diff --git a/packages/shared/src/document-references.test.ts b/packages/shared/src/document-references.test.ts
new file mode 100644
index 00000000000..53bedab1c2b
--- /dev/null
+++ b/packages/shared/src/document-references.test.ts
@@ -0,0 +1,45 @@
+import { describe, expect, it } from "vitest";
+import { buildDocumentReferenceHref, parseDocumentReferenceHref } from "./document-references.js";
+
+describe("parseDocumentReferenceHref", () => {
+  it("parses a company-prefixed documents path", () => {
+    expect(parseDocumentReferenceHref("/PAP/documents/abc-123")).toEqual({
+      documentId: "abc-123",
+      fromIssueKey: null,
+    });
+  });
+
+  it("parses a company-relative documents path", () => {
+    expect(parseDocumentReferenceHref("/documents/abc-123")).toEqual({
+      documentId: "abc-123",
+      fromIssueKey: null,
+    });
+  });
+
+  it("extracts the originating issue key from ?from=issue:<key>", () => {
+    expect(parseDocumentReferenceHref("/documents/abc-123?from=issue:plan")).toEqual({
+      documentId: "abc-123",
+      fromIssueKey: "plan",
+    });
+  });
+
+  it("parses absolute urls", () => {
+    expect(parseDocumentReferenceHref("https://app.example.com/ACME/documents/doc_9")).toEqual({
+      documentId: "doc_9",
+      fromIssueKey: null,
+    });
+  });
+
+  it("returns null for non-document paths", () => {
+    expect(parseDocumentReferenceHref("/PAP/issues/PAP-1")).toBeNull();
+    expect(parseDocumentReferenceHref("/documents")).toBeNull();
+    expect(parseDocumentReferenceHref("not a url at all ::::")).toBeNull();
+  });
+
+  it("round-trips with buildDocumentReferenceHref", () => {
+    expect(buildDocumentReferenceHref("abc-123")).toBe("/documents/abc-123");
+    expect(buildDocumentReferenceHref("abc-123", "plan")).toBe("/documents/abc-123?from=issue:plan");
+    const built = buildDocumentReferenceHref("abc-123", "spec");
+    expect(parseDocumentReferenceHref(built)).toEqual({ documentId: "abc-123", fromIssueKey: "spec" });
+  });
+});
diff --git a/packages/shared/src/document-references.ts b/packages/shared/src/document-references.ts
new file mode 100644
index 00000000000..f1305a51e43
--- /dev/null
+++ b/packages/shared/src/document-references.ts
@@ -0,0 +1,60 @@
+/**
+ * Path-based references to company documents, e.g. `/PAP/documents/<id>` or the
+ * company-relative `/documents/<id>`. Mirrors `issue-references.ts` so comment
+ * bodies can render a cross-issue document mention chip. The `<id>` segment is
+ * the company document id used by the documents library detail route.
+ */
+
+export interface ParsedDocumentReference {
+  documentId: string;
+  /** When the href carries `?from=issue:<key>`, the originating issue document key. */
+  fromIssueKey: string | null;
+}
+
+/** Document ids are UUIDs in practice; accept any non-empty url-safe slug to stay forgiving. */
+const DOCUMENT_ID_RE = /^[A-Za-z0-9][A-Za-z0-9._-]*$/;
+
+function parseFromParam(value: string | null): string | null {
+  if (!value) return null;
+  const trimmed = value.trim();
+  const match = /^issue:(.+)$/i.exec(trimmed);
+  if (!match) return null;
+  const key = match[1]?.trim();
+  return key ? key : null;
+}
+
+export function buildDocumentReferenceHref(documentId: string, fromIssueKey?: string | null): string {
+  const id = documentId.trim();
+  const key = fromIssueKey?.trim();
+  return key ? `/documents/${id}?from=issue:${encodeURIComponent(key)}` : `/documents/${id}`;
+}
+
+export function parseDocumentReferenceHref(href: string): ParsedDocumentReference | null {
+  const raw = href.trim();
+  if (!raw) return null;
+
+  let url: URL;
+  try {
+    url = raw.startsWith("/") ? new URL(raw, "https://paperclip.invalid") : new URL(raw);
+  } catch {
+    return null;
+  }
+
+  const segments = url.pathname
+    .split("/")
+    .map((segment) => segment.trim())
+    .filter(Boolean);
+
+  for (let index = 0; index < segments.length - 1; index += 1) {
+    if (segments[index]?.toLowerCase() !== "documents") continue;
+    const candidate = segments[index + 1] ?? "";
+    if (DOCUMENT_ID_RE.test(candidate)) {
+      return {
+        documentId: candidate,
+        fromIssueKey: parseFromParam(url.searchParams.get("from")),
+      };
+    }
+  }
+
+  return null;
+}
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 5ae9d2a0ce9..d1504a2e9fd 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -813,6 +813,12 @@ export {
   type IssueReferenceMatch,
 } from "./issue-references.js";
 
+export {
+  buildDocumentReferenceHref,
+  parseDocumentReferenceHref,
+  type ParsedDocumentReference,
+} from "./document-references.js";
+
 export {
   anchorSnapshotToSelector,
   createDocumentAnchorSelector,
diff --git a/ui/src/lib/company-routes.test.ts b/ui/src/lib/company-routes.test.ts
index 6278224db81..18c8d0547f4 100644
--- a/ui/src/lib/company-routes.test.ts
+++ b/ui/src/lib/company-routes.test.ts
@@ -65,6 +65,20 @@ describe("company routes", () => {
     );
   });
 
+  // Regression for PAP-10569: document deep-links (`/documents/<id>?from=issue:<key>`)
+  // and the library nav must keep the company prefix so they resolve under
+  // `/:companyPrefix` instead of 404-ing on the unprefixed catch-all.
+  it("treats /documents as a board route that needs a company prefix", () => {
+    expect(isBoardPathWithoutPrefix("/documents")).toBe(true);
+    expect(isBoardPathWithoutPrefix("/documents/doc-123")).toBe(true);
+    expect(extractCompanyPrefixFromPath("/documents/doc-123")).toBeNull();
+    expect(applyCompanyPrefix("/documents", "PAP")).toBe("/PAP/documents");
+    expect(applyCompanyPrefix("/documents/doc-123?from=issue:plan", "PAP")).toBe(
+      "/PAP/documents/doc-123?from=issue:plan",
+    );
+    expect(toCompanyRelativePath("/PAP/documents/doc-123")).toBe("/documents/doc-123");
+  });
+
   it("treats /artifacts as a board route that needs a company prefix", () => {
     expect(isBoardPathWithoutPrefix("/artifacts")).toBe(true);
     expect(extractCompanyPrefixFromPath("/artifacts")).toBeNull();
diff --git a/ui/src/lib/company-routes.ts b/ui/src/lib/company-routes.ts
index 27119d6a579..97bbf179de6 100644
--- a/ui/src/lib/company-routes.ts
+++ b/ui/src/lib/company-routes.ts
@@ -10,6 +10,7 @@ const BOARD_ROUTE_ROOTS = new Set([
   "workspaces",
   "execution-workspaces",
   "issues",
+  "documents",
   "routines",
   "goals",
   "artifacts",