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fix(typing): accept every broker where BrokerUsecase[Any, Any] is annotated - #3222
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…otated Since 0.7.6 each broker binds the third parameter of BrokerUsecase to its own config class. The parameter was invariant with a BrokerConfig default, so `BrokerUsecase[Any, Any]` meant `BrokerUsecase[Any, Any, BrokerConfig]` and rejected every concrete broker: dishka's `setup_dishka(broker=...)` failed mypy with arg-type for all of them. Make the TypeVar covariant, rename it to BrokerConfigType_co as PLC0105 asks, and pin the behaviour in tests/mypy, which mypy, pyright and pyrefly all read. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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…s it to the PR Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
…e commits it to the PR" This reverts commit 272b0c2.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
IvanKirpichnikov
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Sep 23, 2026
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
IvanKirpichnikov
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Sep 23, 2026
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Description
Since 0.7.6 an integration annotated with
BrokerUsecase[Any, Any]rejects every concrete broker. dishka'ssetup_dishka(broker=...)is the reported case:#3029 made each broker bind the third parameter of
BrokerUsecaseto its own config (BrokerUsecase[IncomingMessage, RobustConnection, RabbitBrokerConfig]). That parameter was an invariant TypeVar withdefault=BrokerConfig, soBrokerUsecase[Any, Any]expands toBrokerUsecase[Any, Any, BrokerConfig], and no subclass config matches it. Before 0.7.6 every broker left the parameter at its default, so the types happened to line up.What changes
BrokerConfigTypebecomes covariant and is renamed toBrokerConfigType_co, as ruff's PLC0105 requires and as the other covariant TypeVars in the repo are named. It lives infaststream._internal, so the rename is not public API.tests/mypy/broker.pypasses all six brokers to functions annotated withBrokerUsecase[Any, Any]andBrokerUsecase[Any, Any, Any].tests/mypyis read by mypy, pyright and pyrefly, so the behaviour is pinned under all three.Checked
arg-typeerrors, one per broker. With it, it passes.just mypy(1850 files),just pyright,just pyrefly,just linter,just import-linterandjust slotscheckare clean.Trade-off
self.configis mutable, so covariance is not strictly sound. Neither checker flags it, and it restores what every third-party wrapper relied on until 0.7.5.Type of change