fix: allow empty synergies in fast path validator

CHANGELOG.md

@@ -16,6 +16,7 @@ This format follows Keep a Changelog principles and aims for Semantic Versioning
 ### Changed
 - Theme catalog schema now accepts optional `id` values on entries so refreshed catalogs validate cleanly.
 - CI installs `httpx` with the rest of the web stack and runs pytest via `python -m pytest` so FastAPI tests resolve the local `code` package correctly.
+- Relaxed fast-path catalog validation to allow empty synergy lists while still warning on missing or malformed data types.
 
 ### Fixed
 - Regenerated `logs/perf/theme_preview_warm_baseline.json` to repair preview performance CI regressions caused by a malformed baseline file and verified the regression gate passes with the refreshed data.

RELEASE_NOTES_TEMPLATE.md

@@ -3,6 +3,7 @@
 ## Summary
 - Hardened theme catalog schema to accept optional IDs and refreshed the preview performance baseline to keep CI checks green.
 - CI updates install the missing `httpx` dependency and run pytest through `python -m` to ensure the web stack tests import the local package correctly.
+- Fast-path catalog validation now tolerates empty synergy lists while still flagging missing fields or non-string entries.
 - Delivered multi-theme random builds with deterministic cascade, strict match support, and polished HTMX/UI flows.
 - Added opt-in telemetry counters, reroll throttling safeguards, and structured diagnostics exports.
 - Expanded tooling, documentation, and QA coverage for theme governance, performance profiling, and seed history management.
@@ -31,6 +32,7 @@
 ### Maintenance & CI
 - Theme catalog schema now accepts optional IDs and the preview performance warm baseline was regenerated to restore the regression gate.
 - GitHub Actions now includes `httpx` in the default dependency install and executes pytest via `python -m` so FastAPI TestClient suites run without import errors.
+- Fast path validator treats empty synergy arrays as acceptable and only warns on missing or malformed data, reducing noise during automated catalog generation.
 
 ## Detailed changes
 ### Added

code/scripts/validate_theme_fast_path.py

@@ -62,8 +62,14 @@ def validate(data: t.Any) -> list[Problem]:
         if not th.get('theme'):
             probs.append(Problem('error', f'theme[{i}] theme missing'))
         syns = th.get('synergies')
-        if not isinstance(syns, list) or not syns:
+        if syns is None:
-            probs.append(Problem('warn', f'theme[{i}] synergies empty or not list'))
+            probs.append(Problem('warn', f'theme[{i}] synergies missing'))
+        elif not isinstance(syns, list):
+            probs.append(Problem('warn', f'theme[{i}] synergies not a list'))
+        else:
+            bad_types = [type(item).__name__ for item in syns if not isinstance(item, str)]
+            if bad_types:
+                probs.append(Problem('warn', f'theme[{i}] synergies contain non-string entries: {set(bad_types)}'))
         if 'description' not in th:
             probs.append(Problem('warn', f'theme[{i}] description missing'))
     return probs