Clarify local runtime bundle bootstrap

Stop presenting make runtime-bundle as a turnkey fresh-checkout bootstrap\nwhen the checked-in manifest is intentionally empty. The manifest comments,\nruntimebundle error messages, Make help, README, and AGENTS docs now all\ndescribe the same local-first flow: stage an archive, use a separate local\nmanifest copy with url/sha256, then bootstrap ./runtime from that manifest.\n\nKeep the existing package/fetch commands intact, and add a small runtimebundle\nregression test so the local-manifest guidance does not drift again.\n\nValidated with make help and GOCACHE=/tmp/banger-gocache go test\n./internal/runtimebundle.

AGENTS.md

@@ -9,7 +9,7 @@
 
 ## Build, Test, and Development Commands
 - `make build` builds `./banger` and `./bangerd`.
-- `make runtime-bundle` bootstraps `./runtime/` from `runtime-bundle.toml`.
+- `make runtime-bundle` bootstraps `./runtime/` from the archive referenced by `RUNTIME_MANIFEST`; the checked-in `runtime-bundle.toml` is only a template.
 - `banger` validates required host tools per command and reports actionable missing-tool errors; do not assume one workstation's package set.
 - `./banger vm create --name testbox` creates and starts a VM.
 - `./banger vm ssh testbox` connects to a running guest.

Makefile

@@ -27,7 +27,7 @@ help:
 	@printf '%s\n' \
 	  'Targets:' \
 	  '  make build   Build ./banger and ./bangerd' \
-	  '  make runtime-bundle Download and unpack ./runtime from runtime-bundle.toml' \
+	  '  make runtime-bundle Fetch and unpack ./runtime from the archive referenced by $(RUNTIME_MANIFEST)' \
 	  '  make runtime-package Package $(RUNTIME_SOURCE_DIR) into $(RUNTIME_ARCHIVE) and print its SHA256' \
 	  '  make install Build and install binaries plus the runtime bundle into $(DESTDIR)$(BINDIR) and $(DESTDIR)$(RUNTIMEDIR)' \
 	  '  make test    Run go test ./...' \

README.md

@@ -30,22 +30,43 @@ The bundle contains:
 - `id_ed25519`
 - the helper scripts used by image builds and installs
 
-Bootstrap a source checkout explicitly:
+Bootstrap a source checkout from a local or published runtime archive. The
+checked-in [`runtime-bundle.toml`](/home/thales/projects/personal/banger/runtime-bundle.toml)
+is a template and intentionally ships with empty `url` and `sha256`.
+
+If you need to create a local archive first, do that from a checkout or machine
+that already has a populated `./runtime/` tree:
 ```bash
-make runtime-bundle
+make runtime-package
+cp dist/banger-runtime.tar.gz /path/to/fresh-checkout/dist/
 ```
 
-`make runtime-bundle` reads [`runtime-bundle.toml`](/home/thales/projects/personal/banger/runtime-bundle.toml),
-downloads the published bundle, verifies its SHA256, and unpacks it into
-`./runtime/`. `make install` will not fetch artifacts for you. The manifest
-must point at a published or locally staged bundle before bootstrap can work.
+In the fresh checkout:
+```bash
+cp runtime-bundle.toml runtime-bundle.local.toml
+```
+
+Edit `runtime-bundle.local.toml` to point at the staged archive and checksum:
+```toml
+url = "./dist/banger-runtime.tar.gz"
+sha256 = "<sha256 printed by make runtime-package>"
+```
+
+Then bootstrap `./runtime/` with the local manifest copy:
+```bash
+make runtime-bundle RUNTIME_MANIFEST=runtime-bundle.local.toml
+```
+
+`url` may be a relative path, absolute path, `file:///...` URL, or HTTP(S)
+URL. `make install` will not fetch artifacts for you.
 
 ## Build
 ```bash
-make runtime-bundle
 make build
 ```
 
+Run `make build` after `./runtime/` has been bootstrapped.
+
 Install into `~/.local/bin` by default, with the runtime bundle under
 `~/.local/lib/banger`:
 ```bash
@@ -206,16 +227,19 @@ make rootfs
 is not available, pass an explicit `--base-rootfs` to `./make-rootfs.sh`.
 
 ## Maintaining The Runtime Bundle
-Maintain the checked-in manifest in [`runtime-bundle.toml`](/home/thales/projects/personal/banger/runtime-bundle.toml)
-with the published bundle URL, SHA256, and `bundle_metadata` defaults.
+The checked-in [`runtime-bundle.toml`](/home/thales/projects/personal/banger/runtime-bundle.toml)
+is a template. Keep `bundle_metadata` accurate there, but use a separate local
+manifest copy when you need concrete `url` and `sha256` values for bootstrap
+testing or publication.
 
-Package a local `./runtime/` tree for publication:
+Package a local `./runtime/` tree into an archive:
 ```bash
 make runtime-package
 ```
 
 That writes `dist/banger-runtime.tar.gz` and prints its SHA256 so you can update
-the manifest before publishing or testing bootstrap changes.
+a local manifest copy before testing bootstrap changes or publishing the
+archive elsewhere.
 
 ## Remaining Shell Helpers
 The runtime VM lifecycle is managed through `banger`. The remaining shell scripts are not the primary user interface:

internal/runtimebundle/bundle.go

@@ -69,10 +69,10 @@ func LoadManifest(path string) (Manifest, error) {
 
 func Bootstrap(ctx context.Context, manifest Manifest, manifestPath, outDir string) error {
 	if manifest.URL == "" {
-		return fmt.Errorf("runtime bundle manifest %s has no url; publish a runtime bundle and update the manifest", manifestPath)
+		return fmt.Errorf("runtime bundle manifest %s has no url; point a local manifest copy at a staged or published runtime bundle archive", manifestPath)
 	}
 	if manifest.SHA256 == "" {
-		return fmt.Errorf("runtime bundle manifest %s has no sha256", manifestPath)
+		return fmt.Errorf("runtime bundle manifest %s has no sha256; add the checksum for the staged or published runtime bundle archive", manifestPath)
 	}
 	manifestDir := filepath.Dir(manifestPath)
 	parentDir := filepath.Dir(outDir)

internal/runtimebundle/bundle_test.go

@@ -71,6 +71,30 @@ func TestBootstrapRejectsChecksumMismatch(t *testing.T) {
 	}
 }
 
+func TestBootstrapRejectsMissingURLWithLocalManifestGuidance(t *testing.T) {
+	manifest := Manifest{
+		SHA256:        strings.Repeat("0", 64),
+		BundleRoot:    "runtime",
+		RequiredPaths: []string{"firecracker"},
+	}
+	err := Bootstrap(context.Background(), manifest, filepath.Join(t.TempDir(), "runtime-bundle.toml"), filepath.Join(t.TempDir(), "runtime"))
+	if err == nil || !strings.Contains(err.Error(), "local manifest copy") {
+		t.Fatalf("Bootstrap() error = %v, want local manifest guidance", err)
+	}
+}
+
+func TestBootstrapRejectsMissingSHAWithArchiveGuidance(t *testing.T) {
+	manifest := Manifest{
+		URL:           "./bundle.tar.gz",
+		BundleRoot:    "runtime",
+		RequiredPaths: []string{"firecracker"},
+	}
+	err := Bootstrap(context.Background(), manifest, filepath.Join(t.TempDir(), "runtime-bundle.toml"), filepath.Join(t.TempDir(), "runtime"))
+	if err == nil || !strings.Contains(err.Error(), "staged or published runtime bundle archive") {
+		t.Fatalf("Bootstrap() error = %v, want archive guidance", err)
+	}
+}
+
 func TestPackageWritesArchive(t *testing.T) {
 	runtimeDir := t.TempDir()
 	for _, rel := range []string{

runtime-bundle.toml

@@ -1,5 +1,6 @@
-# Update `url` and `sha256` to the published runtime bundle before using
-# `make runtime-bundle` in a fresh checkout.
+# Template manifest for local or published runtime bundle archives.
+# Keep this checked-in file empty by default; use a local manifest copy with
+# concrete `url` and `sha256` values when bootstrapping `./runtime/`.
 version = "v0"
 url = ""
 sha256 = ""