feat: add learner memory ingestion

internal/workflows/runner_test.go

@@ -24,6 +24,7 @@ func TestStubRunnerGradesAnswer(t *testing.T) {
 	runner := NewStubRunner()
 
 	grade, err := runner.GradeInterviewAnswer(context.Background(), GradeAnswerInput{
+		UserID:     "user-1",
 		QuestionID: "q-1",
 		AnswerID:   "a-1",
 		AnswerText: "Indexes can speed reads by helping the database find rows, but they add write overhead.",
@@ -37,6 +38,9 @@ func TestStubRunnerGradesAnswer(t *testing.T) {
 	if grade.AnswerID != "a-1" {
 		t.Fatalf("AnswerID = %q", grade.AnswerID)
 	}
+	if grade.UserID != "user-1" {
+		t.Fatalf("UserID = %q", grade.UserID)
+	}
 	if len(grade.Concepts) != 1 {
 		t.Fatalf("concepts = %d, want 1", len(grade.Concepts))
 	}
@@ -44,3 +48,40 @@ func TestStubRunnerGradesAnswer(t *testing.T) {
 		t.Fatalf("evidence = %d, want 1", len(grade.Evidence))
 	}
 }
+
+func TestStubRunnerExtractsLearningMemory(t *testing.T) {
+	runner := NewStubRunner()
+	grade := GradedAnswer{
+		UserID:     "user-1",
+		AnswerID:   "a-1",
+		QuestionID: "q-1",
+		Concepts: []ConceptRef{
+			{ID: "cache-invalidation", Label: "Cache invalidation", Track: "backend-developer"},
+		},
+		Overall: AnswerPartial,
+		Evidence: []EvidenceRef{
+			{Kind: EvidenceAnswer, ID: "a-1", Confidence: 1},
+		},
+		FollowUp: FollowUpRecommendation{
+			Needed:   true,
+			Question: "Can you explain the tradeoff?",
+			Purpose:  FollowUpRepair,
+		},
+	}
+
+	candidate, err := runner.ExtractLearningMemory(context.Background(), grade)
+	if err != nil {
+		t.Fatalf("ExtractLearningMemory error: %v", err)
+	}
+	if candidate.UserID != "user-1" {
+		t.Fatalf("UserID = %q", candidate.UserID)
+	}
+	if len(candidate.Updates) != 4 {
+		t.Fatalf("updates = %d, want 4", len(candidate.Updates))
+	}
+	for _, update := range candidate.Updates {
+		if len(update.Evidence) == 0 {
+			t.Fatal("expected every memory update to carry evidence")
+		}
+	}
+}