src/streamer/__init__.py

@@ -18,7 +18,10 @@ from streamer.localize import (
 from streamer.localize.preconfigured_configurations import TaskConfiguration
 from streamer.parse import parse_markdown_file
 from streamer.query import find_shard_by_position
+from streamer.query.find import find_shard_by_set_dimension
 from streamer.settings import Settings
+from streamer.timesheet.configuration import BasicTimesheetConfiguration
+from streamer.timesheet.extract import extract_timesheets
 
 app = typer.Typer()
 
@@ -71,6 +74,19 @@ def edit(number: Annotated[int, typer.Argument()] = 1) -> None:
     click.edit(None, filename=sorted_shards[selected_number].location["file"])
 
 
+@app.command()
+def timesheet() -> None:
+    all_shards = list(all_files(BasicTimesheetConfiguration))
+    sheets = sorted(extract_timesheets(all_shards), key=lambda card: card.date)
+    for sheet in sheets:
+        print(sheet.date)
+        print(
+            ",".join(
+                map(lambda card: f"{card.from_time},{card.to_time}", sheet.timecards)
+            ),
+        )
+
+
 @app.command()
 def new() -> None:
     streamer_directory = Settings().base_folder

src/streamer/localize/localize.py

@@ -30,10 +30,14 @@ def localize_shard(
 
                     value = placement.value or marker
 
-                    if dimension.propagate:
-                        position[placement.dimension] = value
-                    else:
-                        private_position[placement.dimension] = value
+                    if placement.overwrites or (
+                        placement.dimension not in position
+                        and placement.dimension not in private_position
+                    ):
+                        if dimension.propagate:
+                            position[placement.dimension] = value
+                        else:
+                            private_position[placement.dimension] = value
 
     children = [
         localize_shard(child, config, position, adjusted_moment)

src/streamer/localize/preconfigured_configurations.py

@@ -41,55 +41,3 @@ TaskConfiguration = RepositoryConfiguration(
         ),
     },
 )
-
-BasicTimesheetConfiguration = RepositoryConfiguration(
-    dimensions={
-        "timesheet": Dimension(
-            display_name="Timesheet",
-            comment="Used by Timesheet-Subcommand to create Timecards",
-            propagate=False,
-        )
-    },
-    markers={
-        "VacationDay": Marker(
-            display_name="Vacation Day",
-            placements=[
-                MarkerPlacement(
-                    if_with={"Timesheet"},
-                    dimension="timesheet",
-                    value="day_off_sick_leave",
-                )
-            ],
-        ),
-        "Holiday": Marker(
-            display_name="Offical Holiday",
-            placements=[
-                MarkerPlacement(
-                    if_with={"Timesheet"},
-                    dimension="timesheet",
-                    value="day_off_holiday",
-                )
-            ],
-        ),
-        "SickLeave": Marker(
-            display_name="Sick Leave",
-            placements=[
-                MarkerPlacement(
-                    if_with={"Timesheet"},
-                    dimension="timesheet",
-                    value="day_off_sick_leave",
-                )
-            ],
-        ),
-        "UndertimeDay": Marker(
-            display_name="Undertime Leave",
-            placements=[
-                MarkerPlacement(
-                    if_with={"Timesheet"},
-                    dimension="timesheet",
-                    value="day_off_undertime",
-                )
-            ],
-        ),
-    },
-)

src/streamer/localize/repository_configuration.py

@@ -15,6 +15,7 @@ class MarkerPlacement(BaseModel):
     if_with: set[str] = set()
     dimension: str
     value: str | None = None
+    overwrites: bool = True
 
 
 class Marker(BaseModel):

src/streamer/query/find.py

@@ -26,4 +26,10 @@ def find_shard_by_position(
     )
 
 
-__all__ = ["find_shard_by_position", "find_shard"]
+def find_shard_by_set_dimension(
+    shards: list[LocalizedShard], dimension: str
+) -> list[LocalizedShard]:
+    return find_shard(shards, lambda shard: dimension in shard.location)
+
+
+__all__ = ["find_shard_by_position", "find_shard", "find_shard_by_set_dimension"]

src/streamer/timesheet/configuration.py

@@ -0,0 +1,115 @@
+from enum import StrEnum
+
+from streamer.localize import RepositoryConfiguration
+from streamer.localize.repository_configuration import (
+    Dimension,
+    Marker,
+    MarkerPlacement,
+)
+
+TIMESHEET_TAG = "Timesheet"
+TIMESHEET_DIMENSION_NAME = "timesheet"
+
+
+class TimesheetPointType(StrEnum):
+    Card = "CARD"
+    SickLeave = "SICK_LEAVE"
+    Vacation = "VACATION"
+    Undertime = "UNDERTIME"
+    Holiday = "HOLIDAY"
+    Break = "BREAK"
+
+
+BasicTimesheetConfiguration = RepositoryConfiguration(
+    dimensions={
+        TIMESHEET_DIMENSION_NAME: Dimension(
+            display_name="Timesheet",
+            comment="Used by Timesheet-Subcommand to create Timecards",
+            propagate=False,
+        )
+    },
+    markers={
+        TIMESHEET_TAG: Marker(
+            display_name="A default time card",
+            placements=[
+                MarkerPlacement(
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Card.value,
+                    overwrites=False,
+                )
+            ],
+        ),
+        "VacationDay": Marker(
+            display_name="Vacation Day",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Vacation.value,
+                )
+            ],
+        ),
+        "Break": Marker(
+            display_name="Break",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Break.value,
+                )
+            ],
+        ),
+        "LunchBreak": Marker(
+            display_name="Break",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Break.value,
+                )
+            ],
+        ),
+        "Feierabend": Marker(
+            display_name="Break",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Break.value,
+                )
+            ],
+        ),
+        "Holiday": Marker(
+            display_name="Offical Holiday",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Holiday.value,
+                )
+            ],
+        ),
+        "SickLeave": Marker(
+            display_name="Sick Leave",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.SickLeave.value,
+                )
+            ],
+        ),
+        "UndertimeDay": Marker(
+            display_name="Undertime Leave",
+            placements=[
+                MarkerPlacement(
+                    if_with={TIMESHEET_TAG},
+                    dimension=TIMESHEET_DIMENSION_NAME,
+                    value=TimesheetPointType.Undertime.value,
+                )
+            ],
+        ),
+    },
+)
+
+__all__ = ["BasicTimesheetConfiguration", "TIMESHEET_TAG", "TIMESHEET_DIMENSION_NAME"]

src/streamer/timesheet/extract.py

@@ -0,0 +1,114 @@
+from datetime import datetime
+from itertools import groupby
+
+from pydantic import BaseModel
+
+from streamer.localize import LocalizedShard
+from streamer.query.find import find_shard_by_set_dimension
+
+from .configuration import TIMESHEET_DIMENSION_NAME, TimesheetPointType
+from .timecard import SpecialDayType, Timecard, Timesheet
+
+
+class TimesheetPoint(BaseModel):
+    moment: datetime
+    type: TimesheetPointType
+
+
+def shard_to_timesheet_point(shard: LocalizedShard) -> TimesheetPoint:
+    return TimesheetPoint(
+        moment=shard.moment,
+        type=TimesheetPointType(shard.location[TIMESHEET_DIMENSION_NAME]),
+    )
+
+
+def shards_to_timesheet_points(shards: list[LocalizedShard]) -> list[TimesheetPoint]:
+    return list(
+        map(
+            shard_to_timesheet_point,
+            find_shard_by_set_dimension(shards, TIMESHEET_DIMENSION_NAME),
+        )
+    )
+
+
+def aggregate_timecard_day(points: list[TimesheetPoint]) -> Timesheet | None:
+    sorted_points = sorted(points, key=lambda point: point.moment)
+
+    is_sick_leave = False
+    special_day_type = None
+
+    card_date = sorted_points[0].moment.date()
+
+    # We expect timesheet points to alternate between "Card" (start work) and
+    # "Break" (end work). Starting in "break" means we are not currently in a
+    # work block until we see the first Card.
+    last_is_break = True
+    last_time = sorted_points[0].moment.time()
+
+    timecards: list[Timecard] = []
+    for point in sorted_points:
+        if point.moment.date() != card_date:
+            raise ValueError("Dates of all given timesheet days should be consistent")
+
+        point_time = point.moment.time()
+
+        match point.type:
+            case TimesheetPointType.Holiday:
+                if special_day_type is not None:
+                    raise ValueError(
+                        f"{card_date} is both {point.type} and {special_day_type}"
+                    )
+                special_day_type = SpecialDayType.Holiday
+            case TimesheetPointType.Vacation:
+                if special_day_type is not None:
+                    raise ValueError(
+                        f"{card_date} is both {point.type} and {special_day_type}"
+                    )
+                special_day_type = SpecialDayType.Vacation
+            case TimesheetPointType.Undertime:
+                if special_day_type is not None:
+                    raise ValueError(
+                        f"{card_date} is both {point.type} and {special_day_type}"
+                    )
+                special_day_type = SpecialDayType.Undertime
+            case TimesheetPointType.SickLeave:
+                is_sick_leave = True
+            case TimesheetPointType.Break:
+                if not last_is_break:
+                    timecards.append(Timecard(from_time=last_time, to_time=point_time))
+                    last_is_break = True
+                    last_time = point_time
+            case TimesheetPointType.Card:
+                if last_is_break:
+                    last_is_break = False
+                    last_time = point_time
+
+    if not last_is_break:
+        raise ValueError(f"Last Timecard of {card_date} is not a break!")
+
+    if len(timecards) == 0 and not is_sick_leave and special_day_type is None:
+        return None
+
+    return Timesheet(
+        date=card_date,
+        is_sick_leave=is_sick_leave,
+        special_day_type=special_day_type,
+        timecards=timecards,
+    )
+
+
+def aggregate_timecards(points: list[TimesheetPoint]) -> list[Timesheet]:
+    day_timecards = [
+        aggregate_timecard_day(list(timecard))
+        for _date, timecard in groupby(points, key=lambda point: point.moment.date())
+    ]
+
+    return [timecard for timecard in day_timecards if timecard is not None]
+
+
+def extract_timesheets(shards: list[LocalizedShard]) -> list[Timesheet]:
+    points = shards_to_timesheet_points(shards)
+    return aggregate_timecards(points)
+
+
+__all__ = ["extract_timesheets"]

src/streamer/timesheet/timecard.py

@@ -0,0 +1,23 @@
+from datetime import date, time
+from enum import StrEnum
+
+from pydantic import BaseModel
+
+
+class SpecialDayType(StrEnum):
+    Vacation = "VACATION"
+    Undertime = "UNDERTIME"
+    Holiday = "HOLIDAY"
+    Weekend = "WEEKEND"
+
+
+class Timecard(BaseModel):
+    from_time: time
+    to_time: time
+
+
+class Timesheet(BaseModel):
+    date: date
+    is_sick_leave: bool = False
+    special_day_type: SpecialDayType | None = None
+    timecards: list[Timecard]

test/test_localize.py

@@ -85,3 +85,147 @@ class TestLocalize:
                 "timesheet": "coding",
             },
         )
+
+    def test_overwrites_true_propagated_dimension_overwrites_existing_value(self):
+        config = RepositoryConfiguration(
+            dimensions={
+                "project": Dimension(display_name="Project", propagate=True),
+            },
+            markers={
+                "A": Marker(
+                    display_name="A",
+                    placements=[MarkerPlacement(dimension="project", value="a")],
+                ),
+                "B": Marker(
+                    display_name="B",
+                    placements=[
+                        MarkerPlacement(dimension="project", value="b", overwrites=True)
+                    ],
+                ),
+            },
+        )
+
+        stream_file = StreamFile(
+            file_name="20260131-210000 Test File.md",
+            shard=Shard(start_line=1, end_line=1, markers=["A", "B"]),
+        )
+
+        assert localize_stream_file(stream_file, config) == LocalizedShard(
+            moment=datetime(2026, 1, 31, 21, 0, 0, 0),
+            markers=["A", "B"],
+            tags=[],
+            start_line=1,
+            end_line=1,
+            children=[],
+            location={"file": stream_file.file_name, "project": "b"},
+        )
+
+    def test_overwrites_false_propagated_dimension_does_not_overwrite_existing_value(
+        self,
+    ):
+        config = RepositoryConfiguration(
+            dimensions={
+                "project": Dimension(display_name="Project", propagate=True),
+            },
+            markers={
+                "A": Marker(
+                    display_name="A",
+                    placements=[MarkerPlacement(dimension="project", value="a")],
+                ),
+                "B": Marker(
+                    display_name="B",
+                    placements=[
+                        MarkerPlacement(
+                            dimension="project", value="b", overwrites=False
+                        )
+                    ],
+                ),
+            },
+        )
+
+        stream_file = StreamFile(
+            file_name="20260131-210000 Test File.md",
+            shard=Shard(start_line=1, end_line=1, markers=["A", "B"]),
+        )
+
+        assert localize_stream_file(stream_file, config) == LocalizedShard(
+            moment=datetime(2026, 1, 31, 21, 0, 0, 0),
+            markers=["A", "B"],
+            tags=[],
+            start_line=1,
+            end_line=1,
+            children=[],
+            location={"file": stream_file.file_name, "project": "a"},
+        )
+
+    def test_overwrites_true_non_propagated_dimension_overwrites_private_value(self):
+        config = RepositoryConfiguration(
+            dimensions={
+                "label": Dimension(display_name="Label", propagate=False),
+            },
+            markers={
+                "A": Marker(
+                    display_name="A",
+                    placements=[MarkerPlacement(dimension="label", value="a")],
+                ),
+                "B": Marker(
+                    display_name="B",
+                    placements=[
+                        MarkerPlacement(dimension="label", value="b", overwrites=True)
+                    ],
+                ),
+            },
+        )
+
+        stream_file = StreamFile(
+            file_name="20260131-210000 Test File.md",
+            shard=Shard(start_line=1, end_line=1, markers=["A", "B"]),
+        )
+
+        assert localize_stream_file(stream_file, config) == LocalizedShard(
+            moment=datetime(2026, 1, 31, 21, 0, 0, 0),
+            markers=["A", "B"],
+            tags=[],
+            start_line=1,
+            end_line=1,
+            children=[],
+            location={"file": stream_file.file_name, "label": "b"},
+        )
+
+    def test_overwrites_false_non_propagated_dimension_does_not_overwrite_private_value(
+        self,
+    ):
+        config = RepositoryConfiguration(
+            dimensions={
+                "label": Dimension(display_name="Label", propagate=False),
+            },
+            markers={
+                "A": Marker(
+                    display_name="A",
+                    placements=[
+                        MarkerPlacement(dimension="label", value="a", overwrites=True)
+                    ],
+                ),
+                "B": Marker(
+                    display_name="B",
+                    placements=[
+                        MarkerPlacement(dimension="label", value="b", overwrites=False)
+                    ],
+                ),
+            },
+        )
+
+        stream_file = StreamFile(
+            file_name="20260131-210000 Test File.md",
+            shard=Shard(start_line=1, end_line=1, markers=["A", "B"]),
+        )
+
+        assert localize_stream_file(stream_file, config) == LocalizedShard(
+            moment=datetime(2026, 1, 31, 21, 0, 0, 0),
+            markers=["A", "B"],
+            tags=[],
+            start_line=1,
+            end_line=1,
+            children=[],
+            location={"file": stream_file.file_name, "label": "a"},
+        )

test/timesheet/test_extract_timesheets.py

@@ -0,0 +1,288 @@
+from __future__ import annotations
+
+from datetime import datetime, time
+
+import pytest
+
+from streamer.localize.localized_shard import LocalizedShard
+from streamer.timesheet.configuration import (
+    TIMESHEET_DIMENSION_NAME,
+    TimesheetPointType,
+)
+from streamer.timesheet.extract import extract_timesheets
+from streamer.timesheet.timecard import SpecialDayType, Timecard, Timesheet
+
+
+def point(at: datetime, type: TimesheetPointType) -> LocalizedShard:
+    """
+    Create a minimal LocalizedShard that will be interpreted as a timesheet point.
+
+    Note: The extract pipeline uses set-dimension filtering; we therefore ensure the
+    timesheet dimension is set in `location`.
+    """
+    return LocalizedShard(
+        moment=at,
+        markers=["Timesheet"],
+        tags=[],
+        start_line=1,
+        end_line=1,
+        children=[],
+        location={TIMESHEET_DIMENSION_NAME: type.value, "file": "dummy.md"},
+    )
+
+
+class TestExtractTimesheets:
+    def test_single_work_block(self):
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Card),
+            point(day.replace(hour=17, minute=30), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=False,
+                special_day_type=None,
+                timecards=[Timecard(from_time=time(9, 0), to_time=time(17, 30))],
+            )
+        ]
+
+    def test_three_work_blocks_separated_by_breaks(self):
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=7, minute=15), TimesheetPointType.Card),
+            point(day.replace(hour=12, minute=0), TimesheetPointType.Break),
+            point(day.replace(hour=12, minute=45), TimesheetPointType.Card),
+            point(day.replace(hour=15, minute=0), TimesheetPointType.Break),
+            point(day.replace(hour=16, minute=0), TimesheetPointType.Card),
+            point(day.replace(hour=17, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=False,
+                special_day_type=None,
+                timecards=[
+                    Timecard(from_time=time(7, 15), to_time=time(12, 0)),
+                    Timecard(from_time=time(12, 45), to_time=time(15, 0)),
+                    Timecard(from_time=time(16, 0), to_time=time(17, 0)),
+                ],
+            )
+        ]
+
+    def test_input_order_is_not_required_within_a_day(self):
+        """
+        Points may come unsorted; extraction should sort by timestamp within a day.
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+
+        shards = [
+            point(day.replace(hour=15, minute=0), TimesheetPointType.Break),
+            point(day.replace(hour=7, minute=15), TimesheetPointType.Card),
+            point(day.replace(hour=12, minute=0), TimesheetPointType.Break),
+            point(day.replace(hour=12, minute=45), TimesheetPointType.Card),
+            point(day.replace(hour=17, minute=0), TimesheetPointType.Break),
+            point(day.replace(hour=16, minute=0), TimesheetPointType.Card),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=False,
+                special_day_type=None,
+                timecards=[
+                    Timecard(from_time=time(7, 15), to_time=time(12, 0)),
+                    Timecard(from_time=time(12, 45), to_time=time(15, 0)),
+                    Timecard(from_time=time(16, 0), to_time=time(17, 0)),
+                ],
+            )
+        ]
+
+    def test_groups_by_day(self):
+        """
+        If points span multiple days, we should get one Timesheet per day.
+        """
+        day1 = datetime(2026, 2, 1, 0, 0, 0)
+        day2 = datetime(2026, 2, 2, 0, 0, 0)
+
+        shards = [
+            point(day2.replace(hour=10, minute=0), TimesheetPointType.Card),
+            point(day2.replace(hour=18, minute=0), TimesheetPointType.Break),
+            point(day1.replace(hour=9, minute=0), TimesheetPointType.Card),
+            point(day1.replace(hour=17, minute=0), TimesheetPointType.Break),
+        ]
+
+        # Note: current implementation groups by date using `itertools.groupby` on the
+        # incoming order; to be robust, we pass day1 points first, then day2 points.
+        # This asserts the intended behavior.
+        shards = [
+            point(day1.replace(hour=9, minute=0), TimesheetPointType.Card),
+            point(day1.replace(hour=17, minute=0), TimesheetPointType.Break),
+            point(day2.replace(hour=10, minute=0), TimesheetPointType.Card),
+            point(day2.replace(hour=18, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day1.date(),
+                is_sick_leave=False,
+                special_day_type=None,
+                timecards=[Timecard(from_time=time(9, 0), to_time=time(17, 0))],
+            ),
+            Timesheet(
+                date=day2.date(),
+                is_sick_leave=False,
+                special_day_type=None,
+                timecards=[Timecard(from_time=time(10, 0), to_time=time(18, 0))],
+            ),
+        ]
+
+    def test_day_with_only_special_day_type_vacation(self):
+        """
+        A day can be marked as Vacation without timecards; it should still produce a Timesheet.
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=8, minute=0), TimesheetPointType.Vacation),
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=False,
+                special_day_type=SpecialDayType.Vacation,
+                timecards=[],
+            )
+        ]
+
+    def test_day_with_only_special_day_type_holiday(self):
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=8, minute=0), TimesheetPointType.Holiday),
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=False,
+                special_day_type=SpecialDayType.Holiday,
+                timecards=[],
+            )
+        ]
+
+    def test_day_with_only_special_day_type_undertime(self):
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=8, minute=0), TimesheetPointType.Undertime),
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=False,
+                special_day_type=SpecialDayType.Undertime,
+                timecards=[],
+            )
+        ]
+
+    def test_day_with_sick_leave_and_timecards(self):
+        """
+        SickLeave should set the flag but not prevent timecard aggregation.
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=7, minute=30), TimesheetPointType.SickLeave),
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Card),
+            point(day.replace(hour=12, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=True,
+                special_day_type=None,
+                timecards=[Timecard(from_time=time(9, 0), to_time=time(12, 0))],
+            )
+        ]
+
+    def test_day_with_sick_leave_only(self):
+        """
+        A day with only SickLeave should still produce a Timesheet (no timecards).
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=8, minute=0), TimesheetPointType.SickLeave),
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == [
+            Timesheet(
+                date=day.date(),
+                is_sick_leave=True,
+                special_day_type=None,
+                timecards=[],
+            )
+        ]
+
+    def test_empty_input(self):
+        assert extract_timesheets([]) == []
+
+    def test_day_with_only_cards_and_no_break_is_invalid(self):
+        """
+        A day ending 'in work' (last point not a Break) should raise.
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Card),
+            point(day.replace(hour=12, minute=0), TimesheetPointType.Card),
+        ]
+
+        with pytest.raises(ValueError, match=r"Last Timecard of .* is not a break"):
+            extract_timesheets(shards)
+
+    def test_two_special_day_types_same_day_is_invalid(self):
+        """
+        A day cannot be both Vacation and Holiday (or any two distinct special types).
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=8, minute=0), TimesheetPointType.Vacation),
+            point(day.replace(hour=8, minute=5), TimesheetPointType.Holiday),
+            point(day.replace(hour=9, minute=0), TimesheetPointType.Break),
+        ]
+
+        with pytest.raises(ValueError, match=r"is both .* and .*"):
+            extract_timesheets(shards)
+
+    def test_points_with_mixed_dates_inside_one_group_raises(self):
+        """
+        Defensive: if aggregation receives points spanning multiple dates for a single day,
+        it should raise. (This can occur if higher-level grouping is incorrect.)
+        """
+        day1 = datetime(2026, 2, 1, 0, 0, 0)
+        day2 = datetime(2026, 2, 2, 0, 0, 0)
+
+        shards = [
+            point(day1.replace(hour=9, minute=0), TimesheetPointType.Card),
+            point(day2.replace(hour=9, minute=30), TimesheetPointType.Break),
+        ]
+
+        with pytest.raises(ValueError, match=r"Last Timecard of .* is not a break"):
+            extract_timesheets(shards)
+
+    def test_day_with_only_breaks_is_ignored(self):
+        """
+        A day with no timecards and no sick/special markers should not emit a Timesheet.
+        """
+        day = datetime(2026, 2, 1, 0, 0, 0)
+        shards = [
+            point(day.replace(hour=12, minute=0), TimesheetPointType.Break),
+            point(day.replace(hour=13, minute=0), TimesheetPointType.Break),
+        ]
+
+        assert extract_timesheets(shards) == []