feat(extensions): add OperationValidator.precheck pre-body-parse hook#1548
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cdbartholomew wants to merge 1 commit into
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feat(extensions): add OperationValidator.precheck pre-body-parse hook#1548cdbartholomew wants to merge 1 commit into
cdbartholomew wants to merge 1 commit into
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Add an optional ``precheck`` method to ``OperationValidatorExtension`` that extensions can override to gate a request *before* its body is read off the wire. Wire it as a FastAPI ``Depends`` ahead of the body parameter on the billable POST routes (retain, recall, reflect, file retain, mental-model create, mental-model refresh) so a rejecting precheck short-circuits the request without ever materialising the JSON payload in memory. The post-body-parse ``validate_retain`` / ``validate_recall`` / ``validate_reflect`` hooks are unchanged and remain the source of truth for precise per-call cost and quota arithmetic. ``precheck`` is intentionally a cheap, side-effect-free check — its sole purpose is to let an extension short-circuit work that would otherwise allocate the request body unnecessarily (e.g. a quota-exhausted caller submitting many large bodies). Why before body parse: FastAPI resolves dependencies before deserialising the route's body parameter. A validator that runs only after parse — i.e. inside the route handler's body — sees the already-materialised request, which is the wrong layer for "this caller should not be allowed to spend resources on this request at all" decisions. Wiring as ``Depends`` puts the gate at the right layer with a one-line change per route. Verified: - FastAPI 0.125.0 resolves ``Depends`` raising ``HTTPException`` before Pydantic deserialises the body, regardless of declaration order. A reproducer using a ``model_validator(mode='before')`` recorder confirms zero body-parse calls on the rejection path. - The new ``PrecheckContext`` carries only operation name + bank_id + request_context (already-resolved tenant). No body access — by design. - Default ``precheck`` returns ``ValidationResult.accept()``; existing validators are unaffected. Tests: +7 unit tests covering the default no-op, the FastAPI Depends wiring, accept/reject paths, status-code/reason propagation, and explicit "body never parsed on rejection" assertions for retain / recall / reflect plus a "GET routes are unaffected" guard. All passing.
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Summary
precheck()method toOperationValidatorthat lets an extension gate a request before its body is read.Dependsahead of the body parameter on the billable POST routes (retain, recall, reflect, files retain, mental-model create + refresh).Test plan
tests/test_extensions.pycovering: default no-op accept, rejection short-circuits before body parse (asserted via Pydanticmodel_validator(mode='before')recorder — body never deserialized on reject), rejection returns the validator's status code + reason, GET routes are unaffected, accept lets request through to body parse, body-parse-skipped behaviour holds for retain/recall/reflect.uv run pytest tests/test_extensions.py→ 15 passed). The 21 errors visible in the same run are pre-existing environment issues (missing LLM API key, alembic state) onmainitself — verified independent of this PR.