feat(agentic): apply default plan list limit

Co-Authored-By: Virgil <virgil@lethean.io>

pkg/agentic/plan.go

@@ -127,6 +127,8 @@ type PlanListOutput struct {
 	Plans   []Plan `json:"plans"`
 }
 
+const planListDefaultLimit = 20
+
 // result := c.Action("plan.create").Run(ctx, core.NewOptions(
 //
 //	core.Option{Key: "title", Value: "AX RFC follow-up"},
@@ -468,6 +470,11 @@ func (s *PrepSubsystem) planList(_ context.Context, _ *mcp.CallToolRequest, inpu
 		return nil, PlanListOutput{}, core.E("planList", "failed to access plans directory", err)
 	}
 
+	limit := input.Limit
+	if limit <= 0 {
+		limit = planListDefaultLimit
+	}
+
 	jsonFiles := core.PathGlob(core.JoinPath(dir, "*.json"))
 
 	var plans []Plan
@@ -490,7 +497,7 @@ func (s *PrepSubsystem) planList(_ context.Context, _ *mcp.CallToolRequest, inpu
 		}
 
 		plans = append(plans, *plan)
-		if input.Limit > 0 && len(plans) >= input.Limit {
+		if len(plans) >= limit {
 			break
 		}
 	}

pkg/agentic/plan_crud_test.go

@@ -421,6 +421,25 @@ func TestPlan_PlanList_Good_IgnoresNonJSON(t *testing.T) {
 	assert.Equal(t, 1, out.Count, "should skip non-JSON files")
 }
 
+func TestPlan_PlanList_Good_DefaultLimit(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("CORE_WORKSPACE", dir)
+
+	s := newTestPrep(t)
+	for i := 0; i < 21; i++ {
+		_, _, err := s.planCreate(context.Background(), nil, PlanCreateInput{
+			Title:     core.Sprintf("Plan %d", i+1),
+			Objective: "Test default list limit",
+		})
+		require.NoError(t, err)
+	}
+
+	_, out, err := s.planList(context.Background(), nil, PlanListInput{})
+	require.NoError(t, err)
+	assert.Equal(t, 20, out.Count)
+	assert.Len(t, out.Plans, 20)
+}
+
 // --- planPath edge cases ---
 
 func TestPlan_PlanPath_Bad_PathTraversal(t *testing.T) {