Avoid rescanning unsupported input names

internal/prompt/requirements_test.go

@@ -77,6 +77,35 @@ func TestAnalyzeRequirementsUnknownScopesAffectOptionalEntriesOnlyWhenActive(t *
 	}
 }
 
+func TestRequirementWalkerDoesNotRescanNestedUnsupportedNames(t *testing.T) {
+	for _, depth := range []int{6, 12} {
+		expression := ".selector"
+		for level := 0; level < depth; level++ {
+			expression = `input (printf "%s" (` + expression + `))`
+		}
+		source := "{{" + expression + "}}"
+		compiled := compileRequirementTemplate(t, "computed-name", source)
+		walker := &requirementWalker{
+			ctx: context.Background(), vars: map[string]string{"selector": "binding"},
+			inputs: make(map[string]*inputEvidence), variables: make(map[string]*variableEvidence),
+			issues: make(map[requirementIssueKey]domain.RequirementIssue), complete: true, rootKnown: true,
+		}
+		if err := walker.walkTemplate(compiled); err != nil {
+			t.Fatal(err)
+		}
+		// A generous source-relative bound detects exponential rescanning, not
+		// an exact visit count or a production analysis limit.
+		if walker.dependencies > len(source)*8 {
+			t.Fatalf("depth=%d: %d accesses for %d bytes of source", depth, walker.dependencies, len(source))
+		}
+		result := walker.result(domain.RequirementInspection{})
+		if result.Complete || len(result.Variables) != 1 || result.Variables[0].Name != "selector" ||
+			result.Variables[0].Kind != domain.RequirementConditional || len(result.Issues) == 0 {
+			t.Fatalf("nested unsupported names lost discovery metadata: %+v", result)
+		}
+	}
+}
+
 func TestAnalyzeRequirementsCollectsDeclaredAndLiteralInputs(t *testing.T) {
 	description := "retained metadata"
 	definition := &domain.PromptDefinition{ID: "capture", Version: "v1"}