diff --git a/tools/router-prehook.mjs b/tools/router-prehook.mjs
index 748ad6ca..5fd623be 100644
--- a/tools/router-prehook.mjs
+++ b/tools/router-prehook.mjs
@@ -20,6 +20,7 @@ import { readFileSync, writeFileSync, existsSync, mkdirSync } from 'fs';
 import { join, dirname } from 'path';
 import { homedir } from 'os';
 import { fileURLToPath } from 'url';
+import { readStdinAsUtf8 } from './router-stdin-helper.mjs';
 
 const ENFORCEMENT_TYPES = new Set(['feature', 'planning', 'bugfix', 'refactor', 'cleanup', 'marketing', 'security', 'analysis', 'monitoring']);
 
@@ -54,8 +55,7 @@ function stateFilePath(sessionId) {
 }
 
 async function main() {
-  let input = '';
-  for await (const chunk of process.stdin) input += chunk;
+  const input = await readStdinAsUtf8(process.stdin);
   const event = JSON.parse(input || '{}');
   const sessionId = event.session_id || 'unknown';
   const userPrompt = event.prompt || event.user_prompt || '';
diff --git a/tools/router-prehook.test.mjs b/tools/router-prehook.test.mjs
index 3dc1ae49..f77df3a5 100644
--- a/tools/router-prehook.test.mjs
+++ b/tools/router-prehook.test.mjs
@@ -48,3 +48,10 @@ describe('isEnforcementRequired', () => {
     expect(isEnforcementRequired({ taskType: 'memory-sync', micro: false, recommendedNode: '#33' })).toBe(false);
   });
 });
+
+describe('UTF-8 cyrillic stdin (regression — Stage 3 fix 1)', () => {
+  it('module loads with UTF-8 helper wired (smoke)', async () => {
+    const mod = await import('./router-prehook.mjs');
+    expect(typeof mod.buildStateFromClassification).toBe('function');
+  });
+});
diff --git a/tools/router-stop-gate.mjs b/tools/router-stop-gate.mjs
index 5f1ac9ac..9bdc0d90 100644
--- a/tools/router-stop-gate.mjs
+++ b/tools/router-stop-gate.mjs
@@ -11,6 +11,7 @@ import { readFileSync, writeFileSync, existsSync } from 'fs';
 import { join } from 'path';
 import { homedir } from 'os';
 import { fileURLToPath } from 'url';
+import { readStdinAsUtf8 } from './router-stdin-helper.mjs';
 
 export function extractSkillInvocations(events) {
   return (events || [])
@@ -46,8 +47,7 @@ export function updateChainProgress(state, skillsInvoked, chains) {
 }
 
 async function main() {
-  let input = '';
-  for await (const chunk of process.stdin) input += chunk;
+  const input = await readStdinAsUtf8(process.stdin);
   const event = JSON.parse(input || '{}');
   const sessionId = event.session_id || 'unknown';
   const events = event.turn_events || [];
diff --git a/tools/router-stop-gate.test.mjs b/tools/router-stop-gate.test.mjs
index ba2de30e..49d8bc1a 100644
--- a/tools/router-stop-gate.test.mjs
+++ b/tools/router-stop-gate.test.mjs
@@ -57,3 +57,10 @@ describe('updateChainProgress', () => {
     expect(updated.chainProgress).toEqual(['brainstorming', 'writing-plans']);
   });
 });
+
+describe('UTF-8 cyrillic stdin (regression — Stage 3 fix 1)', () => {
+  it('module loads with UTF-8 helper wired (smoke)', async () => {
+    const mod = await import('./router-stop-gate.mjs');
+    expect(typeof mod.updateChainProgress).toBe('function');
+  });
+});
diff --git a/tools/router-tool-gate.mjs b/tools/router-tool-gate.mjs
index 6efabfe4..0de58591 100644
--- a/tools/router-tool-gate.mjs
+++ b/tools/router-tool-gate.mjs
@@ -86,8 +86,7 @@ function readState(sessionId) {
 }
 
 async function main() {
-  let input = '';
-  for await (const chunk of process.stdin) input += chunk;
+  const input = await readStdinAsUtf8(process.stdin);
   const event = JSON.parse(input || '{}');
   const sessionId = event.session_id || 'unknown';
   const tool = event.tool_name;
@@ -109,4 +108,5 @@ async function main() {
 
 // CLI guard — Windows-cyrillic quirk: use fileURLToPath(import.meta.url)
 import { fileURLToPath } from 'url';
+import { readStdinAsUtf8 } from './router-stdin-helper.mjs';
 if (process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1]) { main(); }
diff --git a/tools/router-tool-gate.test.mjs b/tools/router-tool-gate.test.mjs
index 689b94b3..476c691b 100644
--- a/tools/router-tool-gate.test.mjs
+++ b/tools/router-tool-gate.test.mjs
@@ -97,3 +97,10 @@ describe('decideDecision', () => {
     expect(r.warning).toMatch(/#19/);
   });
 });
+
+describe('UTF-8 cyrillic stdin (regression — Stage 3 fix 1)', () => {
+  it('module loads with UTF-8 helper wired (smoke)', async () => {
+    const mod = await import('./router-tool-gate.mjs');
+    expect(typeof mod.shouldBlock).toBe('function');
+  });
+});