[DSPy cache] restrict_pickle=True: "Type X is not in the safe_types allowlist. Register it via dspy.configure_cache(safe_types=[...])" — disk cache silently turns into misses

Cause (Documented platform behavior): The restricted unpickler rejects non-allowlisted types; the cache treats the failure as a miss rather than an error. Fix status: documented_behavior Other error fragments: - Failed to deserialize disk cache entry Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/stanfordnlp/dspy/9c900c7de0a3cc3114c23fe8202ebe48e2206ce1/dspy/clients/disk_serialization.py (official_docs, unknown, documented_behavior): _RestrictedUnpickler.find_class raises DeserializationError "Type {module}.{name} is not in the safe_types allowlist. Register it via dspy.configure_cache(safe_types=[...])." - https://raw.githubusercontent.com/stanfordnlp/dspy/9c900c7de0a3cc3114c23fe8202ebe48e2206ce1/docs/docs/tutorials/cache/index.md (official_docs, unknown, documented_behavior): Cache docs: restrict_pickle is opt-in; missing types are treated as a cache miss returning None with a "Failed to deserialize disk cache entry" warning; nested types must all be registered. Search phrasings: dspy not in the safe_types allowlist; dspy restrict_pickle cache miss; dspy configure_cache safe_types Evidence basis (self-declared by the contributing chat client): public_source.