feat(notifications): improve AFD change summary with section extraction (#453)

Improves `summarize_discussion_change` to extract meaningful content
from AFD updates:

1. **Primary**: Extracts `.WHAT HAS CHANGED...` section (NWS includes
this in many AFDs)
2. **Fallback**: Extracts `.KEY MESSAGES...` section
3. **Final fallback**: First new line (existing behavior)

Summary truncated to 300 chars for toast readability.

Follow-up to #452.

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Orinks

src/accessiweather/notifications/notification_event_manager.py

@@ -48,11 +48,74 @@ def get_risk_category(risk: int) -> str:
     return "minimal"
 
 
+def _extract_section(text: str, start_marker: str, end_markers: tuple[str, ...]) -> str | None:
+    """
+    Extract the content of a named section from AFD text.
+
+    Args:
+        text: The full AFD text to search.
+        start_marker: The section header to look for (e.g. '.WHAT HAS CHANGED...').
+        end_markers: Tuple of prefixes that indicate the end of the section
+                     (e.g. lines starting with '.' or '&&').
+
+    Returns:
+        The extracted section body (stripped), or None if the section is not found.
+
+    """
+    lines = text.splitlines()
+    in_section = False
+    body_lines: list[str] = []
+    for line in lines:
+        stripped = line.strip()
+        if not in_section:
+            if stripped.upper().startswith(start_marker.upper()):
+                in_section = True
+            continue
+        # We are inside the section — check for terminator
+        if any(stripped.startswith(m) for m in end_markers) or any(
+            stripped.upper().startswith(m.upper()) for m in end_markers
+        ):
+            break
+        body_lines.append(stripped)
+    if not in_section:
+        return None
+    content = " ".join(part for part in body_lines if part)
+    return content if content else None
+
+
 def summarize_discussion_change(previous_text: str | None, current_text: str | None) -> str | None:
-    """Return a short human-friendly summary of what changed in the discussion text."""
+    """
+    Return a short human-friendly summary of what changed in the discussion text.
+
+    Priority order:
+    1. `.WHAT HAS CHANGED...` section — extract body up to the next section marker.
+    2. `.KEY MESSAGES...` section — extract body up to ``&&``.
+    3. First new line not present in the previous discussion text.
+
+    The result is truncated to ~300 characters.
+    """
     if not current_text:
         return None
 
+    # 1. Try .WHAT HAS CHANGED... section
+    section = _extract_section(
+        current_text,
+        start_marker=".WHAT HAS CHANGED",
+        end_markers=(".", "&&"),
+    )
+    if section:
+        return section[:300]
+
+    # 2. Try .KEY MESSAGES... section
+    section = _extract_section(
+        current_text,
+        start_marker=".KEY MESSAGES",
+        end_markers=("&&",),
+    )
+    if section:
+        return section[:300]
+
+    # 3. Fall back to first new line not present in previous text
     previous_lines = {
         line.strip()
         for line in (previous_text or "").splitlines()
@@ -63,7 +126,7 @@ def summarize_discussion_change(previous_text: str | None, current_text: str | N
         if not line or line.startswith("$"):
             continue
         if line not in previous_lines:
-            return line[:160]
+            return line[:300]
     return None
 
 

tests/test_split_notification_timers.py

@@ -49,9 +49,73 @@ def test_first_discussion_returns_first_line(self):
         assert result == "brand new content"
 
     def test_truncates_long_lines(self):
-        long_line = "x" * 200
+        long_line = "x" * 400
         result = summarize_discussion_change(None, long_line)
-        assert len(result) == 160
+        assert len(result) == 300
+
+    # ------------------------------------------------------------------
+    # New section-extraction paths
+    # ------------------------------------------------------------------
+
+    def test_what_has_changed_section_used_when_present(self):
+        """Path 1: .WHAT HAS CHANGED... section is found and returned."""
+        afd = (
+            ".SYNOPSIS...\n"
+            "Some synopsis text\n"
+            ".WHAT HAS CHANGED...\n"
+            "Temperatures have risen significantly across the region.\n"
+            "Winds will increase overnight.\n"
+            ".SHORT TERM...\n"
+            "Short term forecast content.\n"
+            "&&\n"
+        )
+        result = summarize_discussion_change(None, afd)
+        assert result is not None
+        assert "Temperatures have risen" in result
+        assert "Winds will increase overnight" in result
+        # The short-term section body should NOT appear in the summary
+        assert "Short term forecast content" not in result
+
+    def test_key_messages_fallback_when_no_what_has_changed(self):
+        """Path 2: .KEY MESSAGES... section used when no WHAT HAS CHANGED."""
+        afd = (
+            ".SYNOPSIS...\n"
+            "Synopsis text here.\n"
+            ".KEY MESSAGES...\n"
+            "* Heavy rain expected Tuesday.\n"
+            "* Flash flood watch in effect.\n"
+            "&&\n"
+            ".SHORT TERM...\n"
+            "Short term text.\n"
+        )
+        result = summarize_discussion_change(None, afd)
+        assert result is not None
+        assert "Heavy rain expected Tuesday" in result
+        assert "Flash flood watch in effect" in result
+        assert "Short term text" not in result
+
+    def test_first_new_line_fallback_when_no_special_sections(self):
+        """Path 3: falls back to first new line when no special sections exist."""
+        previous = "line one\nline two\n"
+        current = "line one\nline two\nThis is brand new forecast text.\n"
+        result = summarize_discussion_change(previous, current)
+        assert result == "This is brand new forecast text."
+
+    def test_what_has_changed_takes_priority_over_key_messages(self):
+        """WHAT HAS CHANGED is preferred over KEY MESSAGES."""
+        afd = ".WHAT HAS CHANGED...\nChange detail here.\n.KEY MESSAGES...\nKey message here.\n&&\n"
+        result = summarize_discussion_change(None, afd)
+        assert result is not None
+        assert "Change detail here" in result
+        assert "Key message here" not in result
+
+    def test_truncates_section_to_300_chars(self):
+        """Section content is truncated to 300 characters."""
+        body = "word " * 100  # well over 300 chars
+        afd = f".WHAT HAS CHANGED...\n{body}\n.SHORT TERM...\nother stuff\n"
+        result = summarize_discussion_change(None, afd)
+        assert result is not None
+        assert len(result) <= 300
 
 
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