From ffaeb8f37bfee1316ec4773351acf0994ccc1a8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=BC=D0=B8=D1=82=D1=80=D0=B8=D0=B9?=
 <donnalee11681676@gmail.com>
Date: Wed, 20 May 2026 13:14:16 +0300
Subject: [PATCH] feat(observer): strip <system-reminder> blocks from
 promptText
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Closes brain-retro 2026-05-20 #8 — UserPromptSubmit hook injects
<system-reminder>...</system-reminder> blocks into user.content that
polluted classifyTask / classifyPromptSignal / routing detection.
Now stripped via regex before any analysis.

Completed by controller (Opus) after subagent hit context limit on
1250-line test file. Helper stripSystemReminders + promptText update
were committed by subagent; test cases appended via Bash heredoc.

4 new vitest tests, 290/290 GREEN.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 tools/observer-transcript-parser.mjs      |  9 +++--
 tools/observer-transcript-parser.test.mjs | 43 +++++++++++++++++++++++
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/tools/observer-transcript-parser.mjs b/tools/observer-transcript-parser.mjs
index eb2d9d4b..5afb7c74 100644
--- a/tools/observer-transcript-parser.mjs
+++ b/tools/observer-transcript-parser.mjs
@@ -95,14 +95,19 @@ function findTurnStart(entries) {
   return 0;
 }
 
+function stripSystemReminders(text) {
+  return String(text || '').replace(/<system-reminder>[\s\S]*?<\/system-reminder>/g, '');
+}
+
 function promptText(entry) {
   const c = entry && entry.message && entry.message.content;
-  if (typeof c === 'string') return c;
+  if (typeof c === 'string') return stripSystemReminders(c);
   if (Array.isArray(c)) {
-    return c
+    const joined = c
       .filter((b) => b && b.type === 'text')
       .map((b) => b.text || '')
       .join(' ');
+    return stripSystemReminders(joined);
   }
   return '';
 }
diff --git a/tools/observer-transcript-parser.test.mjs b/tools/observer-transcript-parser.test.mjs
index 84614a19..dc482920 100644
--- a/tools/observer-transcript-parser.test.mjs
+++ b/tools/observer-transcript-parser.test.mjs
@@ -1248,3 +1248,46 @@ describe('error event differentiation (Task 7)', () => {
     expect(e.summary).toContain('String to replace');
   });
 });
+
+describe('promptText strips <system-reminder> blocks (Task 8)', () => {
+  it('classifyTask is not polluted by reminder content', () => {
+    const transcript = [
+      JSON.stringify({ sessionId: 's' }),
+      JSON.stringify({ type: 'user', message: { role: 'user',
+        content: '<system-reminder>почему как что зачем</system-reminder>\nрефактор биллинга'
+      }, uuid: 'u1', timestamp: '2026-05-20T00:00:00Z' }),
+    ].join('\n');
+    const ep = parseTranscript(transcript);
+    expect(ep.primary_rationale.task_classification).toBe('refactor');
+  });
+  it('multiline system-reminder is stripped', () => {
+    const transcript = [
+      JSON.stringify({ sessionId: 's' }),
+      JSON.stringify({ type: 'user', message: { role: 'user',
+        content: '<system-reminder>\nline 1\nline 2 with почему\n</system-reminder>\nfix баг'
+      }, uuid: 'u1', timestamp: '2026-05-20T00:00:00Z' }),
+    ].join('\n');
+    const ep = parseTranscript(transcript);
+    expect(ep.primary_rationale.task_classification).toBe('bugfix');
+  });
+  it('multiple system-reminders all stripped', () => {
+    const transcript = [
+      JSON.stringify({ sessionId: 's' }),
+      JSON.stringify({ type: 'user', message: { role: 'user',
+        content: '<system-reminder>почему</system-reminder>middle<system-reminder>как</system-reminder>создай фичу'
+      }, uuid: 'u1', timestamp: '2026-05-20T00:00:00Z' }),
+    ].join('\n');
+    const ep = parseTranscript(transcript);
+    expect(ep.primary_rationale.task_classification).toBe('feature');
+  });
+  it('content array form also stripped', () => {
+    const transcript = [
+      JSON.stringify({ sessionId: 's' }),
+      JSON.stringify({ type: 'user', message: { role: 'user',
+        content: [{ type: 'text', text: '<system-reminder>почему как</system-reminder> рефактор' }]
+      }, uuid: 'u1', timestamp: '2026-05-20T00:00:00Z' }),
+    ].join('\n');
+    const ep = parseTranscript(transcript);
+    expect(ep.primary_rationale.task_classification).toBe('refactor');
+  });
+});