From 0e53c245377dc65e0f1b9853e06975f2e9f4198d Mon Sep 17 00:00:00 2001
From: Aditya Jain <adityaj0714@gmail.com>
Date: Tue, 25 Aug 2026 01:31:37 -0700
Subject: [PATCH] fix(toolkit-lib): cdk validate drops the plugin's
 customSeverity label
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flattenViolations() called normalizeSeverity(violation.severity) without
forwarding violation.customSeverity, even though normalizeSeverity accepts
it specifically to label a 'custom'-severity violation with the plugin's
own severity string. As a result, any validation plugin reporting
{ severity: 'custom', customSeverity: 'BLOCKER' } (or any other label) had
that label silently discarded — cdk validate always printed INFO instead,
understating the plugin's intended severity.

Fixes #1893
---
 .../lib/api/validate/validate-formatting.ts    |  2 +-
 .../api/validate/validate-formatting.test.ts   | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts b/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts
index bf5f032e2..9cf060fb0 100644
--- a/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts
+++ b/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts
@@ -40,7 +40,7 @@ function flattenViolations(reports: PluginReportJson[]): FlattenedViolation[] {
     const pluginName = report.pluginName;
     return report.violations.flatMap((violation) => {
       return violation.violatingConstructs.map((construct) => ({
-        severity: normalizeSeverity(violation.severity),
+        severity: normalizeSeverity(violation.severity, violation.customSeverity),
         description: violation.description,
         ruleName: violation.ruleName,
         pluginName,
diff --git a/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts b/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts
index c70ae4ce5..cb95834b3 100644
--- a/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts
+++ b/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts
@@ -36,6 +36,24 @@ describe('formatValidateResult', () => {
     ]);
   });
 
+  test('uses the plugin-supplied customSeverity label for a "custom" severity violation', () => {
+    const result = makeResult([{
+      pluginName: 'TestPlugin',
+      conclusion: 'failure',
+      violations: [{
+        ruleName: 'r1',
+        description: 'blocker issue',
+        severity: 'custom',
+        customSeverity: 'BLOCKER',
+        violatingConstructs: [{ constructPath: 'Stack/A' }],
+      }],
+    }]);
+
+    const output = formatValidateResult(result);
+    expect(output).toContain('BLOCKER');
+    expect(output).not.toContain('INFO');
+  });
+
   test('formats construct path with logical id', () => {
     const result = makeResult([{
       pluginName: 'TestPlugin',