diff --git a/action/post-review-comments.sh b/action/post-review-comments.sh
index 025588c770..5bd47154a9 100755
--- a/action/post-review-comments.sh
+++ b/action/post-review-comments.sh
@@ -116,14 +116,20 @@ gh_api_safe() {
 extract_review_json() {
     local log_content="$1"
 
-    # Use Python for robust JSON extraction that handles nested braces correctly
+    # Use Python for robust JSON extraction that handles nested braces correctly.
+    # The log file contains stream-json output from Claude Code, with lines like:
+    #   {"type":"user","message":{"content":[...]}}      ← prompt (may contain PR diff!)
+    #   {"type":"assistant","message":{"content":[...]}}  ← Claude's response
+    #   {"type":"result","result":"<Claude's final text>"}
+    # We must extract from the "result" event only, otherwise template JSON
+    # embedded in the PR diff (e.g. security-review.md examples) can be matched.
     local json_block
     json_block=$(echo "$log_content" | python3 -c "
 import sys
 import re
 import json
 
-content = sys.stdin.read()
+raw_input = sys.stdin.read()
 
 def find_json_objects(text):
     '''Find all valid JSON objects in text using bracket matching.'''
@@ -168,35 +174,61 @@ def find_json_objects(text):
             i += 1
     return objects
 
-# First, try to extract from markdown code blocks
-code_block_pattern = r'\`\`\`(?:json)?\s*\n(.*?)\n\`\`\`'
-code_blocks = re.findall(code_block_pattern, content, re.DOTALL)
+def search_for_review(text):
+    '''Search text for a review JSON object. Returns it or None.'''
+    # First, try to extract from markdown code blocks
+    code_block_pattern = r'\`\`\`(?:json)?\s*\n(.*?)\n\`\`\`'
+    code_blocks = re.findall(code_block_pattern, text, re.DOTALL)
 
-# Check code blocks first (in reverse order to get the final summary)
-for block in reversed(code_blocks):
-    for obj in find_json_objects(block):
-        if 'summary' in obj and 'comments' in obj:
-            print(json.dumps(obj))
-            sys.exit(0)
+    # Check code blocks first (in reverse order to get the final summary)
+    for block in reversed(code_blocks):
+        for obj in find_json_objects(block):
+            if 'summary' in obj and 'comments' in obj:
+                return obj
 
-# Then check the full content for bare JSON
-all_objects = find_json_objects(content)
+    # Then check for bare JSON
+    all_objects = find_json_objects(text)
 
-# Look for the summary object (should have summary, verdict, comments)
-for obj in reversed(all_objects):
-    if 'summary' in obj and 'comments' in obj:
-        print(json.dumps(obj))
-        sys.exit(0)
+    # Look for the summary object (should have summary, verdict, comments)
+    for obj in reversed(all_objects):
+        if 'summary' in obj and 'comments' in obj:
+            return obj
+
+    # Fallback: try to find any object with comments array
+    for obj in reversed(all_objects):
+        if 'comments' in obj and isinstance(obj.get('comments'), list):
+            obj.setdefault('summary', 'Review completed.')
+            obj.setdefault('verdict', 'comment')
+            return obj
+
+    return None
+
+# Step 1: Try to extract from stream-json result events.
+# This narrows the search to Claude's actual output, avoiding prompt content.
+result_text = None
+for line in raw_input.splitlines():
+    line = line.strip()
+    if not line:
+        continue
+    try:
+        event = json.loads(line)
+        if isinstance(event, dict) and event.get('type') == 'result' and 'result' in event:
+            result_text = str(event['result'])
+    except (json.JSONDecodeError, TypeError):
+        continue
 
-# Fallback: try to find any object with comments array
-for obj in reversed(all_objects):
-    if 'comments' in obj and isinstance(obj.get('comments'), list):
-        # Add missing fields
-        obj.setdefault('summary', 'Review completed.')
-        obj.setdefault('verdict', 'comment')
-        print(json.dumps(obj))
+if result_text is not None:
+    review = search_for_review(result_text)
+    if review is not None:
+        print(json.dumps(review))
         sys.exit(0)
 
+# Step 2: Fallback — scan full content (backward compat for non-stream-json logs)
+review = search_for_review(raw_input)
+if review is not None:
+    print(json.dumps(review))
+    sys.exit(0)
+
 # No structured output found
 print(json.dumps({
     'summary': 'Review completed but no structured output found.',
diff --git a/action/test_extract_review_json.sh b/action/test_extract_review_json.sh
new file mode 100755
index 0000000000..b22bb1c701
--- /dev/null
+++ b/action/test_extract_review_json.sh
@@ -0,0 +1,158 @@
+#!/usr/bin/env bash
+# test_extract_review_json.sh — Verify extract_review_json parses stream-json correctly
+#
+# Reproduces the PR #152 bug where template JSON in the PR diff (inside a
+# stream-json "user" event) was matched instead of Claude's actual review
+# output (inside the "result" event).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PASS=0
+FAIL=0
+
+# Source the function by providing dummy env vars so the main body's
+# required-var checks pass, then intercepting execution at the main section.
+# We use a subshell trick: extract everything before "Main" section.
+TMPFUNC=$(mktemp)
+trap 'rm -f "$TMPFUNC"' EXIT
+
+# Extract lines from the script: shebang + set options + all functions (up to the Main marker)
+sed -n '1,/^# Main$/p' "$SCRIPT_DIR/post-review-comments.sh" | head -n -1 > "$TMPFUNC"
+
+# Source just the functions (no main execution)
+# shellcheck disable=SC1090
+source "$TMPFUNC"
+
+assert_eq() {
+    local test_name="$1" expected="$2" actual="$3"
+    if [[ "$expected" == "$actual" ]]; then
+        echo "  PASS: $test_name"
+        PASS=$((PASS + 1))
+    else
+        echo "  FAIL: $test_name"
+        echo "    expected: $expected"
+        echo "    actual:   $actual"
+        FAIL=$((FAIL + 1))
+    fi
+}
+
+# ---------------------------------------------------------------------------
+# Test 1: Stream-json log with poisoned prompt (PR #152 reproduction)
+# The user event contains a PR diff that includes template JSON with
+# summary+comments fields. The result event has Claude's real review.
+# ---------------------------------------------------------------------------
+echo "Test 1: Stream-json with poisoned prompt (PR #152 reproduction)"
+
+# Template JSON that would appear in a PR diff of security-review.md
+template_json='{"summary": "No security vulnerabilities found.", "verdict": "approve", "comments": []}'
+
+# Claude's actual review with real findings
+real_review='{"summary": "Found 3 critical issues in auth module.", "verdict": "request_changes", "comments": [{"file": "auth.py", "line": 42, "severity": "critical", "category": "security", "comment": "SQL injection via unsanitized input"}]}'
+
+# Construct stream-json log lines using Python for reliable JSON encoding
+log_content=$(python3 -c "
+import json
+user_event = json.dumps({
+    'type': 'user',
+    'message': {'content': [{'type': 'text', 'text': 'Review this PR.\n\nHere is security-review.md:\n\`\`\`json\n$template_json\n\`\`\`'}]}
+})
+assistant_event = json.dumps({
+    'type': 'assistant',
+    'message': {'content': [{'type': 'text', 'text': \"I'll review the changes.\"}]}
+})
+result_event = json.dumps({
+    'type': 'result',
+    'result': 'Here is my review:\n\n\`\`\`json\n$real_review\n\`\`\`'
+})
+print(user_event)
+print(assistant_event)
+print(result_event)
+")
+
+result=$(extract_review_json "$log_content")
+actual_summary=$(echo "$result" | python3 -c "import sys,json; print(json.load(sys.stdin)['summary'])")
+actual_verdict=$(echo "$result" | python3 -c "import sys,json; print(json.load(sys.stdin)['verdict'])")
+actual_count=$(echo "$result" | python3 -c "import sys,json; print(len(json.load(sys.stdin)['comments']))")
+
+assert_eq "extracts real review summary" "Found 3 critical issues in auth module." "$actual_summary"
+assert_eq "extracts real review verdict" "request_changes" "$actual_verdict"
+assert_eq "extracts real review comments" "1" "$actual_count"
+
+# ---------------------------------------------------------------------------
+# Test 2: Non-stream-json log (backward compatibility)
+# Plain text output without stream-json envelope — should still work.
+# ---------------------------------------------------------------------------
+echo "Test 2: Plain text log (backward compatibility)"
+
+plain_log="Some preamble output...
+
+\`\`\`json
+$real_review
+\`\`\`
+
+Done."
+
+result=$(extract_review_json "$plain_log")
+actual_summary=$(echo "$result" | python3 -c "import sys,json; print(json.load(sys.stdin)['summary'])")
+assert_eq "backward compat extracts review" "Found 3 critical issues in auth module." "$actual_summary"
+
+# ---------------------------------------------------------------------------
+# Test 3: Stream-json log with bare JSON in result (no code block)
+# ---------------------------------------------------------------------------
+echo "Test 3: Stream-json with bare JSON in result"
+
+log_bare=$(python3 -c "
+import json
+user_event = json.dumps({
+    'type': 'user',
+    'message': {'content': [{'type': 'text', 'text': 'Review.\n$template_json'}]}
+})
+result_event = json.dumps({
+    'type': 'result',
+    'result': '$real_review'
+})
+print(user_event)
+print(result_event)
+")
+
+result=$(extract_review_json "$log_bare")
+actual_summary=$(echo "$result" | python3 -c "import sys,json; print(json.load(sys.stdin)['summary'])")
+assert_eq "bare JSON in result event" "Found 3 critical issues in auth module." "$actual_summary"
+
+# ---------------------------------------------------------------------------
+# Test 4: No review JSON at all
+# ---------------------------------------------------------------------------
+echo "Test 4: No review JSON found"
+
+log_empty=$(python3 -c "
+import json
+print(json.dumps({'type': 'result', 'result': 'I reviewed the code and it looks fine.'}))
+")
+result=$(extract_review_json "$log_empty")
+actual_summary=$(echo "$result" | python3 -c "import sys,json; print(json.load(sys.stdin)['summary'])")
+assert_eq "fallback when no JSON" "Review completed but no structured output found." "$actual_summary"
+
+# ---------------------------------------------------------------------------
+# Test 5: Multiple result events — should use the last one
+# ---------------------------------------------------------------------------
+echo "Test 5: Multiple result events (uses last)"
+
+log_multi=$(python3 -c "
+import json
+print(json.dumps({'type': 'result', 'result': json.dumps({'summary': 'First pass.', 'verdict': 'comment', 'comments': []})}))
+print(json.dumps({'type': 'result', 'result': json.dumps({'summary': 'Final review.', 'verdict': 'approve', 'comments': []})}))
+")
+
+result=$(extract_review_json "$log_multi")
+actual_summary=$(echo "$result" | python3 -c "import sys,json; print(json.load(sys.stdin)['summary'])")
+assert_eq "uses last result event" "Final review." "$actual_summary"
+
+# ---------------------------------------------------------------------------
+# Summary
+# ---------------------------------------------------------------------------
+echo ""
+echo "Results: $PASS passed, $FAIL failed"
+if [[ "$FAIL" -gt 0 ]]; then
+    exit 1
+fi
+echo "All tests passed."