feat(loop): port run_loop.sh to Python lib_py.loop with thin wrapper and strict parser (Phase 3)

.agents/skills/lib_py/loop/parser.py

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+"""Strict parser for reviewer reports, verdicts, and workflow tags.
+
+Issue #5 Phase 3.
+Implements fence-aware parsing so markdown code blocks (e.g. documentation or
+examples quoted inside reports) cannot trigger or spoof verdicts, escalations,
+or rebuttals.
+"""
+
+from __future__ import annotations
+
+import os
+import re
+from pathlib import Path
+from typing import List, Optional
+
+# Fences start with at least 3 backticks or tildes: ``` or ~~~
+_FENCE_START_RE = re.compile(r"^[ \t]*(```+|~~~+)")
+_VERDICT_RE = re.compile(r"^\[VERDICT:\s*(PASS|NOT PASS)\]\s*$")
+
+
+def strip_code_fences(text: str) -> str:
+    """Remove lines that are inside markdown code blocks (``` or ~~~)."""
+    clean_lines = []
+    in_fence = False
+    fence_char = ""
+    fence_len = 0
+
+    for line in text.splitlines():
+        match = _FENCE_START_RE.match(line)
+        if match:
+            marker = match.group(1)
+            char = marker[0]
+            length = len(marker)
+            if not in_fence:
+                in_fence = True
+                fence_char = char
+                fence_len = length
+                continue
+            else:
+                # Closing fence must match the fence character and have at least the opening length
+                if char == fence_char and length >= fence_len:
+                    in_fence = False
+                    fence_char = ""
+                    fence_len = 0
+                    continue
+        if not in_fence:
+            clean_lines.append(line)
+
+    return "\n".join(clean_lines)
+
+
+def parse_verdict(content: str) -> Optional[str]:
+    """Extract verdict ('PASS' or 'NOT PASS') from the last non-blank line outside code fences.
+
+    Returns None if no valid verdict line is found or if content is malformed.
+    """
+    stripped = strip_code_fences(content)
+    lines = [line.strip() for line in stripped.splitlines() if line.strip()]
+    if not lines:
+        return None
+
+    last_line = lines[-1]
+    match = _VERDICT_RE.match(last_line)
+    if match:
+        return match.group(1)
+    return None
+
+
+def has_verdict(file_or_content: str | Path, expected: str) -> bool:
+    """Check whether a report file or content ends with [VERDICT: <expected>]."""
+    content = ""
+    if isinstance(file_or_content, Path) or (isinstance(file_or_content, str) and os.path.isfile(file_or_content)):
+        try:
+            content = Path(file_or_content).read_text(encoding="utf-8", errors="replace")
+        except OSError:
+            return False
+    else:
+        content = str(file_or_content)
+
+    verdict = parse_verdict(content)
+    return verdict == expected
+
+
+def has_tag_line(file_or_content: str | Path, tag: str) -> bool:
+    """Detect a standalone '[TAG]' line anywhere outside code fences."""
+    content = ""
+    if isinstance(file_or_content, Path) or (isinstance(file_or_content, str) and os.path.isfile(file_or_content)):
+        try:
+            content = Path(file_or_content).read_text(encoding="utf-8", errors="replace")
+        except OSError:
+            return False
+    else:
+        content = str(file_or_content)
+
+    stripped = strip_code_fences(content)
+    pattern = re.compile(rf"^\[{re.escape(tag)}\]\s*$", re.MULTILINE)
+    return bool(pattern.search(stripped))
+
+
+def extract_tag_values(file_or_content: str | Path, key: str) -> List[str]:
+    """Emit the trimmed payload of every standalone '[KEY: value]' line outside code fences.
+
+    Preserves appearance order and eliminates duplicates.
+    """
+    content = ""
+    if isinstance(file_or_content, Path) or (isinstance(file_or_content, str) and os.path.isfile(file_or_content)):
+        try:
+            content = Path(file_or_content).read_text(encoding="utf-8", errors="replace")
+        except OSError:
+            return []
+    else:
+        content = str(file_or_content)
+
+    stripped = strip_code_fences(content)
+    pattern = re.compile(rf"^\[{re.escape(key)}:\s*([^\]]*)\]\s*$", re.MULTILINE)
+    results = []
+    seen = set()
+
+    for match in pattern.finditer(stripped):
+        val = match.group(1).strip()
+        if val and val not in seen:
+            seen.add(val)
+            results.append(val)
+
+    return results