German date display + optional street address for precise geocoding

- Date pickers (entry form + edit dialog) now display TT.MM.JJJJ instead of
  ISO (DATE_DISPLAY_FORMAT). Storage stays YYYY-MM-DD; parse_date() already
  accepted both formats, so existing data and the self-updater are unaffected.
- New optional "Straße" field (street + house number) in the entry form and
  edit dialog, backed by a new `street` CSV column. geocode_city() and
  GeocoderWorker.enqueue() gained a street parameter: when set, a full-address
  query is tried first for a much more precise map point, falling back
  automatically to the existing city/PLZ search if it doesn't resolve.
- Tab 2 and the entry queue show a Straße column; Tab 2 search now also
  matches on street.
- Fix: pandas turns a blank CSV cell into NaN even for a dtype=str column, so
  every existing (blank-street) row would have shown literal "nan" in Tab 2.
  DataStore._load now does street.fillna("") after every read.

Verified with a non-GUI test suite (date parsing, query construction, CSV
round-trip incl. the NaN case) and a full GUI build/drive test on Python
3.12/Tk 9. Docs updated (changelog, overview, architecture, data-model,
dev-notes, improvements).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/architecture.md

@@ -7,8 +7,8 @@ Everything lives in [`app.py`](../app.py). There is no package structure.
 | Class / function | Responsibility |
 |------------------|----------------|
 | `DataStore` | Owns `orte.csv`. Loads it into a pandas `DataFrame`, exposes read helpers (`get_map_data`, `get_autocomplete_strings`, `total_count`, `find_duplicates`) and write helpers (`append_rows`, `update_row`, `delete_rows`). All writes go through `_save_csv` → rotating backup + atomic write. All columns are read as strings. Falls back to an empty frame (or the newest backup) if `orte.csv` is missing/empty/corrupt. |
-| `geocode_city()` | Pure function: `(city, plz) -> (lat, lon) | None`. Tries several Nominatim queries with a configurable regional bias (`GEOCODE_REGIONS`). Raises `GeocodingUnavailable` if *every* query failed on a service/network error (vs. simply not finding the place). |
-| `GeocoderWorker` | A `threading.Thread` (daemon). Holds a FIFO list of `(row_id, city, plz, callback)` items guarded by a lock, woken by an `Event`. Processes one item per second, calls `geocode_city`, then invokes `callback` **from the worker thread**. Each item is wrapped in `try/except` so one failure never kills the thread; after `SERVICE_ERROR_THRESHOLD` consecutive service errors it fires the optional `on_service_error` callback. |
+| `geocode_city()` | Pure function: `(city, plz, street="") -> (lat, lon) | None`. Tries several Nominatim queries with a configurable regional bias (`GEOCODE_REGIONS`); if `street` is given, a full-address query is tried first and falls back to the city/PLZ-only queries on no match. Raises `GeocodingUnavailable` if *every* query failed on a service/network error (vs. simply not finding the place). |
+| `GeocoderWorker` | A `threading.Thread` (daemon). Holds a FIFO list of `(row_id, city, plz, street, callback)` items guarded by a lock, woken by an `Event`. Processes one item per second, calls `geocode_city`, then invokes `callback` **from the worker thread**. Each item is wrapped in `try/except` so one failure never kills the thread; after `SERVICE_ERROR_THRESHOLD` consecutive service errors it fires the optional `on_service_error` callback. |
 | `parse_date()` / `parse_coord()` / helpers | Module-level pure functions for normalizing user input (date → ISO, coordinate strings → float, `"City (PLZ)"` splitting). Shared by the entry tab and `EditDialog`. |
 | `generate_map()` | Builds `karte.html` from `DataStore.get_map_data()` with Folium. |
 | `EditDialog` | `tk.Toplevel` modal dialog for editing one row. Returns its result via `self.result`. |
@@ -22,7 +22,7 @@ Everything lives in [`app.py`](../app.py). There is no package structure.
 user types -> _on_add_row()
   -> append dict to self._queue
   -> insert row into Tab-1 Treeview (coords = "⏳ wird gesucht…")
-  -> geocoder.enqueue(row_id, city, plz, self._geocode_done)
+  -> geocoder.enqueue(row_id, city, plz, street, self._geocode_done)
 
 GeocoderWorker thread (1/sec):
   coords = geocode_city(...)

docs/changelog.md

@@ -2,6 +2,28 @@
 
 Notable changes to the app. Newest first.
 
+## 2026-09-12 — German date display + optional street address for geocoding
+
+- **Date fields now display `TT.MM.JJJJ`** (e.g. `12.09.2026`) instead of ISO,
+  in both the entry form and the edit dialog (`DATE_DISPLAY_FORMAT`). Storage on
+  disk is unchanged (`YYYY-MM-DD`) — `parse_date()` still accepts either format
+  when typed, so nothing about existing data changes.
+- **New optional "Straße" field** (street + house number) on the entry form and
+  in the edit dialog, and a new `street` CSV column. When set, geocoding tries
+  the full address first for a much more precise map point, falling back to the
+  existing city/PLZ search if the address doesn't resolve — see
+  [overview.md](overview.md#geocoding-behaviour). `geocode_city()` and
+  `GeocoderWorker.enqueue()` both gained a `street` parameter.
+- Tab 2 and the entry queue both show a **Straße** column; the Tab 2 search box
+  now also matches on street.
+- Fixed a bug this surfaced immediately: pandas turns a **blank CSV cell into
+  `NaN`, even for a column forced to `dtype=str`** — every pre-existing row (all
+  blank on `street`) would have displayed the literal text `nan`. `DataStore._load`
+  now does `self.df["street"] = self.df["street"].fillna("")`. See
+  [dev-notes.md](dev-notes.md#pandas-turns-blank-csv-cells-into-nan-even-with-dtypestr).
+- `find_duplicates` intentionally still ignores `street` (unchanged: date + city
+  + PLZ only).
+
 ## 2026-09-07 — fix: right-click context menu instantly triggered its first item
 
 On Linux the Tab 2 (and queue) right-click menu flashed and immediately ran

docs/data-model.md

@@ -7,14 +7,19 @@ just the header if it does not exist.
 
 | Column | Type on disk | Meaning | Notes |
 |--------|--------------|---------|-------|
-| `date` | string | Assignment date | Always stored as `YYYY-MM-DD`. Input is validated and normalized by `parse_date()` (accepts `YYYY-MM-DD`, `DD.MM.YYYY`, `DD.MM.YY`, `YYYY/MM/DD`); invalid input is rejected before saving. Rows written before this change may still hold non-ISO strings. |
+| `date` | string | Assignment date | Always **stored as `YYYY-MM-DD`**, regardless of display. Input is validated and normalized by `parse_date()` (accepts `YYYY-MM-DD`, `DD.MM.YYYY`, `DD.MM.YY`, `YYYY/MM/DD`); invalid input is rejected before saving. The date pickers *display* `TT.MM.JJJJ` (`DATE_DISPLAY_FORMAT`) since the 2026-09-12 change, but that's cosmetic — parsing/storage is unchanged, so old and new rows are identical on disk. |
 | `city` | string | Place name | Free text. Used for autocomplete and duplicate detection (trimmed, case-insensitive). |
 | `postal_code` | string | German PLZ | Optional. Kept as a string so leading zeros survive. Regex elsewhere accepts 4–5 digits. |
+| `street` | string | Street + house number | Optional (e.g. `"Hauptstraße 12"`). Added 2026-09-12 for more precise geocoding — see [overview.md](overview.md#geocoding-behaviour). Rows written before that date have it blank. |
 | `lat` | string | Latitude | Blank until geocoded. Rounded to 5 dp. Parsed with `pd.to_numeric(errors="coerce")` when building the map. |
 | `lon` | string | Longitude | As above. |
 
 Every column is read as a string (`dtype={"postal_code": str, "lat": str, "lon": str}`
-plus `city`/`date` default object). Numeric conversion happens only where needed.
+plus `city`/`date` default object) — **except this doesn't stop a blank cell from
+coming back as `NaN`** (a float), even for a column forced to `dtype=str`. This
+bit `street` immediately (all pre-existing rows have it blank): `_load()` now
+does `self.df["street"] = self.df["street"].fillna("")` right after reading.
+See [dev-notes.md](dev-notes.md#pandas-turns-blank-csv-cells-into-nan-even-with-dtypestr).
 
 ### Row identity
 
@@ -33,7 +38,10 @@ that ends up wrong.
 
 `find_duplicates` flags a queued row when an existing row matches on all three
 of: `date` (string-equal), `city` (trimmed, lower-cased), `postal_code`
-(trimmed). It only produces a status-bar hint; duplicates are still written.
+(trimmed). `street` is **not** part of the match (unchanged by the 2026-09-12
+address feature) — two visits to the same city/PLZ on the same day are flagged
+as possible duplicates even with different streets. A modal now asks whether to
+save anyway (see [changelog.md](changelog.md)).
 
 ### Map aggregation
 

docs/dev-notes.md

@@ -57,6 +57,32 @@ Lesson: a tile source that works from `curl` or an `http://` page can still fail
 from `file://`. Test the map by **opening the generated `karte.html` directly**,
 not just by checking the URL in the HTML.
 
+## pandas turns blank CSV cells into NaN even with `dtype=str` (2026-09-12)
+
+Assumption that turned out wrong: forcing a column's dtype (e.g.
+`dtype={"street": str}`) does **not** stop `pd.read_csv` from parsing a truly
+empty field as `NaN` (a float) instead of `""`. Verified directly:
+
+```python
+>>> pd.read_csv(io.StringIO("a\n\n"), dtype={"a": str})["a"][0]
+nan          # not ''
+>>> str(pd.read_csv(io.StringIO("a\n\n"), dtype={"a": str})["a"][0])
+'nan'        # !!
+```
+
+This is *why* `lat`/`lon` already needed `_is_blank()` / `_coord_str()` helpers
+— but the new `street` column (added 2026-09-12) hit it immediately and much
+harder: it's optional, so *every* existing row has it blank, and without a fix
+every one of them would show the literal text `nan` in Tab 2. Fix: after
+`pd.read_csv` (all three load paths — normal, empty-file, backup-recovery),
+`DataStore._load` runs `self.df["street"] = self.df["street"].fillna("")`.
+
+Rule for this codebase: **any column that can legitimately be blank needs an
+explicit `.fillna("")` (or the `_is_blank`/`_coord_str` treatment) right after
+`pd.read_csv`** — `dtype=str` alone is not enough. `city`/`postal_code` haven't
+needed this only because they're rarely actually blank in practice, not because
+they're immune.
+
 ## Tk popup menus: bind `<ButtonRelease-3>`, not `<Button-3>` (2026-09-07)
 
 `widget.bind("<Button-3>", …)` + `menu.tk_popup(x, y)` + `finally:

docs/improvements.md

@@ -215,6 +215,20 @@ Open follow-ups: no rollback if a pushed update is broken (mitigated by
 `--ff-only` from a branch Patrick controls + pip errors caught pre-restart);
 `run.sh` / `.desktop` still not committed (item 5).
 
+## German date + street address (2026-09-12) — ✅ done, one idea deferred
+
+Date pickers display `TT.MM.JJJJ`; storage untouched. New optional `street`
+CSV column feeds a full-address geocode attempt before falling back to
+city/PLZ. See [changelog.md](changelog.md).
+
+**Deferred idea, not requested:** since the same person is often logged at the
+same city repeatedly, the address autocomplete could remember and suggest the
+last-used street for a selected city (the way selecting a city already
+auto-fills its PLZ). Would remove re-typing the same street each time, at the
+cost of a bit more state to reason about. Worth doing if re-typing the address
+turns out to be annoying in practice — not implemented now to keep the change
+minimal.
+
 ## Suggested order of remaining work
 
 1. Deploy to the laptop: `git clone` + `./install.sh` (see [setup.md](setup.md)).

docs/overview.md

@@ -16,14 +16,16 @@ Workflow: build up a **queue** of entries, let them geocode in the background,
 then save the whole batch at once.
 
 1. **Entry form** – date (a **calendar picker**, `ttkbootstrap.DateEntry`,
-   pre-filled with today; typed input is accepted in `JJJJ-MM-TT` or
-   `TT.MM.JJJJ` and **validated** – an invalid date is rejected with a dialog),
-   city (autocomplete combobox), postal code (optional). Pressing `Return` in any
-   field, or the **+ Hinzufügen** button, adds the row to the queue.
-   The PLZ field only accepts digits.
-2. **Queue table** – shows date, city, PLZ, and a live coordinate column that
-   updates from `⏳ wird gesucht…` to either `lat / lon` or `⚠ nicht gefunden`
-   as the background geocoder works through the queue.
+   pre-filled with today and **displayed as `TT.MM.JJJJ`**, e.g. `12.09.2026`;
+   typed input also accepts `JJJJ-MM-TT` and is **validated** – an invalid date
+   is rejected with a dialog), city (autocomplete combobox), postal code
+   (optional, digits only), and **Straße** (street + house number, optional,
+   second row of the form) — see [Geocoding behaviour](#geocoding-behaviour) for
+   why it's worth filling in. Pressing `Return` in any field, or the
+   **+ Hinzufügen** button, adds the row to the queue.
+2. **Queue table** – shows date, city, PLZ, street, and a live coordinate column
+   that updates from `⏳ wird gesucht…` to either `lat / lon` or
+   `⚠ nicht gefunden` as the background geocoder works through the queue.
    - Select a row and press <kbd>Delete</kbd>, use the **"Auswahl entfernen"**
      button, or click the `✕` cell.
    - Right-click a row for *Entfernen* / *Koordinaten erneut suchen*.
@@ -38,10 +40,12 @@ then save the whole batch at once.
 
 A table view of everything in `orte.csv`.
 
-- **Columns:** Datum, Ort, PLZ, and **Karte** – a status column showing `✓` when
-  the row has coordinates or a red `fehlt` when it doesn't (the whole row is red
-  too). The raw lat/lon numbers live in the edit dialog, not this table.
-- **Search box** – live filter across date, city, and PLZ (substring match).
+- **Columns:** Datum, Ort, PLZ, Straße, and **Karte** – a status column showing
+  `✓` when the row has coordinates or a red `fehlt` when it doesn't (the whole
+  row is red too). The raw lat/lon numbers live in the edit dialog, not this
+  table.
+- **Search box** – live filter across date, city, PLZ, **and street**
+  (substring match).
 - **Sortable columns** – click a header to sort; clicking again reverses. The
   active column shows a ▲/▼ arrow. Default sort is by date, newest first.
   Sorting by **Karte** groups the rows without coordinates together.
@@ -49,10 +53,11 @@ A table view of everything in `orte.csv`.
   coordinates yet. The hint line always shows the total count, plus how many are
   missing coordinates.
 - **Edit** – double-click a row (or *Bearbeiten*) opens a modal dialog to change
-  date (calendar picker, validated) / city / PLZ. Two ways to fix coordinates:
-  a "Koordinaten automatisch neu suchen" toggle re-runs geocoding after saving,
-  or the **Breitengrad / Längengrad** fields let you type them in by hand
-  (both empty = no map marker).
+  date (calendar picker, `TT.MM.JJJJ`, validated) / city / PLZ / **Straße**. Two
+  ways to fix coordinates: a "Koordinaten automatisch neu suchen" toggle re-runs
+  geocoding after saving (now using the street if one is set), or the
+  **Breitengrad / Längengrad** fields let you type them in by hand (both empty =
+  no map marker).
 - **Right-click → Koordinaten suchen** – runs geocoding for that one row
   (handy for rows that failed the first time).
 - **Delete** – *Löschen* removes the selected row(s) after a confirmation
@@ -87,13 +92,22 @@ Generated by `generate_map()`:
 
 ## Geocoding behaviour
 
-`geocode_city(city, postal_code)` tries a series of queries in order and returns
-the first hit:
+`geocode_city(city, postal_code, street="")` tries a series of queries in order
+and returns the **first hit**:
 
-1. `"<PLZ> <city>, Germany"` (only if a PLZ was given)
-2. `"<city>, Baden-Württemberg, Germany"`
-3. `"<city>, Hessen, Germany"`
-4. `"<city>, Germany"`
+1. `"<street>, <PLZ> <city>, Germany"` — only if a **street** was given (with
+   PLZ if there is one, without it if not). This is what the optional Straße
+   field is for: a full address geocodes far more precisely than a city name
+   alone (a point in the right town vs. the right building).
+2. `"<PLZ> <city>, Germany"` (only if a PLZ was given)
+3. `"<city>, Baden-Württemberg, Germany"`
+4. `"<city>, Hessen, Germany"`
+5. `"<city>, Germany"`
+
+If the street-level query (1) doesn't match anything in Nominatim (typo, house
+number Nominatim doesn't know, etc.), it **falls back automatically** to the
+same city/PLZ-level searches used when no street is given — a bad street never
+makes geocoding *worse* than before, only better when it resolves.
 
 The regional bias is the `GEOCODE_REGIONS` constant (`Baden-Württemberg`,
 `Hessen`) near the top of `app.py`. Results are rounded to five decimal places.