fix: Avoid importing feast.feature_store at mcp_server import time - #6634
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ntkathole merged 1 commit intoJul 23, 2026
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## master #6634 +/- ##
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- Coverage 45.75% 45.75% -0.01%
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ntkathole
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Jul 23, 2026
mcp_server used a module-level `from feast.feature_store import FeatureStore` solely for a type annotation on add_mcp_support_to_app. Because the feast.infra.mcp_servers package __init__ eagerly imports mcp_server, importing the package pulled in the entire feature_store import graph. Under parallel unit-test collection (pytest -n) this intermittently raced with an in-progress feature_store import and failed collection of test_mcp_server.py with `KeyError: 'feast.infra.mcp_servers.mcp_server'`. Move the import under TYPE_CHECKING and use a forward reference, so importing mcp_server no longer triggers the feature_store graph. Public API and the annotation are unchanged. Signed-off-by: Larry Singleton <166439969+larrysingleton007@users.noreply.github.com>
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July 23, 2026 10:11
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What this PR does / why we need it:
feast/infra/mcp_servers/mcp_server.py imported feast.feature_store.FeatureStore at module load, but used it only for a type annotation on add_mcp_support_to_app. Because the feast.infra.mcp_servers package __init__ eagerly imports mcp_server, importing the package pulled the entire feature_store import graph in as a side effect.
Under parallel unit-test collection (pytest -n), that heavy import intermittently raced with an in-progress feature_store import and failed collection of tests/unit/infra/feature_servers/test_mcp_server.py with KeyError: 'feast.infra.mcp_servers.mcp_server'. The tests pass in isolation, so it shows up as a flaky unit-test-python failure.
Moving the import under TYPE_CHECKING with a forward-reference annotation removes feature_store from mcp_server's module-load path, so importing mcp_server no longer triggers that graph. Public API and the annotation are unchanged.
Which issue(s) this PR fixes:
Fixes #6633
Checks
Testing Strategy
test_mcp_server.py passes (23), and feast.infra.mcp_servers still exposes add_mcp_support_to_app and McpFeatureServerConfig. ruff and mypy clean.
Misc
Release note: NONE.
As an outside contributor I can't apply labels, so a maintainer will need to add kind/bug and run ok-to-test.