fix: make BaseBootstrapper.bootstrap() idempotent#106
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teardown() already short-circuits when is_bootstrapped is False, but bootstrap() previously didn't guard the symmetric case: calling bootstrapper.bootstrap() twice would re-invoke every instrument's bootstrap, causing user-visible side effects (e.g. mounting the FastMCP access-log middleware twice would double every access record; re-registering a Prometheus /metrics route raises). Add the symmetric guard at the top of bootstrap(): when is_bootstrapped, return the prepared application without re-running the instruments. Adds test_bootstrap_is_idempotent next to the existing test_teardown_is_idempotent in test_free_bootstrap.py. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
BaseBootstrapper.teardown()short-circuits whenis_bootstrappedis False, butbootstrap()had no symmetric guard. Callingbootstrapper.bootstrap()twice would re-invoke every instrument'sbootstrap, with user-visible side effects:/metricsroute viaapplication.custom_route(...)raises._TeardownProviderregistered twice on FastMCP.Add the symmetric guard at the top of
bootstrap(): when already bootstrapped, return the prepared application without re-running the instruments.Test plan
just test— full suite (149 tests, +1 new) passesjust lint— cleantest_bootstrap_is_idempotentmirrors the shape of the existingtest_teardown_is_idempotent— wires twoMagicMock()instruments onto the bootstrapper, callsbootstrap()twice, asserts each instrument'sbootstrapwas called exactly once andis_bootstrappedis TrueFlagged as a follow-up during review of #105 (FastMCP bootstrapper) — the MCP access middleware made the double-mount symptom user-visible.
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