knowledge(performance): add community rules for JIT, locks, and false positives

These articles capture BC-specific mechanics agents still invert: partial-record JIT on writes, Reset clearing SetLoadFields, HttpClient inside write transactions, and batched number series, plus negative guidance that stops over-eager Query and IsEmpty "fixes".

Co-authored-by: Cursor <cursoragent@cursor.com>

community/knowledge/performance/validate-on-partial-record-forces-jit.md

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+---
+bc-version: [all]
+domain: performance
+keywords: [validate, setloadfields, jit-load, table-relation, onvalidate, partial-record]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Validate on a partial record forces JIT loads
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+`Validate` runs the field's `OnValidate` trigger and TableRelation lookups. Those code paths routinely touch other fields on the same record. On a partial row those extra fields are not loaded, so the platform JIT-loads them — often the rest of the row — plus any related-table reads the trigger performs. Distinct from `skip-setloadfields-on-write-and-transferfields.md`: the write may be `Modify(false)`; `Validate` is what blows the partial load. Agents that combine `SetLoadFields` with `Validate` in a loop produce slower code than an unoptimized assignment.
+
+## Best Practice
+
+In a partial-record loop, assign fields directly when trigger side effects are not required. If `Validate` is required, do not use `SetLoadFields` on that iterator, or `AddLoadFields` every field the validate path can touch before the read.
+
+See sample: `validate-on-partial-record-forces-jit.good.al`.
+
+## Anti Pattern
+
+`SetLoadFields` on a handful of columns, then `Validate` inside the loop. The load list looks optimal; runtime JIT and TableRelation I/O dominate. The signal is `Validate(` on a record that still has a `SetLoadFields` in the same procedure.
+
+See sample: `validate-on-partial-record-forces-jit.bad.al`.