diff --git a/docs/observer/STATUS.md b/docs/observer/STATUS.md
index 90d49dc5..9809728a 100644
--- a/docs/observer/STATUS.md
+++ b/docs/observer/STATUS.md
@@ -1,6 +1,6 @@
 # Brain Status (auto-generated)
 
-Last updated: 2026-05-19T07:27:33.112Z
+Last updated: 2026-05-19T07:31:46.792Z
 
 | Контролёр | Состояние | Детали |
 |---|---|---|
diff --git a/tools/observer-stop-hook.mjs b/tools/observer-stop-hook.mjs
index d3388c5f..f3bbb5fb 100644
--- a/tools/observer-stop-hook.mjs
+++ b/tools/observer-stop-hook.mjs
@@ -17,7 +17,8 @@
 import { appendFileSync, existsSync, mkdirSync, readFileSync } from 'fs';
 import { join } from 'path';
 import { sanitize } from './observer-pii-filter.mjs';
-import { parseTranscript } from './observer-transcript-parser.mjs';
+import { parseTranscript, extractLastUserPromptText } from './observer-transcript-parser.mjs';
+import { detectMethodDirected, loadKnownNodes } from './observer-routing-detector.mjs';
 
 const REQUIRED_FIELDS = ['task_id', 'timestamps', 'path_type', 'outcome', 'primary_rationale'];
 const V2_FIELDS = ['schema_version', 'decision_provenance', 'environment', 'task_size', 'task_ref'];
@@ -146,6 +147,30 @@ export function buildObserverError(ctx = {}, err) {
   };
 }
 
+/**
+ * Routing-gate decision (spec §5.1, 3a). Pure — the CLI calls this.
+ * Blocks the Stop-event (decision: block) when the user dictated a method
+ * but the turn carries no routing tag. Skipped when stop_hook_active is true
+ * (the gate fires at most once per turn — no infinite loop).
+ * @returns {{block: boolean, reason: string|null}}
+ */
+export function routingGateDecision(episode, promptText, knownNodes, stopHookActive) {
+  if (stopHookActive) return { block: false, reason: null };
+  const det = detectMethodDirected(promptText, knownNodes);
+  if (!det.directed) return { block: false, reason: null };
+  if (episode && episode.decision_provenance && episode.decision_provenance.kind === 'user_directed_method') {
+    return { block: false, reason: null };
+  }
+  return {
+    block: true,
+    reason:
+      `[observer routing-gate] Похоже, метод навязан пользователем (узел "${det.node}"), ` +
+      `но routing-тег в этом ходе отсутствует. Добавь в свой ответ ровно одну строку:\n` +
+      `<!-- routing: provenance=user_directed_method node=${det.node} ` +
+      `counterfactual=<узел, который ты выбрал бы автономно> -->`,
+  };
+}
+
 function currentMonth() {
   const d = new Date();
   return `${d.getUTCFullYear()}-${String(d.getUTCMonth() + 1).padStart(2, '0')}`;
@@ -161,7 +186,7 @@ if (process.argv[1] && process.argv[1].replace(/\\/g, '/').endsWith('/observer-s
       const raw = Buffer.concat(chunks).toString('utf-8');
       if (raw.trim()) ctx = JSON.parse(raw);
     } catch (_e) {
-      // best-effort: write minimal episode even if stdin is malformed
+      // best-effort: build a minimal episode even if stdin is malformed
     }
     // Claude Code's Stop-event supplies transcript_path — the real source of
     // session data. Read it best-effort; fall back to ctx-only on any error.
@@ -174,13 +199,29 @@ if (process.argv[1] && process.argv[1].replace(/\\/g, '/').endsWith('/observer-s
         transcriptText = null;
       }
     }
-    const ep = buildEpisodeFromContext(ctx, transcriptText);
     try {
+      const ep = buildEpisodeFromContext(ctx, transcriptText);
+      // Always write the episode first — exit-0-safe (spec §5.1 step 1).
       appendEpisode(ep);
+      // Then the routing-gate (spec §5.1 steps 2-4).
+      if (transcriptText) {
+        const promptText = extractLastUserPromptText(transcriptText);
+        const gate = routingGateDecision(ep, promptText, loadKnownNodes(), ctx.stop_hook_active === true);
+        if (gate.block) {
+          process.stdout.write(JSON.stringify({ decision: 'block', reason: gate.reason }));
+          process.exit(0);
+        }
+      }
       process.exit(0);
     } catch (err) {
+      // Visible failure (spec §5.2): write an observer_error marker, never a silent skip.
+      try {
+        appendEpisode(buildObserverError(ctx, err));
+      } catch (_e2) {
+        // last-resort: even the marker failed — do not crash the Stop-event
+      }
       console.error(`[observer-stop-hook] error: ${err.message}`);
-      process.exit(0); // never block Stop-event
+      process.exit(0); // never block the Stop-event on an internal error
     }
   });
 }
diff --git a/tools/observer-stop-hook.test.mjs b/tools/observer-stop-hook.test.mjs
index ac1cad00..9372b066 100644
--- a/tools/observer-stop-hook.test.mjs
+++ b/tools/observer-stop-hook.test.mjs
@@ -2,7 +2,7 @@ import { describe, it, expect, beforeEach, afterEach } from 'vitest';
 import { writeFileSync, readFileSync, existsSync, mkdtempSync, rmSync, mkdirSync } from 'fs';
 import { join } from 'path';
 import { tmpdir } from 'os';
-import { appendEpisode, buildEpisodeFromContext, buildObserverError } from './observer-stop-hook.mjs';
+import { appendEpisode, buildEpisodeFromContext, buildObserverError, routingGateDecision } from './observer-stop-hook.mjs';
 
 let workdir;
 
@@ -160,3 +160,30 @@ describe('buildObserverError', () => {
     expect(marker.timestamps.started_at).toBeTruthy();
   });
 });
+
+describe('routingGateDecision', () => {
+  const NODES = ['discovery-interview', 'brainstorming'];
+  const autonomousEp = v2Episode();
+  const taggedEp = v2Episode({ decision_provenance: { kind: 'user_directed_method', claude_would_have_chosen: 'brainstorming' } });
+
+  it('blocks when a method was directed but no routing tag is present', () => {
+    const gate = routingGateDecision(autonomousEp, 'запусти discovery-interview', NODES, false);
+    expect(gate.block).toBe(true);
+    expect(gate.reason).toContain('discovery-interview');
+  });
+
+  it('does not block when the routing tag is present', () => {
+    const gate = routingGateDecision(taggedEp, 'запусти discovery-interview', NODES, false);
+    expect(gate.block).toBe(false);
+  });
+
+  it('does not block when no method was directed', () => {
+    const gate = routingGateDecision(autonomousEp, 'добавь колонку Город', NODES, false);
+    expect(gate.block).toBe(false);
+  });
+
+  it('does not block when stop_hook_active is true (loop guard)', () => {
+    const gate = routingGateDecision(autonomousEp, 'запусти discovery-interview', NODES, true);
+    expect(gate.block).toBe(false);
+  });
+});