skill-sdd-implement-feature

name	skill-sdd-implement-feature
description	Lean SDD, implement AL objects from a spec folder. Triggers on: speckit.implement, implement feature, implement spec, lean SDD implement, implement from spec.md, implement plan.md.

Skill: Lean SDD, Implement Feature

Purpose

Read a spec folder (specs/SDD/YYYY-MM-DD-<slug>/) and implement the required AL objects in app/ and test/ following the phases in plan.md. This is the implementation step of the lean feature loop.

When to Load

Load when:

• The user says "implement", /speckit.implement, or "implement feature"
• spec.md + plan.md + tasks.md exist for the target spec folder
• tasks.md has unchecked implementation tasks

Prerequisites

1. specs/SDD/YYYY-MM-DD-<slug>/spec.md, requirements
2. specs/SDD/YYYY-MM-DD-<slug>/plan.md, implementation order
3. specs/SDD/YYYY-MM-DD-<slug>/tasks.md, acceptance checklist
4. .specify/memory/constitution.md, naming conventions and prefix

Step 1, Read Spec Folder

Read specs/<slug>/spec.md     → requirements, AC, data model
Read specs/<slug>/plan.md     → phase order, file map
Read specs/<slug>/tasks.md    → task checklist (to mark off as implemented)
Read .specify/memory/constitution.md  → prefix, id range

<slug> is the dated subfolder under specs/SDD/, e.g. specs/SDD/2026-07-08-fleet-registration/.

Step 2, Verify Symbols Before Writing

For every base-app object referenced in spec.md:

1. Run al_symbolsearch or bclsp_documentSymbols to confirm the symbol exists.
2. Run bclsp_hover on the publisher codeunit + event name to confirm the exact event signature.
3. Record verification result in spec.md event table (Verified? ✅).

If a symbol cannot be confirmed, move it to the spec's Open Questions, do not write code against an unverified symbol.

Step 3, Implement Phase by Phase

Work through plan.md phases in order. After each phase:

• Mark completed tasks in tasks.md
• Run al_get_diagnostics to confirm 0 errors

AL Code Rules (always in force)

These are enforced by the auto-applied instructions; this is a reminder, not a copy:

• Naming: <ObjectName>.<ObjectType>.al, ≤26 chars (PascalCase), {Prefix} on every custom object
• Folders: src/{FeatureName}/ for app objects, test/{FeatureName}/ for test codeunits
• DataClassification: Required on every custom table field
• No hardcoded strings: Use Label variables for all user-visible text
• Extension-only: tableextension, pageextension, eventsubscriber, never modify base objects
• Event subscribers: local procedure, no Commit inside, exact base-app signature
• Performance: SetLoadFields before Find*, no CalcFields in loops, set-based writes

Pattern: Table Extension

tableextension 50100 "{Prefix} {BaseName} Ext" extends "{BaseName}"
{
    fields
    {
        field(50100; "{Prefix} {FieldName}"; {Type})
        {
            Caption = '{Caption}', Comment = '{lang}';
            DataClassification = CustomerContent;
        }
    }
}

Pattern: Event Subscriber

[EventSubscriber(ObjectType::Codeunit, Codeunit::"{Publisher}", '{EventName}', '', false, false)]
local procedure {Publisher}_{EventName}({params})
begin
    // Guard: only handle when relevant
    if not {Condition} then
        exit;

    {BusinessLogic}
end;

Pattern: TryFunction Error Handling

[TryFunction]
local procedure TryExecute{Action}(): Boolean
begin
    {RiskyOperation}
end;

procedure Execute{Action}()
var
    ErrorMsg: Label 'Failed to {action}: %1', Comment = '%1 = error detail';
begin
    if not TryExecute{Action}() then
        Error(ErrorMsg, GetLastErrorText());
end;

Step 4, Write Tests (RED → GREEN)

After each implementation phase, create or extend the test codeunit with Given/When/Then tests that match the acceptance criteria in tasks.md.

[Test]
procedure {Scenario_AC1}()
var
    // test variables
begin
    // [SCENARIO] {AC description}
    Initialize();

    // [GIVEN] {setup}

    // [WHEN] {action}

    // [THEN] {assertion}
    Assert.AreEqual({expected}, {actual}, '{AC}');
end;

After tests compile and pass, mark the corresponding AC row in tasks.md as done.

Step 5, Run Diagnostics

al_get_diagnostics   → 0 errors required before marking phase complete

If errors exist, fix them before moving to the next phase.

Step 6, Update tasks.md

After each completed phase, check off the implementation tasks:

- [x] T1: data-layer task, ✅ {ObjectName} (ID: {id})
- [x] T2: business-logic task, ✅ {CUName}.{ProcName}

Update specs/roadmap.md status to 🔄 In progress (or leave if already set).

Skills Evidencing

> **Skills loaded**: skill-sdd-implement-feature (implement phase)