cache PlanExeConfig / PlanExeDotEnv / PlanExeLLMConfig loaders

[neoneye]

Summary

Follow-up to #671. That PR cached _load_llm_config in llm_factory, but the underlying loaders still re-parsed on every direct caller — most visibly run_plan_pipeline.resolve_luigi_workers calling PlanExeLLMConfig.load(...) directly. Each PlanExeLLMConfig.load also fans out into two PlanExeConfig.load calls (one direct, one via PlanExeDotEnv.load), so the production logs kept emitting:

INFO  planexe_config        - Optional file '.env' not found …
INFO  planexe_config        - Optional configuration file '.env' not found; relying on environment variables only.
WARN  planexe_llmconfig     - Environment variable 'OPENAI_API_KEY' not found.
WARN  planexe_llmconfig     - Environment variable 'DASHSCOPE_API_KEY' not found.
WARN  planexe_llmconfig     - Environment variable 'DEEPSEEK_API_KEY' not found.
INFO  planexe_llmconfig     - Applied PLANEXE_LLM_CONFIG_WHITELISTED_CLASSES=…

…on essentially every Luigi task.

Changes

Move the body of each loader's load(...) classmethod into a module-level @functools.cache-decorated _load_cached(...) helper.

• PlanExeConfig.load(...)
• PlanExeDotEnv.load() (singleton — no args)
• PlanExeLLMConfig.load(...)

The classmethod normalizes inputs to hashable form (stripping ModelProfileEnum to its str value) and delegates. Cache keys are plain tuples of normalized inputs. cache_clear() is available on each _load_cached if a test ever needs to reset.

Reorder PlanExeLLMConfig.load: filter by whitelisted classes BEFORE substituting env vars. With PLANEXE_LLM_CONFIG_WHITELISTED_CLASSES=OpenRouter in production, entries that need OPENAI_API_KEY / DASHSCOPE_API_KEY / DEEPSEEK_API_KEY are dropped before substitution looks for those vars — those warnings stop firing entirely, even on first cache miss.

Each Luigi worker subprocess still parses once on startup. That's a hard limit of in-process caching across subprocess boundaries — expect one batch of warnings per fresh process, not zero.

Test plan

• Run a full plan in production. Verify Optional file '.env' not found / Environment variable 'X' not found lines appear at most once per worker process (not once per task).
• With PLANEXE_LLM_CONFIG_WHITELISTED_CLASSES=OpenRouter, verify OPENAI_API_KEY / DASHSCOPE_API_KEY / DEEPSEEK_API_KEY warnings no longer appear at all.
• Confirm get_llm("openrouter-…") still resolves to a working model.

🤖 Generated with Claude Code