Add new action skills for AL testing and documentation

- Introduced `al-test-writer` to generate AL test codeunits for production objects based on TDD principles.
- Added `al-userguide-test-writer` to create test codeunits from user guide steps, mapping actions and assertions.
- Implemented `bc-extension-test-guide` to generate a comprehensive TEST_GUIDE.md for Business Central extensions, covering various categories.
- Created `bc-webclient-runner` to automate UI testing of the Business Central web client, capturing screenshots and asserting UI states.
- Developed `page-scripting-e2e` to produce a recording plan for Page Scripting, ensuring a structured approach to browser-level testing.

custom/knowledge/integration/use-a-framing-record-for-inbound-polling.good.al

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+// Best practice: one framing record per feed. It remembers where the last run stopped,
+// caps how much one run pulls, and carries a lock with a stale timeout so two overlapping
+// Job Queue runs can never fetch the same window.
+
+table 50130 "Inbound Feed Frame"
+{
+    DataClassification = SystemMetadata;
+
+    fields
+    {
+        field(1; "Feed Code"; Code[20]) { Caption = 'Feed Code'; }
+        // The watermark: the next run starts here, so no run ever re-pulls old data.
+        field(2; "Last Fetch At"; DateTime) { Caption = 'Last Fetch At'; }
+        // The cap: a long-quiet feed catches up over several bounded runs instead of one huge pull.
+        field(3; "Max Window (Hours)"; Integer) { Caption = 'Max Window (Hours)'; }
+        // Opaque continuation token from the source's paged API, when it offers one.
+        field(4; "Cursor"; Text[250]) { Caption = 'Cursor'; }
+        // The lock: a second concurrent run sees this set and backs off.
+        field(5; "Locked"; Boolean) { Caption = 'Locked'; }
+        // Stamped when the lock is taken, so a crashed run's lock can be reclaimed after a timeout.
+        field(6; "Locked At"; DateTime) { Caption = 'Locked At'; }
+    }
+
+    keys { key(PK; "Feed Code") { Clustered = true; } }
+}
+
+codeunit 50131 "Inbound Poller"
+{
+    TableNo = "Job Queue Entry";
+
+    procedure Poll(FeedCode: Code[20])
+    var
+        Frame: Record "Inbound Feed Frame";
+        WindowEnd: DateTime;
+    begin
+        Frame.Get(FeedCode);
+
+        // Acquire the lock first. If another run already owns this feed, exit quietly:
+        // overlap is the whole problem we are preventing.
+        if not TryAcquireLock(Frame) then
+            exit;
+
+        // Bounded incremental window: from the watermark up to a capped end. Never "fetch all".
+        WindowEnd := CapWindow(Frame."Last Fetch At", Frame."Max Window (Hours)");
+        FetchAndStage(Frame, Frame."Last Fetch At", WindowEnd);
+
+        // Advance the watermark and cursor so the NEXT run starts exactly where this one ended.
+        // Sequential runs therefore never overlap their windows.
+        Frame."Last Fetch At" := WindowEnd;
+        Frame."Cursor" := NextCursor();
+        ReleaseLock(Frame);
+    end;
+
+    local procedure TryAcquireLock(var Frame: Record "Inbound Feed Frame"): Boolean
+    begin
+        // If the lock is held AND fresh, someone is actively polling: do not steal it.
+        if Frame."Locked" and (CurrentDateTime() - Frame."Locked At" < GetStaleTimeoutMs()) then
+            exit(false);
+
+        // Either free, or stale (a previous run crashed without releasing). Reclaim it.
+        Frame."Locked" := true;
+        Frame."Locked At" := CurrentDateTime();
+        Frame.Modify(true);
+        Commit(); // make the lock durable before the long fetch starts
+        exit(true);
+    end;
+
+    local procedure ReleaseLock(var Frame: Record "Inbound Feed Frame")
+    begin
+        Frame."Locked" := false;
+        Frame.Modify(true);
+    end;
+
+    local procedure GetStaleTimeoutMs(): Integer
+    begin
+        exit(300000); // 5 minutes: longer than a healthy run, short enough to recover from a crash
+    end;
+}