issues-checkout-wakeup.js";
 import {
   isInlineAttachmentContentType,
+  isAllowedContentType,
   normalizeIssueAttachmentMaxBytes,
   normalizeContentType,
   SVG_CONTENT_TYPE,
@@ -1103,12 +1105,67 @@ export function issueRoutes(
   }
 
   function withContentPath<T extends { id: string }>(attachment: T) {
+    const contentPath = `/api/attachments/${attachment.id}/content`;
     return {
       ...attachment,
-      contentPath: `/api/attachments/${attachment.id}/content`,
+      contentPath,
+      openPath: contentPath,
+      downloadPath: `${contentPath}?download=1`,
     };
   }
 
+  type ParsedAttachmentRange =
+    | { kind: "none" }
+    | { kind: "invalid" }
+    | { kind: "range"; start: number; end: number };
+
+  function parseAttachmentRangeHeader(raw: string | undefined, contentLength: number): ParsedAttachmentRange {
+    if (!raw) return { kind: "none" };
+    if (!Number.isSafeInteger(contentLength) || contentLength <= 0) return { kind: "invalid" };
+
+    const prefix = "bytes=";
+    if (!raw.toLowerCase().startsWith(prefix)) return { kind: "invalid" };
+    const spec = raw.slice(prefix.length).trim();
+    if (!spec || spec.includes(",")) return { kind: "invalid" };
+
+    const [startRaw, endRaw] = spec.split("-", 2);
+    if (endRaw === undefined) return { kind: "invalid" };
+
+    if (startRaw === "") {
+      const suffixLength = Number.parseInt(endRaw, 10);
+      if (!Number.isSafeInteger(suffixLength) || suffixLength <= 0) return { kind: "invalid" };
+      const start = Math.max(contentLength - suffixLength, 0);
+      return { kind: "range", start, end: contentLength - 1 };
+    }
+
+    const start = Number.parseInt(startRaw, 10);
+    if (!Number.isSafeInteger(start) || start < 0 || start >= contentLength) return { kind: "invalid" };
+    const end = endRaw === "" ? contentLength - 1 : Number.parseInt(endRaw, 10);
+    if (!Number.isSafeInteger(end) || end < start) return { kind: "invalid" };
+    return { kind: "range", start, end: Math.min(end, contentLength - 1) };
+  }
+
+  function createByteRangeStream(start: number, end: number) {
+    let offset = 0;
+    return new Transform({
+      transform(chunk: Buffer | string, _encoding, callback) {
+        const buffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk);
+        const chunkStart = offset;
+        const chunkEnd = offset + buffer.length - 1;
+        offset += buffer.length;
+
+        if (chunkEnd < start || chunkStart > end) {
+          callback();
+          return;
+        }
+
+        const sliceStart = Math.max(start - chunkStart, 0);
+        const sliceEnd = Math.min(end - chunkStart + 1, buffer.length);
+        callback(null, buffer.subarray(sliceStart, sliceEnd));
+      },
+    });
+  }
+
   function parseBooleanQuery(value: unknown) {
     return value === true || value === "true" || value === "1";
   }
@@ -6081,6 +6138,10 @@ export function issueRoutes(
       res.status(422).json({ error: "Attachment is empty" });
       return;
     }
+    if (!isAllowedContentType(contentType)) {
+      res.status(422).json({ error: `Unsupported attachment content type: ${contentType}` });
+      return;
+    }
 
     const parsedMeta = createIssueAttachmentMetadataSchema.safeParse(req.body ?? {});
     if (!parsedMeta.success) {
@@ -6139,22 +6200,49 @@ export function issueRoutes(
     }
     assertCompanyAccess(req, attachment.companyId);
 
+    const contentLength = attachment.byteSize;
+    const range = parseAttachmentRangeHeader(
+      typeof req.headers.range === "string" ? req.headers.range : undefined,
+      contentLength,
+    );
+    res.setHeader("Accept-Ranges", "bytes");
+    if (range.kind === "invalid") {
+      res.setHeader("Content-Range", `bytes */${contentLength}`);
+      res.status(416).end();
+      return;
+    }
+
     const object = await storage.getObject(attachment.companyId, attachment.objectKey);
     const responseContentType = normalizeContentType(attachment.contentType || object.contentType);
     res.setHeader("Content-Type", responseContentType);
-    res.setHeader("Content-Length", String(attachment.byteSize || object.contentLength || 0));
     res.setHeader("Cache-Control", "private, max-age=60");
     res.setHeader("X-Content-Type-Options", "nosniff");
     if (responseContentType === SVG_CONTENT_TYPE) {
       res.setHeader("Content-Security-Policy", "sandbox; default-src 'none'; img-src 'self' data:; style-src 'unsafe-inline'");
     }
     const filename = attachment.originalFilename ?? "attachment";
-    const disposition = isInlineAttachmentContentType(responseContentType) ? "inline" : "attachment";
+    const disposition = parseBooleanQuery(req.query.download)
+      ? "attachment"
+      : isInlineAttachmentContentType(responseContentType) ? "inline" : "attachment";
     res.setHeader("Content-Disposition", `${disposition}; filename=\"${filename.replaceAll("\"", "")}\"`);
 
     object.stream.on("error", (err) => {
       next(err);
     });
+    if (range.kind === "range") {
+      const rangeLength = range.end - range.start + 1;
+      res.status(206);
+      res.setHeader("Content-Length", String(rangeLength));
+      res.setHeader("Content-Range", `bytes ${range.start}-${range.end}/${contentLength}`);
+      const rangeStream = createByteRangeStream(range.start, range.end);
+      rangeStream.on("error", (err) => {
+        next(err);
+      });
+      object.stream.pipe(rangeStream).pipe(res);
+      return;
+    }
+
+    res.setHeader("Content-Length", String(contentLength || object.contentLength || 0));
     object.stream.pipe(res);
   });