Address review guidance feedback

Preserve independent event seams, cover loop-carried handled state, strengthen checkpoint and UI-handler fixtures, and align DeleteAll fallback guidance.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 10646e50-2d8b-4cca-b02b-dfa78629e6a1

microsoft/knowledge/events/initialize-ishandled-to-false-before-publishing.bad.al

@@ -17,6 +17,20 @@ codeunit 50241 "IsHandled Init Bad Sample"
             DiscountPct += 2;
     end;
 
+    procedure ApplyLineDiscounts(var SalesLine: Record "Sales Line")
+    var
+        LineIsHandled: Boolean;
+    begin
+        if SalesLine.FindSet() then
+            repeat
+                // Bug: the local initializes only once. A subscriber that handles
+                // one line leaves true for every later iteration.
+                OnBeforeApplyLineDiscount(SalesLine, LineIsHandled);
+                if not LineIsHandled then
+                    SalesLine.Validate("Line Discount %", 5);
+            until SalesLine.Next() = 0;
+    end;
+
     [IntegrationEvent(false, false)]
     local procedure OnBeforeApplyHeaderDiscount(var SalesHeader: Record "Sales Header"; var DiscountPct: Decimal; var IsHandled: Boolean)
     begin
@@ -26,4 +40,9 @@ codeunit 50241 "IsHandled Init Bad Sample"
     local procedure OnBeforeApplyPaymentDiscount(var SalesHeader: Record "Sales Header"; var DiscountPct: Decimal; var IsHandled: Boolean)
     begin
     end;
+
+    [IntegrationEvent(false, false)]
+    local procedure OnBeforeApplyLineDiscount(var SalesLine: Record "Sales Line"; var IsHandled: Boolean)
+    begin
+    end;
 }

microsoft/knowledge/events/initialize-ishandled-to-false-before-publishing.good.al

@@ -4,19 +4,18 @@ codeunit 50240 "IsHandled Init Good Sample"
     procedure ApplyDiscounts(var SalesHeader: Record "Sales Header")
     var
         DiscountPct: Decimal;
-        IsHandled: Boolean;
+        HeaderIsHandled: Boolean;
+        PaymentIsHandled: Boolean;
     begin
-        // A freshly declared local Boolean is false.
-        OnBeforeApplyHeaderDiscount(SalesHeader, DiscountPct, IsHandled);
-        if IsHandled then
-            exit;
-        DiscountPct := 5;
+        // Each fresh local is false and belongs to one non-looping raise.
+        OnBeforeApplyHeaderDiscount(SalesHeader, DiscountPct, HeaderIsHandled);
+        if not HeaderIsHandled then
+            DiscountPct := 5;
 
-        // Reaching this point proves that IsHandled is still false.
-        OnBeforeApplyPaymentDiscount(SalesHeader, DiscountPct, IsHandled);
-        if IsHandled then
-            exit;
-        DiscountPct += 2;
+        // Handling the header event does not suppress this independent seam.
+        OnBeforeApplyPaymentDiscount(SalesHeader, DiscountPct, PaymentIsHandled);
+        if not PaymentIsHandled then
+            DiscountPct += 2;
     end;
 
     [IntegrationEvent(false, false)]

microsoft/knowledge/events/initialize-ishandled-to-false-before-publishing.md

@@ -11,16 +11,16 @@ application-area: [all]
 
 ## Description
 
-A routine that raises an `OnBefore…` integration event with a `var IsHandled: Boolean` parameter passes that variable by reference, so a pre-existing `true` can affect the following control flow. AL [automatically initializes Boolean variables to `false`](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-al-variables#initialization), so a freshly declared local Boolean passed to one event is already deterministic. The same is true when control flow proves the variable is `false`; for example, reaching a second raise after `if IsHandled then exit;` proves that the first raise did not leave it `true`.
+A routine that raises an `OnBefore…` integration event with a `var IsHandled: Boolean` parameter passes that variable by reference, so a pre-existing `true` can affect the following control flow. AL [automatically initializes Boolean variables to `false`](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-al-variables#initialization), so a freshly declared local Boolean passed to one event exactly once per procedure invocation is already deterministic. Initialization does not repeat for each loop iteration: a local declared outside a loop can carry `true` from one iteration to the next even when the source contains only one textual event raise. Outside a loop, reaching a later raise after `if IsHandled then exit;` also proves the value is `false`, provided that early exit is semantically correct and does not skip required downstream events.
 
 ## Best Practice
 
-Reset `IsHandled := false;` before a raise only when the value might otherwise carry over as `true`: the same variable is reused after an earlier raise without a control-flow proof that it is false, the value comes from an input parameter, field, or global, or earlier code seeds it. A reset on a guaranteed-false fresh local can be retained for readability, but its absence is not a correctness finding.
+Reset `IsHandled := false;` before a raise only when the value might otherwise carry over as `true`: the same variable is reused after an earlier raise without a control-flow proof that it is false, a raise is re-entered by a loop, the value comes from an input parameter, field, or global, or earlier code seeds it. Prefer separate fresh locals when independent event seams need independent handled state. A reset on a guaranteed-false fresh local used by one non-looping raise, or before a later raise reached only after a semantically valid `if IsHandled then exit;`, can be retained for readability, but its absence is not a correctness finding.
 
 See sample: `initialize-ishandled-to-false-before-publishing.good.al`.
 
 ## Anti Pattern
 
-Raising `OnBeforeX(…, IsHandled)` when the variable can still be `true` from an earlier raise or another source, so the new publisher call starts with stale state. Do not match a single raise using a fresh local Boolean, or a later raise reached only after `if IsHandled then exit;`.
+Raising `OnBeforeX(…, IsHandled)` when the variable can still be `true` from an earlier raise, an earlier loop iteration, or another source, so the publisher call starts with stale state. Do not match a single non-looping raise using a fresh local Boolean, or a later raise reached only after a semantically valid `if IsHandled then exit;` proves the value is false.
 
 See sample: `initialize-ishandled-to-false-before-publishing.bad.al`.