validate-operators-init flags every read of a template-field parameter in __init__. That is right for reads of the value, but wrong for reads of provision — "did the author pass this argument?" — which is what mutually-exclusive-argument checks ask.

The constructor is in fact the only place that can answer it. 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. Forcing the move also turns a static authoring mistake into a per-task-instance runtime failure, and — because a rendered value can legitimately be falsy — invites truthiness tests that silently accept conflicting arguments.

This adds one sanctioned pattern: field is None / field is not None on a template-field parameter (or self.<field>) is allowed in __init__. Everything else — truthiness, in, .startswith, isinstance, transformations — stays flagged.

Measured against the burn-down. Replaying both checkers over every exemption entry ever removed (31 PRs, 48 entries): 8 entries across 5 PRs would have needed no operator code change at all — #70341, #70338, #70348, #70392, #70326 moved pure is None exclusivity checks into execute() verbatim. Two cost more than churn: #70348 broke the Rendered Templates view and needed follow-up #70373, and #70326 made a released operator argument required. Five currently-listed entries clear with no code change and are removed here; two of them are already claimed by contributors on #70296.

That replay counted only reverts that are free — entries whose findings drop to zero with no edit to the operator. It says nothing about provision checks written as truthiness (if a and b: raise), which score identically under both checkers and so are invisible to it; those needed a rewrite to stay in __init__, not just the narrowed rule. A separate pass over guard shape found 10 such guards across 6 PRs; the 4 mutually-exclusive ones are tracked on #70503, and the doc now warns that rewriting a required-argument check to is None loosens it.

The remaining 40 entries stay flagged, correctly — they are genuine value reads (ruleset.strip(), isinstance(mongo_query, list), source not in SUPPORTED_SOURCES).

Second half of the change: nested statements are now checked for invalid template-field assignments. Sanctioning the is None read would otherwise let if field is None: self.field = derive(other) through, since the assignment check only looked at top-level statements. A nested assignment still cannot satisfy the requirement that the field be assigned — it may not run — and nested def/class scopes are skipped. That also closes a pre-existing hole with an unrelated guard.

• scripts/tests/ci/prek/test_validate_operators_init.py: 35 passed. 8 of the 10 new/changed cases fail against the pre-change checker; the 2 that don't are guards against over-sanctioning (truthiness and foo.get('x') is None must stay flagged).
• Hook run over all 541 files matching its files: regex: exit 0, no stale exemptions.
• prek run --from-ref main --stage pre-commit: clean (includes mypy for scripts).

Five merged burn-down PRs moved pure provision checks into execute() and left comments and regression tests asserting that placement. Nothing breaks — the new rule permits is None in __init__, it does not require it — but those files now demonstrate the pattern the docs discourage, and contributors on #70296 learn the rule by reading them. Reverting them is tracked separately so this PR stays reviewable.