Refuse to run on config keys the builder cannot build

build_demo.py reads every key with cfg.get(), so a config describing objects it does
not implement was skipped in silence — it printed DONE over an empty database. That
is the same "reports success over an environment that isn't" failure the purge section
exists to prevent, one layer up, and it is how a vertical config (take-offs, progress
statements) would have failed.

Unknown top-level keys now list themselves and abort. DEMO_ALLOW_UNKNOWN_KEYS=1
overrides for a deliberate partial run. Keys starting with _ stay free for comments,
so the shipped example config passes clean.

SKILL.md now states outright that build_demo.py is a per-engagement template rather
than an engine, since that is what makes the failure mode surprising.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/build_demo.py

@@ -14,6 +14,24 @@ from odoo_connect import x, get_or_create, URL, DB
 CFG = os.path.join(os.path.dirname(os.path.abspath(__file__)), "demo_config.json")
 cfg = json.load(open(CFG, encoding="utf-8"))
 
+# Every key below is read with cfg.get(), so anything this script does not know about is
+# silently skipped. That is how a vertical config (take-offs, progress statements, ...) fed
+# to the stock builder prints DONE over an empty database. Fail loudly instead: this script
+# is a per-engagement TEMPLATE, and an unknown key means it has not been adapted yet.
+KNOWN_KEYS = {
+    "client", "currency", "use_credit_limit", "scope_modules", "products", "customers",
+    "vehicles", "pricelist", "prestage_receivables", "heroes",
+}
+unknown = sorted(k for k in cfg if k not in KNOWN_KEYS and not k.startswith("_"))
+if unknown:
+    print("!! demo_config.json has keys this builder does not implement:")
+    for k in unknown:
+        print(f"     {k}")
+    print("!! They will NOT be created. Either extend this script to handle them, or")
+    print("!! remove them so the config reflects what actually gets built.")
+    if os.environ.get("DEMO_ALLOW_UNKNOWN_KEYS") != "1":
+        raise SystemExit("aborting: unimplemented config keys (set DEMO_ALLOW_UNKNOWN_KEYS=1 to override)")
+
 # 1. currency (must run before invoices)
 cur = cfg.get("currency")
 if cur: