Restore argument-provision checks to __init__ in operators fixed by the burn-down #70503

Background

validate-operators-init flags every read of a template-field parameter in __init__. A companion PR narrows that: a field is None / field is not None check reads whether the argument was passed, not its value, and belongs in the constructor. (With render_template_as_native_obj=True a provided field renders to None, so the same check in execute() reports a supplied argument as missing; and raising at construction surfaces a static authoring mistake as a Dag import error rather than per task instance.)

Replaying both checker versions over every exemption entry removed so far (31 PRs, 48 entries) shows 8 entries across 5 PRs where the old rule forced a change that was not needed. Those PRs are merged and green — nothing is broken — but the files now carry comments and regression tests asserting the placement the docs discourage, and contributors working #70296 learn the rule by reading them.

This issue tracks putting them back. Each is independent; separate PRs are fine.

Blocked on #70505. Until it merges, validate-operators-init still flags every read of a template-field parameter in __init__, so a restored check fails the hook — a revert landed earlier would have to re-add the exemption entry it just removed.

Revert

• providers/common/ai/.../operators/agent.py (Validate template fields after rendering in common.ai operators #70338) — message_history is not None and enable_hitl_review is pure provision. Restore to __init__, revert test_agent.py::test_message_history_with_hitl_review_raises to constructor-raises. The comment # message_history is a template field; validate the combination after rendering. states the rule wrongly and must go.
• providers/databricks/.../operators/databricks_repos.py (Validate Databricks Repos operators' template fields after rendering #70341) — all four branch/tag/repo_id/repo_path checks in DatabricksReposCreate/Update/DeleteOperator are pure provision. Restore to __init__; revert the two tests docstringed "rejected at execute, after rendering".
• providers/neo4j/.../operators/neo4j.py (Fix Neo4jOperator templated query validation #70348) — if cypher is None: raise returns to __init__. The deprecation-warning placement is a separate question; Show the deprecated Neo4jOperator sql query in Rendered Templates #70373's rationale stands independently.

Split, don't revert

• providers/common/ai/.../operators/document_loader.py (Validate template fields after rendering in common.ai operators #70338) — the source_path/source_bytes exclusivity is provision and returns to __init__. The third check, source_bytes is not None and file_type is None, backs the downstream assert self.file_type is not None; file_type is a template field, so that assumption only holds after rendering and it stays in execute(). Update the comment to say which is which — this is the canonical example of the boundary.

Rewrite, don't revert

The replay above only finds reverts that are free — entries whose findings drop to zero with no edit. Provision checks written as truthiness (if a and b: raise) score the same under both checkers, so they never showed up in it, but they are the same kind of check and moving them to execute() cost more: on rendered values a mutual-exclusion check silently accepts the conflict when one side renders empty. Restoring these means rewriting and to is not None and, which is strictly stricter — it also rejects field="" alongside a second argument, and both were supplied.

• providers/amazon/.../aws/operators/dms.py (Move amazon dms operators template-field validation to execute() #70450) — DmsModifyTaskOperator (cdc_start_time and cdc_start_position) and DmsStartReplicationOperator (self.cdc_start_time and self.cdc_start_pos). Revert the two tests to constructor-raises; while there, DmsStartReplicationOperator should raise ValueError rather than AirflowException. The commit is not in providers-amazon/9.33.0rc1, so fixing before the next release costs no changelog entry.
• providers/databricks/.../sensors/databricks.py (Validate DatabricksSQLStatementsSensor statement fields after rendering #70340) — DatabricksSQLStatementsSensor, the statement and statement_id exclusivity check only. Its not statement and not statement_id sibling is a required-argument check — see below.
• providers/snowflake/.../operators/snowpark_containers.py (Move SnowparkContainerJobOperator template-field validation to execute #70332) — SnowparkContainerJobOperator, the self.spec_text and (self.spec or self.spec_stage) exclusivity check only. Same split as above for its inverse.

Leave alone (listed so nobody reverts them by pattern-match)

• providers/weaviate/.../operators/weaviate.py (Fix WeaviateIngestOperator input_data validation before rendering #70326) — making input_data required is already released; reverting would be a second API break. The execute() check becomes belt-and-braces and is harmless.
• providers/teradata/.../transfers/teradata_to_teradata.py (Fix Teradata transfer template field initialization #70392) — self.sql_params or {} at the use site is equivalent. No value in churning it back.

Required-argument checks written as truthiness stay in execute() too. if not field: raise there still raises — it is later feedback, never a silent accept — and rewriting it to if field is None: raise in __init__ would loosen it, letting field="" through. Splitting each into a provision check plus a value check is more churn than the placement is worth:

• providers/papermill/.../operators/papermill.py (Fix template-field validation in PapermillOperator #70435) — not input_nb, not output_nb
• providers/apache/kafka/.../operators/produce.py (Validate ProduceToTopicOperator topic after rendering #70333) — not (self.topic and self.producer_function)
• providers/databricks/.../sensors/databricks.py (Validate DatabricksSQLStatementsSensor statement fields after rendering #70340) — not statement and not statement_id
• providers/cncf/kubernetes/.../operators/resource.py (Validate KubernetesResourceBaseOperator yaml_conf after rendering #70337) — not any([self.yaml_conf, self.yaml_conf_file])
• providers/snowflake/.../operators/snowpark_containers.py (Move SnowparkContainerJobOperator template-field validation to execute #70332) — not self.spec_text and not (self.spec and self.spec_stage)

Not in scope

The other 40 exemption entries removed so far are genuine value reads (ruleset.strip(), isinstance(mongo_query, list), source not in SUPPORTED_SOURCES, ...). They stay flagged under the narrowed rule and must not be reverted.

Verifying a revert

Run the hook on the file after the change — all classes above are clean under the narrowed rule, so no exemption entries need re-adding:

uv run --script scripts/ci/prek/validate_operators_init.py <path>

related: #70296

Drafted-by: Claude Code (Opus 5) (no human review before posting)