feat: survive an outage, and keep the counts that predate the event log

Two gaps kuhy pointed at, both about not losing messages the bot was not
awake for.

Missed *counts* already worked and now have a test saying so: an event
is keyed by Signal's own send timestamp, signal-cli keeps receiving in
json-rpc mode while the bot is down, and the replay on reconnect is
absorbed by the primary key. Messages sent during an outage come back
filed under the day they were actually sent.

Missed *reports* did not. A bot that was down at 21:37 never posted that
day and never went back for it. The last day reported is now written
down per group, so returning from an outage posts every day it owes,
oldest first, bounded at a week. A day nobody spoke on is marked settled
rather than reconsidered forever; a day whose send *failed* is
deliberately left unmarked so the next run retries it.

The pre-0.1.0 counter is carried over rather than discarded: 342
messages across four groups, 319 of them in the real group. What the
counter cannot say is when, so before assuming, four places were checked
for a real inbound timestamp -- journald (commands only), signal-cli's
account.db (19 tables, none inbound; message_send_log is the bot's own
outgoing resend buffer), Signal Desktop (unlinked, empty, and it does
not backfill on link), and signal-api/attachments (the one dated
artifact). The attachment mtimes put 12 files on 29 Aug against 79 on
30 Aug inside the counter's window, which is why the whole counter is
filed under 30 Aug rather than split.

That day is marked in group_meta, and a marked day claims no average
message length -- those messages have a count but no lengths, so
"średnio 0 znaków" would be a measurement nobody took. The mark is also
what will keep the day out of personal records: a merged 22-hour day
would otherwise hand somebody a record they never set.

render_day's options move into a DayView value object; the keyword list
had reached eight and this renderer is about to be shared by several
commands that each want a different subset.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015d48t4qsQLBJnDwDeo2Nom

signal_bot/bot.py

@@ -24,8 +24,10 @@ from signal_bot.popes_command import register_pope_command
 from signal_bot.portraits import PortraitCache
 from signal_bot.registry import CommandRegistry
 from signal_bot.stats import periods
+from signal_bot.stats.backfill import backfilled_day
+from signal_bot.stats.nightly import days_to_report, mark_reported
 from signal_bot.stats.queries_day import day_rows, day_totals, with_silent
-from signal_bot.stats.render_day import render_day
+from signal_bot.stats.render_day import DayView, render_day
 from signal_bot.versioning import POPE, __version__
 
 if TYPE_CHECKING:
@@ -82,27 +84,41 @@ class Bot:
         group refusing the report -- the bot removed from it, a transient send
         failure -- must not cost every other group its report.
         """
-        day = periods.previous_day(self.clock())
+        latest = periods.previous_day(self.clock())
         for group_id in self.directory.groups:
-            rows = day_rows(self.store.events, group_id, day)
-            if not rows:
-                # Logged, not posted. The bot is in every group it was ever
-                # added to, so posting "nobody spoke" would mean a nightly
-                # ping into every quiet group, forever.
-                logger.info("no messages in %s on %s; not posting a report", group_id, day)
-                continue
-            named = self.store.events.roster(group_id, self.directory.member_identities(group_id))
-            rows = with_silent(rows, [(p.uuid, p.display_name) for p in named])
-            text = render_day(
-                day,
-                rows,
-                day_totals(rows),
+            for day in days_to_report(self.store, group_id, latest):
+                if not await self._report_one(group_id, day):
+                    # Left unmarked on purpose, so the next run retries it
+                    # rather than skipping the day forever.
+                    break
+                mark_reported(self.store, group_id, day)
+
+    async def _report_one(self, group_id: str, day: str) -> bool:
+        """Post one group's report for one day. False means try again later."""
+        rows = day_rows(self.store.events, group_id, day)
+        if not rows:
+            # Settled, not pending. The bot is in every group it was ever
+            # added to, so posting "nobody spoke" would mean a nightly ping
+            # into every quiet group, forever.
+            logger.info("no messages in %s on %s; not posting a report", group_id, day)
+            return True
+        named = self.store.events.roster(group_id, self.directory.member_identities(group_id))
+        with_zeros = with_silent(rows, [(p.uuid, p.display_name) for p in named])
+        text = render_day(
+            day,
+            with_zeros,
+            day_totals(with_zeros),
+            DayView(
                 since=self.store.events.first_day(group_id),
-            )
-            try:
-                await self.transport.send_text(text, group_id)
-            except Exception:
-                logger.exception("daily report failed for group %s", group_id)
+                approximate=backfilled_day(self.store, group_id) == day,
+            ),
+        )
+        try:
+            await self.transport.send_text(text, group_id)
+        except Exception:
+            logger.exception("daily report failed for group %s", group_id)
+            return False
+        return True
 
     async def announce_release(self) -> None:
         """Tell every watched group about a version it has not seen yet."""

signal_bot/stats/backfill.py

@@ -0,0 +1,88 @@
+# Copyright (c) 2026 Krzysztof Rudnicki. MIT licence.
+"""Carrying the pre-0.1.0 counter into the event log, once.
+
+Before 0.1.0 the bot kept one integer per person and deleted it after each
+nightly post. When the event log arrived there were 319 messages sitting in
+that counter, accumulated since the last successful post. Throwing them away
+would have been tidier, but they are real messages and they are the group's
+only pre-history.
+
+What the counter cannot say is *when*. It has no timestamp column, and its
+window straddles two calendar days -- from the previous night's post to
+whenever the migration runs. So a backfilled day is filed under the day that
+holds most of that window, and marked, because a merged 22-hour day pretending
+to be a normal one would hand somebody a personal record they never set and
+would drag every "average day" figure with it.
+
+Marked days keep their totals and stay out of records and per-hour statistics.
+``group_meta`` carries the mark, so this needs no schema change.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Final
+
+from signal_bot.stats.events import MessageEvent
+
+if TYPE_CHECKING:
+    from signal_bot.store import Store
+
+BACKFILL_KEY: Final = "backfill_day"
+# Noon: a backfilled event has no real hour, and midnight would look like a
+# deliberate reading rather than an absent one. The day is marked anyway, so
+# nothing that cares about hours will read these.
+BACKFILL_HOUR: Final = 12
+
+
+def has_legacy_counter(store: Store) -> bool:
+    """True when this database predates 0.1.0 and still holds the old table."""
+    row = store.events.connection.execute(
+        "SELECT name FROM sqlite_master WHERE type = 'table' AND name = 'message_counts'"
+    ).fetchone()
+    return row is not None
+
+
+def backfilled_day(store: Store, group_id: str) -> str | None:
+    """The one day whose totals came from the old counter, if any."""
+    return store.meta(group_id, BACKFILL_KEY)
+
+
+def seed_from_counter(store: Store, day: str) -> dict[str, int]:
+    """Copy every surviving tally into the event log as one marked day.
+
+    Args:
+        store: The open database, which must still hold ``message_counts``.
+        day: The Warsaw day to file the counts under. Choose the day covering
+            most of the counter's window.
+
+    Returns:
+        Messages seeded per group id, for reporting.
+    """
+    rows = store.events.connection.execute(
+        "SELECT group_id, uuid, display_name, count FROM message_counts WHERE count > 0"
+    ).fetchall()
+
+    seeded: dict[str, int] = {}
+    for row in rows:
+        group_id = row["group_id"]
+        for index in range(row["count"]):
+            # Synthetic, strictly increasing, and unique per person per group,
+            # because (group, uuid, sent_at_ms) is the primary key. They are
+            # not timestamps anybody should read as one, which is what the
+            # day marking is for.
+            store.events.record(
+                MessageEvent(
+                    group_id=group_id,
+                    uuid=row["uuid"],
+                    display_name=row["display_name"],
+                    sent_at_ms=index + 1,
+                    day=day,
+                    local_hour=BACKFILL_HOUR,
+                )
+            )
+        store.events.note_person(group_id, row["uuid"], row["display_name"], "", day)
+        seeded[group_id] = seeded.get(group_id, 0) + row["count"]
+
+    for group_id in seeded:
+        store.set_meta(group_id, BACKFILL_KEY, day)
+    return seeded

signal_bot/stats/nightly.py

@@ -0,0 +1,71 @@
+# Copyright (c) 2026 Krzysztof Rudnicki. MIT licence.
+"""Which days still owe the group a report, and posting them.
+
+The event log already survives an outage: a message carries Signal's own send
+timestamp, signal-cli keeps receiving while the bot is down, and the replay on
+reconnect is absorbed by the primary key. So the *counts* come back on their
+own, filed under the day they were actually sent.
+
+The *report* did not. A bot that was down at 21:37 simply never posted that
+day, and nothing ever went back for it -- the old counter merged the day into
+the next one instead, which is the bug this release exists to remove. So the
+last day reported is written down per group, and every day since then gets
+posted when the bot comes back.
+
+Bounded, because coming back from a fortnight offline should not open with a
+fortnight of back-posts.
+"""
+
+from __future__ import annotations
+
+import logging
+from typing import TYPE_CHECKING, Final
+
+from signal_bot.stats.periods import shift
+
+if TYPE_CHECKING:
+    from signal_bot.store import Store
+
+logger = logging.getLogger(__name__)
+
+LAST_REPORTED_KEY: Final = "last_reported_day"
+# At most a week of catch-up in one go. Long enough to cover a weekend
+# outage nobody noticed, short enough that a month offline is not a wall.
+CATCHUP_LIMIT: Final = 7
+
+
+def days_to_report(store: Store, group_id: str, latest: str) -> list[str]:
+    """Every day up to ``latest`` that has not been reported yet, oldest first.
+
+    Args:
+        store: The open database, which holds the per-group marker.
+        group_id: The group being reported on.
+        latest: The most recent day eligible for a report, normally yesterday.
+
+    Returns:
+        The days to post, oldest first. A group with no marker gets only
+        ``latest``: the marker is absent on a brand-new group and on the first
+        run after this release, and neither should trigger a backlog.
+    """
+    last = store.meta(group_id, LAST_REPORTED_KEY)
+    if last is None:
+        return [latest]
+    if last >= latest:
+        return []
+
+    days = []
+    day = shift(last, 1)
+    while day <= latest:
+        days.append(day)
+        day = shift(day, 1)
+    return days[-CATCHUP_LIMIT:]
+
+
+def mark_reported(store: Store, group_id: str, day: str) -> None:
+    """Record that a day no longer owes this group a report.
+
+    Called for a day that was posted *and* for a day nobody spoke on -- an
+    empty day is settled, not pending, and leaving it unmarked would make the
+    bot reconsider it every night forever.
+    """
+    store.set_meta(group_id, LAST_REPORTED_KEY, day)

signal_bot/stats/render_day.py

@@ -14,6 +14,7 @@ off is worse than a shorter leaderboard.
 
 from __future__ import annotations
 
+from dataclasses import dataclass
 from typing import TYPE_CHECKING, Final
 
 from signal_bot.stats import text
@@ -52,35 +53,63 @@ def silence_line(rows: list[DayRow], unnamed: int) -> str:
     return "Cisza: " + ", ".join(names) if names else ""
 
 
-def summary_line(totals: DayTotals) -> str:
-    """Commands and average length -- the two facts that qualify the count."""
+def summary_line(totals: DayTotals, *, approximate: bool = False) -> str:
+    """Commands and average length -- the two facts that qualify the count.
+
+    ``approximate`` drops the length claim. It is set for the one day carried
+    over from the pre-0.1.0 counter, whose messages have a count but no
+    lengths: reporting "średnio 0 znaków" would be a measurement nobody took.
+    """
     if not totals.messages:
         return ""
-    parts = [f"średnio {text.characters(totals.average_length)}"]
+    parts = [] if approximate else [f"średnio {text.characters(totals.average_length)}"]
     if totals.commands:
         parts.insert(0, f"z tego {text.commands(totals.commands)}")
+    if not parts:
+        return ""
     return parts[0].capitalize() + (f", {parts[1]}." if len(parts) > 1 else ".")
 
 
+@dataclass(frozen=True, slots=True)
+class DayView:
+    """How one day is presented, apart from its numbers.
+
+    A value object rather than a widening keyword list: this renderer is
+    shared by the nightly post and several commands, each wanting a different
+    combination of these, and they keep accumulating.
+    """
+
+    since: str | None = None
+    unnamed: int = 0
+    highlights: tuple[str, ...] = ()
+    heading: str | None = None
+    # The day's messages have counts but no lengths -- see stats.backfill.
+    approximate: bool = False
+
+
 def render_day(
     day: str,
     rows: list[DayRow],
     totals: DayTotals,
-    *,
-    since: str | None = None,
-    unnamed: int = 0,
-    highlights: list[str] | None = None,
-    heading: str | None = None,
+    view: DayView | None = None,
 ) -> str:
     """Compose the day block, trimmed to MAX_LINES."""
+    view = view or DayView()
     header = (
-        heading
+        view.heading
         or f"{CHART} {pl_date(day)} — {text.messages(totals.messages)}{_media(totals.media)}"
     )
-    tail = [line for line in (silence_line(rows, unnamed), summary_line(totals)) if line]
-    picks = highlights or []
-    if since:
-        tail.append(f"(liczymy od {pl_day_month(since)})")
+    tail = [
+        line
+        for line in (
+            silence_line(rows, view.unnamed),
+            summary_line(totals, approximate=view.approximate),
+        )
+        if line
+    ]
+    picks = list(view.highlights)
+    if view.since:
+        tail.append(f"(liczymy od {pl_day_month(view.since)})")
 
     # Everything except the speakers is mandatory, and at least one highlight
     # slot is reserved before any speaker is allowed a line.

tests/test_bot.py

@@ -13,6 +13,7 @@ from signal_bot.bot import Bot, build_bot, now_local
 from signal_bot.discovery import GroupDirectory
 from signal_bot.liveness import Liveness
 from signal_bot.stats.events import MessageEvent
+from signal_bot.stats.nightly import LAST_REPORTED_KEY, mark_reported
 from signal_bot.stats.periods import WARSAW
 from signal_bot.transport_fake import FakeTransport
 from signal_bot.trust import InviteTrust
@@ -98,6 +99,60 @@ async def test_the_report_covers_yesterday_not_today(
     assert "Bob" not in transport.texts[0]
 
 
+async def test_a_missed_day_is_posted_when_the_bot_returns(
+    config: Config, store: Store, transport: FakeTransport, directory: GroupDirectory
+) -> None:
+    """An outage over 21:37 used to lose that day's report entirely."""
+    wrote(store, WATCHED_GROUP, "u1", "Alice", 2, day="2026-08-30")
+    wrote(store, WATCHED_GROUP, "u1", "Alice", 3, day="2026-08-31")
+    wrote(store, WATCHED_GROUP, "u1", "Alice", 4, day=YESTERDAY)
+    mark_reported(store, WATCHED_GROUP, "2026-08-29")
+
+    await _bot(config, store, transport, directory).publish_report()
+
+    assert len(transport.texts) == 3
+    assert "30 sierpnia" in transport.texts[0]
+    assert "31 sierpnia" in transport.texts[1]
+    assert "1 września" in transport.texts[2]
+    assert store.meta(WATCHED_GROUP, LAST_REPORTED_KEY) == YESTERDAY
+
+
+async def test_a_day_nobody_spoke_is_settled_not_retried_forever(
+    config: Config, store: Store, transport: FakeTransport, directory: GroupDirectory
+) -> None:
+    wrote(store, WATCHED_GROUP, "u1", "Alice", 1, day=YESTERDAY)
+    mark_reported(store, WATCHED_GROUP, "2026-08-30")
+
+    await _bot(config, store, transport, directory).publish_report()
+
+    assert len(transport.texts) == 1
+    assert store.meta(WATCHED_GROUP, LAST_REPORTED_KEY) == YESTERDAY
+
+
+async def test_a_failed_send_leaves_its_day_unmarked(
+    config: Config, store: Store, directory: GroupDirectory
+) -> None:
+    """So the next run retries it instead of losing the day silently."""
+    wrote(store, WATCHED_GROUP, "u1", "Alice", 1, day=YESTERDAY)
+    mark_reported(store, WATCHED_GROUP, "2026-08-31")
+    transport = RefusingTransport(refuses=WATCHED_GROUP)
+
+    await _bot(config, store, transport, directory).publish_report()
+
+    assert store.meta(WATCHED_GROUP, LAST_REPORTED_KEY) == "2026-08-31"
+
+
+async def test_publishing_twice_posts_once(
+    config: Config, store: Store, transport: FakeTransport, directory: GroupDirectory
+) -> None:
+    """The marker is what stops a restart re-posting the same day."""
+    wrote(store, WATCHED_GROUP, "u1", "Alice", 3)
+    bot = _bot(config, store, transport, directory)
+    await bot.publish_report()
+    await bot.publish_report()
+    assert len(transport.texts) == 1
+
+
 async def test_nothing_is_deleted_after_publishing(
     config: Config, store: Store, transport: FakeTransport, directory: GroupDirectory
 ) -> None:
@@ -105,8 +160,10 @@ async def test_nothing_is_deleted_after_publishing(
     wrote(store, WATCHED_GROUP, "u1", "Alice", 3)
     bot = _bot(config, store, transport, directory)
     await bot.publish_report()
+    first = transport.texts[0]
+    store.set_meta(WATCHED_GROUP, LAST_REPORTED_KEY, "2026-08-31")
     await bot.publish_report()
-    assert transport.texts[0] == transport.texts[1]
+    assert transport.texts[1] == first
 
 
 async def test_publish_report_falls_back_to_uuid_when_unnamed(

tests/test_stats_backfill.py

@@ -0,0 +1,114 @@
+# Copyright (c) 2026 Krzysztof Rudnicki. MIT licence.
+"""Carrying the pre-0.1.0 counter into the event log."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from signal_bot.stats.backfill import (
+    BACKFILL_HOUR,
+    backfilled_day,
+    has_legacy_counter,
+    seed_from_counter,
+)
+from signal_bot.stats.queries_day import day_rows, day_totals
+
+if TYPE_CHECKING:
+    from signal_bot.store import Store
+
+GROUP = "group-a=="
+OTHER = "group-b=="
+DAY = "2026-08-30"
+
+LEGACY = """
+CREATE TABLE message_counts (
+    group_id     TEXT NOT NULL,
+    uuid         TEXT NOT NULL,
+    display_name TEXT NOT NULL,
+    count        INTEGER NOT NULL DEFAULT 0,
+    PRIMARY KEY (group_id, uuid)
+);
+"""
+
+
+def give_legacy_counter(store: Store, rows: list[tuple[str, str, str, int]]) -> None:
+    """Recreate the pre-0.1.0 table and fill it, as a real old database has."""
+    store.events.connection.executescript(LEGACY)
+    store.events.connection.executemany(
+        "INSERT INTO message_counts (group_id, uuid, display_name, count) VALUES (?, ?, ?, ?)",
+        rows,
+    )
+    store.events.connection.commit()
+
+
+def test_a_fresh_database_has_no_legacy_counter(store: Store) -> None:
+    """0.1.0 stopped declaring the table, so a new file never has one."""
+    assert has_legacy_counter(store) is False
+
+
+def test_an_old_database_is_detected(store: Store) -> None:
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 3)])
+    assert has_legacy_counter(store) is True
+
+
+def test_counts_become_events_on_the_named_day(store: Store) -> None:
+    give_legacy_counter(
+        store,
+        [(GROUP, "u1", "Mithra", 3), (GROUP, "u2", "kuhy", 2), (OTHER, "u1", "Mithra", 1)],
+    )
+    seeded = seed_from_counter(store, DAY)
+
+    assert seeded == {GROUP: 5, OTHER: 1}
+    rows = day_rows(store.events, GROUP, DAY)
+    assert [(r.display_name, r.messages) for r in rows] == [("Mithra", 3), ("kuhy", 2)]
+    assert day_totals(rows).messages == 5
+
+
+def test_the_seeded_day_is_marked_per_group(store: Store) -> None:
+    """Marked, so records and hour statistics can leave it out."""
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 1), (OTHER, "u2", "kuhy", 1)])
+    seed_from_counter(store, DAY)
+    assert backfilled_day(store, GROUP) == DAY
+    assert backfilled_day(store, OTHER) == DAY
+
+
+def test_an_unseeded_group_is_not_marked(store: Store) -> None:
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 1)])
+    seed_from_counter(store, DAY)
+    assert backfilled_day(store, OTHER) is None
+
+
+def test_zero_counts_are_skipped(store: Store) -> None:
+    """A row at zero is somebody who was reset, not somebody who spoke."""
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 0)])
+    assert seed_from_counter(store, DAY) == {}
+    assert day_rows(store.events, GROUP, DAY) == []
+    assert backfilled_day(store, GROUP) is None
+
+
+def test_seeded_people_are_known_to_the_roster(store: Store) -> None:
+    """Otherwise they would show as unnamed strangers in the first report."""
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 2)])
+    seed_from_counter(store, DAY)
+    assert [p.display_name for p in store.events.roster(GROUP, ["u1"])] == ["Mithra"]
+
+
+def test_seeded_events_carry_no_invented_detail(store: Store) -> None:
+    """No hours, no lengths, no media -- the counter knew none of them."""
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 2)])
+    seed_from_counter(store, DAY)
+    rows = store.events.connection.execute(
+        "SELECT local_hour, char_len, media_count, is_command FROM message_events"
+    ).fetchall()
+    assert len(rows) == 2
+    for row in rows:
+        assert row["local_hour"] == BACKFILL_HOUR
+        assert (row["char_len"], row["media_count"], row["is_command"]) == (0, 0, 0)
+
+
+def test_seeding_twice_does_not_double_the_totals(store: Store) -> None:
+    """The synthetic keys are deterministic, so a rerun is absorbed."""
+    give_legacy_counter(store, [(GROUP, "u1", "Mithra", 3)])
+    seed_from_counter(store, DAY)
+    seed_from_counter(store, DAY)
+    assert day_totals(day_rows(store.events, GROUP, DAY)).messages == 3

tests/test_stats_nightly.py

@@ -0,0 +1,75 @@
+# Copyright (c) 2026 Krzysztof Rudnicki. MIT licence.
+"""Catching up on reports the bot was offline for."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from signal_bot.stats.nightly import (
+    CATCHUP_LIMIT,
+    LAST_REPORTED_KEY,
+    days_to_report,
+    mark_reported,
+)
+
+if TYPE_CHECKING:
+    from signal_bot.store import Store
+
+GROUP = "group-a=="
+
+
+def test_a_group_with_no_marker_gets_only_yesterday(store: Store) -> None:
+    """A new group, and the first run after this release, must not backlog."""
+    assert days_to_report(store, GROUP, "2026-09-01") == ["2026-09-01"]
+
+
+def test_an_up_to_date_group_owes_nothing(store: Store) -> None:
+    mark_reported(store, GROUP, "2026-09-01")
+    assert days_to_report(store, GROUP, "2026-09-01") == []
+
+
+def test_the_day_after_the_marker_is_owed(store: Store) -> None:
+    mark_reported(store, GROUP, "2026-08-31")
+    assert days_to_report(store, GROUP, "2026-09-01") == ["2026-09-01"]
+
+
+def test_an_outage_is_caught_up_oldest_first(store: Store) -> None:
+    """Four days offline: all four get posted, in the order they happened."""
+    mark_reported(store, GROUP, "2026-08-28")
+    assert days_to_report(store, GROUP, "2026-09-01") == [
+        "2026-08-29",
+        "2026-08-30",
+        "2026-08-31",
+        "2026-09-01",
+    ]
+
+
+def test_catch_up_is_bounded(store: Store) -> None:
+    """A month offline must not open with a month of back-posts."""
+    mark_reported(store, GROUP, "2026-07-01")
+    days = days_to_report(store, GROUP, "2026-09-01")
+    assert len(days) == CATCHUP_LIMIT
+    # The most recent ones, not the oldest.
+    assert days[-1] == "2026-09-01"
+    assert days[0] == "2026-08-26"
+
+
+def test_a_marker_ahead_of_yesterday_owes_nothing(store: Store) -> None:
+    """Defends the clock going backwards, e.g. an NTP correction."""
+    mark_reported(store, GROUP, "2026-09-05")
+    assert days_to_report(store, GROUP, "2026-09-01") == []
+
+
+def test_the_marker_is_per_group(store: Store) -> None:
+    mark_reported(store, GROUP, "2026-09-01")
+    assert store.meta(GROUP, LAST_REPORTED_KEY) == "2026-09-01"
+    assert store.meta("group-b==", LAST_REPORTED_KEY) is None
+
+
+def test_a_month_boundary_is_crossed_by_the_date(store: Store) -> None:
+    mark_reported(store, GROUP, "2026-08-30")
+    assert days_to_report(store, GROUP, "2026-09-02") == [
+        "2026-08-31",
+        "2026-09-01",
+        "2026-09-02",
+    ]

tests/test_stats_render_day.py

@@ -4,7 +4,7 @@
 from __future__ import annotations
 
 from signal_bot.stats.queries_day import DayRow, day_totals, with_silent
-from signal_bot.stats.render_day import MAX_LINES, render_day, summary_line
+from signal_bot.stats.render_day import MAX_LINES, DayView, render_day, summary_line
 
 # The real group, so the rendered example is a case that can actually occur.
 GROUP = [
@@ -39,8 +39,7 @@ def test_the_nightly_block_for_a_real_day() -> None:
         "2026-09-01",
         day_rows_,
         day_totals(day_rows_),
-        since="2026-08-30",
-        highlights=["🏆 Mithra 76 — rekord życiowy (poprzedni 71)"],
+        DayView(since="2026-08-30", highlights=("🏆 Mithra 76 — rekord życiowy (poprzedni 71)",)),
     )
     assert rendered == (
         "📊 Wtorek, 1 września — 220 wiadomości (16 📷)\n"
@@ -70,6 +69,14 @@ def test_commands_are_broken_out() -> None:
     assert summary_line(day_totals(day)) == "Z tego 4 komendy, średnio 47 znaków."
 
 
+def test_an_approximate_day_claims_no_average_length() -> None:
+    """The backfilled day has counts but no lengths; 0 would be a lie."""
+    day = rows([("kuhy", 10, 0)])
+    assert summary_line(day_totals(day), approximate=True) == ""
+    with_commands = rows([("kuhy", 10, 0)], commands=4)
+    assert summary_line(day_totals(with_commands), approximate=True) == "Z tego 4 komendy."
+
+
 def test_summary_is_empty_on_a_day_nobody_spoke() -> None:
     assert summary_line(day_totals([])) == ""
     assert day_totals([]).average_length == 0
@@ -78,7 +85,7 @@ def test_summary_is_empty_on_a_day_nobody_spoke() -> None:
 def test_unnamed_members_are_counted_never_named() -> None:
     """Their only spellings are a uuid or a phone number; both would leak."""
     day = with_silent(rows([("kuhy", 3, 0)]), [("u9", "Marek")])
-    rendered = render_day("2026-09-01", day, day_totals(day), unnamed=2)
+    rendered = render_day("2026-09-01", day, day_totals(day), DayView(unnamed=2))
     assert "Cisza: Marek, i 2 osoby bez ani jednej wiadomości tutaj" in rendered
 
 
@@ -89,8 +96,7 @@ def test_a_big_group_is_truncated_and_still_fits() -> None:
         "2026-09-01",
         big,
         day_totals(big),
-        since="2026-08-30",
-        highlights=["🏆 rekord", "👑 korona", "📅 wtorki"],
+        DayView(since="2026-08-30", highlights=("🏆 rekord", "👑 korona", "📅 wtorki")),
     )
     lines = rendered.split("\n")
     assert len(lines) <= MAX_LINES
@@ -105,13 +111,12 @@ def test_the_hidden_tail_reports_its_own_total() -> None:
         "2026-09-01",
         day,
         day_totals(day),
-        since="2026-08-30",
-        highlights=["h1", "h2", "h3"],
+        DayView(since="2026-08-30", highlights=("h1", "h2", "h3")),
     )
     assert len(rendered.split("\n")) <= MAX_LINES
 
 
 def test_a_custom_heading_replaces_the_date() -> None:
     day = rows([("kuhy", 1, 0)])
-    rendered = render_day("2026-09-01", day, day_totals(day), heading="Dziś, na razie")
+    rendered = render_day("2026-09-01", day, day_totals(day), DayView(heading="Dziś, na razie"))
     assert rendered.startswith("Dziś, na razie\n")