license: relicense to AGPL-3.0-only with commercial dual-license

- LICENSE -> verbatim GNU AGPL-3.0; add LICENSE-COMMERCIAL.md + SECURITY.md
- CLA -> exclusive-license grant (contributors keep copyright); add README
  anti-rugpull covenant + relicense record
- NOTICE / README / CONTRIBUTING / CLAUDE.md / package.json x5 updated;
  contact routed through GitHub (no email placeholders)
- AGPL section 13 source offer: operator-configurable BACKSPACE_SOURCE_URL +
  build-injected commit; sourceCodeUrl+commit on /api/instance/info;
  SourceCodeLink on login/register/settings/desktop; docs + .env.example updated

packages/web/src/components/auth/LoginPage.tsx

@@ -1,7 +1,9 @@
 import React, { useState, useEffect } from 'react';
 import { Link, useNavigate, useSearchParams } from 'react-router-dom';
 import { useAuthStore } from '../../stores/authStore';
-import { RateLimitError } from '../../api/client';
+import { api, RateLimitError } from '../../api/client';
+import type { InstanceInfoResponse } from '@backspace/shared';
+import { SourceCodeLink } from '../ui/SourceCodeLink';
 
 export function LoginPage() {
   const [username, setUsername] = useState('');
@@ -14,6 +16,17 @@ export function LoginPage() {
   const [searchParams] = useSearchParams();
   const redirect = searchParams.get('redirect');
 
+  // AGPL § 13: anonymous users must be able to reach the source of the running
+  // version. Fetched from the unauthenticated public info endpoint.
+  const [instanceInfo, setInstanceInfo] = useState<InstanceInfoResponse | null>(null);
+  useEffect(() => {
+    let cancelled = false;
+    api.instance.info()
+      .then((info) => { if (!cancelled) setInstanceInfo(info); })
+      .catch(() => { /* Non-critical — link is simply omitted if unreachable. */ });
+    return () => { cancelled = true; };
+  }, []);
+
   useEffect(() => {
     if (retryAfter <= 0) return;
     const timer = setInterval(() => {
@@ -129,6 +142,12 @@ export function LoginPage() {
             </Link>
           </p>
         </form>
+
+        {instanceInfo && (
+          <div className="mt-6 pt-4 border-t border-white/[0.04] flex justify-center">
+            <SourceCodeLink sourceCodeUrl={instanceInfo.sourceCodeUrl} version={instanceInfo.version} commit={instanceInfo.commit} />
+          </div>
+        )}
       </div>
     </div>
   );

packages/web/src/components/auth/RegisterPage.tsx

@@ -9,6 +9,7 @@ import type { AvatarColor, CheckInviteResponse, InstanceInfoResponse } from '@ba
 import { api, RateLimitError } from '../../api/client';
 import { useTransferStore } from '../../stores/transferStore';
 import { waitForTransferAttachment } from '../../utils/waitForTransfer';
+import { SourceCodeLink } from '../ui/SourceCodeLink';
 
 // Single-source regex for extracting a bare invite token from a pasted full URL.
 // Token format: 22 chars base64url ([A-Za-z0-9_-]).
@@ -727,6 +728,13 @@ export function RegisterPage() {
             </div>
           </div>
         )}
+
+        {/* AGPL § 13: source offer for anonymous visitors, shown on both steps. */}
+        {instanceInfo && (
+          <div className="mt-6 pt-4 border-t border-white/[0.04] flex justify-center">
+            <SourceCodeLink sourceCodeUrl={instanceInfo.sourceCodeUrl} version={instanceInfo.version} commit={instanceInfo.commit} />
+          </div>
+        )}
         </div>
       </div>
 

packages/web/src/components/modals/UserSettings.tsx

@@ -1,6 +1,9 @@
 import { useState, useEffect } from 'react';
 import { Modal } from '../ui/Modal';
 import { Avatar } from '../ui/Avatar';
+import { SourceCodeLink } from '../ui/SourceCodeLink';
+import { api } from '../../api/client';
+import type { InstanceInfoResponse } from '@backspace/shared';
 import { useUIStore } from '../../stores/uiStore';
 import { useAuthStore } from '../../stores/authStore';
 import { AccountPanel } from './settingsPanels/AccountPanel';
@@ -59,9 +62,21 @@ export function UserSettingsModal() {
 
   const [tab, setTab] = useState<SettingsTab>('account');
   const [mobileView, setMobileView] = useState<'tabs' | 'content'>('tabs');
+  // AGPL § 13: home-instance source offer. Fetched from the public info endpoint
+  // so the source link reflects the version this instance is actually running.
+  const [instanceInfo, setInstanceInfo] = useState<InstanceInfoResponse | null>(null);
 
   const isOpen = activeModal === 'userSettings';
 
+  useEffect(() => {
+    if (!isOpen) return;
+    let cancelled = false;
+    api.instance.info()
+      .then((info) => { if (!cancelled) setInstanceInfo(info); })
+      .catch(() => { /* Non-critical — link falls back to hidden if unreachable. */ });
+    return () => { cancelled = true; };
+  }, [isOpen]);
+
   // Deep-linking: read modalData.tab when opening
   useEffect(() => {
     if (isOpen) {
@@ -148,6 +163,12 @@ export function UserSettingsModal() {
             >
               Log Out
             </button>
+
+            {instanceInfo && (
+              <div className="px-3 pt-2">
+                <SourceCodeLink sourceCodeUrl={instanceInfo.sourceCodeUrl} version={instanceInfo.version} commit={instanceInfo.commit} />
+              </div>
+            )}
           </div>
         </div>
 
@@ -196,6 +217,12 @@ export function UserSettingsModal() {
               >
                 Log Out
               </button>
+
+              {instanceInfo && (
+                <div className="px-3 pt-2">
+                  <SourceCodeLink sourceCodeUrl={instanceInfo.sourceCodeUrl} version={instanceInfo.version} commit={instanceInfo.commit} />
+                </div>
+              )}
             </div>
           </div>
         )}

packages/web/src/components/ui/SourceCodeLink.tsx

@@ -0,0 +1,55 @@
+interface SourceCodeLinkProps {
+  /** URL to the Corresponding Source of the running version (AGPL § 13). */
+  sourceCodeUrl: string;
+  /** Running version string, e.g. "1.0.0". Omitted from the label when unknown. */
+  version?: string;
+  /** Short git commit/tag of the running build; appended to pin the exact version. */
+  commit?: string | null;
+  /** Extra classes for layout composition (alignment, spacing) at the call site. */
+  className?: string;
+}
+
+/**
+ * AGPL-3.0 § 13 "network-use source offer".
+ *
+ * Renders an accessible external link to the Corresponding Source of the version
+ * the instance is actually running. The URL is operator-configurable server-side
+ * (BACKSPACE_SOURCE_URL) and surfaced via GET /api/instance/info, so a modified
+ * self-hosted fork points humans at its own source.
+ *
+ * Rendered on every network-facing surface (settings sidebars, pre-auth pages)
+ * so any network user — authenticated or anonymous — can reach the source.
+ */
+export function SourceCodeLink({ sourceCodeUrl, version, commit, className }: SourceCodeLinkProps) {
+  const build = version ? `v${version}${commit ? ` (${commit})` : ''}` : '';
+  const label = build ? `Source code (AGPL) · ${build}` : 'Source code (AGPL)';
+
+  return (
+    <a
+      href={sourceCodeUrl}
+      target="_blank"
+      rel="noreferrer noopener"
+      className={`inline-flex items-center gap-1.5 text-xs text-txt-tertiary hover:text-txt-secondary transition-colors${
+        className ? ` ${className}` : ''
+      }`}
+      title="View the source code of the version this instance is running (AGPL-3.0)"
+    >
+      <svg
+        width="12"
+        height="12"
+        viewBox="0 0 24 24"
+        fill="none"
+        stroke="currentColor"
+        strokeWidth="2"
+        strokeLinecap="round"
+        strokeLinejoin="round"
+        aria-hidden="true"
+        className="flex-shrink-0"
+      >
+        <polyline points="16 18 22 12 16 6" />
+        <polyline points="8 6 2 12 8 18" />
+      </svg>
+      <span>{label}</span>
+    </a>
+  );
+}