bcquality/microsoft/skills/review/al-breaking-changes-review.md

---
kind: action-skill
id: al-breaking-changes-review
version: 1
title: AL breaking changes review
description: Reviews AL source changes against breaking-changes guidance from BCQuality.
inputs: [pr-diff, file-path, folder-path]
outputs: [findings-report]
bc-version: [all]
technologies: [al]
countries: [w1]
application-area: [all]
---

# AL breaking changes review

Reviews AL source changes against the `breaking-changes` knowledge domain in BCQuality and emits a findings report. This is a leaf action skill: it invokes no sub-skills. It is one of the skills composed by `al-code-review`.

An orchestrator invokes this skill with a `pr-diff`, `file-path`, or `folder-path`. The skill produces a single JSON document conforming to the DO output contract.

## Source

Use READ's **Bounded retrieval for review skills** workflow with `-Domain breaking-changes`. Consume every catalog page across enabled layers before applying this leaf's Relevance and Worklist; preserve each exact catalog path and open complete bodies only for exact paths selected by the Worklist. If the helper or prepared index is unavailable or invalid, use READ's explicit path-discovery and bounded native-read fallback.

## Relevance

Apply the frontmatter matching rules defined in READ (*Frontmatter matching semantics*) against the task context:

- `bc-version` — the target BC version from the PR branch's `app.json` or the orchestrator-supplied version. If unavailable, the dimension is `unknown`.
- `technologies` — `[al]`.
- `countries` — the countries declared in the consuming app's `app.json`. Default to the orchestrator's configured context; if absent, `unknown`.
- `application-area` — the union of application areas declared by the changed objects. Pass the actual set; do not substitute `[all]`. If the area cannot be determined from the changes, the dimension is `unknown`.

Discard files that are not applicable. Retain conditionally applicable files (any dimension `unknown`) only when the orchestrator's configuration permits them; findings derived from those files MUST have `confidence` no higher than `medium`, AND the finding's `message` MUST name the dimension or dimensions that were unknown.

## Worklist

Narrow the relevant files to the subset that applies to the changes under review. For each relevant file, compute overlap against:

- The changed AL object names and types — especially codeunits, tables, and table extensions that expose procedures, fields, or events to other apps, and any member whose access is being widened.
- The changed procedures, fields, and triggers, weighted toward non-`local` procedures, published table fields, event publishers, and any member whose signature, access modifier, or obsolete state is being altered.
- Tokens extracted from the diff that relate to API stability and deprecation (`signature`, `parameter`, `return`, `var`, `Obsolete`, `ObsoleteState`, `ObsoleteReason`, `ObsoleteTag`, `Pending`, `Removed`, `CLEAN`, `SecretText`, `token`, `internal`, `local`, `public`, `protected`, `Scope`).

A file enters the candidate worklist when its `keywords` intersect the extracted tokens or its topic (derived from the index entry's `path`, `title`, and `description`) matches a changed object type. Read an article's full file — its `## Best Practice` / `## Anti Pattern` bodies — only after it makes the worklist; candidate selection uses the index alone.

The following targeted checks cover every current `breaking-changes` article:

- A helper or object changes between `local`, `internal`, `protected`, or public access, or a new implementation detail is exposed without a supported-API reason — `choose-access-modifiers-deliberately`.
- A public member is removed or replaced without first going through the `[Obsolete]` lifecycle — `deprecate-public-members-with-the-obsolete-lifecycle`.
- A published procedure changes parameter count/order/type/name, `var`, return type, or array shape instead of preserving the old signature and adding an overload — `do-not-change-published-procedure-signatures`.
- A public procedure/event/interface exposes a credential or other sensitive value through `Text` or an externally callable contract — `do-not-expose-sensitive-data-through-public-api`.
- Code already marked obsolete is expanded with new behavior instead of routing new callers to its replacement — `do-not-modify-code-already-marked-obsolete`.
- A shipped table field is deleted, renamed, renumbered, or replaced without retaining the original field as `ObsoleteState = Pending` and migrating its data — `obsolete-table-fields-instead-of-deleting-them`.

For `obsolete-table-fields-instead-of-deleting-them`, compare the baseline ID and name before emitting. When the original field remains under the same ID and name with `ObsoleteState = Pending`, and the replacement uses a new ID, the change follows the rule and must not be flagged.

Once the candidate worklist is known, resolve layer-precedence conflicts per READ. Drop lower-precedence files whose normative guidance (`## Best Practice` or `## Anti Pattern`) directly contradicts a higher-precedence candidate, and record each dropped file in `suppressed` with `reason: "layer-precedence"`. Files that would have been candidates but are hidden because their layer is disabled in consumer configuration are recorded with `reason: "configuration"`. Files that never became candidates are NOT recorded in `suppressed`.

When the post-conflict worklist is empty because no applicable breaking-changes knowledge exists, or because configuration suppressed every candidate, emit `outcome: "no-knowledge"`. When the worklist is empty because no applicable breaking-changes knowledge matched the changes, emit `outcome: "completed"` with an empty `findings` array.

## Action

For each worklist entry, evaluate the diff against the file's `## Best Practice` and `## Anti Pattern` sections. Emit findings as follows:

- When the diff contains a clear match for an Anti Pattern, emit a finding with severity `major` or `blocker`, a message summarizing the anti-pattern, `location` pointing to the offending line or range, and a `references` entry pointing to the knowledge file. Use `blocker` only when the knowledge file states the anti-pattern violates a platform-level guarantee. When the file does not make such a claim, the ceiling is `major`.
- When the diff contains code that contradicts a Best Practice without being a full anti-pattern, emit `minor` with the same reference shape.
- Applicability alone is not a finding. Emit `info` only for a concrete, non-actionable observation the article explicitly defines; otherwise emit nothing when no violation is present.

Set `confidence` to:

- `high` when the detection is based on an unambiguous pattern match (identifier, syntax, object type).
- `medium` when detection relies on heuristics or when any frontmatter dimension was `unknown`.
- `low` when the finding is an advisory derived only from applicability.

After evaluating each worklist entry, also consider whether the diff exhibits a breaking-changes defect the agent recognises from its general AL knowledge that no knowledge file in the worklist covers. Such candidates are agent findings within this skill's domain — emit them with `references: []`, an `id` slug prefixed with `agent:`, `confidence` capped at `medium`, `severity` capped at `minor` (agent findings are advisory and non-gating), and a `message` that is self-contained (describing both the issue and a concrete recommendation, since there is no knowledge-file footer for the consumer to fall back on). Hold every candidate to the precision bar in `skills/do.md` (*Agent findings*): emit only a concrete, material API-stability defect a knowledgeable BC reviewer would agree is wrong — steelman it first and drop anything stylistic, speculative, dependent on code outside the diff, or merely a valid alternative; when in doubt, omit. The scope is strictly breaking changes; defects outside this domain belong to other leaves and MUST NOT be emitted here. Before emitting, check the worklist for a knowledge file that matches the candidate — if one exists, upgrade the candidate to a knowledge-backed finding instead. See `skills/do.md` for the full contract.

For every emitted finding, decide whether the fix is mechanical. A fix is mechanical when it is small, local, and unambiguous from the diff context (for example: restore a published procedure's parameter list and add a new overload for the extra argument; add an `[Obsolete]` attribute to a member being removed; change a needlessly `public` helper to `internal`). For mechanical findings, emit `findings[].suggested-code` with the literal replacement for the source lines indicated by `location`. The payload must be a verbatim replacement — no diff markers, no fences, no commentary — that the consumer can render as a one-click suggestion. When a `.good.al` companion exists and the diff context matches the `.bad.al` shape, adapt the `.good.al` replacement into `suggested-code`.

Omit `suggested-code` only when the appropriate fix depends on context the skill cannot determine, when multiple defensible replacements exist, or when the fix spans non-contiguous code. If a finding is mechanical-looking but you omit `suggested-code`, set `findings[].suggested-code-omission-reason` to a short explanation. See `skills/do.md` for the full contract.

Outcome selection:

- `completed` — the skill evaluated every worklist item; default when the skill finishes normally, including when the resulting `findings` array is empty.
- `no-knowledge` — no applicable breaking-changes knowledge survived Source, Relevance, configuration filtering, and conflict resolution. `findings` is empty.
- `not-applicable` — the task context lacks an AL dimension (no AL changes in the diff, or `technologies` filter rejected the task).
- `partial` — a time or token budget was hit before the worklist was exhausted. `summary.coverage` reflects the evaluated subset; `outcome-reason` explains the cause.
- `failed` — an unrecoverable error occurred. `outcome-reason` is required.

## Output

Output conforms to the DO output contract. Every finding this skill emits MUST set `findings[].domain` to `"Breaking Changes"`. A populated example:

```json
{
  "skill": { "id": "al-breaking-changes-review", "version": 1 },
  "outcome": "completed",
  "summary": {
    "counts": { "blocker": 0, "major": 1, "minor": 1, "info": 0 },
    "coverage": { "worklist-size": 2, "items-evaluated": 2 }
  },
  "findings": [
    {
      "id": "microsoft/knowledge/breaking-changes/do-not-change-published-procedure-signatures.md",
      "severity": "major",
      "message": "A parameter was added to the published procedure CalculateDiscount, breaking every dependent extension that called the previous form. Add a new overload alongside the unchanged procedure instead.",
      "location": {
        "file": "src/Sales/DiscountApi.Codeunit.al",
        "line": 12,
        "range": { "start-line": 12, "end-line": 15 }
      },
      "references": [
        { "path": "microsoft/knowledge/breaking-changes/do-not-change-published-procedure-signatures.md" }
      ],
      "confidence": "high",
      "domain": "Breaking Changes"
    },
    {
      "id": "microsoft/knowledge/breaking-changes/choose-access-modifiers-deliberately.md",
      "severity": "minor",
      "message": "An implementation-detail helper is declared public with no reason to support it externally, making it a de-facto API. Default it to internal or local.",
      "location": {
        "file": "src/Sales/OrderProcessor.Codeunit.al",
        "line": 20
      },
      "references": [
        { "path": "microsoft/knowledge/breaking-changes/choose-access-modifiers-deliberately.md" }
      ],
      "confidence": "medium",
      "domain": "Breaking Changes"
    }
  ],
  "suppressed": []
}
```

When no applicable breaking-changes knowledge is available, the report is:

```json
{
  "skill": { "id": "al-breaking-changes-review", "version": 1 },
  "outcome": "no-knowledge",
  "summary": {
    "counts": { "blocker": 0, "major": 0, "minor": 0, "info": 0 },
    "coverage": { "worklist-size": 0, "items-evaluated": 0 }
  },
  "findings": [],
  "suppressed": []
}
```