bcquality/custom/skills/review/al-performance-reviewer.md

kind	id	version	title	description	inputs	outputs	bc-version	technologies	countries	application-area
action-skill	al-performance-reviewer	1	AL performance anti-pattern review	Reviews AL for N+1 queries, missing keys, FlowField overuse on lists, missing SetLoadFields, and FindFirst on growing tables, and emits a findings report.	pr-diff file-path	findings-report	all	al	w1	all

AL performance anti-pattern review

Reads AL with a single question: at ten times tenant scale, where does this fall over? It targets the patterns the AL compiler will not warn about but that compound badly under data scale: N+1 per-row sibling lookups and per-row CalcFields, a SetCurrentKey with no matching key, FindFirst on tables that grow without bound (ledger entries, document headers), FlowField columns on list-page repeaters, missing SetLoadFields, destructive DeleteAll/ModifyAll with no filter, heavy OnAfterGetRecord, HTTP calls inside a loop, and Commit inside iterations. This skill sources from the performance knowledge domain and cites those files where they match. It overlaps the platform al-performance-review, so its primary added value is agent findings for the scale patterns the corpus does not yet cover. This is a leaf action skill: it invokes no sub-skills.

An orchestrator invokes this skill with a pr-diff (the standard PR-review entry point) or a file-path (single-file review). It produces a single JSON document conforming to the DO output contract.

Source

Read the BCQuality knowledge index once (the knowledge-index.json Entry's preparation step regenerates over the live, already-filtered clone). Take the index entries whose domain is performance as the citable candidate set across every enabled layer: a Get inside a loop on a large table, CalcSums instead of CalcFields in a loop, applying filters before iterating, SetLoadFields for partial records, IsEmpty for existence checks, Get instead of FindFirst on a full primary key, and commit boundaries each map onto a curated rule and MUST cite it rather than be paraphrased. Do not open individual article files at this step; open an article's full body only once it enters the Worklist below. Where a concrete scale defect has no curated rule (a FlowField column added to a heavily rendered list repeater, a FindFirst on a known unbounded ledger table with no tight filter, a missing HasFilter guard before a destructive iteration), emit an agent finding within this skill's performance domain (see Action).

Relevance

Apply the frontmatter matching rules defined in READ against the task context:

• bc-version: the target BC version from the branch app.json, or unknown if unavailable.
• technologies: [al].
• countries: the consuming app's declared countries, or unknown.
• application-area: the application areas of the changed objects, or unknown.

Discard files that are not applicable. Retain conditionally applicable files (any dimension unknown) only when configuration permits; findings derived from them have confidence no higher than medium, and the finding message names the unknown dimensions.

Worklist

Narrow the relevant files to the subset that applies to the changes, computing overlap against:

• Record-iteration code: FindSet/FindFirst/FindLast and repeat..until loops, weighted toward a per-row Get/Find on a sibling table (N+1) and a per-row CalcFields.
• List pages and their SourceTable, weighted toward FlowField columns on the repeater and heavy OnAfterGetRecord bodies.
• Keys defined on the table compared against the SetCurrentKey plus SetRange/SetFilter combinations the code actually uses; a SetCurrentKey with no matching key.
• FindFirst against tables that grow without bound (Item Ledger Entry, Value Entry, G/L Entry, Vendor Ledger Entry, Sales Header, Purchase Header) with no tight SetRange.
• Reads that use only a few fields and could SetLoadFields; DeleteAll/ModifyAll with no prior filter or HasFilter guard; HttpClient.Send or Commit inside an iteration.

A curated performance file enters the worklist when its keywords intersect these tokens or its topic matches a changed object kind. Read its full ## Best Practice / ## Anti Pattern body only after it makes the worklist. Resolve layer-precedence conflicts per READ and record dropped files in suppressed.

Action

For each worklist entry, evaluate the diff against the file's ## Best Practice and ## Anti Pattern sections. When the diff clearly matches an anti-pattern (a Get inside a loop on a large table, a CalcFields per row, a FindFirst on a full primary key), emit a knowledge-backed finding citing the file: id equal to the file path, the file as primary reference, severity blocker only when the file states a platform-level guarantee otherwise major, location on the offending line or range, confidence high for an unambiguous match. When the diff contradicts a best practice without being a full anti-pattern, emit minor with the same reference shape.

When a concrete scale defect has no curated rule, emit an agent finding within this skill's performance domain: references: [], id slug prefixed agent: (for example agent:flowfield-on-list-repeater or agent:findfirst-on-unbounded-table), confidence capped at medium, severity capped at minor, and a self-contained message that states the cost at scale (one extra query per visible row per render, a full scan on a table that only grows) and a concrete fix (move the FlowField to a factbox, add a SetRange that resolves via a key). Where the impact would normally gate (a destructive DeleteAll with no filter), keep severity at minor but say so plainly in the message and note the concern should be promoted to a knowledge-backed rule before it can gate. Hold every candidate to the precision bar in skills/do.md: steelman that the table is small, the filter is set elsewhere, or the cost is documented and accepted before emitting, and omit when in doubt. The scope is strictly performance; defects outside this domain belong to other skills. Before emitting any agent candidate, check the worklisted knowledge for a match and upgrade it to a knowledge-backed finding if one exists.

Set suggested-code when the fix is mechanical (replacing Count() > 0 with not IsEmpty(), adding a SetLoadFields before a FindSet, adding a HasFilter guard before a DeleteAll); otherwise set suggested-code-omission-reason (for example requires choosing the right secondary key to add).

Outcome selection: completed when every worklist item was evaluated (including an empty findings); no-knowledge when no curated knowledge survived and no agent finding was raised; not-applicable when the diff has no AL to review; partial or failed per the DO contract with outcome-reason.

Output

Output conforms to the DO output contract. A populated example:

{
  "skill": { "id": "al-performance-reviewer", "version": 1 },
  "outcome": "completed",
  "summary": {
    "counts": { "blocker": 0, "major": 1, "minor": 1, "info": 0 },
    "coverage": { "worklist-size": 3, "items-evaluated": 3 }
  },
  "findings": [
    {
      "id": "microsoft/knowledge/performance/avoid-get-inside-loop-on-large-table.md",
      "severity": "major",
      "message": "Inside a FindSet over Vendor, Data Sync Mgt.SyncVendors calls Cache.Get for each row, firing one query per vendor. Pre-load the cache table into a Dictionary outside the loop and look up per row instead.",
      "location": {
        "file": "src/DataSyncMgt.Codeunit.al",
        "line": 142,
        "range": { "start-line": 142, "end-line": 146 }
      },
      "references": [
        { "path": "microsoft/knowledge/performance/avoid-get-inside-loop-on-large-table.md" }
      ],
      "confidence": "high"
    },
    {
      "id": "agent:flowfield-on-list-repeater",
      "severity": "minor",
      "message": "A FlowField column Total Amount was added to the Vendors list repeater, so every visible row triggers a CalcFields on each render. On a 50-row list that is 50 extra aggregate queries per render. Move the field to a factbox, which renders once per selected row, or document and accept the cost. This concern should be promoted to a knowledge-backed rule before it can gate.",
      "location": {
        "file": "src/Vendors.Page.al",
        "line": 28
      },
      "references": [],
      "confidence": "medium",
      "suggested-code-omission-reason": "fix is a layout decision between factbox placement and accepted cost"
    }
  ],
  "suppressed": []
}