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

[shahar1]

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.

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.

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.

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 six 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

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

[ColtenOuO]

I'd like to try the neo4j one >< (I have open PR #70508 as draft and wait #70505 merged)

[ColtenOuO]

Hi @shahar1 , sorry for the direct ping, and no rush at all.

Since #70508 no reviewer is assigned yet, would you have time to take a look whenever it suits you? I'd mainly like to confirm the approach is what you had in mind - in particular, I moved both provision checks rather than only cypher is None: after #70373, Neo4jOperator(sql=...) is valid with cypher unset, so the constructor check has to be cypher is None and sql is None, and
splitting it from the mutual-exclusivity check felt arbitrary once written that way.

If the approach looks right, I'd be glad to take databricks_repos.py, agent.py and document_loader.py as well.