Add 15 community knowledge articles from BC Code Intel ingest (#66)
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* Add 15 community knowledge articles from BC Code Intel ingest

Ingests net-new /community knowledge from BC Code Intelligence, surviving
the admission test, gray-zone salvage, and dedup against the full corpus.

Domains: ui (6), error-handling (3), performance (2), upgrade (1),
appsource (1), security (1), telemetry (1). The two BC24 No. Series
migration drafts are merged into one article.

Adds good/bad AL samples for the clean-fit articles (error-handling,
performance, security, telemetry). UI and appsource remain knowledge-only.

Validator and knowledge-index checks pass (207 articles).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Correct SetLoadFields JIT-load article to match MS docs

The draft claimed accessing an unlisted field "reloads the entire row"
per record. Microsoft's partial-records docs say otherwise: the platform
does an implicit Get that loads the missing field(s), and in a direct var
loop the first JIT updates the enumerator so later iterations do not
re-load. The genuine per-row penalty is the pass-by-value case, where the
copy's enumerator is not updated.

Rewrite the article around JIT loading and the by-value footgun, rename
the slug from ...full-reload to ...jit-load, and fix the good/bad samples
to demonstrate the by-value repetition accurately.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Jeremy Vyska <jeremy@sparebrained.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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---
bc-version: [all]
domain: ui
keywords: [enqueuebackgroundtask, async-calculation, child-session, factbox, cue-tile, onaftergetcurrrecord, responsive-page, read-only]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Offload Slow Read-Only Page Calculations To Background Tasks
> Contributions welcome — open a PR to refine or extend this article.
## Description
Pages that compute statistics, aggregates, or external lookups inline block the page from rendering until the calculation finishes, producing a visible freeze on FactBoxes, cue tiles, and calculated fields. Business Central provides page background tasks: `CurrPage.EnqueueBackgroundTask` runs a dedicated codeunit in a read-only child session and returns values via `OnPageBackgroundTaskCompleted`, so the page opens immediately and fills in computed values as they arrive. This matters because users should never wait on a calculation they may not need. The mechanism has specific rules that are easy to get wrong, which is why it warrants an explicit pattern.
## Best Practice
Move any noticeable read-only computation off the synchronous render path into a background task. Enqueue from `OnAfterGetCurrRecord` so the task is tied to the currently focused record, and pass small payloads through the `Dictionary of [Text, Text]` input/output, converting types with `Format` and `Evaluate`. Keep each task focused on one value or a small related set rather than one large task, and show a placeholder until results land. Because tasks auto-cancel when the page closes, the record changes, or a same-ID task is re-enqueued, always supply sensible defaults and handle the timeout path in `OnPageBackgroundTaskError` — never let critical functionality depend on completion. For tests, drive the task synchronously with `RunPageBackgroundTask`.
## Anti Pattern
Enqueuing from `OnAfterGetRecord` on a list page fires the task for every row, and each cancels the instant the selection moves to the next row — pure wasted child-session churn; a reviewer spots `EnqueueBackgroundTask` called from `OnAfterGetRecord` (or from `OnOpenPage`, where the record context is not yet stable). The other tell is a task codeunit attempting a database write or `Modify`: background tasks run read-only and the write fails at runtime. Inline heavy calculation directly in `OnAfterGetCurrRecord` with no task at all is the baseline smell — it reintroduces the page freeze the feature exists to remove.