fix(mosaic): prevent init prompt code execution

packages/mosaic/framework/tools/_scripts/mosaic-init

@@ -99,7 +99,7 @@ prompt_if_empty() {
 
   if [[ $NON_INTERACTIVE -eq 1 ]]; then
     if [[ -n "$default_value" ]]; then
-      eval "$var_name=\"$default_value\""
+      printf -v "$var_name" %s "$default_value"
       return
     fi
     echo "[mosaic-init] ERROR: --$var_name is required in non-interactive mode" >&2
@@ -115,7 +115,7 @@ prompt_if_empty() {
   if [[ -z "$value" && -n "$default_value" ]]; then
     value="$default_value"
   fi
-  eval "$var_name=\"$value\""
+  printf -v "$var_name" %s "$value"
 }
 
 prompt_multiline() {
@@ -129,7 +129,7 @@ prompt_multiline() {
   fi
 
   if [[ $NON_INTERACTIVE -eq 1 ]]; then
-    eval "$var_name=\"$default_value\""
+    printf -v "$var_name" %s "$default_value"
     return
   fi
 
@@ -139,7 +139,7 @@ prompt_multiline() {
   if [[ -z "$value" ]]; then
     value="$default_value"
   fi
-  eval "$var_name=\"$value\""
+  printf -v "$var_name" %s "$value"
 }
 
 # ── Existing file detection ────────────────────────────────────

packages/mosaic/framework/tools/_scripts/test-mosaic-init-rce.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Source only the prompt helpers; executing mosaic-init itself requires templates.
+source <(head -n 144 "$(dirname "$0")/mosaic-init")
+
+rm -f /tmp/pwned
+payload='literal "$(touch /tmp/pwned)"'
+AGENT_NAME=""
+prompt_if_empty AGENT_NAME "Agent name" <<<"$payload"
+
+[[ "$AGENT_NAME" == "$payload" ]] || {
+  echo "FAIL: prompt answer did not round-trip literally" >&2
+  exit 1
+}
+[[ ! -e /tmp/pwned ]] || {
+  echo "FAIL: prompt answer executed code" >&2
+  rm -f /tmp/pwned
+  exit 1
+}
+echo "mosaic-init RCE regression: PASS"