Add cross-platform user preferences and gear storage

.github/copilot-instructions.md

@@ -7,7 +7,7 @@ Install dependencies and run:
 uv run python main.py
 ```
 
-The app auto-creates `gear_data.json` with seeded example data on first run, so you can immediately see the full workflow. Use `uv` (recommended) for automatic environment management; fall back to `pip install -r requirements.txt` if needed.
+On first run the app asks for a storage folder, remembers it in the platform's standard application-config location, and creates `gear_data.json` there with seeded example data. Use `uv` (recommended) for automatic environment management; fall back to `pip install -r requirements.txt` if needed.
 
 ---
 
@@ -22,6 +22,11 @@ The app auto-creates `gear_data.json` with seeded example data on first run, so
   - Constants: `CATEGORIES`, `CATEGORY_EMOJI`, `BIG_THREE`, `WEIGHT_TYPES`, thresholds
   - Helper functions: `find_gear()`, `find_trip()`, `compute_trip_summary()`, `total_weight_oz()`, etc.
 
+- **`packrat_preferences.py`** — Cross-platform preference layer. Handles:
+  - OS-standard config and suggested data directories via `platformdirs`
+  - Atomic `preferences.json` reads/writes
+  - Startup precedence between `--data`, remembered storage, and onboarding
+
 - **`gear_tui.py`** — Textual UI layer. Handles:
   - Screens (gear inventory, trips tab, reports tab) and modal dialogs (forms, pickers, confirmations)
   - DataTable widgets, search filtering, keyboard + mouse bindings
@@ -87,6 +92,8 @@ The app auto-creates `gear_data.json` with seeded example data on first run, so
 ### Data Persistence
 - `load_data(path)` — reads JSON; auto-seeds with `example_data()` if file missing
 - `save_data(path, data)` — atomic writes via temp file (`path + ".tmp"`, then `os.replace()`)
+- The selected folder is remembered outside the repository; its library is always named `gear_data.json`
+- `--data` is an exact-file override for one launch and does not update preferences
 - **No locking** — avoid editing from multiple machines simultaneously or sync conflicts will create backup files
 
 ### Markdown Export
@@ -162,7 +169,7 @@ uv run python main.py
 ## Common Gotchas
 
 - **Modal dialogs cut off:** Terminal too small (need ≥130×42). Zoom or expand window.
-- **Data file not created:** Check write permissions in the working directory.
+- **Data file not created:** Check write permissions in the selected storage folder.
 - **Markdown export missing:** Files go to `exports/` subdirectory auto-created next to `gear_data.json`.
 - **Weight calculations wrong:** Verify `qty` is set (defaults to 1) and `weight_type` matches the calculation logic (base/worn/consumable are summed separately).
 - **Stale UI after edit:** Modal dismisses and returns updated dict; catch with `@on(SomeScreen.ScreenType.Submitted)` or similar pattern.

.github/workflows/tests.yml

@@ -10,10 +10,19 @@ permissions:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
-        python-version: ["3.9", "3.12"]
+        include:
+          - os: ubuntu-latest
+            python-version: "3.9"
+          - os: ubuntu-latest
+            python-version: "3.12"
+          - os: windows-latest
+            python-version: "3.12"
+          - os: macos-latest
+            python-version: "3.12"
 
     steps:
       - uses: actions/checkout@v4

README.md

@@ -2,9 +2,11 @@
 
 A mouse-and-keyboard terminal app for tracking backpacking gear and
 building per-trip pack lists, built with [Textual](https://textual.textualize.io).
-Data lives in one JSON file next to the code, so the whole thing is
-portable — drop the folder in iCloud Drive / Dropbox / OneDrive and run it
-from any Mac or Windows machine.
+Data lives in one JSON file in a folder you choose on first launch. Packrat
+remembers that folder in your operating system's standard application-config
+location, so the code and your personal data remain separate. Choose an
+iCloud Drive, Dropbox, or OneDrive folder if you want the library synced
+between Windows, macOS, and Linux computers.
 
 ## Requirements
 
@@ -19,14 +21,19 @@ With `uv` (installs the right Python packages automatically, no manual venv):
 uv run python main.py
 ```
 
+The first launch opens a short setup screen. Accept the suggested
+platform-specific folder or enter another folder; Packrat creates
+`gear_data.json` there with clearly labeled example items.
+
 Without `uv`:
 
 ```bash
-pip install -r requirements.txt   # or: pip install textual
+pip install -r requirements.txt   # or: pip install textual platformdirs
 python3 main.py
 ```
 
-To point at a data file somewhere else (e.g. a specific iCloud folder):
+To use an exact data file for one launch without changing the remembered
+preference:
 
 ```bash
 uv run python main.py --data "/Users/you/Library/Mobile Documents/com~apple~CloudDocs/Gear/gear_data.json"
@@ -38,9 +45,10 @@ uv run python main.py --data "/Users/you/Library/Mobile Documents/com~apple~Clou
 - `gear_tui.py` — the Textual UI: screens, forms, tables, styling.
 - `gear_core.py` — data model, JSON persistence, and Markdown rendering.
   Pure functions, no UI code — this is what generates the pack-list exports.
-- `gear_data.json` — your data. Created automatically on first run if it
-  doesn't exist, seeded with a few example items/trip (clearly labeled) so
-  the format is obvious.
+- `packrat_preferences.py` — cross-platform preference paths and persistence.
+- `gear_data.json` — created in your selected storage folder and seeded with
+  a few example items/trip (clearly labeled) so the format is obvious. The
+  repository copy is not used as the runtime default.
 - `pyproject.toml` / `uv.lock` — project + locked dependencies for `uv`.
 - `requirements.txt` — plain-pip fallback if you're not using `uv`.
 
@@ -58,6 +66,8 @@ are:
   edits an item's quantity/note and **P** opens the pack audit.
 - **Ctrl+S** saves forms and picker dialogs; **Enter** confirms confirmations.
 - **Ctrl+B** writes a manual `.bak` snapshot beside your data file.
+- **Ctrl+P** opens Storage Preferences to open another library or copy the
+  current library to a new folder and switch to it.
 
 - **Click a table row** to select it; **click it again** (or press Enter)
   to open/edit it. This two-step click mirrors how most file browsers work
@@ -99,6 +109,19 @@ It is still a flat JSON file rather than a mergeable database. If Packrat
 reports an external-change conflict, restart it to load the newer file before
 editing again.
 
+## Storage preferences
+
+The setup screen and Storage Preferences select a folder; the library inside
+that folder is always named `gear_data.json`. **Open / Create** opens an
+existing valid library or creates a new example library. **Copy Current &
+Switch** copies the active library to an unused destination and leaves the
+original file intact. It will not overwrite an existing destination library.
+
+If the saved preference is damaged or its library cannot be opened, Packrat
+returns to setup with the error instead of silently using another data file.
+The `--data` option remains useful for scripts and one-off libraries and never
+changes the remembered folder by itself.
+
 ## Backing it up
 
 Press **Ctrl+B** for an on-demand snapshot, copy the JSON file whenever you

gear_core.py

@@ -35,11 +35,6 @@
 AUDIT_STATUSES = ("covered", "omitted", "unresolved")
 DATA_VERSION = 2
 
-SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
-DEFAULT_DATA_PATH = os.path.join(SCRIPT_DIR, "gear_data.json")
-DEFAULT_EXPORT_DIR = os.path.join(SCRIPT_DIR, "exports")
-
-
 class DataValidationError(ValueError):
     """Raised when a data file doesn't match Packrat's expected schema."""