Phast gives a person one portable MCP plus a programmable Prefab home. Connect `my.phast.app/mcp` to an agent to create and manage Phasts. A created Phast has two matching surfaces:
-`user.phast.app` — human / Prefab home
-`user.phast.app/mcp` — the user's portable MCP tool belt
## V0 contract
`phast.json` is deliberately boring. It is mostly:
1. the MCP tool list and provider connections;
2. references to delegated credential authority (Persimmons, never raw secrets);
3. Prefab home/widget settings.
The browser and chat are two editors for the same declaration.
### Browser flow
Home → Edit Home → Add Widget → provider search → connect if necessary → place/configure widget.
### Agent flow
Connect once to `my.phast.app/mcp` → create/manage `user.phast.app` → search providers → add tools/widgets → stream/taste-test Prefab in chat → persist accepted UI to the same `phast.json`.
## Boundaries
- **Phast composes.** It owns the portable MCP/tool belt and Prefab composition.
- **Oracle discovers.** Provider/MCP/OAuth discovery comes from the capability graph, not a hard-coded Phast directory.
- **Clients are replaceable.** ChatGPT, Claude, Codex, or another MCP client should be able to use the same Phast without recollecting the user's tools.
V0 is intentionally not arbitrary app generation. Prove the portable-tool-belt + editable-home loop first.
