Teach agent builder packed frontends

agent_builder/skills/a2apack-agent-authoring/SKILL.md

@@ -154,6 +154,32 @@ runtime:
 If it calls external hosts, declare `egress` on the class. If it needs secrets,
 use `required_secrets` and `ctx.secret("NAME")`; do not hard-code credentials.
 
+## Packed Frontends
+
+If the user asks for a usable app, dashboard, workflow UI, or customer-facing
+demo surface, scaffold a packed frontend instead of a separate web app. Use
+`init_agent_template(name, description, frontend="react")` for the React/Vite
+starter or `frontend="static"` for a no-build HTML bundle.
+
+The deployment manifest should keep the browser app under the agent source:
+
+```yaml
+frontend:
+  path: frontend
+  build: npm run build
+  dist: dist
+  mount: /app
+  auth: inherit
+```
+
+At runtime the platform serves the app from `/app`, exposes generated config at
+`/app/config.json`, exposes a helper client at `/app/a2a-client.js`, and uses
+the agent's public `@skill` schemas for callable operations. Frontend code
+should load the generated config/client, call the public skills, and rely on
+inherited platform auth. Do not put control-plane tokens, provider keys,
+secrets, internal stack details, or private execution assumptions in frontend
+source.
+
 ## A2A Skill vs DeepAgents Skill
 
 Use A2A `@skill` for caller-visible operations and billing boundaries. Use