fix: delete+repost schedule on weekly rollover for bottom placement

The Monday rollover was chat_update-ing in place, which only refreshes
content without moving the message to the bottom. Now it chat_deletes
the old post and chat_postMessages a fresh one so the schedule lands
at the bottom every Monday, independent of in-week activity.

Also added info-level logging to the bump handler silent return paths
so skipped bumps are observable at runtime.

docs/sticky-schedule-post.md

@@ -80,13 +80,12 @@ is therefore not a substitute for bottom-stickiness.
 
 ### Weekly rollover — `src/weekly-post/app.py`
 
-- **Drop the unconditional `chat_delete` + always-repost.** On Monday,
-  `chat_update` the stored post to roll the two-week window forward, keeping the
-  same `ts` (the activity bump is what moves it to the bottom; the rollover just
-  refreshes content).
-- **First-run / recovery fallback:** when there is no stored post or the
-  `chat_update` fails (e.g. the message was deleted manually), `chat_postMessage`
-  a fresh message and store its `ts`.
+- **Delete + repost on Monday** — the previous week's stored post is
+  `chat_delete`d and a fresh schedule is `chat_postMessage`d so the message
+  lands at the bottom of the channel every Monday regardless of in-week
+  activity. The delete failure is non-fatal; the handler always reposts.
+- **First-run:** when there is no stored post to delete, the handler
+  `chat_postMessage`s a fresh message and stores its `ts`.
 - The `pins:write` scope and the `_pin_schedule_post` helper are removed — the
   pin is fully replaced by bottom-stickiness.
 
@@ -123,16 +122,18 @@ request URL. On a `message.channels` event in the schedule channel
 
 All three paths converge on the **single stored `ts`** and never fight:
 
-- **Monday rollover** — `chat_update` the stored `ts` (content refresh; same
-  message), clearing `last_bump_ts` so the next activity is free to bump.
-- **In-week shift edits** — `_refresh_schedule_post` `chat_update`s the same
+- **Monday rollover** — `chat_delete`s the old stored `ts`, `chat_postMessage`s
+  a fresh post at the bottom, and saves the new `ts` (clearing `last_bump_ts` so
+  the next activity is free to bump).
+- **In-week shift edits** — `_refresh_schedule_post` `chat_update`s the current
   stored `ts`; it does not change the `ts` or touch `last_bump_ts`.
 - **Activity bump** — deletes the stored `ts`, reposts the same content at the
   bottom, and saves the new `ts`. Subsequent rollovers and edits then operate on
   that new `ts`.
 
-Because only the bump ever mints a new `ts` (and it always re-saves it
-immediately), the other two paths always read the current `ts` from the record.
+Both the rollover and the bump mint a new `ts` on repost and re-save it
+immediately, so `_refresh_schedule_post` always reads the current `ts` from the
+record.
 
 ## Scope / manifest impact
 

src/slack-bot/app.py

@@ -461,15 +461,25 @@ def handle_channel_message(event, client, schedule, schedule_channel, retry_num=
         logger.info("Ignoring retried message event (retry %s)", retry_num)
         return
     if not schedule_channel or event.get("channel") != schedule_channel:
+        logger.info(
+            "Skipping bump — channel mismatch (expected %s, got %s)",
+            schedule_channel,
+            event.get("channel"),
+        )
         return
     # Ignore the bot's own posts and non-user message events (edits, deletes,
     # joins, …), plus thread replies — a threaded reply doesn't push the
     # schedule down the main timeline, so it isn't worth a delete+repost.
     if event.get("bot_id") or event.get("subtype") or event.get("thread_ts"):
+        logger.info(
+            "Skipping bump — bot message, subtype %s, or thread reply",
+            event.get("subtype"),
+        )
         return
 
     post = schedule.get_schedule_post(schedule_channel)
     if not post or not post.get("message_ts"):
+        logger.info("Skipping bump — no stored schedule post for %s", schedule_channel)
         return
 
     now = time.time()
@@ -478,6 +488,11 @@ def handle_channel_message(event, client, schedule, schedule_channel, retry_num=
         last_bump is not None
         and now - float(last_bump) < SCHEDULE_BUMP_DEBOUNCE_SECONDS
     ):
+        logger.info(
+            "Skipping bump — debounced (last bump %.0fs ago, window %ds)",
+            now - float(last_bump),
+            SCHEDULE_BUMP_DEBOUNCE_SECONDS,
+        )
         return
 
     # Optimistically stamp the debounce window *before* the delete/repost, so a

src/weekly-post/app.py

@@ -318,39 +318,31 @@ def handler(event, context):
         f"to {end_date.strftime('%b %-d')}"
     )
 
-    # Roll the two-week window forward by editing the stored message in place
-    # (same ts) so the Monday rollover, in-week shift edits, and the activity
-    # bump all converge on a single stored ts. Fall back to a fresh post when
-    # there is no stored message or the edit fails (e.g. it was deleted).
+    # Delete the previous week's schedule post + repost a fresh one so the
+    # message lands at the bottom of the channel every Monday. The activity
+    # bump (handle_channel_message) handles in-week bottom-stickiness; this
+    # ensures the rollover itself re-places the post at the bottom.
     old_post = schedule.get_schedule_post(channel_id)
-    message_ts = None
     if old_post and old_post.get("message_ts"):
         try:
-            slack.chat_update(
-                channel=channel_id,
-                ts=old_post["message_ts"],
-                blocks=blocks,
-                text=fallback_text,
-            )
-            message_ts = old_post["message_ts"]
+            slack.chat_delete(channel=channel_id, ts=old_post["message_ts"])
             logger.info(
-                "Rolled schedule post %s forward to week of %s",
-                message_ts,
-                week_start,
+                "Deleted previous schedule post %s for weekly rollover",
+                old_post["message_ts"],
             )
         except Exception:
             logger.warning(
-                "Could not update existing schedule post; reposting", exc_info=True
+                "Could not delete old schedule post for rollover; continuing",
+                exc_info=True,
             )
 
-    if message_ts is None:
-        result = slack.chat_postMessage(
-            channel=channel_id, blocks=blocks, text=fallback_text
-        )
-        message_ts = result["ts"]
-        logger.info(
-            "Posted new weekly schedule to channel %s (ts=%s)", channel_id, message_ts
-        )
+    result = slack.chat_postMessage(
+        channel=channel_id, blocks=blocks, text=fallback_text
+    )
+    message_ts = result["ts"]
+    logger.info(
+        "Posted new weekly schedule to channel %s (ts=%s)", channel_id, message_ts
+    )
 
     schedule.save_schedule_post(channel_id, message_ts, week_start)
     return {

tests/weekly_post/test_handler.py

@@ -83,24 +83,26 @@ def test_pay_email_failure_does_not_block_schedule_post(
 
 @freeze_time(MON_0800)
 def test_rolls_existing_post_forward(weeklypost_app, schedule, seed, slack, env):
-    # An existing post is edited in place (stable permalink), never deleted.
+    # An existing post is deleted + reposted so it lands at the bottom every
+    # Monday. The old ts is cleaned up and a new one is stored.
     seed.schedule_post("C_TEST", "111.111")
     result = weeklypost_app.handler({"force": True}, None)
 
-    slack.chat_delete.assert_not_called()
-    slack.chat_update.assert_called_once()
-    assert slack.chat_update.call_args.kwargs["ts"] == "111.111"
-    # The stored ts is unchanged, so the permalink stays stable.
-    assert result["message_ts"] == "111.111"
-    assert schedule.get_schedule_post("C_TEST")["message_ts"] == "111.111"
+    slack.chat_delete.assert_called_once()
+    assert slack.chat_delete.call_args.kwargs["ts"] == "111.111"
+    slack.chat_update.assert_not_called()
+    slack.chat_postMessage.assert_called_once()
+    # New ts from the repost is stored.
+    assert result["message_ts"] == "999.000"
+    assert schedule.get_schedule_post("C_TEST")["message_ts"] == "999.000"
 
 
 @freeze_time(MON_0800)
-def test_reposts_when_update_fails(weeklypost_app, schedule, seed, slack, env):
-    # A stored post that can no longer be edited (e.g. deleted manually) falls
-    # back to a fresh post and re-saves the new ts.
+def test_reposts_when_delete_fails(weeklypost_app, schedule, seed, slack, env):
+    # A stored post that can no longer be deleted (e.g. was already removed
+    # manually) still reposts — the delete failure is non-fatal.
     seed.schedule_post("C_TEST", "111.111")
-    slack.chat_update.side_effect = Exception("message_not_found")
+    slack.chat_delete.side_effect = Exception("message_not_found")
 
     result = weeklypost_app.handler({"force": True}, None)