Add real runtime materialization pipeline and bundle artifacts

README.md

@@ -44,6 +44,37 @@ Host requirements still apply:
 make setup
 ```
 
+## Build runtime bundle
+
+```bash
+make runtime-bundle
+```
+
+This builds the packaged runtime bundle from `runtime_sources/` and syncs the result into `src/pyro_mcp/runtime_bundle/`.
+For real artifacts, first materialize upstream sources into `build/runtime_sources/`.
+
+Available staged targets:
+- `make runtime-binaries`
+- `make runtime-kernel`
+- `make runtime-rootfs`
+- `make runtime-agent`
+- `make runtime-validate`
+- `make runtime-manifest`
+- `make runtime-sync`
+- `make runtime-clean`
+
+Available real-runtime targets:
+- `make runtime-fetch-binaries`
+- `make runtime-build-kernel-real`
+- `make runtime-build-rootfs-real`
+- `make runtime-materialize`
+
+Current limitation:
+- the pipeline is real, but the checked-in source artifacts in `runtime_sources/` are still shim/placeholder inputs
+- the real-source path depends on `docker`, outbound access to GitHub and Debian snapshot mirrors, and enough disk for kernel/rootfs builds
+- replacing those inputs with real Firecracker binaries, a real kernel, and real rootfs images is what upgrades the packaged bundle from `host_compat` to true guest execution
+- the next artifact-replacement steps are documented in `runtime_sources/README.md`
+
 ## Run deterministic lifecycle demo
 
 ```bash