[CLAUDE] Tests: Plan AB Chunk A2 — fix Plan M tests filter LogTransition entry post Plan AB

Plan AB Chunk A thêm Changelog entry mới (EntityType=Workflow + Summary
"Trả lại (...)" + ContextNote=null) trong ApplyReturnModeAsync end-of-function.
Plan M edge case tests (OneLevel_AtStep1Level1 + OneStep_AtStep1) assert
ContextNote.Contains("không lùi được") qua OrderByDescending(CreatedAt) — SQLite
frozen test clock cùng CreatedAt 2 entry → tie-break non-deterministic → pick
Plan AB entry (ContextNote=null) → FAIL.

Fix: Test query filter by Summary.Contains("Chuyển phase") để pick đúng
LogTransitionAsync entry (chứa "không lùi được" trong ContextNote).

Verify:
- dotnet test SolutionErp.slnx — 111/111 PASS (58 Domain + 53 Infra)
- KHÔNG đụng code Plan AB Chunk A — code stays clean, tests get more specific
- Pattern saved: multi-Changelog.Add() per transaction → tests filter by EntityType/Summary discriminator

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/SolutionErp.Infrastructure.Tests/Services/PurchaseEvaluationWorkflowServiceReturnModeTests.cs

@@ -301,8 +301,11 @@ public class PurchaseEvaluationWorkflowServiceReturnModeTests
             // Audit log "không lùi được" phải xuất hiện ở ContextNote (LogTransitionAsync
             // append summary từ ApplyReturnModeAsync vào field này — line 96-99 service).
             // Summary field cố định "Chuyển phase {from} → {to}".
+            // Plan AB S25 thêm Changelog entry mới (EntityType=Workflow + Summary="Trả lại (...)"
+            // + ContextNote=null) → cùng CreatedAt SQLite tie-break non-deterministic. Filter
+            // by Summary "Chuyển phase" để pick đúng LogTransitionAsync entry.
             var changelog = await db.PurchaseEvaluationChangelogs
-                .Where(c => c.PurchaseEvaluationId == pe.Id)
+                .Where(c => c.PurchaseEvaluationId == pe.Id && c.Summary!.Contains("Chuyển phase"))
                 .OrderByDescending(c => c.CreatedAt)
                 .FirstAsync();
             changelog.ContextNote.Should().NotBeNull();
@@ -343,8 +346,10 @@ public class PurchaseEvaluationWorkflowServiceReturnModeTests
             pe.CurrentApprovalLevelOrder.Should().Be(1, "Pointer reset Cấp 1 (bàn giao về Approver A)");
             pe.SlaDeadline.Should().NotBeNull("SLA reset 7d cho approver mới");
 
+            // Plan AB S25 — thêm Changelog Workflow entry, filter LogTransition entry
+            // qua Summary "Chuyển phase" để pick đúng row có ContextNote.
             var changelog = await db.PurchaseEvaluationChangelogs
-                .Where(c => c.PurchaseEvaluationId == pe.Id)
+                .Where(c => c.PurchaseEvaluationId == pe.Id && c.Summary!.Contains("Chuyển phase"))
                 .OrderByDescending(c => c.CreatedAt)
                 .FirstAsync();
             changelog.ContextNote.Should().NotBeNull();