diff --git a/packages/shared/src/validators/work-product.test.ts b/packages/shared/src/validators/work-product.test.ts
index 214a9637..82ccb711 100644
--- a/packages/shared/src/validators/work-product.test.ts
+++ b/packages/shared/src/validators/work-product.test.ts
@@ -16,4 +16,26 @@ describe("attachmentArtifactWorkProductMetadataSchema", () => {
     expect(parsed.contentType).toBe("video/mp4");
     expect(parsed.downloadPath).toContain("download=1");
   });
+
+  it("rejects off-route or scriptable paths", () => {
+    const parsed = attachmentArtifactWorkProductMetadataSchema.safeParse({
+      attachmentId: "11111111-1111-4111-8111-111111111111",
+      contentType: "video/mp4",
+      byteSize: 1234,
+      contentPath: "https://evil.example/video.mp4",
+      openPath: "javascript:alert(1)",
+      downloadPath: "/api/attachments/11111111-1111-4111-8111-111111111111/content",
+      originalFilename: "demo.mp4",
+    });
+
+    expect(parsed.success).toBe(false);
+    if (parsed.success) {
+      throw new Error("Expected invalid attachment artifact metadata");
+    }
+    expect(parsed.error.issues.map((issue) => issue.path.join("."))).toEqual([
+      "contentPath",
+      "openPath",
+      "downloadPath",
+    ]);
+  });
 });
diff --git a/packages/shared/src/validators/work-product.ts b/packages/shared/src/validators/work-product.ts
index ca8d3852..ac31b476 100644
--- a/packages/shared/src/validators/work-product.ts
+++ b/packages/shared/src/validators/work-product.ts
@@ -1,5 +1,9 @@
 import { z } from "zod";
 
+function attachmentContentPath(attachmentId: string): string {
+  return `/api/attachments/${attachmentId}/content`;
+}
+
 export const issueWorkProductTypeSchema = z.enum([
   "preview_url",
   "runtime_service",
@@ -37,6 +41,29 @@ export const attachmentArtifactWorkProductMetadataSchema = z.object({
   openPath: z.string().min(1),
   downloadPath: z.string().min(1),
   originalFilename: z.string().optional().nullable(),
+}).superRefine((value, ctx) => {
+  const contentPath = attachmentContentPath(value.attachmentId);
+  if (value.contentPath !== contentPath) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      path: ["contentPath"],
+      message: "contentPath must point to the same-origin attachment content route",
+    });
+  }
+  if (value.openPath !== contentPath) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      path: ["openPath"],
+      message: "openPath must point to the same-origin attachment content route",
+    });
+  }
+  if (value.downloadPath !== `${contentPath}?download=1`) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      path: ["downloadPath"],
+      message: "downloadPath must point to the same-origin attachment download route",
+    });
+  }
 });
 
 export type AttachmentArtifactWorkProductMetadata = z.infer<typeof attachmentArtifactWorkProductMetadataSchema>;
diff --git a/server/src/__tests__/issue-attachment-routes.test.ts b/server/src/__tests__/issue-attachment-routes.test.ts
index 04f93a68..1386c245 100644
--- a/server/src/__tests__/issue-attachment-routes.test.ts
+++ b/server/src/__tests__/issue-attachment-routes.test.ts
@@ -13,6 +13,11 @@ const mockIssueService = vi.hoisted(() => ({
 const mockCompanyService = vi.hoisted(() => ({
   getById: vi.fn(),
 }));
+const mockWorkProductService = vi.hoisted(() => ({
+  createForIssue: vi.fn(),
+  getById: vi.fn(),
+  update: vi.fn(),
+}));
 
 const mockLogActivity = vi.hoisted(() => vi.fn(async () => undefined));
 
@@ -97,7 +102,7 @@ function registerRouteMocks() {
     routineService: () => ({
       syncRunStatusForIssue: vi.fn(async () => undefined),
     }),
-    workProductService: () => ({}),
+    workProductService: () => mockWorkProductService,
   }));
 }
 
@@ -144,6 +149,7 @@ async function createApp(storage: StorageService, options?: { companyIds?: strin
     vi.importActual<typeof import("../routes/issues.js")>("../routes/issues.js"),
   ]);
   const app = express();
+  app.use(express.json());
   app.use((req, _res, next) => {
     (req as any).actor = {
       type: "board",
@@ -219,6 +225,9 @@ describe("issue attachment routes", () => {
       id: "company-1",
       attachmentMaxBytes: 1024 * 1024 * 1024,
     });
+    mockWorkProductService.createForIssue.mockReset();
+    mockWorkProductService.getById.mockReset();
+    mockWorkProductService.update.mockReset();
   });
 
   it("accepts zip uploads for issue attachments", async () => {
@@ -429,4 +438,160 @@ describe("issue attachment routes", () => {
     expect(res.status).toBe(403);
     expect(storage.getObject).not.toHaveBeenCalled();
   });
+
+  it("canonicalizes paperclip artifact metadata before creating a work product", async () => {
+    const storage = createStorageService();
+    const issue = {
+      id: "11111111-1111-4111-8111-111111111111",
+      companyId: "company-1",
+      identifier: "PAP-1",
+      projectId: null,
+    };
+    mockIssueService.getById.mockResolvedValue(issue);
+    mockIssueService.getAttachmentById.mockResolvedValue({
+      ...makeAttachment("video/mp4", "clip.mp4"),
+      id: "22222222-2222-4222-8222-222222222222",
+      byteSize: 6,
+      issueId: issue.id,
+    });
+    mockWorkProductService.createForIssue.mockResolvedValue({
+      id: "work-product-1",
+      issueId: issue.id,
+      companyId: issue.companyId,
+      type: "artifact",
+      provider: "paperclip",
+      title: "Clip",
+      metadata: null,
+    });
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .post(`/api/issues/${issue.id}/work-products`)
+      .send({
+        type: "artifact",
+        provider: "paperclip",
+        title: "Clip",
+        metadata: {
+          attachmentId: "22222222-2222-4222-8222-222222222222",
+          contentType: "video/mp4",
+          byteSize: 6,
+          contentPath: "https://evil.example/clip.mp4",
+          openPath: "javascript:alert(1)",
+          downloadPath: "javascript:alert(2)",
+          originalFilename: "clip.mp4",
+        },
+      });
+
+    expect(res.status).toBe(201);
+    expect(mockWorkProductService.createForIssue).toHaveBeenCalledWith(
+      issue.id,
+      issue.companyId,
+      expect.objectContaining({
+        type: "artifact",
+        provider: "paperclip",
+        metadata: {
+          attachmentId: "22222222-2222-4222-8222-222222222222",
+          contentType: "video/mp4",
+          byteSize: 6,
+          contentPath: "/api/attachments/22222222-2222-4222-8222-222222222222/content",
+          openPath: "/api/attachments/22222222-2222-4222-8222-222222222222/content",
+          downloadPath: "/api/attachments/22222222-2222-4222-8222-222222222222/content?download=1",
+          originalFilename: "clip.mp4",
+        },
+      }),
+    );
+  });
+
+  it("rejects paperclip artifact metadata that references another issue's attachment", async () => {
+    const storage = createStorageService();
+    const issue = {
+      id: "11111111-1111-4111-8111-111111111111",
+      companyId: "company-1",
+      identifier: "PAP-1",
+      projectId: null,
+    };
+    mockIssueService.getById.mockResolvedValue(issue);
+    mockIssueService.getAttachmentById.mockResolvedValue({
+      ...makeAttachment("video/mp4", "clip.mp4"),
+      id: "22222222-2222-4222-8222-222222222222",
+      issueId: "different-issue",
+    });
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .post(`/api/issues/${issue.id}/work-products`)
+      .send({
+        type: "artifact",
+        provider: "paperclip",
+        title: "Clip",
+        metadata: {
+          attachmentId: "22222222-2222-4222-8222-222222222222",
+        },
+      });
+
+    expect(res.status).toBe(422);
+    expect(res.body.error).toBe("Attachment artifact must reference an attachment on the same issue");
+    expect(mockWorkProductService.createForIssue).not.toHaveBeenCalled();
+  });
+
+  it("canonicalizes paperclip artifact metadata on work product updates", async () => {
+    const storage = createStorageService();
+    const issue = {
+      id: "11111111-1111-4111-8111-111111111111",
+      companyId: "company-1",
+      identifier: "PAP-1",
+      projectId: null,
+    };
+    mockWorkProductService.getById.mockResolvedValue({
+      id: "work-product-1",
+      issueId: issue.id,
+      companyId: issue.companyId,
+      type: "artifact",
+      provider: "paperclip",
+      title: "Clip",
+      metadata: null,
+    });
+    mockIssueService.getById.mockResolvedValue(issue);
+    mockIssueService.getAttachmentById.mockResolvedValue({
+      ...makeAttachment("video/webm", "clip.webm"),
+      id: "22222222-2222-4222-8222-222222222222",
+      issueId: issue.id,
+      byteSize: 8,
+    });
+    mockWorkProductService.update.mockResolvedValue({
+      id: "work-product-1",
+      issueId: issue.id,
+      companyId: issue.companyId,
+      type: "artifact",
+      provider: "paperclip",
+      title: "Clip",
+      metadata: null,
+    });
+
+    const app = await createApp(storage);
+    const res = await request(app)
+      .patch("/api/work-products/work-product-1")
+      .send({
+        metadata: {
+          attachmentId: "22222222-2222-4222-8222-222222222222",
+          openPath: "javascript:alert(1)",
+        },
+      });
+
+    expect(res.status).toBe(200);
+    expect(mockWorkProductService.update).toHaveBeenCalledWith(
+      "work-product-1",
+      expect.objectContaining({
+        metadata: {
+          attachmentId: "22222222-2222-4222-8222-222222222222",
+          contentType: "video/webm",
+          byteSize: 8,
+          contentPath: "/api/attachments/22222222-2222-4222-8222-222222222222/content",
+          openPath: "/api/attachments/22222222-2222-4222-8222-222222222222/content",
+          downloadPath: "/api/attachments/22222222-2222-4222-8222-222222222222/content?download=1",
+          originalFilename: "clip.webm",
+        },
+      }),
+    );
+  });
 });
diff --git a/server/src/routes/issues.ts b/server/src/routes/issues.ts
index 6f1c6a23..b5b7251f 100644
--- a/server/src/routes/issues.ts
+++ b/server/src/routes/issues.ts
@@ -17,6 +17,7 @@ import {
 import {
   addIssueCommentSchema,
   acceptIssueThreadInteractionSchema,
+  attachmentArtifactWorkProductMetadataSchema,
   cancelIssueThreadInteractionSchema,
   companySearchQuerySchema,
   createIssueAttachmentMetadataSchema,
@@ -181,6 +182,26 @@ function applyCreateIssueStatusDefault(req: Request, res: Response, next: () =>
   next();
 }
 
+function buildAttachmentContentPath(attachmentId: string): string {
+  return `/api/attachments/${attachmentId}/content`;
+}
+
+function requiresPaperclipAttachmentMetadata(input: {
+  type?: unknown;
+  provider?: unknown;
+}, fallback?: {
+  type?: string | null;
+  provider?: string | null;
+}) {
+  const type = typeof input.type === "string" ? input.type : fallback?.type ?? null;
+  const provider = typeof input.provider === "string" ? input.provider : fallback?.provider ?? null;
+  return type === "artifact" && provider === "paperclip";
+}
+
+const attachmentArtifactMetadataInputSchema = z.object({
+  attachmentId: z.string().uuid(),
+}).passthrough();
+
 function buildCreateIssueActivityStatusDetails(
   issue: { assigneeAgentId: string | null; status: string },
   res: Response,
@@ -1233,6 +1254,38 @@ export function issueRoutes(
     }, "failed to wake assignee on document annotation comment"));
   }
 
+  async function canonicalizePaperclipArtifactMetadata(input: {
+    issue: { id: string; companyId: string };
+    metadata: Record<string, unknown> | null | undefined;
+  }) {
+    const parsed = attachmentArtifactMetadataInputSchema.safeParse(input.metadata);
+    if (!parsed.success) {
+      throw unprocessable("Invalid attachment artifact metadata", {
+        code: "invalid_attachment_artifact_metadata",
+        details: parsed.error.issues,
+      });
+    }
+
+    const attachment = await svc.getAttachmentById(parsed.data.attachmentId);
+    if (!attachment || attachment.companyId !== input.issue.companyId || attachment.issueId !== input.issue.id) {
+      throw unprocessable("Attachment artifact must reference an attachment on the same issue", {
+        code: "invalid_attachment_artifact_metadata",
+        attachmentId: parsed.data.attachmentId,
+      });
+    }
+
+    const contentPath = buildAttachmentContentPath(attachment.id);
+    return attachmentArtifactWorkProductMetadataSchema.parse({
+      attachmentId: attachment.id,
+      contentType: normalizeContentType(attachment.contentType),
+      byteSize: attachment.byteSize,
+      contentPath,
+      openPath: contentPath,
+      downloadPath: `${contentPath}?download=1`,
+      originalFilename: attachment.originalFilename ?? null,
+    });
+  }
+
   async function assertIssueEnvironmentSelection(
     companyId: string,
     environmentId: string | null | undefined,
@@ -3245,10 +3298,17 @@ export function issueRoutes(
     assertCompanyAccess(req, issue.companyId);
     if (!(await assertAgentIssueMutationAllowed(req, res, issue))) return;
     if (!(await assertDeliverableMutationAllowedByRunContext(req, res, issue))) return;
-    const product = await workProductsSvc.createForIssue(issue.id, issue.companyId, {
+    const createInput = {
       ...req.body,
       projectId: req.body.projectId ?? issue.projectId ?? null,
-    });
+    };
+    if (requiresPaperclipAttachmentMetadata(createInput)) {
+      createInput.metadata = await canonicalizePaperclipArtifactMetadata({
+        issue,
+        metadata: req.body.metadata ?? null,
+      });
+    }
+    const product = await workProductsSvc.createForIssue(issue.id, issue.companyId, createInput);
     if (!product) {
       res.status(422).json({ error: "Invalid work product payload" });
       return;
@@ -3289,7 +3349,19 @@ export function issueRoutes(
     }
     if (!(await assertAgentIssueMutationAllowed(req, res, issue))) return;
     if (!(await assertDeliverableMutationAllowedByRunContext(req, res, issue))) return;
-    const product = await workProductsSvc.update(id, req.body);
+    const patch = { ...req.body };
+    if (requiresPaperclipAttachmentMetadata(patch, existing)) {
+      if (patch.metadata !== undefined) {
+        patch.metadata = await canonicalizePaperclipArtifactMetadata({
+          issue,
+          metadata: patch.metadata ?? null,
+        });
+      } else if (!requiresPaperclipAttachmentMetadata(existing)) {
+        res.status(422).json({ error: "Attachment-backed artifact metadata is required" });
+        return;
+      }
+    }
+    const product = await workProductsSvc.update(id, patch);
     if (!product) {
       res.status(404).json({ error: "Work product not found" });
       return;
diff --git a/ui/src/lib/issue-output.test.ts b/ui/src/lib/issue-output.test.ts
index 15bb3508..a7f681ea 100644
--- a/ui/src/lib/issue-output.test.ts
+++ b/ui/src/lib/issue-output.test.ts
@@ -100,6 +100,7 @@ describe("getIssueOutputs", () => {
     const result = getIssueOutputs([
       makeWorkProduct({ id: "pr-1", type: "pull_request" }),
       makeWorkProduct({ id: "doc-1", type: "document" }),
+      makeWorkProduct({ id: "artifact-1", type: "artifact", provider: "custom", metadata: videoMetadata() }),
     ]);
     expect(result.count).toBe(0);
     expect(result.primary).toBeNull();
diff --git a/ui/src/lib/issue-output.ts b/ui/src/lib/issue-output.ts
index 9e396ab6..b3ae947f 100644
--- a/ui/src/lib/issue-output.ts
+++ b/ui/src/lib/issue-output.ts
@@ -123,7 +123,7 @@ function toTime(value: string | Date): number {
  *   marked primary) comes first, then remaining artifacts by most-recent.
  */
 export function getIssueOutputs(workProducts: IssueWorkProduct[] | null | undefined): IssueOutputs {
-  const artifacts = (workProducts ?? []).filter((wp) => wp.type === "artifact");
+  const artifacts = (workProducts ?? []).filter((wp) => wp.type === "artifact" && wp.provider === "paperclip");
 
   const items: IssueOutputItem[] = artifacts.map((wp) => {
     const parsed = attachmentArtifactWorkProductMetadataSchema.safeParse(wp.metadata);