Calm Filters MVP: device-local personalization across feed/brief/counts

- API endpoints (feed, brief, category-counts) accept a 'prefs' JSON query
  param, parsed tolerantly into FilterPrefs (bad blobs never break the feed).
- Feed over-fetches then applies word-boundary filters in Python and slices to
  the page; brief is filtered down (no refill); counts are computed over the
  same filtered set so browse numbers match the feed exactly.
- Pause.active() coerces naive datetimes to UTC; FilterPrefs.from_dict skips
  malformed pauses and non-string list entries.
- Static site adds the humane ladder (Not today / Less like this / Always hide)
  plus a Calm filters panel managing pauses, mutes, and avoid-terms in
  localStorage. Nothing leaves the device.
- Tests now 38 (added forgiving-parse and naive-now cases). README documents it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

goodnews/filters.py

@@ -13,9 +13,10 @@ rather not see.
 
 from __future__ import annotations
 
+import json
 import re
 from dataclasses import dataclass, field
-from datetime import datetime
+from datetime import datetime, timezone
 
 # Split on any run of non-alphanumerics so matching is punctuation- and
 # case-insensitive, and anchored to whole words/phrases (no substring surprises:
@@ -51,6 +52,12 @@ class Pause:
             until = datetime.fromisoformat(self.until.replace("Z", "+00:00"))
         except (ValueError, AttributeError):
             return False
+        # Defensive: never crash on an aware-vs-naive comparison. Treat a naive
+        # `now` (and a naive `until`) as UTC.
+        if now.tzinfo is None:
+            now = now.replace(tzinfo=timezone.utc)
+        if until.tzinfo is None:
+            until = until.replace(tzinfo=timezone.utc)
         return until > now
 
 
@@ -65,14 +72,30 @@ class FilterPrefs:
 
     @classmethod
     def from_dict(cls, data: dict | None) -> "FilterPrefs":
-        data = data or {}
+        if not isinstance(data, dict):
+            return cls()
+
+        def _str_list(value: object) -> list[str]:
+            if not isinstance(value, list):
+                return []
+            return [str(v) for v in value if isinstance(v, str)]
+
+        # Be forgiving: a malformed pause is skipped, never raised — a bad
+        # localStorage/API blob must not break the feed.
+        pauses: list[Pause] = []
+        for p in data.get("pauses") or []:
+            try:
+                pauses.append(Pause(kind=p["kind"], value=p["value"], until=p["until"]))
+            except (KeyError, TypeError):
+                continue
+
         return cls(
-            include_topics=list(data.get("include_topics") or []),
-            include_flavors=list(data.get("include_flavors") or []),
-            mute_topics=list(data.get("mute_topics") or []),
-            mute_flavors=list(data.get("mute_flavors") or []),
-            avoid_terms=list(data.get("avoid_terms") or []),
-            pauses=[Pause(**p) for p in (data.get("pauses") or [])],
+            include_topics=_str_list(data.get("include_topics")),
+            include_flavors=_str_list(data.get("include_flavors")),
+            mute_topics=_str_list(data.get("mute_topics")),
+            mute_flavors=_str_list(data.get("mute_flavors")),
+            avoid_terms=_str_list(data.get("avoid_terms")),
+            pauses=pauses,
         )
 
     def muted_topics(self, now: datetime) -> set[str]:
@@ -97,6 +120,21 @@ class FilterPrefs:
         )
 
 
+def prefs_from_json(raw: str | None) -> FilterPrefs:
+    """Parse a JSON prefs string (from a query param) into FilterPrefs.
+
+    Never raises on bad input — a malformed blob yields empty prefs so the feed
+    keeps working.
+    """
+    if not raw:
+        return FilterPrefs()
+    try:
+        data = json.loads(raw)
+    except (ValueError, TypeError):
+        return FilterPrefs()
+    return FilterPrefs.from_dict(data)
+
+
 def allows(article: dict, prefs: FilterPrefs, now: datetime) -> bool:
     """True if an article (a feed/brief row dict) survives the preferences."""
     topic = article.get("topic")