Stick schedule post to bottom of channel

Replace the native pin with true bottom-of-channel stickiness: a
debounced message.channels handler in the slack-bot Lambda deletes and
re-posts the tracked schedule message on new activity so it stays last,
while the Monday rollover and in-week edits keep editing the same stored
ts. The pin only gave header reachability, not bottom placement.

Refs: #135

CHANGELOG.md

@@ -12,15 +12,15 @@ fine and still supported.
 
 ## v1.13.0 — June 27, 2026
 
-**The two-week schedule post now stays put instead of being reposted every
+**The two-week schedule post now sticks to the bottom of the channel.** It used
-week.** Each Monday the bot used to delete last week's schedule message and post
+to drift up out of sight as people chatted through the day. Now, whenever there's
-a brand-new one — which pinged the channel again, changed the message's link,
+new activity in the channel, the bot quietly moves the schedule back down to the
-and dropped any replies or reactions. Now it simply edits the existing post to
+bottom so it's always the last thing you see. To avoid spamming during a busy
-roll the two-week window forward, so the link stays stable, there's no weekly
+back-and-forth, it only does this at most once every few minutes. The trade-off
-re-notification, and any thread stays attached. The post is also pinned, so you
+for keeping it at the bottom is that the post's link changes each time it moves,
-can always reach it from the channel header even after a busy day of chat. (The
+and moving it re-pings the channel. (This needs a one-time app reinstall to
-pin needs a one-time app reinstall to switch on; until then everything else still
+switch on the new permission; until then the schedule still updates in place as
-works.)
+before.)
 
 ## v1.12.0 — June 26, 2026
 

docs/sticky-schedule-post.md

@@ -2,52 +2,54 @@
 
 _Spike for issue #135 — decide how the Monday two-week schedule post should
 behave across weeks. This document records the decision and the rationale; the
-recommended option (a) is implemented in the same PR._
+recommended option (b) is implemented in the same PR._
 
 ## Background
 
-`src/weekly-post/app.py` (the Monday 7am ET Lambda) currently, every week:
+`src/weekly-post/app.py` (the Monday 7am ET Lambda) originally, every week:
 
 1. `chat_delete` the previous week's schedule post (stored `ts` from
    `get_schedule_post`),
 2. `chat_postMessage` a brand-new two-week schedule message, and
 3. `save_schedule_post(channel_id, new_ts, …)`.
 
-So every Monday the post gets a new `ts` (new permalink), re-notifies the
+So every Monday the post got a new `ts` (new permalink), re-notified the
-channel, and loses any thread/reactions. During the week it steadily sinks as
+channel, and lost any thread/reactions. During the week it steadily sank as
-people chat.
+people chatted.
 
 The infrastructure to edit in place **already exists**: in-week shift changes
 (`pick` / `drop` / `swap` / `admin`) call `_refresh_schedule_post()`
 (`src/slack-bot/app.py`), which does a `chat_update` against the stored `ts`.
-The weekly rollover is the *only* place that creates a fresh message.
 
 ## Options considered
 
-### (a) Reuse the same post across weeks — **recommended**
+### (a) Reuse the same post across weeks — pin for reachability
 
 On Monday, `chat_update` the existing message to roll the two-week window
-forward instead of delete + repost.
+forward instead of delete + repost, and add a native Slack pin so the post is
+reachable from the channel header.
 
 - **Pros:** stable permalink; no weekly re-notification; keeps any
   thread/reactions; trivial change (reuses the `_refresh_schedule_post`
   `chat_update` pattern already in the codebase).
 - **Cons:** the message stays where it was first posted — it does **not** rise
-  to the bottom as the channel gets new activity.
+  to the bottom as the channel gets new activity. A native pin only surfaces the
+  post in the channel's pinned-items panel (the header); it does **not** hold the
+  message at the bottom of the timeline, which is the actual requirement from
+  #135.
 
-### (b) True stickybot behavior — keep it pinned to the bottom
+### (b) True stickybot behavior — keep it at the bottom — **recommended**
 
 Slack has no native "sticky" message. Stickybot-style bots subscribe to channel
 message events and **delete + repost** the bot message whenever someone else
 posts, so it is always last.
 
-- **Pros:** always visible at the bottom of the channel.
+- **Pros:** the schedule post is always at the literal bottom of the channel
-- **Cons:** directly conflicts with (a)'s stable permalink (every repost = new
+  timeline — exactly the behavior #135 asks for.
-  `ts`); requires a new event subscription (`message.channels`) and the
+- **Cons:** every bump is a new `ts` (the permalink changes); the post
-  `channels:history` scope (a reinstall); needs dedupe/debounce plus Slack
+  re-surfaces / re-notifies on activity; requires a new `message.channels` event
-  rate-limit handling; constant repost churn; many more moving parts and a new
+  subscription, the `channels:history` scope (a one-time reinstall), and
-  always-on event path to operate. The benefit (bottom-of-channel visibility)
+  debounce machinery to avoid thrashing on bursts.
-  is marginal for a low-traffic on-call channel.
 
 ### (c) Status quo — delete + repost weekly
 
@@ -57,58 +59,85 @@ posts, so it is always last.
 
 ## Decision
 
-Adopt **(a) reuse-in-place**, complemented by a **native Slack pin** so the post
+Adopt **(b) true bottom-of-channel stickiness**. Adam wants literal
-stays reachable from the channel header even as the channel fills with chatter.
+bottom-of-channel placement of the schedule post, and explicitly accepts the
-Reject **(b)** — its only advantage over a pin is keeping the post at the literal
+tradeoffs that come with it:
-bottom, which is not worth a new event subscription, an extra scope, and
-rate-limit/debounce machinery for this channel. The pin recovers most of the
-discoverability that the weekly bump used to provide, at the cost of one extra
-API call and one extra scope (`pins:write`), with no new event path to operate.
 
-## What changes (option a)
+1. **The permalink changes on each bump** — every delete + repost produces a new
+   `ts`, so any saved link to the post goes stale.
+2. **The post re-surfaces / re-notifies on activity** — re-posting pings the
+   channel (subject to the debounce window below), rather than sitting quietly.
+3. **New machinery** — a `message.channels` event subscription, the
+   `channels:history` scope (one-time reinstall), and a debounce to avoid
+   thrashing on bursts.
 
-In `src/weekly-post/app.py`, on the Monday rollover:
+The **native pin (option a's complement) was rejected**: it only gives header
+reachability — the post shows up in the pinned-items panel — but it does **not**
+hold the message at the bottom of the timeline, which is the requirement. A pin
+is therefore not a substitute for bottom-stickiness.
 
-- **Drop the unconditional `chat_delete`.** There is no previous message to
+## What changes (option b)
-  remove when we reuse the same one.
-- **`chat_update` the stored post** to roll the two-week window forward, keeping
-  the same `ts` (stable permalink, no re-notification).
-- **First-run / recovery fallback:** when there is no stored post, or the
-  `chat_update` fails (e.g. the message was deleted manually), fall back to
-  `chat_postMessage` and **pin** the new message.
-- **Keep `save_schedule_post` / `get_schedule_post`.** Still needed — they hold
-  the `ts` that both the weekly rollover and `_refresh_schedule_post` edit. On
-  reuse the stored `ts` is unchanged; on a fresh post it is updated to the new
-  `ts` and the new `week_start`.
 
-### Interaction with `_refresh_schedule_post`
+### Weekly rollover — `src/weekly-post/app.py`
 
-No change needed. Both paths now converge on a single long-lived message keyed
+- **Drop the unconditional `chat_delete` + always-repost.** On Monday,
-by the stored `ts`: the weekly Lambda rolls the window forward each Monday, and
+  `chat_update` the stored post to roll the two-week window forward, keeping the
-in-week shift changes keep editing the same message. They never fight because
+  same `ts` (the activity bump is what moves it to the bottom; the rollover just
-neither creates a new `ts` while one already exists.
+  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`.
+- The `pins:write` scope and the `_pin_schedule_post` helper are removed — the
+  pin is fully replaced by bottom-stickiness.
 
-### The "ever-growing edited message" / retention question
+### Activity bump — `src/slack-bot/app.py`
 
-A `chat_update` does not grow channel history — it rewrites one message in place
+The bump lives in the **slack-bot** Lambda, which already owns the Slack events
-rather than appending. Slack keeps the message's original post time, so an
+request URL. On a `message.channels` event in the schedule channel
-edited-forever post sorts by where it was first posted (hence the pin). There is
+(`handle_channel_message`):
-no retention or history-size concern from editing the same message indefinitely.
+
+- **Debounced** so a burst of chatter triggers at most one bump:
+  `SCHEDULE_BUMP_DEBOUNCE_SECONDS = 180` (3 minutes). The last bump time is
+  stored as `last_bump_ts` on the schedule-post record, so the debounce check
+  reads no channel history.
+- **Idempotent / safe** — the bump is skipped when:
+  - there is no stored post,
+  - the triggering message is the bot's own (`bot_id`) or a non-user message
+    subtype (edits, deletes, joins, …),
+  - the debounce window has not elapsed, or
+  - the bot isn't in the channel (`not_in_channel`).
+- Otherwise it `chat_delete`s the stored post and `chat_postMessage`s the current
+  `build_week_schedule` blocks, then `save_schedule_post`s the new `ts` (with
+  `last_bump_ts`). If the old message is already gone, it still reposts so the
+  channel always ends with the schedule.
+
+### Interaction with `_refresh_schedule_post` and the rollover
+
+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
+  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.
 
 ## Scope / manifest impact
 
-- `pins:write` is added to `slack-app-manifest.yaml` for the native pin. This is
+- `channels:history` (bot scope) and `message.channels` (bot event) are added to
-  a new OAuth scope, so the app must be **reinstalled** once for the pin to take
+  `slack-app-manifest.yaml` so the slack-bot Lambda receives channel messages and
-  effect. The pin call is best-effort: until the reinstall happens (or if the
+  can run the bump. This is a new scope + event, so the app must be
-  bot lacks the scope) it logs and is skipped, and the reuse-in-place behavior
+  **reinstalled** once for them to take effect.
-  still works without it.
+- `pins:write` is **removed** — the pin is no longer used.
-- No new event subscriptions. Option (b)'s `message.channels` event and
-  `channels:history` scope are **not** added.
 
 ## Follow-ups (not in this PR)
 
-- After deploy, reinstall the Slack app so `pins:write` takes effect, then
+- After deploy, reinstall the Slack app so `channels:history` /
-  confirm the first rolled-forward post gets pinned.
+  `message.channels` take effect, then confirm a new channel message bumps the
-- Optional: a one-line threaded note on the rolled-forward post if we later
+  schedule post to the bottom (and that bursts are debounced).
-  decide we still want a light weekly nudge (kept out here on purpose — the whole
+- If the re-notification on each bump proves noisy, revisit the debounce window
-  point of (a) is to stop the weekly re-notification).
+  or consider posting without a broadcast.

slack-app-manifest.yaml

@@ -5,10 +5,11 @@
 # reconcile it against the live app config (App settings → App Manifest) so no
 # existing scope or setting is dropped.
 #
-# This release adds the bot `pins:write` scope so the Monday rollover can natively
+# This release adds the `channels:history` bot scope and the `message.channels`
-# pin the reused two-week schedule post. A new OAuth scope means a one-time
+# bot event so the slack-bot Lambda can keep the two-week schedule post stuck to
-# reinstall is required for the pin to take effect (the pin is best-effort and is
+# the bottom of the channel: on new activity it deletes and re-posts the tracked
-# skipped until then). Replace <API_URL> with the SlackBotApiUrl stack output.
+# message (debounced). The new scope + event require a one-time reinstall to take
+# effect. Replace <API_URL> with the SlackBotApiUrl stack output.
 #
 # A prior release added the App Home tab (no new scope):
 #   - settings.event_subscriptions.bot_events: + app_home_opened
@@ -39,16 +40,19 @@ oauth_config:
       - chat:write
       - im:write
       - users:read
-      # pins:write lets the Monday rollover natively pin the reused schedule post
+      # channels:history lets the bot receive message.channels events for the
-      # so it stays reachable from the channel header. Adding it requires a
+      # schedule channel, which drive the activity bump that keeps the schedule
-      # one-time reinstall; the pin is best-effort until then.
+      # post at the bottom of the channel. Requires a one-time reinstall.
-      - pins:write
+      - channels:history
 
 settings:
   event_subscriptions:
     request_url: <API_URL>
     bot_events:
       - app_home_opened
+      # message.channels drives the activity bump that keeps the schedule post
+      # at the bottom of the channel (debounced delete + repost).
+      - message.channels
   interactivity:
     is_enabled: true
     request_url: <API_URL>

src/shared/shared/schedule.py

@@ -561,16 +561,24 @@ class ShiftSchedule:
         return resp.get("Item")
 
     def save_schedule_post(
-        self, channel_id: str, message_ts: str, week_start: str
+        self,
+        channel_id: str,
+        message_ts: str,
+        week_start: str,
+        last_bump_ts: float | None = None,
     ) -> None:
-        self.table.put_item(
+        """Store the tracked schedule post. ``last_bump_ts`` (epoch seconds) is
-            Item={
+        the debounce marker for the activity bump; omit it on the weekly
-                "PK": "SCHEDULE_POST",
+        rollover so the next channel message is free to bump to the bottom."""
-                "SK": channel_id,
+        item = {
-                "message_ts": message_ts,
+            "PK": "SCHEDULE_POST",
-                "week_start": week_start,
+            "SK": channel_id,
-            }
+            "message_ts": message_ts,
-        )
+            "week_start": week_start,
+        }
+        if last_bump_ts is not None:
+            item["last_bump_ts"] = Decimal(str(last_bump_ts))
+        self.table.put_item(Item=item)
 
     # ── Pay records ─────────────────────────────────────────────────────
 

src/slack-bot/CHANGELOG.md

@@ -12,15 +12,15 @@ fine and still supported.
 
 ## v1.13.0 — June 27, 2026
 
-**The two-week schedule post now stays put instead of being reposted every
+**The two-week schedule post now sticks to the bottom of the channel.** It used
-week.** Each Monday the bot used to delete last week's schedule message and post
+to drift up out of sight as people chatted through the day. Now, whenever there's
-a brand-new one — which pinged the channel again, changed the message's link,
+new activity in the channel, the bot quietly moves the schedule back down to the
-and dropped any replies or reactions. Now it simply edits the existing post to
+bottom so it's always the last thing you see. To avoid spamming during a busy
-roll the two-week window forward, so the link stays stable, there's no weekly
+back-and-forth, it only does this at most once every few minutes. The trade-off
-re-notification, and any thread stays attached. The post is also pinned, so you
+for keeping it at the bottom is that the post's link changes each time it moves,
-can always reach it from the channel header even after a busy day of chat. (The
+and moving it re-pings the channel. (This needs a one-time app reinstall to
-pin needs a one-time app reinstall to switch on; until then everything else still
+switch on the new permission; until then the schedule still updates in place as
-works.)
+before.)
 
 ## v1.12.0 — June 26, 2026
 

src/slack-bot/app.py

@@ -11,6 +11,7 @@ import json
 import logging
 import os
 import re
+import time
 from datetime import datetime, timedelta
 from zoneinfo import ZoneInfo
 
@@ -46,6 +47,12 @@ from shared.three_cx_client import ThreeCXClient
 logger = logging.getLogger(__name__)
 EASTERN = ZoneInfo("America/New_York")
 
+# Activity-bump debounce: don't re-post the schedule to the bottom of the
+# channel more than once per this many seconds, so a burst of chatter triggers
+# at most one delete+repost. The window is stored as ``last_bump_ts`` on the
+# schedule-post record (avoids reading channel history).
+SCHEDULE_BUMP_DEBOUNCE_SECONDS = 180
+
 DAY_NAMES = [
     "monday",
     "tuesday",
@@ -392,8 +399,19 @@ def _droppable_shifts(schedule, date_str, day_name, employee_ext) -> list[str]:
     return held
 
 
+def _schedule_fallback_text() -> str:
+    """Notification fallback text for the two-week schedule post."""
+    now = datetime.now(EASTERN)
+    this_monday = now - timedelta(days=now.weekday())
+    end_date = this_monday + timedelta(days=13)
+    return (
+        f"After-Hours Schedule — {this_monday.strftime('%b %-d')} "
+        f"to {end_date.strftime('%b %-d')}"
+    )
+
+
 def _refresh_schedule_post(schedule, schedule_channel, client):
-    """Update the pinned schedule message in-place after a shift change."""
+    """Update the tracked schedule message in-place after a shift change."""
     channel = schedule_channel
     if not channel:
         return
@@ -401,20 +419,88 @@ def _refresh_schedule_post(schedule, schedule_channel, client):
     if not post or not post.get("message_ts"):
         return
     try:
-        blocks = build_week_schedule(schedule)
-        now = datetime.now(EASTERN)
-        this_monday = now - timedelta(days=now.weekday())
-        end_date = this_monday + timedelta(days=13)
         client.chat_update(
             channel=channel,
             ts=post["message_ts"],
-            blocks=blocks,
+            blocks=build_week_schedule(schedule),
-            text=f"After-Hours Schedule — {this_monday.strftime('%b %-d')} to {end_date.strftime('%b %-d')}",
+            text=_schedule_fallback_text(),
         )
     except Exception:
         logger.warning("Could not update schedule post", exc_info=True)
 
 
+def _slack_error_code(exc) -> str | None:
+    """Best-effort Slack API error code (e.g. ``not_in_channel``) from an exc."""
+    response = getattr(exc, "response", None)
+    if response is None:
+        return None
+    try:
+        return response.get("error")
+    except Exception:
+        return None
+
+
+def handle_channel_message(event, client, schedule, schedule_channel):
+    """Bump the schedule post to the bottom of the channel on new activity.
+
+    Debounced delete+repost of the tracked post so it stays at the bottom of
+    the channel timeline. Idempotent/safe: skips when there is no stored post,
+    when the triggering message is the bot's own / an edit-delete subtype, when
+    debounced inside the window, or when the bot isn't in the channel.
+    """
+    if not schedule_channel or event.get("channel") != schedule_channel:
+        return
+    # Ignore the bot's own posts and non-user message events (edits, deletes,
+    # joins, …) — only genuine new user messages should bump.
+    if event.get("bot_id") or event.get("subtype"):
+        return
+
+    post = schedule.get_schedule_post(schedule_channel)
+    if not post or not post.get("message_ts"):
+        return
+
+    now = time.time()
+    last_bump = post.get("last_bump_ts")
+    if (
+        last_bump is not None
+        and now - float(last_bump) < SCHEDULE_BUMP_DEBOUNCE_SECONDS
+    ):
+        return
+
+    blocks = build_week_schedule(schedule)
+    text = _schedule_fallback_text()
+    try:
+        client.chat_delete(channel=schedule_channel, ts=post["message_ts"])
+    except Exception as exc:
+        if _slack_error_code(exc) == "not_in_channel":
+            logger.info("Bot not in schedule channel; skipping bump")
+            return
+        # The old message may already be gone — keep going and repost a fresh
+        # one so the channel still ends with the schedule.
+        logger.info("Could not delete old schedule post for bump", exc_info=True)
+
+    try:
+        result = client.chat_postMessage(
+            channel=schedule_channel, blocks=blocks, text=text
+        )
+    except Exception as exc:
+        if _slack_error_code(exc) == "not_in_channel":
+            logger.info("Bot not in schedule channel; skipping bump")
+            return
+        logger.warning("Could not repost schedule for bump", exc_info=True)
+        return
+
+    schedule.save_schedule_post(
+        schedule_channel,
+        result["ts"],
+        post.get("week_start", ""),
+        last_bump_ts=now,
+    )
+    logger.info(
+        "Bumped schedule post to bottom of %s (ts=%s)", schedule_channel, result["ts"]
+    )
+
+
 # ── Command dispatch ────────────────────────────────────────────────────
 
 
@@ -2112,4 +2198,8 @@ def create_app(
             return
         publish_home(client, event["user"], _changelog_text())
 
+    @app.event("message")
+    def handle_message_event(event, client):
+        handle_channel_message(event, client, schedule, schedule_channel)
+
     return app

src/weekly-post/app.py

@@ -247,16 +247,6 @@ def _send_pay_email(week_label: str, pay_record: dict) -> None:
     logger.info("Sent pay email to %s", recipients)
 
 
-def _pin_schedule_post(slack, channel_id, message_ts):
-    """Best-effort native pin so a freshly posted schedule stays reachable from
-    the channel header even as the channel fills with chatter."""
-    try:
-        slack.pins_add(channel=channel_id, timestamp=message_ts)
-        logger.info("Pinned schedule post %s", message_ts)
-    except Exception:
-        logger.info("Could not pin schedule post %s", message_ts, exc_info=True)
-
-
 def handler(event, context):
     now = datetime.now(EASTERN)
 
@@ -328,11 +318,10 @@ def handler(event, context):
         f"to {end_date.strftime('%b %-d')}"
     )
 
-    # Reuse the same post across weeks: roll the two-week window forward by
+    # Roll the two-week window forward by editing the stored message in place
-    # editing the existing message in place (stable permalink, no weekly
+    # (same ts) so the Monday rollover, in-week shift edits, and the activity
-    # re-notification, keeps any thread/reactions) instead of delete + repost.
+    # bump all converge on a single stored ts. Fall back to a fresh post when
-    # Fall back to a fresh, pinned post when there is no stored message or the
+    # there is no stored message or the edit fails (e.g. it was deleted).
-    # edit fails (e.g. the message was deleted manually).
     old_post = schedule.get_schedule_post(channel_id)
     message_ts = None
     if old_post and old_post.get("message_ts"):
@@ -359,7 +348,6 @@ def handler(event, context):
             channel=channel_id, blocks=blocks, text=fallback_text
         )
         message_ts = result["ts"]
-        _pin_schedule_post(slack, channel_id, message_ts)
         logger.info(
             "Posted new weekly schedule to channel %s (ts=%s)", channel_id, message_ts
         )

tests/slack_bot/test_channel_bump.py

@@ -0,0 +1,130 @@
+"""Tests for the activity bump that keeps the schedule post at the bottom of
+the channel (slack-bot handle_channel_message)."""
+
+import time
+
+from freezegun import freeze_time
+
+CHANNEL = "C_TEST"
+MON = "2026-06-08 12:00:00"
+
+
+class _SlackError(Exception):
+    """Stand-in for slack_sdk.errors.SlackApiError with a `.response` dict."""
+
+    def __init__(self, code):
+        super().__init__(code)
+        self.response = {"error": code}
+
+
+def _msg(channel=CHANNEL, user="U_ALICE", ts="100.500", **extra):
+    return {"channel": channel, "user": user, "ts": ts, **extra}
+
+
+@freeze_time(MON)
+def test_bumps_on_new_message(slackbot_app, schedule, seed, client):
+    seed.schedule_post(CHANNEL, "111.111")
+    client.chat_postMessage.return_value = {"ts": "222.222"}
+
+    slackbot_app.handle_channel_message(_msg(), client, schedule, CHANNEL)
+
+    client.chat_delete.assert_called_once()
+    assert client.chat_delete.call_args.kwargs["ts"] == "111.111"
+    client.chat_postMessage.assert_called_once()
+    # The stored ts now points at the freshly reposted message + debounce stamp.
+    post = schedule.get_schedule_post(CHANNEL)
+    assert post["message_ts"] == "222.222"
+    assert post.get("last_bump_ts") is not None
+
+
+@freeze_time(MON)
+def test_debounce_skips_within_window(slackbot_app, schedule, client):
+    schedule.save_schedule_post(
+        CHANNEL, "111.111", "2026-06-08", last_bump_ts=time.time()
+    )
+
+    slackbot_app.handle_channel_message(_msg(), client, schedule, CHANNEL)
+
+    client.chat_delete.assert_not_called()
+    client.chat_postMessage.assert_not_called()
+    # Stored post is untouched.
+    assert schedule.get_schedule_post(CHANNEL)["message_ts"] == "111.111"
+
+
+@freeze_time(MON)
+def test_bumps_after_debounce_window(slackbot_app, schedule, client):
+    old = time.time() - (slackbot_app.SCHEDULE_BUMP_DEBOUNCE_SECONDS + 60)
+    schedule.save_schedule_post(CHANNEL, "111.111", "2026-06-08", last_bump_ts=old)
+    client.chat_postMessage.return_value = {"ts": "222.222"}
+
+    slackbot_app.handle_channel_message(_msg(), client, schedule, CHANNEL)
+
+    client.chat_postMessage.assert_called_once()
+    assert schedule.get_schedule_post(CHANNEL)["message_ts"] == "222.222"
+
+
+@freeze_time(MON)
+def test_skips_when_no_stored_post(slackbot_app, schedule, client):
+    slackbot_app.handle_channel_message(_msg(), client, schedule, CHANNEL)
+
+    client.chat_delete.assert_not_called()
+    client.chat_postMessage.assert_not_called()
+
+
+@freeze_time(MON)
+def test_skips_bots_own_message(slackbot_app, schedule, seed, client):
+    seed.schedule_post(CHANNEL, "111.111")
+
+    slackbot_app.handle_channel_message(_msg(bot_id="B123"), client, schedule, CHANNEL)
+
+    client.chat_delete.assert_not_called()
+    client.chat_postMessage.assert_not_called()
+
+
+@freeze_time(MON)
+def test_skips_message_edit_and_delete_subtypes(slackbot_app, schedule, seed, client):
+    seed.schedule_post(CHANNEL, "111.111")
+
+    slackbot_app.handle_channel_message(
+        _msg(subtype="message_changed"), client, schedule, CHANNEL
+    )
+
+    client.chat_delete.assert_not_called()
+    client.chat_postMessage.assert_not_called()
+
+
+@freeze_time(MON)
+def test_skips_other_channel(slackbot_app, schedule, seed, client):
+    seed.schedule_post(CHANNEL, "111.111")
+
+    slackbot_app.handle_channel_message(
+        _msg(channel="C_OTHER"), client, schedule, CHANNEL
+    )
+
+    client.chat_delete.assert_not_called()
+    client.chat_postMessage.assert_not_called()
+
+
+@freeze_time(MON)
+def test_skips_when_bot_not_in_channel(slackbot_app, schedule, seed, client):
+    seed.schedule_post(CHANNEL, "111.111")
+    client.chat_delete.side_effect = _SlackError("not_in_channel")
+
+    slackbot_app.handle_channel_message(_msg(), client, schedule, CHANNEL)
+
+    # No repost, and the stored post is left intact.
+    client.chat_postMessage.assert_not_called()
+    assert schedule.get_schedule_post(CHANNEL)["message_ts"] == "111.111"
+
+
+@freeze_time(MON)
+def test_reposts_when_old_message_already_gone(slackbot_app, schedule, seed, client):
+    # A stale ts (deleted manually) → delete fails non-fatally; still reposts.
+    seed.schedule_post(CHANNEL, "111.111")
+    client.chat_delete.side_effect = _SlackError("message_not_found")
+    client.chat_postMessage.return_value = {"ts": "222.222"}
+
+    slackbot_app.handle_channel_message(_msg(), client, schedule, CHANNEL)
+
+    client.chat_postMessage.assert_called_once()
+    assert schedule.get_schedule_post(CHANNEL)["message_ts"] == "222.222"

tests/weekly_post/test_handler.py

@@ -95,27 +95,16 @@ def test_rolls_existing_post_forward(weeklypost_app, schedule, seed, slack, env)
     assert schedule.get_schedule_post("C_TEST")["message_ts"] == "111.111"
 
 
-@freeze_time(MON_0800)
-def test_pins_post_on_first_run(weeklypost_app, schedule, seed, slack, env):
-    # No existing post → post a fresh message and natively pin it.
-    result = weeklypost_app.handler({"force": True}, None)
-
-    slack.chat_postMessage.assert_called()
-    slack.pins_add.assert_called_once()
-    assert slack.pins_add.call_args.kwargs["timestamp"] == "999.000"
-    assert result["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, pinned post and re-saves the new ts.
+    # back to a fresh post and re-saves the new ts.
     seed.schedule_post("C_TEST", "111.111")
     slack.chat_update.side_effect = Exception("message_not_found")
 
     result = weeklypost_app.handler({"force": True}, None)
 
-    slack.pins_add.assert_called_once()
+    slack.chat_postMessage.assert_called()
     assert result["message_ts"] == "999.000"
     assert schedule.get_schedule_post("C_TEST")["message_ts"] == "999.000"