schema: cover deeper-heading skip in countSameLevelMatches

Adds TestCountSameLevelMatches_SkipsDeeperHeadings to exercise
the level filter inside countSameLevelMatches via the trailing
max-exceeded path. A `### Detail` between two `## B`s must not
count toward B's max=2 so only the third `## B` is flagged.

https://claude.ai/code/session_012GGH62fZUzLuzP8T4ocGkJ

Author: claude

internal/schema/plan156_coverage_test.go

@@ -2,6 +2,7 @@ package schema
 
 import (
 	"strconv"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -289,6 +290,38 @@ func TestScopeMatchesHeading_NilScope(t *testing.T) {
 	assert.False(t, scopeMatchesHeading(Scope{}, DocHeading{Text: "x"}, nil))
 }
 
+// TestCountSameLevelMatches_SkipsDeeperHeadings covers the
+// level filter inside countSameLevelMatches via the trailing
+// max-exceeded path: a deeper heading between matching same-
+// level occurrences must not count toward the scope's max.
+func TestCountSameLevelMatches_SkipsDeeperHeadings(t *testing.T) {
+	raw := map[string]any{
+		"sections": []any{
+			map[string]any{"heading": "A"},
+			map[string]any{"heading": map[string]any{
+				"regex":  "B",
+				"repeat": map[string]any{"max": 2},
+			}},
+		},
+	}
+	sch, err := ParseInline(raw, "kind x")
+	require.NoError(t, err)
+	// Doc: B (out of order), nested ### Detail, A, B, B.
+	// Three Bs at level 2, with a deeper Detail mixed in. Only
+	// the third B (4th match attempt) should be flagged.
+	doc := newDocFile(t, "doc.md",
+		"# T\n\n## B\n\n### Detail\n\nx\n\n## A\n\ny\n\n## B\n\nz\n\n## B\n\nw\n")
+	diags := Validate(doc, sch, nil, false, makeDiagForTest)
+	var exceeded int
+	for _, d := range diags {
+		if strings.Contains(d.Message, "exceeds scope") {
+			exceeded++
+		}
+	}
+	assert.Equal(t, 1, exceeded,
+		"deeper Detail heading must not count toward B's max")
+}
+
 // TestScopeRunIndices_NilMatcherReturnsNil covers the early
 // return for a nil-matcher scope (preamble-shaped scope routed
 // through the helper directly).