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Python
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9 entries01Writing
Filtering kwargs with inspect.signature: a function that takes **kwargs looks like it accepts nothing, and a retry lost its model_path2026-11-08inspect.signature(f).parameters lists only declared parameters; **kwargs shows up as a single entry named kwargs. Checking by name whether a callee accepts an argument lets nothing through to the most permissive function. Autarkia’s empty-reply retry lost its model_path this way and fell back to the default model; the resulting 400s landed among upstream 503s, and that day’s error triage filed them as gateway noise.#Python#LLM#DebuggingGenerator Exceptions Surface on the First next(): try Around create_chat_completion(stream=True) Never Sees the Context Window Error2026-11-08Calling a generator function only builds a generator; the body, including any raise in it, runs on the first next(). llama-cpp-python checks the context window inside such a body, so the try around a streaming call, and the shrink-and-retry under it, never fire with the real library. The test double raised at call time, so the tests passed with 100% coverage.#Python#LLM#Error Handling#Testing#AutarkiaLLM Request Observability: Logs Count Messages, and the Native Tools Schema Shows Up Nowhere2026-11-07With native function calling, tool definitions go in the tools parameter, not in messages. A log that measures message length can’t see them, and streaming responses omit usage by default. Autarkia sent 82 tools and 47,898 characters of schema every turn while the prompt log showed about 2,200 characters; the API counted 21k–23k tokens.#LLM#Python#Observability#AutarkiaBreaking Out of an Async Generator Triggers aclose(): Code After the Last Yield Never Runs2026-11-07The consumer breaks on the last event, the async generator gets aclose(), GeneratorExit is thrown into the suspended yield, and the create_task after it never runs while a finally would. Autarkia’s conversation-history save never ran once because of it; the pattern was fixed in April and reintroduced in August for a reasonable-sounding reason.#Python#asyncio#Streaming#AutarkiaOne pop() in a subclass payload builder: max_tokens deleted before sending, invisible to callers, logs and tests2026-10-21The parent class builds the request body, the subclass pops a field before returning it, and whatever the caller passes stops mattering without any error. Autarkia’s MiniMax client has deleted every caller’s max_tokens since the first commit, leaving a reasoning model with no output ceiling, and it was mentioned three times in my notes without being changed.#Python#LLM#ObservabilityComputing the project root twice: Path(__file__).parents[N] silently points elsewhere once the file moves2026-10-19Finding the project root by counting levels up from __file__ is a second copy of where the file lives, and it doesn’t update when the file moves or the snippet is copied to a different depth. In Autarkia one module wrote its data into an auto-created directory under core/, froze the old data, and never raised an error.#Python#Single Source of Truth#File PathsMagicMock accepts any arguments: the caller passes one too many, the test passes, production raises TypeError and except swallows it2026-10-17A MagicMock without a spec doesn’t check call signatures; when the code under test passes the wrong arguments, the double still returns whatever you configured. In Autarkia this meant a block of prompt context was never injected: the real method took only self, the caller passed a user_id, the test double accepted it, and in production the TypeError was swallowed by an outer except.#Python#Testing
02Notes
time.strftime uses the system time zone: write with the configured zone, read with the system one, green locally and a day off on UTC CI2026-10-17The project had a helper that takes today’s date in the configured time zone, and scattered time.strftime("%Y-%m-%d") calls next to it. On a dev machine whose zone matches the config, both always agree; CI runs in UTC, and between midnight and 8 a.m. Beijing time the reading side goes looking for yesterday’s file.#Python#Time#Testingjson.dump iterates while it writes: save outside the lock and you get “dictionary changed size during iteration”, save inside and every writer waits2026-10-16json.dump(data, f) doesn’t serialize first and then write; it uses the pure-Python encoder and writes while iterating, so serialization and disk I/O can’t be separated. Inside a lock, writers wait as long as the disk takes; outside, any concurrent change to the dict raises RuntimeError. Autarkia’s memory save went back and forth between the two.#Python#Concurrency