feat: replace per-author cap with interleaving to avoid dropping posts in feed and home

The old `diversify_by_author` capped each author to 2 posts per page, silently dropping excess rows. The new `interleave_by_author` reorders the full result set so no two consecutive posts share an author, preserving every post while breaking up same-author runs. `paginate_diverse` loses its `max_per_author` and `pool` parameters; the home route now fetches exactly 6 rows and interleaves them instead of over-fetching 50 and capping. Tests are rewritten to verify interleaving behavior and per-author chronological order preservation.

devplacepy/database.py

@@ -2222,18 +2222,36 @@ def paginate(
     return rows, next_cursor
 
 
-def diversify_by_author(rows, max_per_author=2, limit=None, uid_key="user_uid"):
-    counts: dict = {}
-    kept = []
-    for row in rows:
+def interleave_by_author(rows, uid_key="user_uid"):
+    queues: dict = {}
+    appearance: list = []
+    for position, row in enumerate(rows):
         owner = row.get(uid_key)
-        if counts.get(owner, 0) >= max_per_author:
-            continue
-        counts[owner] = counts.get(owner, 0) + 1
-        kept.append(row)
-        if limit is not None and len(kept) >= limit:
-            break
-    return kept
+        queue = queues.get(owner)
+        if queue is None:
+            queue = queues[owner] = []
+            appearance.append(owner)
+        queue.append((position, row))
+    spread = []
+    last_owner = object()
+    while len(spread) < len(rows):
+        chosen = None
+        for owner in appearance:
+            queue = queues[owner]
+            if not queue or owner == last_owner:
+                continue
+            count = len(queue)
+            head_position = queue[0][0]
+            if (
+                chosen is None
+                or count > chosen[0]
+                or (count == chosen[0] and head_position < chosen[1])
+            ):
+                chosen = (count, head_position, owner)
+        owner = last_owner if chosen is None else chosen[2]
+        spread.append(queues[owner].pop(0)[1])
+        last_owner = owner
+    return spread
 
 
 def paginate_diverse(
@@ -2242,29 +2260,18 @@ def paginate_diverse(
     before=None,
     order=None,
     cursor_field="created_at",
-    max_per_author=2,
     uid_key="user_uid",
-    pool=200,
     **filters,
 ):
-    order = order or ["-" + cursor_field]
-    clauses = list(clauses)
-    if table.has_column("deleted_at") and "deleted_at" not in filters:
-        clauses.append(table.table.columns.deleted_at.is_(None))
-    if before:
-        clauses.append(table.table.columns[cursor_field] < before)
-    rows = list(table.find(*clauses, **filters, order_by=order, _limit=pool + 1))
-    exhausted = len(rows) <= pool
-    rows = rows[:pool]
-    kept = diversify_by_author(
-        rows, max_per_author=max_per_author, limit=PAGE_SIZE, uid_key=uid_key
+    rows, next_cursor = paginate(
+        table,
+        *clauses,
+        before=before,
+        order=order,
+        cursor_field=cursor_field,
+        **filters,
     )
-    if not kept:
-        return [], None
-    last_cursor = kept[-1][cursor_field]
-    older_exists = (not exhausted) or any(r[cursor_field] < last_cursor for r in rows)
-    next_cursor = last_cursor if older_exists else None
-    return kept, next_cursor
+    return interleave_by_author(rows, uid_key=uid_key), next_cursor
 
 
 def get_user_post_count(user_uid: str) -> int:

devplacepy/docs_api.py

@@ -695,7 +695,7 @@ four ways to sign requests.
                 summary=(
                     "The home page. Guests see the marketing splash; authenticated users see a "
                     "personalized home (welcome, feed shortcut, latest posts, news). It no longer "
-                    "redirects to /feed. The latest-posts section shows at most two posts per author."
+                    "redirects to /feed. The latest-posts section interleaves authors so no two consecutive posts share an author."
                 ),
                 auth="public",
                 interactive=True,
@@ -705,7 +705,7 @@ four ways to sign requests.
                 method="GET",
                 path="/feed",
                 title="Browse the feed",
-                summary="The main post feed. Returns an HTML page. Each page shows at most two posts per author.",
+                summary="The main post feed. Returns an HTML page. Each page interleaves authors so no two consecutive posts share an author.",
                 auth="public",
                 interactive=True,
                 params=[

devplacepy/main.py

@@ -31,7 +31,7 @@ from devplacepy.database import (
     get_news_images_by_uids,
     get_setting,
     get_int_setting,
-    diversify_by_author,
+    interleave_by_author,
     get_user_post_count,
 )
 from devplacepy.templating import templates
@@ -506,9 +506,9 @@ async def landing(request: Request):
     if "posts" in db.tables:
         posts_table = get_table("posts")
         raw_posts = list(
-            posts_table.find(deleted_at=None, order_by=["-created_at"], _limit=50)
+            posts_table.find(deleted_at=None, order_by=["-created_at"], _limit=6)
         )
-        raw_posts = diversify_by_author(raw_posts, max_per_author=2, limit=6)
+        raw_posts = interleave_by_author(raw_posts)
         if raw_posts:
             post_uids = [p["uid"] for p in raw_posts]
             author_uids = [p["user_uid"] for p in raw_posts]

devplacepy/routers/docs/pages.py

@@ -51,6 +51,12 @@ DOCS_PAGES = [
         "kind": "prose",
         "section": SECTION_GENERAL,
     },
+    {
+        "slug": "feed",
+        "title": "The feed",
+        "kind": "prose",
+        "section": SECTION_GENERAL,
+    },
     {
         "slug": "devii",
         "title": "Devii Assistant",

devplacepy/routers/feed.py

@@ -52,7 +52,6 @@ def get_feed_posts(
             *search_clauses,
             before=before,
             order=order,
-            max_per_author=2,
         )
     else:
         filters = {"topic": topic} if topic else {}
@@ -61,7 +60,6 @@ def get_feed_posts(
             *search_clauses,
             before=before,
             order=order,
-            max_per_author=2,
             **filters,
         )