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/reset-clears-partial-record-selection.md

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+---
+bc-version: [all]
+domain: performance
+keywords: [reset, setloadfields, partial-record, load-selection, findset]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Reset and empty SetLoadFields restore a full-row load
+
+> Contributions welcome — open a PR to refine or extend this article.
+
+## Description
+
+`SetLoadFields(...)` sticks to the record variable until something clears it. `Reset()` "changes fields select for loading back to all", and `SetLoadFields()` with no arguments does the same. A later `FindSet` or `Get` then materializes every normal field. Agents often place `SetLoadFields` first, then `Reset` to apply new filters, and assume the partial selection survives. It does not.
+
+## Best Practice
+
+Call `Reset` (or empty `SetLoadFields()`) first when the variable must be reused, then call `SetLoadFields` with the fields the next read actually uses, then apply filters and read. After `Reset`, a new `SetLoadFields` is required; the previous list is gone.
+
+See sample: `reset-clears-partial-record-selection.good.al`.
+
+## Anti Pattern
+
+`SetLoadFields(...)` followed by `Reset()` (or by parameterless `SetLoadFields()`) and then `FindSet` without restoring the load list. The filters look correct; the SQL still selects every column.
+
+See sample: `reset-clears-partial-record-selection.bad.al`.