[grade=B] feat(auth): onboard missing credentials into encrypted vault

dashcaddy-installer/install.sh

@@ -630,10 +630,15 @@ generate_caddyfile() {
 SNIP
 
   local auth_snippet="(dashcaddy_auth) {
-  forward_auth localhost:${API_PORT} {
+  @needsAuth not path /dashcaddy-sso
+  forward_auth @needsAuth localhost:${API_PORT} {
     uri /api/v1/auth/gate/{args[0]}
     copy_headers Authorization X-Api-Key X-App-Cookie X-Emby-Token X-Plex-Token
   }
+  handle /dashcaddy-sso {
+    rewrite * /api/v1/auth/sso-exchange
+    reverse_proxy localhost:${API_PORT}
+  }
 }"
 
   local site_body="  root * ${DASHBOARD_DIR}

dashcaddy-installer/src/main/caddyfile-generator.js

@@ -51,10 +51,15 @@ class CaddyfileGenerator {
   _authSnippet(apiPort) {
     return `# DashCaddy SSO auth snippet
 (dashcaddy_auth) {
-  forward_auth localhost:${apiPort} {
+  @needsAuth not path /dashcaddy-sso
+  forward_auth @needsAuth localhost:${apiPort} {
     uri /api/v1/auth/gate/{args[0]}
     copy_headers Authorization X-Api-Key X-App-Cookie X-Emby-Token X-Plex-Token
   }
+  handle /dashcaddy-sso {
+    rewrite * /api/v1/auth/sso-exchange
+    reverse_proxy localhost:${apiPort}
+  }
 }
 `;
   }

dashcaddy-installer/src/main/caddyfile-generator.sso.test.js

@@ -0,0 +1,35 @@
+const fs = require('fs');
+const path = require('path');
+const { spawnSync } = require('child_process');
+const CaddyfileGenerator = require('./caddyfile-generator');
+
+describe('cross-host SSO installer contract', () => {
+  test('generated auth snippet exposes the public one-time exchange landing route', () => {
+    const snippet = new CaddyfileGenerator()._authSnippet(3001);
+    expect(snippet).toContain('@needsAuth not path /dashcaddy-sso');
+    expect(snippet).toContain('handle /dashcaddy-sso');
+    expect(snippet).toContain('rewrite * /api/v1/auth/sso-exchange');
+    expect(snippet).toContain('reverse_proxy localhost:3001');
+  });
+
+  test('shell installer emits the same exchange landing contract', () => {
+    const installer = fs.readFileSync(path.join(__dirname, '..', '..', 'install.sh'), 'utf8');
+    expect(installer).toContain('@needsAuth not path /dashcaddy-sso');
+    expect(installer).toContain('handle /dashcaddy-sso');
+    expect(installer).toContain('rewrite * /api/v1/auth/sso-exchange');
+  });
+
+  test('Caddy parser accepts a complete service config using the generated snippet', () => {
+    const available = spawnSync('caddy', ['version'], { encoding: 'utf8' });
+    if (available.status !== 0) return;
+
+    const generator = new CaddyfileGenerator();
+    const config = `${generator._authSnippet(3001)}\nexample.test {\n  import dashcaddy_auth plex\n  respond "ok" 200\n}\n`;
+    const result = spawnSync('caddy', ['validate', '--config', '-', '--adapter', 'caddyfile'], {
+      input: config,
+      encoding: 'utf8',
+    });
+    expect(result.status).toBe(0);
+    expect(`${result.stdout}\n${result.stderr}`).toContain('Valid configuration');
+  });
+});