R-8: the tool runner's own fingerprint reaches no bundle; a bundle reads the one its module is composed with

Builds: design 47 G §519, §618

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

node-tools/internal/runtime/runtime.go

@@ -59,6 +59,10 @@ type ListedTool struct {
 // NodeRuntimeModule is the module that is a machine's runtime, serving every module on it.
 const NodeRuntimeModule = "node-tools"
 
+// fingerprintEnv is the word the node-engine starts each process with, the fingerprint of the want it applies (mesh-sdk's
+// process.FingerprintEnv; this package imports no SDK): the runtime's own is no bundle's.
+const fingerprintEnv = "MESH_FINGERPRINT"
+
 // runtimeOnly are the words of the runtime's own environment no bundle is given.
 var runtimeOnly = map[string]bool{ToolEnv: true, ToolModules: true, "MESH_BROKER_FILE": true,
 	"MESH_BROKER_URL": true, "MESH_CONSOLE_LISTEN": true, LedgersFile: true}
@@ -1369,11 +1373,13 @@ func (b *moduleBus) bind(key string, stop func()) {
 // BundleEnv is what one module's bundle is started with: the runtime's environment without its own words,
 // the module's composed words over it, and the module's and machine's names. **No bus word reaches a
 // bundle** (security review of 2026-10-08): the credential and the bus's address are the runtime's, and a
-// bundle reaches the bus only through the runtime.
+// bundle reaches the bus only through the runtime. **The runtime's own fingerprint reaches none either**: a bundle reads
+// only the `MESH_FINGERPRINT` its module's composed words hold, the build the node-engine applied for that module, and with
+// none it has none (design 47 G §519, §618).
 func BundleEnv(base []string, given map[string]string, module, node string) []string {
 	words := map[string]string{}
 	for _, kv := range base {
-		if k, v, ok := strings.Cut(kv, "="); ok && !runtimeOnly[k] {
+		if k, v, ok := strings.Cut(kv, "="); ok && !runtimeOnly[k] && k != fingerprintEnv {
 			words[k] = v
 		}
 	}