fix(advice): find the marker however the model formats it

The instruction asks for "ADVICE:", but the model writes "**ADVICE:**",
"## ADVICE:" or puts it in a code block.  The extraction has to cope,
because leftover markdown in the advice is visible to the brewer.

The marker is now matched case-insensitively and with the decoration the
model puts around it, and the leftover formatting is stripped.

    plain marker         -> 'Warm it to 20C and wait.'
    bold marker          -> 'Warm it to 20C and wait.'
    in a code block      -> 'Warm it to 20C and wait.'
    marker mid-text      -> 'Warm it to 20C and wait.'
    markdown heading     -> 'Warm it to 20C and wait.'
    lowercase marker     -> 'Warm it to 20C and wait.'
    no marker            -> 'Warm it to 20C and wait.'
    bold + code block    -> 'Warm it to 20C and wait.'

182 tests (up from 181).

src/flask/brew_advice.py

@@ -25,6 +25,7 @@ from __future__ import annotations
 import json
 import logging
 import os
+import re
 import urllib.error
 import urllib.request
 
@@ -271,12 +272,38 @@ def _strip_reasoning(text: str) -> str:
     working did leak in, the brewer sees a slightly rambling reply
     rather than no advice at all.
     """
-    index = text.find(_ADVICE_MARKER)
-    if index == -1:
+    index = _find_marker(text)
+    if index is None:
         return text.strip()
 
-    advice = text[index + len(_ADVICE_MARKER):].strip()
-    return advice or ""
+    advice = text[index:].strip()
+
+    # The model may wrap the marker in markdown or a code block.  Strip
+    # the leftover formatting so the advice reads as prose.
+    advice = re.sub(r"^\*\*|\*\*$", "", advice).strip()
+    if advice.startswith("```"):
+        advice = advice[3:]
+    if advice.endswith("```"):
+        advice = advice[:-3]
+    if advice.startswith("##"):
+        advice = advice.lstrip("#").strip()
+
+    return advice.strip() or ""
+
+
+def _find_marker(text: str) -> int | None:
+    """Where the advice starts, or ``None`` if there is no marker.
+
+    The marker is matched case-insensitively and with the markdown
+    decoration the model might put around it - ``**ADVICE:**``,
+    ``## ADVICE:`` - because the instruction asks for "ADVICE:" but the
+    model formats it its own way often enough to matter.
+    """
+    match = re.search(r"^[\s#>\*]*advice\s*:[\s\*>]*", text,
+                      re.IGNORECASE | re.MULTILINE)
+    if match:
+        return match.end()
+    return None
 
 
 def generate_advice(run: dict, reading: dict, history: list[dict], *,