Temporary setup of alternative to advertisements

.gitignore

@@ -43,3 +43,10 @@ app.*.map.json
 /android/app/debug
 /android/app/profile
 /android/app/release
+
+# Release signing credentials — never commit. The keystore itself lives
+# outside the repo entirely (~/.android/), but the passwords in here are
+# sensitive regardless.
+/android/key.properties
+*.jks
+*.keystore

PRIVACY_POLICY.md

@@ -0,0 +1,92 @@
+# Privacy Policy — Show Me The Fuel Refund
+
+**Effective date:** August 17, 2026
+
+This policy explains what "Show Me The Fuel Refund" (the "app") does and does not
+do with your data. If anything here is unclear, contact
+**ohbrer+ShowMeTheFuelRefund@gmail.com**.
+
+## Overview
+
+The app helps you collect and organize Missouri fuel purchase receipts so you can
+claim Missouri's Motor Fuel Tax Refund. It has no server or backend of its own —
+every vehicle, fuel receipt, and photo you log is stored locally on your device,
+and optionally backed up to a cloud storage account **you** choose and control.
+We (the developer) never receive, see, or have access to a copy of your data.
+
+## Data Stored Locally
+
+The app stores the following on your device only, unless you connect a cloud
+storage account (see below):
+
+- Vehicle information you enter (VIN, nickname)
+- Fuel purchase records (date, gallons, price, total cost)
+- Receipt photos you capture or select
+
+This data is never transmitted to us. Uninstalling the app, or never connecting a
+cloud backup, means this data exists only on that device.
+
+## Optional Cloud Backup
+
+If you connect a cloud storage account in Settings, a copy of the data above is
+also stored there — in storage **you** control:
+
+- **Google Drive** — via Google Sign-In and the Drive API
+- **Dropbox** — via the Dropbox API
+- **Microsoft OneDrive** — via the Microsoft Graph API
+- **WebDAV** — your own self-hosted server (Nextcloud, ownCloud, or similar)
+
+For OAuth-based providers (Google Drive, Dropbox, OneDrive), the app requests
+only the permissions needed to create, read, and write files in a folder it
+manages there. We do not read, log, or have access to anything stored in these
+accounts — the connection is directly between your device and the provider you
+chose. For WebDAV, your server credentials are stored using your device's
+OS-level encrypted storage (Android Keystore) and are used only to connect
+directly to the server you specify.
+
+## Advertising (Google AdMob)
+
+Unless you've purchased "Remove Ads for a Year," the app shows a single
+interstitial ad, at most once per app session, via Google AdMob. AdMob may
+collect data such as an advertising identifier and coarse, IP-based location to
+serve and measure ads. This collection is Google's, governed by
+[Google's own privacy policy](https://policies.google.com/privacy) and
+[AdMob's data disclosure](https://support.google.com/admob/answer/6128543) — it
+is not something this app adds on top of, and we have no access to it.
+
+## In-App Purchases
+
+"Remove Ads for a Year" is processed entirely through Google Play Billing. We do
+not receive or store payment information — that's handled by Google Play
+directly.
+
+## What We Don't Do
+
+- No analytics SDKs
+- No crash-reporting SDKs
+- No tracking of your usage or behavior
+- No server of ours that receives, stores, or processes your data
+- No selling or sharing of data with anyone, for any reason
+
+## Data Deletion
+
+You can delete your data at any time from **Settings > Data > Advanced**
+(purge all data, or a specific date range), and disconnect any cloud storage
+account from **Settings > Data**. Deleting the app removes everything stored
+locally; anything already backed up to your own cloud storage account remains
+there under your control until you delete it yourself.
+
+## Children's Privacy
+
+This app is not directed at children under 13 and does not knowingly collect
+data from them.
+
+## Changes to This Policy
+
+If this policy changes, the effective date above will be updated. Continued use
+of the app after a change constitutes acceptance of the updated policy.
+
+## Contact
+
+Questions, problem receipts/VINs, or error reports:
+**ohbrer+ShowMeTheFuelRefund@gmail.com**

README.md

@@ -3,37 +3,227 @@
 A Flutter app (Android + iOS) for logging fuel purchases per vehicle. Snap a
 photo of a gas receipt, it OCRs the gallons/price-per-gallon/total on-device,
 you confirm or correct the numbers, and it's saved alongside the receipt
-photo to a data file in a folder you choose.
+photo. Vehicles and fuel entries live in a local SQLite database that's kept
+in sync with a shared folder on **Google Drive, Dropbox, OneDrive, or your
+own WebDAV server** (your choice), so multiple people can log fuel against
+the same pool of vehicles from their own phones, offline or online.
 
 ## Features
 
-- Manage a list of vehicles (make, model, color, license plate).
-- Capture a fuel receipt photo per vehicle and OCR it on-device with Google
-  ML Kit — no internet connection or API key required.
-- Review/edit the parsed gallons, price per gallon, and total cost before
-  saving (OCR on printed receipts is usually good but not perfect).
+- Manage a list of vehicles, identified by **VIN** (required, and unique
+  across active vehicles — but editable, e.g. to fix a typo from a misread
+  scan; scan it from a photo of the door-jamb sticker or dashboard plate
+  instead of typing all 17 characters). An optional **nickname** ("Mom's
+  Car", "Red Ford F-150") is what's shown as the primary label everywhere;
+  without one, the VIN is shown instead.
+- Capture a fuel receipt photo per vehicle — from the camera or an existing
+  photo in your library — and OCR it on-device with Google ML Kit — no
+  internet connection or API key required for the OCR itself.
+- If a receipt's address shows a state other than Missouri, a warning
+  explains that the fuel tax refund only covers Missouri purchases and lets
+  you choose whether to log the entry anyway.
+- Review/edit the parsed gallons, price per gallon, total cost, *and*
+  date/time before saving (OCR on printed receipts is usually good but not
+  perfect; the date/time picker is always available as a manual fallback
+  when a date can't be found on the receipt).
 - Per-vehicle fuel log with running gallons total, tap-to-zoom receipt
   photos, and delete.
-- Settings screen to choose where receipt photos and the data file are
-  stored (defaults to the app's own documents folder; existing data is
-  copied over when you change it).
+- Connect **Google Drive, Dropbox, OneDrive, or a self-hosted WebDAV
+  server** (Nextcloud, ownCloud, a Synology NAS, or any generic WebDAV
+  endpoint) and pick any folder you have access to — including one someone
+  else created and shared with you — as the shared storage location. The
+  app looks for (or creates) a `Show Me The Fuel Refund` subfolder there
+  (using it directly, without nesting, if the folder you picked is already
+  named that), so anyone pointed at the same shared parent converges on the
+  same data automatically, regardless of which of the four providers each
+  person is using. WebDAV is the only one of the four that needs no
+  developer-console setup at all — just a server URL, username, and
+  password.
+- Works fully offline: writes always land in the local SQLite database
+  first; a background sync pushes changes to the cloud and pulls others'
+  changes down once online.
+- Settings lets you choose whether a receipt photo's local copy is deleted
+  once it's safely uploaded to the cloud (the default — keeps the phone's
+  storage footprint small) or kept on the phone for offline viewing.
+- Settings → Advanced lets you tune the sync lock's staleness timeout (how
+  long before another device's abandoned lock is cleared so sync isn't
+  stuck waiting forever), from 1–60 minutes.
 
 ## Project layout
 
 ```
 lib/
-  models/       Vehicle, FuelEntry — plain data classes with JSON (de)serialization
+  models/       Vehicle, FuelEntry — plain data classes with SQLite row (de)serialization
+                (toMap/fromMap). Both carry `updatedAt` (merge conflict resolution) and
+                `deletedAt` (a soft-delete tombstone, so deletions sync too). Vehicle's
+                `id` is a hidden, generated, immutable primary key — never shown in the
+                UI — that FuelEntry.vehicleId references and sync merges on; `vin` is a
+                required, unique-among-active-vehicles, but user-editable field, and
+                `nickname` is optional. FuelEntry can hold a local `receiptImagePath`, a
+                `receiptDriveFileId`, or both at once if "keep photos on this phone" is
+                on — see `needsReceiptUpload` vs. `isReceiptUploadedToDrive` for the
+                distinction.
   services/
-    app_state.dart        In-memory state + CRUD, backed by StorageService, exposed via Provider
-    storage_service.dart  Owns the data.json file + receipts/ folder and the configurable save path
-    ocr_service.dart      Thin wrapper around google_mlkit_text_recognition
-    receipt_parser.dart   Regex-based extraction of gallons/price/total from OCR text
+    app_state.dart          In-memory read cache + CRUD, exposed via Provider. Stamps
+                             updatedAt on mutations and triggers background sync.
+    database_service.dart   Owns the local SQLite database (vehicles + fuel_entries)
+                             and the receipts/ folder, always at
+                             ApplicationDocumentsDirectory/FuelTaxTracker.
+    db_schema.dart           CREATE TABLE statements and the merge SQL — shared between
+                             the app and its tests so they can never drift apart.
+    cloud/
+      cloud_storage_provider.dart  The CloudStorageProvider/CloudStorageSession
+                             interface every backend implements (auth, folder
+                             browsing, file upload/download, lock file ops) —
+                             this is what cloud_sync_service.dart and the rest
+                             of the app talk to; they never know which of the
+                             three providers below is actually active.
+      google_drive_provider.dart  Google sign-in + the googleapis DriveApi client.
+      dropbox_provider.dart       Hand-rolled OAuth2 PKCE + Dropbox's path-addressed
+                             REST API (files/list_folder, files/upload, etc).
+      onedrive_provider.dart      Hand-rolled OAuth2 PKCE + Microsoft Graph
+                             (/me/drive/...), ID-addressed like Drive.
+      webdav_provider.dart        Generic WebDAV (PROPFIND/MKCOL/PUT/GET/DELETE)
+                             over HTTP Basic Auth — no OAuth, no developer
+                             console, just a server URL + username + password.
+                             For self-hosted servers (Nextcloud, ownCloud, a
+                             Synology NAS, etc). Path-addressed like Dropbox;
+                             uses the resource's ETag as its versionTag.
+      oauth_pkce.dart        PKCE code_verifier/code_challenge generation, shared
+                             by the Dropbox and OneDrive providers (Google's own
+                             SDK handles its OAuth flow itself, and WebDAV uses
+                             plain Basic Auth, so neither needs this).
+    cloud_oauth_config.dart Fill in your OAuth client IDs/keys here for whichever
+                             provider(s) you want to use — see setup below.
+    cloud_sync_service.dart Orchestrates one sync round against whichever
+                             CloudStorageProvider is active: acquire the
+                             cross-device lock, ATTACH + merge the remote database
+                             into the local one, upload pending receipt photos,
+                             push the local database back up, release the lock.
+    lock_coordinator.dart   The ticket-based lock-file mutex, as pure injectable
+                             logic (independently unit-tested without a real backend).
+    ocr_service.dart        Thin wrapper around google_mlkit_text_recognition.
+    receipt_parser.dart     Regex-based extraction of gallons/price/total/date from OCR
+                             text — falls back to manual entry (date picker, or the
+                             gallons*price derivation) for whatever isn't found.
   screens/      One file per screen (vehicle list, add/edit vehicle, vehicle detail,
-                confirm fuel entry, receipt viewer, settings)
+                confirm fuel entry, receipt viewer, settings, cloud folder browser).
 ```
 
-Data is stored as a single `fuel_tax_data.json` file plus a `receipts/`
-subfolder of photos, both inside whatever directory Settings points at.
+## Manual setup required (cloud storage)
+
+You only need to complete setup for whichever provider(s) you actually want
+to offer in the app. Google Drive, Dropbox, and OneDrive all follow the same
+shape: I can't provision cloud resources on your behalf, so each needs an
+app/OAuth client you create yourself in that provider's own developer
+console, with the resulting IDs pasted into
+`lib/services/cloud_oauth_config.dart` — Settings only shows a "Connect"
+button for one of these three once its config fields are filled in with
+real values. **WebDAV needs none of this** — see its section below.
+
+### Google Drive (Google Cloud Console)
+
+In [Google Cloud Console](https://console.cloud.google.com/):
+
+1. Create/select a project, enable the **Google Drive API** (APIs & Services
+   → Library).
+2. **OAuth consent screen**: set it to **External**, keep it in **Testing**
+   status, and add your Google account plus everyone else's you're sharing
+   with as **test users**. This avoids Google's formal verification review,
+   which the broad `drive` scope would otherwise require — fine for a known,
+   small group, not a public release.
+3. Add scope `https://www.googleapis.com/auth/drive` to the consent screen
+   (shows as "restricted/sensitive" — expected, fine in Testing mode).
+4. **Credentials → Create Credentials → OAuth client ID**, three times:
+   - **Android**: package name `com.ohbrer.show_me_the_fuel_refund` + the
+     SHA-1 of your debug keystore (`keytool -list -v -keystore
+     ~/.android/debug.keystore`, password `android`), and later your release
+     keystore's SHA-1 too. This client ID itself is never referenced in
+     code — it exists purely so Android's Credential Manager trusts this
+     specific signed app.
+   - **Web application**: no redirect URIs needed. Copy its **Client ID** —
+     this is what Android sign-in actually authenticates against (a
+     Credential Manager quirk: it needs a *web* client ID, passed as
+     `serverClientId`, even for a mobile app).
+   - **iOS**: bundle ID matching the Xcode project. Copy its **Client ID**
+     and note the reversed form (`com.googleusercontent.apps.<...>`).
+5. Fill in `lib/services/cloud_oauth_config.dart`:
+   - `googleAndroidServerClientId` ← the **Web application** client's ID.
+   - `googleIosClientId` ← the **iOS** client's ID.
+6. Replace the placeholder in `ios/Runner/Info.plist`'s `CFBundleURLTypes` →
+   `CFBundleURLSchemes` with your iOS client's reversed ID.
+
+### Dropbox (Dropbox App Console)
+
+Dropbox has no official Flutter sign-in SDK, so this uses a hand-built
+OAuth2 Authorization Code + PKCE flow (no client secret needed — safe for a
+public/mobile app) via `flutter_web_auth_2`, which opens the system browser
+and catches the redirect through a custom URL scheme already registered in
+`AndroidManifest.xml` / `Info.plist`.
+
+1. Create an app at [dropbox.com/developers/apps](https://www.dropbox.com/developers/apps).
+2. Access type: **Full Dropbox** (not "App folder") — needed because
+   browsing to and reusing a folder someone *else* created and shared
+   requires seeing the whole account, the same reasoning as Google's full
+   `drive` scope above.
+3. Under **OAuth 2** → **Redirect URIs**, add
+   `mofueltaxback-dropbox://oauth2redirect` (this exact scheme is already
+   wired up in the Android manifest and iOS Info.plist; use a different one
+   only if you also update those two files to match).
+4. Copy the app's **App key** from the Settings tab.
+5. Fill in `lib/services/cloud_oauth_config.dart`:
+   - `dropboxAppKey` ← the App key.
+   - `dropboxRedirectUri` ← `mofueltaxback-dropbox://oauth2redirect`.
+6. While the app is in **Development** status, only your own Dropbox
+   account can sign in; add teammates under the app's **Permissions** /
+   member-access settings, or apply for **Production** status, once you're
+   ready to share it with others.
+
+### OneDrive (Azure Portal / Microsoft Graph)
+
+Same PKCE approach as Dropbox, against the Microsoft identity platform and
+Microsoft Graph.
+
+1. In [Azure Portal](https://portal.azure.com/) → **Microsoft Entra ID** →
+   **App registrations** → **New registration**.
+2. Supported account types: **Personal Microsoft accounts only** (or "any
+   organizational directory and personal Microsoft accounts" if you also
+   want work/school accounts to be able to sign in — those may additionally
+   need their tenant admin's consent for the scopes below).
+3. Under **Authentication** → **Add a platform** → **Mobile and desktop
+   applications**, add the redirect URI `mofueltaxback-onedrive://auth`
+   (this exact scheme is already wired up in the Android manifest and iOS
+   Info.plist; use a different one only if you also update those two files
+   to match).
+4. Under **API permissions**, add Microsoft Graph **delegated** permissions
+   `Files.ReadWrite.All` and `offline_access` (the latter is required to get
+   a refresh token back from the token endpoint).
+5. Copy the **Application (client) ID** from the Overview page.
+6. Fill in `lib/services/cloud_oauth_config.dart`:
+   - `oneDriveClientId` ← the Application (client) ID.
+   - `oneDriveRedirectUri` ← `mofueltaxback-onedrive://auth`.
+
+### WebDAV (self-hosted — no developer console needed)
+
+This is the option for a personal cloud server you already run — Nextcloud,
+ownCloud, a Synology/QNAP NAS's built-in WebDAV support, or a bare
+Apache/nginx WebDAV endpoint. There's no OAuth app to register anywhere;
+tapping "Connect WebDAV" in Settings just opens a form asking for:
+
+- **Server URL** — the full WebDAV endpoint, e.g.
+  `https://cloud.example.com/remote.php/dav/files/yourusername/` for
+  Nextcloud/ownCloud, or whatever your NAS's WebDAV documentation gives you.
+  `https://` is assumed if you omit the scheme.
+- **Username** and **Password** — for servers that support app-specific
+  passwords (Nextcloud: Settings → Security → "Create new app password"),
+  use one of those instead of your real account password, so this app can
+  be revoked independently later.
+
+The app verifies the URL and credentials with a harmless `PROPFIND` request
+before treating you as signed in, so a typo or wrong password fails
+immediately with a clear error rather than surfacing later during sync.
+Nothing needs to be filled in `cloud_oauth_config.dart` or the
+Android/iOS manifest files for this provider.
 
 ## Running it
 
@@ -51,43 +241,145 @@ flutter build ios --release      # iOS (requires a full Xcode install + signing
 
 This was scaffolded and verified with Flutter 3.44.9. `flutter analyze` and
 `flutter test` are clean, and `flutter build apk --debug` has been confirmed
-to produce a working APK.
+to produce a working APK. None of the three providers' sign-in/sync paths
+can be exercised end-to-end until you've done that provider's manual OAuth
+setup above.
 
 ## Permissions
 
 - **Camera**: `NSCameraUsageDescription` (iOS, `ios/Runner/Info.plist`) and
   `android.permission.CAMERA` (Android, `AndroidManifest.xml`) are already
   set up for receipt capture.
-- **Storage**: no explicit storage permission is declared. The default save
-  location is inside the app's own sandbox (no permission needed). If you
-  point Settings at a location outside the sandbox, the OS-native folder
-  picker (via `file_picker`) is what grants access — see the caveat below.
+- **Network**: `INTERNET` and `ACCESS_NETWORK_STATE` are declared in the
+  main Android manifest (needed for release builds; debug builds get
+  `INTERNET` for free).
+- **OAuth redirects**: no manifest changes are needed for `google_sign_in`
+  itself when not using `google-services.json` — see the Google setup
+  section above instead. Dropbox and OneDrive's browser-based OAuth redirect
+  is already wired up via a `flutter_web_auth_2` callback activity
+  (Android) / extra `CFBundleURLTypes` entries (iOS) for the
+  `mofueltaxback-dropbox://` and `mofueltaxback-onedrive://` schemes — you
+  only need to register the matching redirect URI in each provider's own
+  console (see setup above), not touch these files, unless you deliberately
+  choose different scheme names.
+
+## How sync works
+
+Every local change (add/edit a vehicle, log a fuel entry) writes to the
+local SQLite database immediately, then triggers a best-effort background
+sync — also triggered whenever connectivity comes back or the app starts.
+Every row carries `updated_at` (for merge resolution), `deleted_at` (a
+soft-delete tombstone — see below), and a local-only `dirty` flag (pending
+push to Drive, never itself treated as meaningful sync data). Sync:
+
+1. Creates a lock file `{email}-{utcEpochMillis}.lock` in the shared cloud
+   folder, then waits until no *other* lock file older than its own remains
+   (polling every second, deleting any it finds older than the configured
+   staleness timeout — Settings → Advanced, 1–60 minutes, default 10 — as
+   orphaned/stale) — a ticket-based mutex using the cloud folder itself as
+   the coordination point, so two devices never overwrite each other's
+   edits to the shared database mid-write. This logic (`lock_coordinator.dart`)
+   is identical regardless of which of the four providers is active.
+2. Checks the remote database file's change-detection tag (Drive's
+   `md5Checksum`, Dropbox's `content_hash`, OneDrive's `cTag`, or a WebDAV
+   resource's `ETag` — an opaque `versionTag` as far as the sync engine is
+   concerned) against the last one seen (a metadata-only call, no content
+   download) to decide if a pull is even needed. If it changed: downloads
+   it to a temp file, `ATTACH`es it to
+   the local database, and runs one `INSERT OR REPLACE ... SELECT ... WHERE
+   local.<key> IS NULL OR remote.updated_at > local.updated_at` per table
+   (`id` for both tables — vehicles' hidden generated id, not the
+   user-editable VIN). Rows that statement doesn't match — including this
+   device's own not-yet-pushed edits — are left untouched, so no separate
+   "keep local" step is needed.
+3. Uploads any receipt photos still needing it (a local path but no cloud
+   file ID yet — see `FuelEntry.needsReceiptUpload`), recording the cloud
+   file ID. The local copy is then deleted or kept depending on the
+   Settings "keep photos on this phone" toggle. If any upload fails, the
+   push step below is skipped entirely this cycle — a row is never pushed
+   while it still holds a local-only, not-yet-uploaded path.
+4. Reads the local database file directly (sqflite's default journal mode
+   isn't WAL, so the file is complete and consistent as soon as the last
+   write's `Future` resolves; `PRAGMA wal_checkpoint` runs first anyway as
+   cheap insurance) and uploads it as the new remote copy, then clears the
+   `dirty` flag on every row now that local matches what's on the cloud.
+5. Releases the lock.
+
+**Deletions propagate correctly**, unlike a naive "union records" merge:
+deleting sets `deleted_at` instead of removing the row, so a deletion is
+just another change with its own `updated_at`, and rides the same
+newest-wins rule as any edit — no separate deletion-handling logic needed.
 
 ## Known caveats / things to revisit
 
-- **`file_picker` is pinned to `10.3.10`**, not the latest release. Versions
-  11.0.0–11.0.3 skip applying the Kotlin Gradle plugin when they detect AGP
-  9+ (assuming AGP's built-in Kotlin support handles it), but that isn't
-  actually wired up for library modules in this Flutter/AGP combination yet,
-  so the plugin's own Kotlin sources never get compiled and the build fails
-  with `cannot find symbol: FilePickerPlugin`. 10.3.11 fixes that but is
-  retracted on pub.dev, hence 10.3.10. Worth revisiting this pin next time
-  you bump dependencies — check the package's CHANGELOG for when this is
-  properly resolved upstream.
-- **iOS folder picking and app restarts**: `file_picker`'s directory picker
-  on iOS uses `UIDocumentPickerViewController`, which hands back a
-  security-scoped URL. This app does not currently persist a security-scoped
-  bookmark for that URL, so if you pick a folder outside the app's own
-  sandbox (e.g. an iCloud Drive folder) on iOS, continued write access after
-  an app restart is not guaranteed. Picking the default in-sandbox location,
-  or a folder on Android, does not have this limitation. If cross-restart
-  external storage on iOS matters for your use case, this needs a proper
-  bookmark implementation (`NSURL` bookmarkData + `startAccessingSecurityScopedResource`).
+- **Field-level conflicts aren't merged.** Two people editing the *same*
+  record at the same time: whole record, newer `updated_at` wins — not a
+  field-by-field merge.
+- **Lock acquisition has no hard timeout** beyond the configurable
+  staleness reap (Settings → Advanced). Fine at the scale this is built for
+  (a handful of people); could in theory spin under many simultaneous
+  contenders.
+- **VIN uniqueness is checked, but not race-proof across devices.** Editing
+  or adding a vehicle checks for an existing active vehicle with the same
+  VIN before saving, but two offline devices could still each independently
+  create (or rename into) the same VIN before either has seen the other's
+  change — same category of accepted limitation as "field-level conflicts
+  aren't merged" above. `mergeVehiclesSql` merges on the hidden `id`, not
+  `vin`, specifically so this doesn't corrupt the merge itself if it
+  happens — you'd just end up with two vehicle rows sharing a VIN until
+  someone notices and fixes it by hand.
+- **`google_sign_in` v7's Android path requires a *Web* OAuth client ID**
+  (`serverClientId`), not just the Android client's SHA-1 registration —
+  see the manual setup section. This is a quirk of the Credential
+  Manager-based implementation and easy to miss if you're used to older
+  `google_sign_in` versions.
+- **Dropbox and OneDrive's sign-in isn't restored across a cold app
+  restart.** Their OAuth refresh tokens are kept in memory only for now
+  (Google's own SDK handles its own persistent session separately, and
+  WebDAV persists its credentials to OS-encrypted storage — see below — so
+  this only affects these two hand-built OAuth providers) —
+  `attemptSilentSignIn()` always returns false for them, so you'll need to
+  reconnect once per app launch until refresh-token persistence is added.
+- **WebDAV credentials are stored via `flutter_secure_storage`** (Keystore
+  on Android, Keychain on iOS) so `attemptSilentSignIn()` can restore the
+  session after a cold restart — it re-verifies them with the same PROPFIND
+  check `signInWithCredentials` uses rather than trusting the stored values
+  blindly, since the server or password could have changed since. A wrong
+  or revoked password just silently fails the restore (same as no
+  connection ever having been made); there's no proactive UI nudge to
+  reconnect beyond the sync error that shows up on the next sync attempt.
+- **No automatic retry-on-401 for Dropbox/OneDrive.** Each session checks
+  the access token's expiry before every call and refreshes proactively,
+  but a token revoked or invalidated out-of-band (e.g. from that provider's
+  own "manage app access" page) surfaces as a failed sync (visible in
+  Settings as "Last sync failed") rather than prompting a fresh sign-in
+  automatically.
+- **Dropbox has no distinct "Shared with me" tab** in the folder browser
+  (the interface's `sharedWithMe` parameter is a no-op for
+  `DropboxProvider`) — Dropbox auto-mounts *accepted* shares directly into
+  the account's normal folder tree, so they already show up under "My
+  Files" in the common case. Revisit if an unmounted/pending share needs to
+  be browsable directly.
+- **WebDAV has no "Shared with me" concept at all** (it's not part of the
+  base WebDAV protocol) — `WebDavProvider.supportsSharedWithMe` is false,
+  same as Dropbox, and it's up to the server/user to point the app at
+  whatever path a share is mounted under. WebDAV credentials are also sent
+  as HTTP Basic Auth on every request, so an **HTTPS server URL is
+  effectively required** — the app doesn't block a plain `http://` URL, but
+  it would send the password in the clear.
 - **Receipt parsing is best-effort regex matching** on the OCR'd text
   (`lib/services/receipt_parser.dart`), tuned against common receipt phrasing
   ("GALLONS", "PRICE/GAL", "PPG", "TOTAL", etc.). Unusual receipt layouts may
   parse partially or not at all — the confirm screen always lets you fill in
   or correct whatever wasn't found.
-- No automated tests exercise the OCR or camera capture path itself (that
-  requires a real device/emulator with a camera); `receipt_parser_test.dart`
-  covers the parsing logic against fixed OCR text.
+- No automated tests exercise the OCR, camera/gallery picker, or real Drive
+  API calls (those need a real device/emulator and live credentials);
+  `receipt_parser_test.dart`, `lock_coordinator_test.dart`,
+  `db_merge_test.dart`, and `pending_receipt_upload_test.dart` (the latter
+  two using `sqflite_common_ffi` to run real SQL against temp SQLite files
+  on the Dart VM) cover the pure logic pieces against fixed inputs —
+  `receipt_parser_test.dart` in particular is transcribed from 13 real
+  photographed receipts across different gas station chains.
+- No migration path exists from the earlier JSON-file storage format —
+  not needed since no real data had accumulated under it yet, but flag it
+  if that's no longer true for you.

android/app/build.gradle.kts

@@ -1,11 +1,24 @@
+import java.io.FileInputStream
+import java.util.Properties
+
 plugins {
     id("com.android.application")
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
     id("dev.flutter.flutter-gradle-plugin")
 }
 
+// Release signing credentials — see key.properties (gitignored; the
+// keystore file itself lives outside the repo, at the path it points to).
+// Missing entirely just means a debug-signed release build, same as
+// before, so this doesn't break local dev if key.properties isn't set up.
+val keystoreProperties = Properties()
+val keystorePropertiesFile = rootProject.file("key.properties")
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(FileInputStream(keystorePropertiesFile))
+}
+
 android {
-    namespace = "com.courtneyarnold.fuel_tax_tracker"
+    namespace = "com.ohbrer.show_me_the_fuel_refund"
     compileSdk = flutter.compileSdkVersion
     ndkVersion = flutter.ndkVersion
 
@@ -15,8 +28,7 @@ android {
     }
 
     defaultConfig {
-        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId = "com.courtneyarnold.fuel_tax_tracker"
+        applicationId = "com.ohbrer.show_me_the_fuel_refund"
         // You can update the following values to match your application needs.
         // For more information, see: https://flutter.dev/to/review-gradle-config.
         minSdk = flutter.minSdkVersion
@@ -25,11 +37,31 @@ android {
         versionName = flutter.versionName
     }
 
+    signingConfigs {
+        if (keystorePropertiesFile.exists()) {
+            create("release") {
+                keyAlias = keystoreProperties["keyAlias"] as String
+                keyPassword = keystoreProperties["keyPassword"] as String
+                storeFile = file(keystoreProperties["storeFile"] as String)
+                storePassword = keystoreProperties["storePassword"] as String
+            }
+        }
+    }
+
     buildTypes {
         release {
-            // TODO: Add your own signing config for the release build.
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig = signingConfigs.getByName("debug")
+            // Real release signing once key.properties exists (see above);
+            // falls back to the debug key otherwise, so `flutter run
+            // --release` still works for local testing without it.
+            signingConfig = if (keystorePropertiesFile.exists()) {
+                signingConfigs.getByName("release")
+            } else {
+                signingConfigs.getByName("debug")
+            }
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
         }
     }
 }

android/app/proguard-rules.pro

@@ -0,0 +1,35 @@
+# google_mlkit_text_recognition's plugin code references all of ML Kit's
+# regional script recognizers (Chinese/Devanagari/Japanese/Korean)
+# generically, even though this app only depends on (and only ever uses)
+# the default Latin recognizer. R8 can't resolve the others since their
+# artifacts genuinely aren't on the classpath — safe to silence, they're
+# never called at runtime here.
+-dontwarn com.google.mlkit.vision.text.chinese.ChineseTextRecognizerOptions$Builder
+-dontwarn com.google.mlkit.vision.text.chinese.ChineseTextRecognizerOptions
+-dontwarn com.google.mlkit.vision.text.devanagari.DevanagariTextRecognizerOptions$Builder
+-dontwarn com.google.mlkit.vision.text.devanagari.DevanagariTextRecognizerOptions
+-dontwarn com.google.mlkit.vision.text.japanese.JapaneseTextRecognizerOptions$Builder
+-dontwarn com.google.mlkit.vision.text.japanese.JapaneseTextRecognizerOptions
+-dontwarn com.google.mlkit.vision.text.korean.KoreanTextRecognizerOptions$Builder
+-dontwarn com.google.mlkit.vision.text.korean.KoreanTextRecognizerOptions
+
+# The -dontwarn rules above only silence build-time warnings — they don't
+# stop R8 from stripping/renaming classes the Latin recognizer actually
+# does use at runtime via reflection. Without an explicit -keep, release
+# builds installed and launched fine but every OCR attempt threw
+# "Attempt to invoke virtual method 'java.lang.Class
+# java.lang.Object.getClass()' on a null object reference" from inside the
+# ML Kit plugin, silently swallowed by receipt_capture.dart's catch block
+# and surfaced to the user as "Couldn't automatically read this receipt."
+-keep class com.google.mlkit.** { *; }
+-keep class com.google.android.gms.internal.mlkit_vision_text_common.** { *; }
+
+# AndroidX WorkManager (pulled in transitively by one of the Google SDKs,
+# not used directly by this app) initializes its Room-backed WorkDatabase
+# reflectively at process startup via androidx.startup.InitializationProvider
+# — R8 was stripping/renaming those generated Room implementation classes,
+# crashing every release build before Flutter even started ("Failed to
+# create an instance of androidx.work.impl.WorkDatabase"). Keeping the
+# whole (small, self-contained) impl package is the standard fix.
+-keep class androidx.work.impl.** { *; }
+-keep class androidx.room.** { *; }

android/app/src/main/AndroidManifest.xml

@@ -1,8 +1,13 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.CAMERA"/>
     <uses-feature android:name="android.hardware.camera" android:required="false"/>
+    <!-- Required for Drive sign-in/sync. Debug builds get this for free via
+         android/app/src/debug/AndroidManifest.xml, but release builds need
+         it declared here explicitly. -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
     <application
-        android:label="fuel_tax_tracker"
+        android:label="Receipt Tracker"
         android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
@@ -27,6 +32,28 @@
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
+        <!-- Dropbox & OneDrive OAuth: flutter_web_auth_2 captures the
+             browser redirect via this activity + custom URL scheme(s).
+             These scheme values must exactly match whatever is set as
+             dropboxRedirectUri/oneDriveRedirectUri in
+             lib/services/cloud_oauth_config.dart. -->
+        <activity
+            android:name="com.linusu.flutter_web_auth_2.CallbackActivity"
+            android:exported="true">
+            <intent-filter android:label="flutter_web_auth_2">
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data android:scheme="mofueltaxback-dropbox" />
+                <data android:scheme="mofueltaxback-onedrive" />
+            </intent-filter>
+        </activity>
+        <!-- Real AdMob App ID (from your own AdMob console). The interstitial
+             unit served under it (lib/services/ad_service.dart) is also a
+             real one from the same account, not Google's test ID. -->
+        <meta-data
+            android:name="com.google.android.gms.ads.APPLICATION_ID"
+            android:value="ca-app-pub-9212406812117696~6413414381"/>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
         <meta-data
@@ -43,5 +70,13 @@
             <action android:name="android.intent.action.PROCESS_TEXT"/>
             <data android:mimeType="text/plain"/>
         </intent>
+        <!-- Lets url_launcher open the Missouri DOR forms link on the
+             Reports tab — without this, canLaunchUrl/launchUrl can't see
+             any browser app on Android 11+ due to package visibility
+             restrictions. -->
+        <intent>
+            <action android:name="android.intent.action.VIEW"/>
+            <data android:scheme="https"/>
+        </intent>
     </queries>
 </manifest>

android/app/src/main/kotlin/com/ohbrer/show_me_the_fuel_refund/MainActivity.kt

@@ -1,4 +1,4 @@
-package com.courtneyarnold.fuel_tax_tracker
+package com.ohbrer.show_me_the_fuel_refund
 
 import io.flutter.embedding.android.FlutterActivity
 

android/app/src/main/res/drawable-night-v21/launch_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
+</layer-list>

android/app/src/main/res/drawable-night/launch_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
+</layer-list>

android/app/src/main/res/drawable-v21/launch_background.xml

@@ -1,12 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="?android:colorBackground" />
-
-    <!-- You can insert your own image assets here -->
-    <!-- <item>
-        <bitmap
-            android:gravity="center"
-            android:src="@mipmap/launch_image" />
-    </item> -->
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
 </layer-list>

android/app/src/main/res/drawable/launch_background.xml

@@ -1,12 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="@android:color/white" />
-
-    <!-- You can insert your own image assets here -->
-    <!-- <item>
-        <bitmap
-            android:gravity="center"
-            android:src="@mipmap/launch_image" />
-    </item> -->
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
 </layer-list>

android/app/src/main/res/values-night-v31/styles.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is on -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
+        <item name="android:windowSplashScreenBackground">#101110</item>
+        <item name="android:windowSplashScreenAnimatedIcon">@drawable/android12splash</item>
+        <item name="android:windowSplashScreenIconBackgroundColor">#101110</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

android/app/src/main/res/values-night/styles.xml

@@ -5,6 +5,10 @@
         <!-- Show a splash screen on the activity. Automatically removed when
              the Flutter engine draws its first frame -->
         <item name="android:windowBackground">@drawable/launch_background</item>
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
     </style>
     <!-- Theme applied to the Android Window as soon as the process has started.
          This theme determines the color of the Android Window while your

android/app/src/main/res/values-v31/styles.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
+        <item name="android:windowSplashScreenBackground">#24603A</item>
+        <item name="android:windowSplashScreenAnimatedIcon">@drawable/android12splash</item>
+        <item name="android:windowSplashScreenIconBackgroundColor">#24603A</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

android/app/src/main/res/values/styles.xml

@@ -5,6 +5,10 @@
         <!-- Show a splash screen on the activity. Automatically removed when
              the Flutter engine draws its first frame -->
         <item name="android:windowBackground">@drawable/launch_background</item>
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
     </style>
     <!-- Theme applied to the Android Window as soon as the process has started.
          This theme determines the color of the Android Window while your

app-ads.txt

@@ -0,0 +1 @@
+google.com, pub-9212406812117696, DIRECT, f08c47fec0942fa0

docs/class-diagram.md

@@ -0,0 +1,425 @@
+# Application class diagram
+
+Fuel Tax Tracker is a Flutter app. Screens read and mutate through `AppState` (a `ChangeNotifier` provided at the root). Persistence is `DatabaseService` (SQLite); cloud I/O goes through `CloudStorageProvider` so sync never depends on a specific backend.
+
+Private Flutter `State` / painter classes are omitted. Functions that are not classes (`buildFuelReport`, `estimatedFuelRefund`, `acquireLock`) are noted where they sit in the design.
+
+## Domain and application facade
+
+```mermaid
+classDiagram
+    class Vehicle {
+        +String id
+        +String vin
+        +String? nickname
+        +DateTime updatedAt
+        +DateTime? deletedAt
+        +String displayLabel
+        +copyWith() Vehicle
+        +toMap() Map
+        +fromMap(map) Vehicle
+    }
+
+    class FuelEntry {
+        +String id
+        +String vehicleId
+        +DateTime date
+        +double gallons
+        +double pricePerGallon
+        +double totalCost
+        +String? receiptImagePath
+        +String? receiptDriveFileId
+        +DateTime updatedAt
+        +DateTime? deletedAt
+        +bool isReceiptUploadedToDrive
+        +bool needsReceiptUpload
+        +copyWith() FuelEntry
+        +toMap() Map
+        +fromMap(map) FuelEntry
+    }
+
+    class DuplicateVinException {
+        +String vin
+    }
+
+    class AppState {
+        +DatabaseService database
+        +AdService adService
+        +PurchaseService purchaseService
+        +List~CloudStorageProvider~ availableProviders
+        +CloudStorageProvider? activeProvider
+        +CloudSyncService? cloudSync
+        +List~Vehicle~ vehicles
+        +List~FuelEntry~ fuelEntries
+        +DateTime? adFreeUntil
+        +bool adsCurrentlyDisabled
+        +bool isCloudConnected
+        +bool hasCloudBackupConfigured
+        +init()
+        +addVehicle()
+        +updateVehicle()
+        +deleteVehicle()
+        +addFuelEntry() FuelEntry
+        +updateFuelEntry()
+        +deleteFuelEntry()
+        +syncNow()
+        +connectProvider()
+        +disconnectCloud()
+        +purgeAllData()
+    }
+
+    class DatabaseService {
+        +Directory rootDirectory
+        +Database rawDb
+        +init()
+        +getVehicles() List~Vehicle~
+        +getFuelEntries() List~FuelEntry~
+        +getAdFreeUntil() DateTime?
+        +setAdFreeUntil()
+        +vinExists() bool
+        +saveVehicle()
+        +saveFuelEntry()
+        +softDeleteVehicle()
+        +softDeleteFuelEntry()
+        +storeReceiptImage() String
+        +purgeAllData()
+    }
+
+    Vehicle "1" <-- "0..*" FuelEntry : vehicleId
+    AppState "1" *-- "1" DatabaseService
+    AppState "1" --> "*" Vehicle : caches
+    AppState "1" --> "*" FuelEntry : caches
+    AppState ..> DuplicateVinException : throws
+    DatabaseService --> Vehicle
+    DatabaseService --> FuelEntry
+    AppState --|> ChangeNotifier
+```
+
+`ad_free_entitlement` has **no** Dart model. `DatabaseService.getAdFreeUntil` / `setAdFreeUntil` read and write that singleton row; `AppState.adFreeUntil` is the in-memory cache.
+
+## Cloud storage and sync
+
+```mermaid
+classDiagram
+    class CloudProviderId {
+        <<enumeration>>
+        googleDrive
+        dropbox
+        oneDrive
+        webdav
+    }
+
+    class CloudStorageProvider {
+        <<abstract>>
+        +CloudProviderId id
+        +String displayName
+        +bool isSignedIn
+        +String? accountLabel
+        +attemptSilentSignIn() bool
+        +signIn() String
+        +signOut()
+        +beginSession() CloudStorageSession
+    }
+
+    class CloudStorageSession {
+        <<abstract>>
+        +bool supportsSharedWithMe
+        +listFolders() List~CloudFolder~
+        +findOrCreateFolder() String
+        +moveFolder() String
+        +findFile() CloudFileInfo?
+        +downloadFileBytes() List~int~
+        +uploadFile() CloudFileInfo
+        +deleteFile()
+        +createLockFile() String
+        +listLockFiles() List~CloudLockFile~
+        +close()
+    }
+
+    class ManualCredentialCloudStorageProvider {
+        <<abstract>>
+        +signInWithCredentials() String
+    }
+
+    class GoogleDriveProvider
+    class DropboxProvider
+    class OneDriveProvider
+    class WebDavProvider
+
+    class GoogleDriveSession
+    class DropboxSession
+    class OneDriveSession
+    class WebDavSession
+
+    class CloudFolder {
+        +String id
+        +String name
+    }
+
+    class CloudFileInfo {
+        +String id
+        +String? versionTag
+    }
+
+    class CloudLockFile {
+        +String id
+        +String username
+        +DateTime createdAtUtc
+    }
+
+    class CloudNotAuthorizedException {
+        +String providerName
+    }
+
+    class CloudSyncService {
+        +CloudStorageProvider provider
+        +DatabaseService databaseService
+        +bool isConfigured
+        +configure(appFolderId)
+        +clearConfiguration()
+        +selectAppFolder() String
+        +syncNow() SyncResult
+    }
+
+    class SyncResult {
+        +bool ranSync
+        +Object? error
+        +bool adGateBlocked
+        +skipped() SyncResult
+        +success() SyncResult
+        +failure(error) SyncResult
+        +adGateBlocked() SyncResult
+    }
+
+    CloudStorageProvider <|.. GoogleDriveProvider
+    CloudStorageProvider <|.. DropboxProvider
+    CloudStorageProvider <|.. OneDriveProvider
+    CloudStorageProvider <|.. WebDavProvider
+    ManualCredentialCloudStorageProvider <|.. WebDavProvider
+
+    CloudStorageSession <|.. GoogleDriveSession
+    CloudStorageSession <|.. DropboxSession
+    CloudStorageSession <|.. OneDriveSession
+    CloudStorageSession <|.. WebDavSession
+
+    CloudStorageProvider --> CloudStorageSession : beginSession()
+    CloudStorageProvider --> CloudProviderId
+    CloudStorageSession --> CloudFolder
+    CloudStorageSession --> CloudFileInfo
+    CloudStorageSession --> CloudLockFile
+
+    CloudSyncService --> CloudStorageProvider
+    CloudSyncService --> DatabaseService
+    CloudSyncService --> SyncResult
+    AppState o-- CloudStorageProvider : activeProvider
+    AppState o-- CloudSyncService : cloudSync
+    AppState "1" *-- "*" CloudStorageProvider : availableProviders
+```
+
+Lock acquisition is a free function, `acquireLock` in `lock_coordinator.dart`, injected with create/list/delete callbacks so it can be unit-tested without a network. `CloudSyncService` is the only production caller.
+
+OAuth helpers (`PkcePair`, `CloudOAuthConfig`) support Dropbox and OneDrive sign-in. Google uses its own SDK; WebDAV uses HTTP Basic Auth.
+
+## Reports, OCR, ads, purchases
+
+```mermaid
+classDiagram
+    class FuelReport {
+        +DateTime startDate
+        +DateTime endDate
+        +List~VehicleReportRow~ rows
+        +double totalGallons
+        +double totalCost
+        +int fillCount
+        +List~ReportEntry~ allEntries
+        +List~MonthlyTotal~ monthlyTotals
+    }
+
+    class VehicleReportRow {
+        +Vehicle vehicle
+        +List~FuelEntry~ entries
+        +double totalGallons
+        +double totalCost
+        +int entryCount
+    }
+
+    class ReportEntry {
+        +FuelEntry entry
+        +Vehicle vehicle
+    }
+
+    class MonthlyTotal {
+        +DateTime month
+        +int fillCount
+        +double totalGallons
+        +double totalCost
+        +double avgPricePerGallon
+    }
+
+    class ParsedReceipt {
+        +double? gallons
+        +double? pricePerGallon
+        +double? totalCost
+        +DateTime? date
+        +String? state
+        +String rawText
+    }
+
+    class ReceiptParser {
+        +parse(text) ParsedReceipt$
+    }
+
+    class OcrService {
+        +recognizeText(imageFile) String
+        +dispose()
+    }
+
+    class VinParser {
+        +parse(text) String?$
+    }
+
+    class AdService {
+        +initialize()
+        +showGateAd() AdGateResult
+    }
+
+    class AdGateResult {
+        <<enumeration>>
+        alreadyOpen
+        justShown
+        blocked
+    }
+
+    class PurchaseService {
+        +String adFreeYearProductId$
+        +String? priceLabel
+        +initialize()
+        +buyAdFreeYear()
+        +dispose()
+    }
+
+    class ReceiptImageLoadResult {
+        +Map bytesByEntryId
+        +List~FuelEntry~ failedEntries
+    }
+
+    FuelReport "1" *-- "*" VehicleReportRow
+    VehicleReportRow --> Vehicle
+    VehicleReportRow --> FuelEntry
+    FuelReport --> ReportEntry
+    ReportEntry --> FuelEntry
+    ReportEntry --> Vehicle
+    FuelReport --> MonthlyTotal
+    ReceiptParser --> ParsedReceipt
+    OcrService ..> ReceiptParser : raw text in
+    AdService --> AdGateResult
+    AppState *-- AdService
+    AppState *-- PurchaseService
+```
+
+`buildFuelReport(...)` (in `fuel_report.dart`) constructs a `FuelReport` from the in-memory vehicle/entry lists. `buildFuelReportPdf(...)` renders it; `loadReceiptImageBytes(...)` resolves local or cloud receipt photos into a `ReceiptImageLoadResult`. `estimatedFuelRefund(gallons)` is a pure function (Missouri highway rate, $0.125/gal).
+
+## UI structure
+
+Widgets consume `AppState` via `Provider` / `context.watch`. They do not talk to SQLite or cloud APIs directly.
+
+```mermaid
+classDiagram
+    class FuelTaxTrackerApp {
+        <<StatelessWidget>>
+    }
+    class AppRoot {
+        <<StatelessWidget>>
+    }
+    class UserAgreementScreen {
+        <<StatelessWidget>>
+    }
+    class MainShell {
+        <<StatefulWidget>>
+    }
+    class ReceiptsScreen {
+        <<StatefulWidget>>
+    }
+    class HomeScreen {
+        <<StatelessWidget>>
+    }
+    class ReportScreen {
+        <<StatefulWidget>>
+    }
+    class SettingsScreen {
+        <<StatelessWidget>>
+    }
+    class DataSettingsScreen {
+        <<StatefulWidget>>
+    }
+    class UiSettingsScreen {
+        <<StatelessWidget>>
+    }
+    class FaqScreen {
+        <<StatelessWidget>>
+    }
+    class AddEditVehicleScreen {
+        <<StatefulWidget>>
+    }
+    class VehicleDetailScreen {
+        <<StatefulWidget>>
+    }
+    class ConfirmFuelEntryScreen {
+        <<StatefulWidget>>
+    }
+    class EditFuelEntryScreen {
+        <<StatefulWidget>>
+    }
+    class ReceiptDetailScreen {
+        <<StatelessWidget>>
+    }
+    class ReceiptImageScreen {
+        <<StatefulWidget>>
+    }
+    class CloudFolderBrowserScreen {
+        <<StatefulWidget>>
+    }
+
+    FuelTaxTrackerApp --> AppRoot
+    FuelTaxTrackerApp --> AppState : ChangeNotifierProvider
+    AppRoot --> UserAgreementScreen : if not accepted
+    AppRoot --> MainShell : after agreement
+    MainShell --> ReceiptsScreen
+    MainShell --> HomeScreen
+    MainShell --> ReportScreen
+    MainShell --> SettingsScreen
+    SettingsScreen --> DataSettingsScreen
+    SettingsScreen --> UiSettingsScreen
+    SettingsScreen --> FaqScreen
+    DataSettingsScreen --> CloudFolderBrowserScreen
+    HomeScreen --> AddEditVehicleScreen
+    HomeScreen --> VehicleDetailScreen
+    HomeScreen --> FaqScreen
+    VehicleDetailScreen --> ConfirmFuelEntryScreen
+    VehicleDetailScreen --> EditFuelEntryScreen
+    VehicleDetailScreen --> ReceiptImageScreen
+    ReceiptsScreen --> ConfirmFuelEntryScreen
+    ReceiptsScreen --> ReceiptDetailScreen
+    ReceiptsScreen --> EditFuelEntryScreen
+    ReceiptDetailScreen --> ReceiptImageScreen
+    ReportScreen --> FuelReport : buildFuelReport()
+```
+
+Shared widgets (not expanded above): `HeroBanner`, `ReceiptThumbnail`, `ReceiptCapture`, `OnboardingTourOverlay`, `BackupReminder`, `AdFreeUpsellDialog`, `ImageSourceSheet`. Theme tokens live on `AppTheme`.
+
+## How the layers connect
+
+```
+UI screens/widgets
+        │  Provider
+        ▼
+    AppState  ──────────► PurchaseService
+        │                 AdService
+        ├── DatabaseService ── SQLite (vehicles, fuel_entries, ad_free_entitlement)
+        │                   └── local receipts/ folder
+        └── CloudSyncService ── CloudStorageProvider
+                                    ├── GoogleDriveProvider
+                                    ├── DropboxProvider
+                                    ├── OneDriveProvider
+                                    └── WebDavProvider
+```

docs/erd.md

@@ -0,0 +1,73 @@
+# SQLite entity-relationship diagram
+
+Local database: `ApplicationDocumentsDirectory/FuelTaxTracker/fuel_tax_tracker.db`  
+Schema version: **5** (defined in `lib/services/database_service.dart` / `lib/services/db_schema.dart`)
+
+```mermaid
+erDiagram
+    VEHICLES ||--o{ FUEL_ENTRIES : "owns (vehicle_id)"
+
+    VEHICLES {
+        TEXT id PK "UUID, hidden, immutable"
+        TEXT vin "required; unique among active rows, app-enforced"
+        TEXT nickname "nullable display label"
+        INTEGER updated_at "UTC millis; newest-wins merge key"
+        INTEGER deleted_at "nullable soft-delete tombstone"
+        INTEGER dirty "local-only; 1 = not yet pushed"
+    }
+
+    FUEL_ENTRIES {
+        TEXT id PK "UUID"
+        TEXT vehicle_id FK "references vehicles.id — no SQLite FK"
+        INTEGER date "purchase datetime, local millis"
+        REAL gallons
+        REAL price_per_gallon
+        REAL total_cost
+        TEXT receipt_image_path "nullable on-device path"
+        TEXT receipt_drive_file_id "nullable cloud file id"
+        INTEGER updated_at "UTC millis; newest-wins merge key"
+        INTEGER deleted_at "nullable soft-delete tombstone"
+        INTEGER dirty "local-only; 1 = not yet pushed"
+    }
+
+    AD_FREE_ENTITLEMENT {
+        INTEGER id PK "always 1 (CHECK id = 1)"
+        INTEGER ad_free_until "nullable UTC millis"
+        INTEGER updated_at "UTC millis; newest-wins merge key"
+    }
+```
+
+## Relationships
+
+| From | To | Cardinality | Enforced by |
+| --- | --- | --- | --- |
+| `vehicles` | `fuel_entries` | 1 : 0..n | Application (`FuelEntry.vehicleId` → `Vehicle.id`). There is **no** `FOREIGN KEY` clause. |
+| `ad_free_entitlement` | — | singleton | `PRIMARY KEY CHECK (id = 1)` |
+
+VIN is **not** the foreign key. Fuel entries reference the hidden vehicle `id` so the user can edit a VIN without breaking receipts or sync history.
+
+## Indexes and constraints
+
+- `vehicles.id` — `PRIMARY KEY`
+- `fuel_entries.id` — `PRIMARY KEY`
+- `idx_fuel_entries_vehicle_id` on `fuel_entries(vehicle_id)`
+- `ad_free_entitlement.id` — `PRIMARY KEY CHECK (id = 1)`
+- VIN uniqueness among **active** (`deleted_at IS NULL`) vehicles is enforced in `DatabaseService.vinExists` / `AppState.addVehicle` / `AppState.updateVehicle`, not by a unique index. Two offline devices can independently add the same VIN; that rare conflict is accepted rather than merged field-by-field.
+
+## Sync and lifecycle columns
+
+Every synced table carries `updated_at`. Cloud merge is last-write-wins on that timestamp (`INSERT OR REPLACE` of a remote row that is new or newer). See `mergeVehiclesSql`, `mergeFuelEntriesSql`, and `mergeAdFreeEntitlementSql` in `db_schema.dart`.
+
+| Column | Scope | Meaning |
+| --- | --- | --- |
+| `updated_at` | all three tables | Newest value wins when merging a remote copy. |
+| `deleted_at` | `vehicles`, `fuel_entries` | Soft-delete tombstone. Rows are never hard-deleted, so a deletion can propagate to other devices instead of being resurrected by a stale remote copy. |
+| `dirty` | `vehicles`, `fuel_entries` only | Local bookkeeping: `1` = not yet pushed. Cleared to `0` on merge-in. **Not** mapped onto the Dart models. |
+| `receipt_image_path` | `fuel_entries` | Device-local filesystem path. Forced to `NULL` when merging a remote row — a path from another phone is never valid here. |
+| `receipt_drive_file_id` | `fuel_entries` | Opaque id of the uploaded receipt on the active cloud provider. Presence means “already uploaded”; a pending upload is `path IS NOT NULL AND drive_file_id IS NULL`. |
+
+`ad_free_entitlement` has no `dirty` or `deleted_at`. It is a single row that exists so a consumable Play Store purchase (which cannot be restored after consume) can survive reinstall via the same cloud merge as vehicles and fuel entries.
+
+## What is *not* in SQLite
+
+Preferences live in `SharedPreferences`, not this database: theme, onboarding/agreement flags, cloud provider + folder ids, keep-photos-locally, stale-lock timeout, estimated-refund toggle.

ios/Runner.xcodeproj/project.pbxproj

@@ -441,7 +441,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
+				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = AppIcon;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";
@@ -498,7 +498,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
+				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = AppIcon;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";

ios/Runner/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -1,122 +1 @@
-{
-  "images" : [
-    {
-      "size" : "20x20",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-20x20@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "20x20",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-20x20@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-29x29@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-29x29@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-29x29@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-40x40@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-40x40@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "60x60",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-60x60@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "60x60",
-      "idiom" : "iphone",
-      "filename" : "Icon-App-60x60@3x.png",
-      "scale" : "3x"
-    },
-    {
-      "size" : "20x20",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-20x20@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "20x20",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-20x20@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-29x29@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "29x29",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-29x29@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-40x40@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "40x40",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-40x40@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "76x76",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-76x76@1x.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "76x76",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-76x76@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "83.5x83.5",
-      "idiom" : "ipad",
-      "filename" : "Icon-App-83.5x83.5@2x.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "1024x1024",
-      "idiom" : "ios-marketing",
-      "filename" : "Icon-App-1024x1024@1x.png",
-      "scale" : "1x"
-    }
-  ],
-  "info" : {
-    "version" : 1,
-    "author" : "xcode"
-  }
-}
+{"images":[{"size":"20x20","idiom":"iphone","filename":"Icon-App-20x20@2x.png","scale":"2x"},{"size":"20x20","idiom":"iphone","filename":"Icon-App-20x20@3x.png","scale":"3x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@1x.png","scale":"1x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@2x.png","scale":"2x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@3x.png","scale":"3x"},{"size":"40x40","idiom":"iphone","filename":"Icon-App-40x40@2x.png","scale":"2x"},{"size":"40x40","idiom":"iphone","filename":"Icon-App-40x40@3x.png","scale":"3x"},{"size":"57x57","idiom":"iphone","filename":"Icon-App-57x57@1x.png","scale":"1x"},{"size":"57x57","idiom":"iphone","filename":"Icon-App-57x57@2x.png","scale":"2x"},{"size":"60x60","idiom":"iphone","filename":"Icon-App-60x60@2x.png","scale":"2x"},{"size":"60x60","idiom":"iphone","filename":"Icon-App-60x60@3x.png","scale":"3x"},{"size":"20x20","idiom":"ipad","filename":"Icon-App-20x20@1x.png","scale":"1x"},{"size":"20x20","idiom":"ipad","filename":"Icon-App-20x20@2x.png","scale":"2x"},{"size":"29x29","idiom":"ipad","filename":"Icon-App-29x29@1x.png","scale":"1x"},{"size":"29x29","idiom":"ipad","filename":"Icon-App-29x29@2x.png","scale":"2x"},{"size":"40x40","idiom":"ipad","filename":"Icon-App-40x40@1x.png","scale":"1x"},{"size":"40x40","idiom":"ipad","filename":"Icon-App-40x40@2x.png","scale":"2x"},{"size":"50x50","idiom":"ipad","filename":"Icon-App-50x50@1x.png","scale":"1x"},{"size":"50x50","idiom":"ipad","filename":"Icon-App-50x50@2x.png","scale":"2x"},{"size":"72x72","idiom":"ipad","filename":"Icon-App-72x72@1x.png","scale":"1x"},{"size":"72x72","idiom":"ipad","filename":"Icon-App-72x72@2x.png","scale":"2x"},{"size":"76x76","idiom":"ipad","filename":"Icon-App-76x76@1x.png","scale":"1x"},{"size":"76x76","idiom":"ipad","filename":"Icon-App-76x76@2x.png","scale":"2x"},{"size":"83.5x83.5","idiom":"ipad","filename":"Icon-App-83.5x83.5@2x.png","scale":"2x"},{"size":"1024x1024","idiom":"ios-marketing","filename":"Icon-App-1024x1024@1x.png","scale":"1x"}],"info":{"version":1,"author":"xcode"}}

ios/Runner/Assets.xcassets/LaunchBackground.imageset/Contents.json

@@ -0,0 +1,22 @@
+{
+  "images" : [
+    {
+      "filename" : "background.png",
+      "idiom" : "universal"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "darkbackground.png",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ios/Runner/Assets.xcassets/LaunchImage.imageset/Contents.json

@@ -1,23 +1,56 @@
 {
   "images" : [
     {
-      "idiom" : "universal",
       "filename" : "LaunchImage.png",
+      "idiom" : "universal",
       "scale" : "1x"
     },
     {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "LaunchImageDark.png",
       "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
       "filename" : "LaunchImage@2x.png",
+      "idiom" : "universal",
       "scale" : "2x"
     },
     {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "LaunchImageDark@2x.png",
       "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
       "filename" : "LaunchImage@3x.png",
+      "idiom" : "universal",
+      "scale" : "3x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "LaunchImageDark@3x.png",
+      "idiom" : "universal",
       "scale" : "3x"
     }
   ],
   "info" : {
-    "version" : 1,
-    "author" : "xcode"
+    "author" : "xcode",
+    "version" : 1
   }
 }

ios/Runner/Base.lproj/LaunchScreen.storyboard

@@ -16,13 +16,19 @@
                     <view key="view" contentMode="scaleToFill" id="Ze5-6b-2t3">
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
-                            <imageView opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" image="LaunchImage" translatesAutoresizingMaskIntoConstraints="NO" id="YRO-k0-Ey4">
-                            </imageView>
+                            <imageView clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleToFill" image="LaunchBackground" translatesAutoresizingMaskIntoConstraints="NO" id="tWc-Dq-wcI"/>
+                            <imageView opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" image="LaunchImage" translatesAutoresizingMaskIntoConstraints="NO" id="YRO-k0-Ey4"></imageView>
                         </subviews>
                         <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                         <constraints>
-                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="centerX" secondItem="Ze5-6b-2t3" secondAttribute="centerX" id="1a2-6s-vTC"/>
-                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="centerY" secondItem="Ze5-6b-2t3" secondAttribute="centerY" id="4X2-HB-R7a"/>
+                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="leading" secondItem="Ze5-6b-2t3" secondAttribute="leading" id="3T2-ad-Qdv"/>
+                            <constraint firstItem="tWc-Dq-wcI" firstAttribute="bottom" secondItem="Ze5-6b-2t3" secondAttribute="bottom" id="RPx-PI-7Xg"/>
+                            <constraint firstItem="tWc-Dq-wcI" firstAttribute="top" secondItem="Ze5-6b-2t3" secondAttribute="top" id="SdS-ul-q2q"/>
+                            <constraint firstAttribute="trailing" secondItem="tWc-Dq-wcI" secondAttribute="trailing" id="Swv-Gf-Rwn"/>
+                            <constraint firstAttribute="trailing" secondItem="YRO-k0-Ey4" secondAttribute="trailing" id="TQA-XW-tRk"/>
+                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="bottom" secondItem="Ze5-6b-2t3" secondAttribute="bottom" id="duK-uY-Gun"/>
+                            <constraint firstItem="tWc-Dq-wcI" firstAttribute="leading" secondItem="Ze5-6b-2t3" secondAttribute="leading" id="kV7-tw-vXt"/>
+                            <constraint firstItem="YRO-k0-Ey4" firstAttribute="top" secondItem="Ze5-6b-2t3" secondAttribute="top" id="xPn-NY-SIU"/>
                         </constraints>
                     </view>
                 </viewController>
@@ -32,6 +38,7 @@
         </scene>
     </scenes>
     <resources>
-        <image name="LaunchImage" width="168" height="185"/>
+        <image name="LaunchImage" width="1024" height="1024"/>
+        <image name="LaunchBackground" width="1" height="1"/>
     </resources>
 </document>

ios/Runner/Info.plist

@@ -1,72 +1,118 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
-<dict>
-	<key>CADisableMinimumFrameDurationOnPhone</key>
-	<true/>
-	<key>CFBundleDevelopmentRegion</key>
-	<string>$(DEVELOPMENT_LANGUAGE)</string>
-	<key>NSCameraUsageDescription</key>
-	<string>Fuel Tax Tracker uses the camera to take photos of fuel receipts.</string>
-	<key>CFBundleDisplayName</key>
-	<string>Fuel Tax Tracker</string>
-	<key>CFBundleExecutable</key>
-	<string>$(EXECUTABLE_NAME)</string>
-	<key>CFBundleIdentifier</key>
-	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
-	<key>CFBundleInfoDictionaryVersion</key>
-	<string>6.0</string>
-	<key>CFBundleName</key>
-	<string>fuel_tax_tracker</string>
-	<key>CFBundlePackageType</key>
-	<string>APPL</string>
-	<key>CFBundleShortVersionString</key>
-	<string>$(FLUTTER_BUILD_NAME)</string>
-	<key>CFBundleSignature</key>
-	<string>????</string>
-	<key>CFBundleVersion</key>
-	<string>$(FLUTTER_BUILD_NUMBER)</string>
-	<key>LSRequiresIPhoneOS</key>
-	<true/>
-	<key>UIApplicationSceneManifest</key>
 	<dict>
-		<key>UIApplicationSupportsMultipleScenes</key>
-		<false/>
-		<key>UISceneConfigurations</key>
+		<key>CADisableMinimumFrameDurationOnPhone</key>
+		<true/>
+		<key>CFBundleDevelopmentRegion</key>
+		<string>$(DEVELOPMENT_LANGUAGE)</string>
+		<key>NSCameraUsageDescription</key>
+		<string>Fuel Tax Tracker uses the camera to take photos of fuel receipts.</string>
+		<key>NSPhotoLibraryUsageDescription</key>
+		<string>Fuel Tax Tracker uses your photo library so you can attach an existing photo of a fuel receipt.</string>
+		<key>CFBundleDisplayName</key>
+		<string>Receipt Tracker</string>
+		<key>CFBundleExecutable</key>
+		<string>$(EXECUTABLE_NAME)</string>
+		<key>CFBundleIdentifier</key>
+		<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+		<key>CFBundleInfoDictionaryVersion</key>
+		<string>6.0</string>
+		<key>CFBundleName</key>
+		<string>fuel_tax_tracker</string>
+		<key>CFBundlePackageType</key>
+		<string>APPL</string>
+		<key>CFBundleShortVersionString</key>
+		<string>$(FLUTTER_BUILD_NAME)</string>
+		<key>CFBundleSignature</key>
+		<string>????</string>
+		<key>CFBundleVersion</key>
+		<string>$(FLUTTER_BUILD_NUMBER)</string>
+		<key>LSRequiresIPhoneOS</key>
+		<true/>
+		<key>UIApplicationSceneManifest</key>
 		<dict>
-			<key>UIWindowSceneSessionRoleApplication</key>
-			<array>
-				<dict>
-					<key>UISceneClassName</key>
-					<string>UIWindowScene</string>
-					<key>UISceneConfigurationName</key>
-					<string>flutter</string>
-					<key>UISceneDelegateClassName</key>
-					<string>$(PRODUCT_MODULE_NAME).SceneDelegate</string>
-					<key>UISceneStoryboardFile</key>
-					<string>Main</string>
-				</dict>
-			</array>
+			<key>UIApplicationSupportsMultipleScenes</key>
+			<false/>
+			<key>UISceneConfigurations</key>
+			<dict>
+				<key>UIWindowSceneSessionRoleApplication</key>
+				<array>
+					<dict>
+						<key>UISceneClassName</key>
+						<string>UIWindowScene</string>
+						<key>UISceneConfigurationName</key>
+						<string>flutter</string>
+						<key>UISceneDelegateClassName</key>
+						<string>$(PRODUCT_MODULE_NAME).SceneDelegate</string>
+						<key>UISceneStoryboardFile</key>
+						<string>Main</string>
+					</dict>
+				</array>
+			</dict>
 		</dict>
+		<key>UIApplicationSupportsIndirectInputEvents</key>
+		<true/>
+		<key>UILaunchStoryboardName</key>
+		<string>LaunchScreen</string>
+		<key>UIMainStoryboardFile</key>
+		<string>Main</string>
+		<key>UISupportedInterfaceOrientations</key>
+		<array>
+			<string>UIInterfaceOrientationPortrait</string>
+			<string>UIInterfaceOrientationLandscapeLeft</string>
+			<string>UIInterfaceOrientationLandscapeRight</string>
+		</array>
+		<key>UISupportedInterfaceOrientations~ipad</key>
+		<array>
+			<string>UIInterfaceOrientationPortrait</string>
+			<string>UIInterfaceOrientationPortraitUpsideDown</string>
+			<string>UIInterfaceOrientationLandscapeLeft</string>
+			<string>UIInterfaceOrientationLandscapeRight</string>
+		</array>
+		<!-- Google Sign-In: required for the OAuth redirect to route back into
+	     the app, regardless of whether the client ID itself is set here or
+	     passed in Dart (see lib/services/drive_oauth_config.dart). Replace
+	     with your iOS OAuth client's REVERSED_CLIENT_ID from Google Cloud
+	     Console (reverse of the client ID, e.g.
+	     com.googleusercontent.apps.XXXXXXXXXXXX-yyyyyyyyyyyyyyyyyyyyyyyyyyyy). -->
+		<key>CFBundleURLTypes</key>
+		<array>
+			<dict>
+				<key>CFBundleTypeRole</key>
+				<string>Editor</string>
+				<key>CFBundleURLSchemes</key>
+				<array>
+					<string>com.googleusercontent.apps.TODO-REPLACE-WITH-REVERSED-CLIENT-ID</string>
+				</array>
+			</dict>
+			<!-- Dropbox & OneDrive OAuth redirects (flutter_web_auth_2). These
+		     scheme values must exactly match dropboxRedirectUri /
+		     oneDriveRedirectUri in lib/services/cloud_oauth_config.dart. -->
+			<dict>
+				<key>CFBundleTypeRole</key>
+				<string>Editor</string>
+				<key>CFBundleURLSchemes</key>
+				<array>
+					<string>mofueltaxback-dropbox</string>
+				</array>
+			</dict>
+			<dict>
+				<key>CFBundleTypeRole</key>
+				<string>Editor</string>
+				<key>CFBundleURLSchemes</key>
+				<array>
+					<string>mofueltaxback-onedrive</string>
+				</array>
+			</dict>
+		</array>
+		<key>UIStatusBarHidden</key>
+		<false/>
+		<!-- Google's official *test* AdMob App ID (safe to publish/commit —
+		     see https://developers.google.com/admob/flutter/test-ads). Swap
+		     for your own real AdMob App ID before shipping — see
+		     lib/services/ad_service.dart for the matching ad unit ID. -->
+		<key>GADApplicationIdentifier</key>
+		<string>ca-app-pub-3940256099942544~1458002511</string>
 	</dict>
-	<key>UIApplicationSupportsIndirectInputEvents</key>
-	<true/>
-	<key>UILaunchStoryboardName</key>
-	<string>LaunchScreen</string>
-	<key>UIMainStoryboardFile</key>
-	<string>Main</string>
-	<key>UISupportedInterfaceOrientations</key>
-	<array>
-		<string>UIInterfaceOrientationPortrait</string>
-		<string>UIInterfaceOrientationLandscapeLeft</string>
-		<string>UIInterfaceOrientationLandscapeRight</string>
-	</array>
-	<key>UISupportedInterfaceOrientations~ipad</key>
-	<array>
-		<string>UIInterfaceOrientationPortrait</string>
-		<string>UIInterfaceOrientationPortraitUpsideDown</string>
-		<string>UIInterfaceOrientationLandscapeLeft</string>
-		<string>UIInterfaceOrientationLandscapeRight</string>
-	</array>
-</dict>
 </plist>

lib/app_navigator.dart

@@ -0,0 +1,14 @@
+import 'package:flutter/material.dart';
+
+/// A stable handle on the app's navigator, for the few places that need to
+/// put something on screen from outside a widget's own build method:
+///
+///  - [AppState.onAdWatched]'s "remove ads for a year" upsell, which fires
+///    from deep inside a background sync rather than from a widget.
+///  - `showAdPlaceholder`, called by [AdService], which owns no
+///    [BuildContext] of its own (real ads are native overlays that never
+///    needed one).
+///
+/// Lives here rather than in `main.dart` so services and widgets can reach
+/// it without importing the app's entry point.
+final navigatorKey = GlobalKey<NavigatorState>();

lib/main.dart

@@ -1,8 +1,12 @@
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
-import 'screens/home_screen.dart';
+import 'app_navigator.dart';
+import 'screens/main_shell.dart';
+import 'screens/user_agreement_screen.dart';
 import 'services/app_state.dart';
+import 'theme/app_theme.dart';
+import 'widgets/ad_free_upsell_dialog.dart';
 
 void main() {
   runApp(const FuelTaxTrackerApp());
@@ -15,15 +19,21 @@ class FuelTaxTrackerApp extends StatelessWidget {
   Widget build(BuildContext context) {
     return ChangeNotifierProvider(
       create: (_) => AppState()..init(),
-      child: MaterialApp(
-        title: 'Fuel Tax Tracker',
-        theme: ThemeData(colorSchemeSeed: Colors.indigo, useMaterial3: true),
-        darkTheme: ThemeData(
-          colorSchemeSeed: Colors.indigo,
-          brightness: Brightness.dark,
-          useMaterial3: true,
-        ),
-        home: const AppRoot(),
+      child: Consumer<AppState>(
+        builder: (context, appState, _) {
+          appState.onAdWatched ??= () {
+            final dialogContext = navigatorKey.currentContext;
+            if (dialogContext != null) showAdFreeUpsellDialog(dialogContext);
+          };
+          return MaterialApp(
+            navigatorKey: navigatorKey,
+            title: 'Receipt Tracker',
+            theme: AppTheme.light,
+            darkTheme: AppTheme.dark,
+            themeMode: appState.themeMode,
+            home: const AppRoot(),
+          );
+        },
       ),
     );
   }
@@ -41,7 +51,36 @@ class AppRoot extends StatelessWidget {
             body: Center(child: CircularProgressIndicator()),
           );
         }
-        return const HomeScreen();
+        if (appState.initError != null) {
+          return Scaffold(
+            body: Center(
+              child: Padding(
+                padding: const EdgeInsets.all(24),
+                child: Column(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    Icon(Icons.error_outline,
+                        size: 48, color: Theme.of(context).colorScheme.error),
+                    const SizedBox(height: 16),
+                    Text(
+                      'Could not start the app:\n${appState.initError}',
+                      textAlign: TextAlign.center,
+                    ),
+                    const SizedBox(height: 16),
+                    FilledButton(
+                      onPressed: () => appState.init(),
+                      child: const Text('Retry'),
+                    ),
+                  ],
+                ),
+              ),
+            ),
+          );
+        }
+        if (!appState.hasAcceptedUserAgreement) {
+          return const UserAgreementScreen();
+        }
+        return const MainShell();
       },
     );
   }

lib/models/fuel_entry.dart

@@ -1,11 +1,21 @@
 class FuelEntry {
   final String id;
+
+  /// References [Vehicle.id] (the hidden, immutable identifier) — not the
+  /// VIN, which is user-editable and so unsuitable as a foreign key.
   final String vehicleId;
+
   final DateTime date;
   final double gallons;
   final double pricePerGallon;
   final double totalCost;
   final String? receiptImagePath;
+  final String? receiptDriveFileId;
+  final DateTime updatedAt;
+
+  /// Soft-delete tombstone: null means active. See [Vehicle.deletedAt] for
+  /// why this is a flag rather than an actual row deletion.
+  final DateTime? deletedAt;
 
   FuelEntry({
     required this.id,
@@ -14,26 +24,75 @@ class FuelEntry {
     required this.gallons,
     required this.pricePerGallon,
     required this.totalCost,
+    required this.updatedAt,
     this.receiptImagePath,
+    this.receiptDriveFileId,
+    this.deletedAt,
   });
 
-  Map<String, dynamic> toJson() => {
+  /// True once the receipt photo has been uploaded to Drive, regardless of
+  /// whether a local copy is also being kept (see the "keep photos on this
+  /// phone" setting). Viewing it locally is preferred when a local copy
+  /// exists; otherwise it requires downloading from Drive on demand.
+  bool get isReceiptUploadedToDrive => receiptDriveFileId != null;
+
+  /// True while a receipt photo still needs to be uploaded to Drive: a
+  /// local file exists but hasn't made it there yet. Once
+  /// [receiptDriveFileId] is set this is false — even if a local copy is
+  /// also being kept — since that field alone is what marks "no longer
+  /// needs uploading", independent of local retention. A row in this state
+  /// is never pushed to Drive as data (a local file path is meaningless on
+  /// another device) — sync uploads the image first, which sets
+  /// [receiptDriveFileId] and clears this.
+  bool get needsReceiptUpload => receiptImagePath != null && receiptDriveFileId == null;
+
+  FuelEntry copyWith({
+    String? receiptImagePath,
+    String? receiptDriveFileId,
+    DateTime? updatedAt,
+    DateTime? deletedAt,
+    bool clearReceiptImagePath = false,
+  }) {
+    return FuelEntry(
+      id: id,
+      vehicleId: vehicleId,
+      date: date,
+      gallons: gallons,
+      pricePerGallon: pricePerGallon,
+      totalCost: totalCost,
+      updatedAt: updatedAt ?? this.updatedAt,
+      receiptImagePath:
+          clearReceiptImagePath ? null : (receiptImagePath ?? this.receiptImagePath),
+      receiptDriveFileId: receiptDriveFileId ?? this.receiptDriveFileId,
+      deletedAt: deletedAt ?? this.deletedAt,
+    );
+  }
+
+  Map<String, Object?> toMap() => {
         'id': id,
-        'vehicleId': vehicleId,
-        'date': date.toIso8601String(),
+        'vehicle_id': vehicleId,
+        'date': date.millisecondsSinceEpoch,
         'gallons': gallons,
-        'pricePerGallon': pricePerGallon,
-        'totalCost': totalCost,
-        'receiptImagePath': receiptImagePath,
+        'price_per_gallon': pricePerGallon,
+        'total_cost': totalCost,
+        'receipt_image_path': receiptImagePath,
+        'receipt_drive_file_id': receiptDriveFileId,
+        'updated_at': updatedAt.millisecondsSinceEpoch,
+        'deleted_at': deletedAt?.millisecondsSinceEpoch,
       };
 
-  factory FuelEntry.fromJson(Map<String, dynamic> json) => FuelEntry(
-        id: json['id'] as String,
-        vehicleId: json['vehicleId'] as String,
-        date: DateTime.parse(json['date'] as String),
-        gallons: (json['gallons'] as num).toDouble(),
-        pricePerGallon: (json['pricePerGallon'] as num).toDouble(),
-        totalCost: (json['totalCost'] as num).toDouble(),
-        receiptImagePath: json['receiptImagePath'] as String?,
+  factory FuelEntry.fromMap(Map<String, Object?> map) => FuelEntry(
+        id: map['id'] as String,
+        vehicleId: map['vehicle_id'] as String,
+        date: DateTime.fromMillisecondsSinceEpoch(map['date'] as int),
+        gallons: (map['gallons'] as num).toDouble(),
+        pricePerGallon: (map['price_per_gallon'] as num).toDouble(),
+        totalCost: (map['total_cost'] as num).toDouble(),
+        receiptImagePath: map['receipt_image_path'] as String?,
+        receiptDriveFileId: map['receipt_drive_file_id'] as String?,
+        updatedAt: DateTime.fromMillisecondsSinceEpoch(map['updated_at'] as int, isUtc: true),
+        deletedAt: map['deleted_at'] != null
+            ? DateTime.fromMillisecondsSinceEpoch(map['deleted_at'] as int, isUtc: true)
+            : null,
       );
 }

lib/models/vehicle.dart

@@ -1,48 +1,79 @@
 class Vehicle {
+  /// Hidden, immutable, generated primary key — never shown in the UI and
+  /// never editable. This is what fuel entries actually reference and what
+  /// sync merges on, so that [vin] itself is free to be edited without
+  /// breaking those references or losing sync history.
   final String id;
-  final String make;
-  final String model;
-  final String color;
-  final String licensePlate;
+
+  /// The vehicle's identification number. Required and must be unique
+  /// among active (non-deleted) vehicles, but — unlike [id] — the user can
+  /// edit it later (e.g. to fix a typo from a misread VIN scan).
+  final String vin;
+
+  /// User-chosen label, e.g. "Mom's Car" or "Red Ford F-150". Optional —
+  /// when absent, screens fall back to other identifying info instead.
+  final String? nickname;
+
+  final DateTime updatedAt;
+
+  /// Soft-delete tombstone: null means active. Deleting sets this instead
+  /// of removing the row, so the deletion itself can be merged/synced like
+  /// any other change (newest `updatedAt` wins) instead of silently
+  /// disappearing and later being resurrected by a device that hasn't seen
+  /// the deletion yet.
+  final DateTime? deletedAt;
 
   Vehicle({
     required this.id,
-    required this.make,
-    required this.model,
-    required this.color,
-    required this.licensePlate,
+    required this.vin,
+    required this.updatedAt,
+    this.nickname,
+    this.deletedAt,
   });
 
-  String get displayName => '$color $make $model ($licensePlate)';
+  /// What screens should show as the vehicle's primary label: the nickname
+  /// if one was given, otherwise the VIN itself.
+  String get displayLabel {
+    final trimmedNickname = nickname?.trim();
+    if (trimmedNickname != null && trimmedNickname.isNotEmpty) {
+      return trimmedNickname;
+    }
+    return vin;
+  }
 
+  /// Note: [id] is intentionally not overridable here — it's the hidden
+  /// identifier, not an editable field.
   Vehicle copyWith({
-    String? make,
-    String? model,
-    String? color,
-    String? licensePlate,
+    String? vin,
+    String? nickname,
+    bool clearNickname = false,
+    DateTime? updatedAt,
+    DateTime? deletedAt,
   }) {
     return Vehicle(
       id: id,
-      make: make ?? this.make,
-      model: model ?? this.model,
-      color: color ?? this.color,
-      licensePlate: licensePlate ?? this.licensePlate,
+      vin: vin ?? this.vin,
+      nickname: clearNickname ? null : (nickname ?? this.nickname),
+      updatedAt: updatedAt ?? this.updatedAt,
+      deletedAt: deletedAt ?? this.deletedAt,
     );
   }
 
-  Map<String, dynamic> toJson() => {
+  Map<String, Object?> toMap() => {
         'id': id,
-        'make': make,
-        'model': model,
-        'color': color,
-        'licensePlate': licensePlate,
+        'vin': vin,
+        'nickname': nickname,
+        'updated_at': updatedAt.millisecondsSinceEpoch,
+        'deleted_at': deletedAt?.millisecondsSinceEpoch,
       };
 
-  factory Vehicle.fromJson(Map<String, dynamic> json) => Vehicle(
-        id: json['id'] as String,
-        make: json['make'] as String,
-        model: json['model'] as String,
-        color: json['color'] as String,
-        licensePlate: json['licensePlate'] as String,
+  factory Vehicle.fromMap(Map<String, Object?> map) => Vehicle(
+        id: map['id'] as String,
+        vin: map['vin'] as String,
+        nickname: map['nickname'] as String?,
+        updatedAt: DateTime.fromMillisecondsSinceEpoch(map['updated_at'] as int, isUtc: true),
+        deletedAt: map['deleted_at'] != null
+            ? DateTime.fromMillisecondsSinceEpoch(map['deleted_at'] as int, isUtc: true)
+            : null,
       );
 }

lib/screens/add_edit_vehicle_screen.dart

@@ -1,15 +1,30 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
+import 'package:image_picker/image_picker.dart';
 import 'package:provider/provider.dart';
 
 import '../models/vehicle.dart';
 import '../services/app_state.dart';
+import '../services/ocr_service.dart';
+import '../services/vin_parser.dart';
+import '../widgets/image_source_sheet.dart';
+import 'vehicle_detail_screen.dart';
 
 /// Add/edit form for a vehicle. Pass an existing [vehicle] to edit it, or
-/// omit it to create a new one.
+/// omit it to create a new one. [promptToCreateForReceipt] is set when this
+/// screen was reached because the user tried to log a receipt with no
+/// vehicle to attach it to yet — it shows an explanatory dialog on arrival
+/// so that's clear, rather than silently landing on the add-vehicle form.
 class AddEditVehicleScreen extends StatefulWidget {
   final Vehicle? vehicle;
+  final bool promptToCreateForReceipt;
 
-  const AddEditVehicleScreen({super.key, this.vehicle});
+  const AddEditVehicleScreen({
+    super.key,
+    this.vehicle,
+    this.promptToCreateForReceipt = false,
+  });
 
   @override
   State<AddEditVehicleScreen> createState() => _AddEditVehicleScreenState();
@@ -17,52 +32,249 @@ class AddEditVehicleScreen extends StatefulWidget {
 
 class _AddEditVehicleScreenState extends State<AddEditVehicleScreen> {
   final _formKey = GlobalKey<FormState>();
-  late final TextEditingController _makeController;
-  late final TextEditingController _modelController;
-  late final TextEditingController _colorController;
-  late final TextEditingController _plateController;
+  late final TextEditingController _nicknameController;
+  late final TextEditingController _vinController;
+
+  bool _saving = false;
+  bool _scanningVin = false;
+  bool _checkingDuplicateVin = false;
+  String? _error;
 
   bool get _isEditing => widget.vehicle != null;
 
   @override
   void initState() {
     super.initState();
-    _makeController = TextEditingController(text: widget.vehicle?.make ?? '');
-    _modelController = TextEditingController(text: widget.vehicle?.model ?? '');
-    _colorController = TextEditingController(text: widget.vehicle?.color ?? '');
-    _plateController = TextEditingController(text: widget.vehicle?.licensePlate ?? '');
+    _nicknameController = TextEditingController(text: widget.vehicle?.nickname ?? '');
+    _vinController = TextEditingController(text: widget.vehicle?.vin ?? '');
+
+    if (widget.promptToCreateForReceipt) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        if (!mounted) return;
+        showDialog<void>(
+          context: context,
+          builder: (context) => AlertDialog(
+            content: const Text('Create a vehicle to attach receipt'),
+            actions: [
+              TextButton(
+                onPressed: () => Navigator.of(context).pop(),
+                child: const Text('OK'),
+              ),
+            ],
+          ),
+        );
+      });
+    }
   }
 
   @override
   void dispose() {
-    _makeController.dispose();
-    _modelController.dispose();
-    _colorController.dispose();
-    _plateController.dispose();
+    _nicknameController.dispose();
+    _vinController.dispose();
     super.dispose();
   }
 
+  void _showVinLocationHelp() {
+    showDialog<void>(
+      context: context,
+      builder: (context) => AlertDialog(
+        title: const Text('Where to find the VIN'),
+        content: SingleChildScrollView(
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              const Text(
+                "It's usually on a sticker in the driver's side door jamb, or on a "
+                'small plate at the base of the windshield.',
+              ),
+              const SizedBox(height: 16),
+              ClipRRect(
+                borderRadius: BorderRadius.circular(8),
+                child: Image.asset('assets/vin_help/door_jamb.jpg'),
+              ),
+              const SizedBox(height: 12),
+              ClipRRect(
+                borderRadius: BorderRadius.circular(8),
+                child: Image.asset('assets/vin_help/windshield.jpg'),
+              ),
+            ],
+          ),
+        ),
+        actions: [
+          TextButton(onPressed: () => Navigator.of(context).pop(), child: const Text('Close')),
+        ],
+      ),
+    );
+  }
+
+  Future<void> _scanVin() async {
+    final source = await chooseImageSource(
+      context,
+      heading: 'VIN From',
+      onInfoTap: _showVinLocationHelp,
+    );
+    if (source == null || !mounted) return;
+
+    final picker = ImagePicker();
+    XFile? photo;
+    try {
+      photo = await picker.pickImage(source: source, imageQuality: 85);
+    } catch (e) {
+      if (mounted) {
+        final sourceLabel = source == ImageSource.camera ? 'camera' : 'photo library';
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('Could not open $sourceLabel: $e')),
+        );
+      }
+      return;
+    }
+    if (photo == null) return;
+
+    setState(() => _scanningVin = true);
+
+    final ocrService = OcrService();
+    String recognizedText = '';
+    try {
+      recognizedText = await ocrService.recognizeText(File(photo.path));
+    } catch (_) {
+      recognizedText = '';
+    } finally {
+      ocrService.dispose();
+    }
+
+    if (!mounted) return;
+
+    final vin = VinParser.parse(recognizedText);
+    setState(() => _scanningVin = false);
+
+    if (vin != null) {
+      _vinController.text = vin;
+      await _checkForExistingVin();
+    } else if (mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: const Text("Couldn't read a VIN from that photo. Please enter it manually."),
+          duration: const Duration(seconds: 8),
+          action: recognizedText.trim().isEmpty
+              ? null
+              // Lets you see exactly what the on-device OCR read, rather
+              // than only knowing "no VIN was found in it" — the
+              // difference between "OCR misread a character" and "OCR
+              // read it fine but the VIN pattern itself needs a fix"
+              // isn't visible any other way.
+              : SnackBarAction(label: 'Show Text', onPressed: () => _showRecognizedText(recognizedText)),
+        ),
+      );
+    }
+  }
+
+  void _showRecognizedText(String text) {
+    showDialog<void>(
+      context: context,
+      builder: (context) => AlertDialog(
+        title: const Text('Recognized Text'),
+        content: SingleChildScrollView(child: SelectableText(text)),
+        actions: [
+          TextButton(onPressed: () => Navigator.of(context).pop(), child: const Text('Close')),
+        ],
+      ),
+    );
+  }
+
+  /// Field-level counterpart to [_checkForExistingVin]'s dialog: catches
+  /// "Required" as before, plus flags the field itself as invalid when the
+  /// VIN belongs to another active vehicle — excluding this vehicle's own
+  /// id while editing, same as [AppState.updateVehicle]'s check, so editing
+  /// a vehicle without touching its VIN doesn't flag itself.
+  String? _validateVin(String? value) {
+    final vin = value?.trim() ?? '';
+    if (vin.isEmpty) return 'Required';
+
+    final existing = context.read<AppState>().vehicleByVin(vin);
+    if (existing != null && existing.id != widget.vehicle?.id) {
+      return 'A vehicle with VIN "$vin" already exists.';
+    }
+    return null;
+  }
+
+  /// Only relevant when adding a new vehicle — editing one already starts
+  /// with its own VIN pre-filled, which would trivially "match itself".
+  /// Guarded against overlapping calls so rapid edits (or the scan-fill
+  /// path firing right after `onChanged`) can't stack multiple dialogs.
+  Future<void> _checkForExistingVin() async {
+    if (_isEditing || _checkingDuplicateVin) return;
+
+    final vin = _vinController.text.trim();
+    if (vin.isEmpty) return;
+    final existing = context.read<AppState>().vehicleByVin(vin);
+    if (existing == null) return;
+
+    _checkingDuplicateVin = true;
+    final openExisting = await showDialog<bool>(
+      context: context,
+      builder: (context) => AlertDialog(
+        title: const Text('Vehicle already exists'),
+        content: Text('Vehicle with the VIN $vin already exists, would you like to open that vehicle?'),
+        actions: [
+          TextButton(onPressed: () => Navigator.of(context).pop(false), child: const Text('No')),
+          TextButton(onPressed: () => Navigator.of(context).pop(true), child: const Text('Yes')),
+        ],
+      ),
+    );
+    _checkingDuplicateVin = false;
+    if (!mounted) return;
+
+    if (openExisting != true) {
+      // Declining to open the existing vehicle leaves them here with a
+      // still-duplicate VIN — surface that on the field itself rather than
+      // only catching it later at Save.
+      _formKey.currentState?.validate();
+      return;
+    }
+
+    Navigator.of(context)
+      ..pop()
+      ..push(MaterialPageRoute(builder: (_) => VehicleDetailScreen(vehicleId: existing.id)));
+  }
+
   Future<void> _save() async {
     if (!_formKey.currentState!.validate()) return;
 
-    final appState = context.read<AppState>();
-    if (_isEditing) {
-      await appState.updateVehicle(widget.vehicle!.copyWith(
-        make: _makeController.text.trim(),
-        model: _modelController.text.trim(),
-        color: _colorController.text.trim(),
-        licensePlate: _plateController.text.trim(),
-      ));
-    } else {
-      await appState.addVehicle(
-        make: _makeController.text.trim(),
-        model: _modelController.text.trim(),
-        color: _colorController.text.trim(),
-        licensePlate: _plateController.text.trim(),
-      );
-    }
+    setState(() {
+      _saving = true;
+      _error = null;
+    });
 
-    if (mounted) Navigator.of(context).pop();
+    final vin = _vinController.text.trim();
+    final nickname = _nicknameController.text.trim();
+    final appState = context.read<AppState>();
+
+    try {
+      if (_isEditing) {
+        await appState.updateVehicle(widget.vehicle!.copyWith(
+          vin: vin,
+          nickname: nickname.isEmpty ? null : nickname,
+          clearNickname: nickname.isEmpty,
+        ));
+      } else {
+        await appState.addVehicle(vin: vin, nickname: nickname.isEmpty ? null : nickname);
+      }
+
+      if (mounted) {
+        // Reached from "log a receipt with no vehicle yet" — once the
+        // vehicle exists, continue straight into the receipt capture flow
+        // the user was actually trying to do, rather than just landing
+        // back on an (again) empty Receipts tab. The caller does the
+        // continuing; this just hands back which vehicle to do it for.
+        final continueToReceipt = !_isEditing && widget.promptToCreateForReceipt;
+        Navigator.of(context).pop(continueToReceipt ? appState.vehicleByVin(vin)?.id : null);
+      }
+    } on DuplicateVinException catch (e) {
+      setState(() => _error = e.toString());
+    } finally {
+      if (mounted) setState(() => _saving = false);
+    }
   }
 
   Future<void> _confirmDelete() async {
@@ -72,7 +284,7 @@ class _AddEditVehicleScreenState extends State<AddEditVehicleScreen> {
         title: const Text('Delete vehicle?'),
         content: Text(
           'This will also delete all fuel entries and receipt photos logged for '
-          '${widget.vehicle!.displayName}. This cannot be undone.',
+          '${widget.vehicle!.displayLabel}. This cannot be undone.',
         ),
         actions: [
           TextButton(onPressed: () => Navigator.of(context).pop(false), child: const Text('Cancel')),
@@ -114,36 +326,49 @@ class _AddEditVehicleScreenState extends State<AddEditVehicleScreen> {
           padding: const EdgeInsets.all(16),
           children: [
             TextFormField(
-              controller: _makeController,
-              decoration: const InputDecoration(labelText: 'Make', hintText: 'e.g. Ford'),
+              controller: _nicknameController,
+              decoration: const InputDecoration(
+                labelText: 'Nickname (optional)',
+                hintText: 'e.g. Mom\'s Car, Red Ford F-150',
+              ),
               textCapitalization: TextCapitalization.words,
-              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
             ),
             const SizedBox(height: 12),
             TextFormField(
-              controller: _modelController,
-              decoration: const InputDecoration(labelText: 'Model', hintText: 'e.g. F-150'),
-              textCapitalization: TextCapitalization.words,
-              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
-            ),
-            const SizedBox(height: 12),
-            TextFormField(
-              controller: _colorController,
-              decoration: const InputDecoration(labelText: 'Color', hintText: 'e.g. Red'),
-              textCapitalization: TextCapitalization.words,
-              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
-            ),
-            const SizedBox(height: 12),
-            TextFormField(
-              controller: _plateController,
-              decoration: const InputDecoration(labelText: 'License Plate'),
+              controller: _vinController,
+              decoration: InputDecoration(
+                labelText: 'VIN *',
+                hintText: 'Vehicle Identification Number',
+                helperText: 'Required — tap the camera to scan it from a photo',
+                suffixIcon: _scanningVin
+                    ? const Padding(
+                        padding: EdgeInsets.all(12),
+                        child: SizedBox(
+                          height: 20,
+                          width: 20,
+                          child: CircularProgressIndicator(strokeWidth: 2),
+                        ),
+                      )
+                    : IconButton(
+                        icon: const Icon(Icons.camera_alt_outlined),
+                        tooltip: 'Scan VIN from a photo',
+                        onPressed: _scanVin,
+                      ),
+              ),
               textCapitalization: TextCapitalization.characters,
-              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
+              validator: _validateVin,
+              onChanged: _isEditing ? null : (_) => _checkForExistingVin(),
             ),
+            if (_error != null) ...[
+              const SizedBox(height: 12),
+              Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
+            ],
             const SizedBox(height: 24),
             FilledButton(
-              onPressed: _save,
-              child: Text(_isEditing ? 'Save Changes' : 'Add Vehicle'),
+              onPressed: _saving ? null : _save,
+              child: _saving
+                  ? const SizedBox(height: 20, width: 20, child: CircularProgressIndicator(strokeWidth: 2))
+                  : Text(_isEditing ? 'Save Changes' : 'Add Vehicle'),
             ),
           ],
         ),

lib/screens/cloud_folder_browser_screen.dart

@@ -0,0 +1,229 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../services/app_state.dart';
+import '../services/cloud/cloud_storage_provider.dart';
+
+enum _BrowseRoot { myFiles, sharedWithMe }
+
+/// Lets the user navigate whichever cloud storage provider is connected —
+/// their own files, and (if the provider supports it) files others have
+/// shared with them — and pick a parent location. Confirming looks for (or
+/// creates) the `Show Me The Fuel Refund` folder under that location, so
+/// two people pointing at the same shared parent converge on the same app
+/// folder, regardless of which provider each of them is using. Picking a
+/// folder that's already named that directly (e.g. a shared folder set up
+/// by someone else) uses it as-is instead of nesting another one inside —
+/// see `CloudSyncService.selectAppFolder`.
+class CloudFolderBrowserScreen extends StatefulWidget {
+  const CloudFolderBrowserScreen({super.key});
+
+  @override
+  State<CloudFolderBrowserScreen> createState() => _CloudFolderBrowserScreenState();
+}
+
+class _CloudFolderBrowserScreenState extends State<CloudFolderBrowserScreen> {
+  late final CloudStorageSession _session;
+
+  _BrowseRoot _root = _BrowseRoot.myFiles;
+  final List<CloudFolder> _pathStack = [];
+
+  List<CloudFolder>? _folders;
+  bool _loading = true;
+  String? _error;
+  bool _confirming = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _session = context.read<AppState>().activeProvider!.beginSession();
+    _load();
+  }
+
+  @override
+  void dispose() {
+    _session.close();
+    super.dispose();
+  }
+
+  String get _rootLabel => _root == _BrowseRoot.myFiles ? 'My Files' : 'Shared with me';
+
+  /// The folder ID that "Use This Folder" would act on, or null if the
+  /// current view is a virtual listing (top-level "Shared with me") rather
+  /// than an actual folder.
+  String? get _currentFolderId {
+    if (_pathStack.isNotEmpty) return _pathStack.last.id;
+    if (_root == _BrowseRoot.myFiles) return 'root';
+    return null;
+  }
+
+  /// The currently browsed-into folder's own name, so [_useThisFolder] can
+  /// tell whether the user picked a folder already named
+  /// `Show Me The Fuel Refund` — null at a virtual root ("My Files"),
+  /// which is never itself named that.
+  String? get _currentFolderName => _pathStack.isNotEmpty ? _pathStack.last.name : null;
+
+  String get _breadcrumbPath =>
+      ([_rootLabel] + _pathStack.map((f) => f.name).toList()).join(' / ');
+
+  Future<void> _load() async {
+    setState(() {
+      _loading = true;
+      _error = null;
+    });
+
+    try {
+      List<CloudFolder> folders;
+      if (_pathStack.isNotEmpty) {
+        folders = await _session.listFolders(parentId: _pathStack.last.id);
+      } else if (_root == _BrowseRoot.myFiles) {
+        folders = await _session.listFolders(parentId: 'root');
+      } else {
+        folders = await _session.listFolders(sharedWithMe: true);
+      }
+      if (!mounted) return;
+      setState(() {
+        _folders = folders;
+        _loading = false;
+      });
+    } catch (e) {
+      if (!mounted) return;
+      setState(() {
+        _error = 'Could not load folders: $e';
+        _loading = false;
+      });
+    }
+  }
+
+  void _switchRoot(_BrowseRoot root) {
+    if (root == _root) return;
+    setState(() {
+      _root = root;
+      _pathStack.clear();
+    });
+    _load();
+  }
+
+  void _openFolder(CloudFolder folder) {
+    setState(() => _pathStack.add(folder));
+    _load();
+  }
+
+  void _goToBreadcrumb(int index) {
+    // index == -1 means the root label itself.
+    setState(() {
+      if (index < 0) {
+        _pathStack.clear();
+      } else {
+        _pathStack.removeRange(index + 1, _pathStack.length);
+      }
+    });
+    _load();
+  }
+
+  Future<void> _useThisFolder() async {
+    final parentId = _currentFolderId;
+    if (parentId == null) return;
+
+    setState(() => _confirming = true);
+    try {
+      await context.read<AppState>().chooseCloudFolder(
+            parentId: parentId,
+            breadcrumbPath: _breadcrumbPath,
+            currentFolderName: _currentFolderName,
+          );
+      if (mounted) Navigator.of(context).pop();
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('Could not use this folder: $e')),
+        );
+      }
+    } finally {
+      if (mounted) setState(() => _confirming = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final providerName = context.read<AppState>().activeProvider!.displayName;
+    final canUseCurrentFolder = _currentFolderId != null;
+
+    return Scaffold(
+      appBar: AppBar(title: Text('Choose $providerName Folder')),
+      body: Column(
+        children: [
+          if (_session.supportsSharedWithMe)
+            SegmentedButton<_BrowseRoot>(
+              segments: const [
+                ButtonSegment(value: _BrowseRoot.myFiles, label: Text('My Files')),
+                ButtonSegment(value: _BrowseRoot.sharedWithMe, label: Text('Shared with me')),
+              ],
+              selected: {_root},
+              onSelectionChanged: (selection) => _switchRoot(selection.first),
+            ),
+          Padding(
+            padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+            child: SingleChildScrollView(
+              scrollDirection: Axis.horizontal,
+              child: Row(
+                children: [
+                  TextButton(
+                    onPressed: () => _goToBreadcrumb(-1),
+                    child: Text(_rootLabel),
+                  ),
+                  for (var i = 0; i < _pathStack.length; i++) ...[
+                    const Icon(Icons.chevron_right, size: 18),
+                    TextButton(
+                      onPressed: () => _goToBreadcrumb(i),
+                      child: Text(_pathStack[i].name),
+                    ),
+                  ],
+                ],
+              ),
+            ),
+          ),
+          const Divider(height: 1),
+          Expanded(child: _buildBody()),
+        ],
+      ),
+      bottomNavigationBar: SafeArea(
+        child: Padding(
+          padding: const EdgeInsets.all(16),
+          child: FilledButton.icon(
+            onPressed: (!canUseCurrentFolder || _confirming) ? null : _useThisFolder,
+            icon: _confirming
+                ? const SizedBox(height: 16, width: 16, child: CircularProgressIndicator(strokeWidth: 2))
+                : const Icon(Icons.check),
+            label: Text('Use "$_breadcrumbPath"'),
+          ),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildBody() {
+    if (_loading) {
+      return const Center(child: CircularProgressIndicator());
+    }
+    if (_error != null) {
+      return Center(child: Padding(padding: const EdgeInsets.all(24), child: Text(_error!)));
+    }
+    final folders = _folders ?? [];
+    if (folders.isEmpty) {
+      return const Center(child: Text('No folders here.'));
+    }
+    return ListView.builder(
+      itemCount: folders.length,
+      itemBuilder: (context, index) {
+        final folder = folders[index];
+        return ListTile(
+          leading: const Icon(Icons.folder_outlined),
+          title: Text(folder.name),
+          trailing: const Icon(Icons.chevron_right),
+          onTap: () => _openFolder(folder),
+        );
+      },
+    );
+  }
+}

lib/screens/confirm_fuel_entry_screen.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:io';
 
 import 'package:flutter/material.dart';
@@ -6,6 +7,7 @@ import 'package:provider/provider.dart';
 
 import '../services/app_state.dart';
 import '../services/receipt_parser.dart';
+import '../widgets/backup_reminder.dart';
 import 'receipt_image_screen.dart';
 
 /// Shown right after a receipt photo is captured and OCR'd. Pre-fills
@@ -33,12 +35,16 @@ class _ConfirmFuelEntryScreenState extends State<ConfirmFuelEntryScreen> {
   late final TextEditingController _gallonsController;
   late final TextEditingController _priceController;
   late final TextEditingController _totalController;
-  DateTime _date = DateTime.now();
+  late DateTime _date;
   bool _saving = false;
 
   @override
   void initState() {
     super.initState();
+    // Prefer the date/time printed on the receipt; fall back to now, same
+    // as before, when it couldn't be parsed — the date picker below is
+    // always available either way for manual entry/correction.
+    _date = widget.parsed.date ?? DateTime.now();
     _gallonsController = TextEditingController(
       text: widget.parsed.gallons?.toStringAsFixed(3) ?? '',
     );
@@ -48,6 +54,8 @@ class _ConfirmFuelEntryScreenState extends State<ConfirmFuelEntryScreen> {
     _totalController = TextEditingController(
       text: widget.parsed.totalCost?.toStringAsFixed(2) ?? '',
     );
+    // So an ad is ready by the time _save() finishes without delaying it.
+    context.read<AppState>().preloadFuelSaveAd();
   }
 
   @override
@@ -69,11 +77,20 @@ class _ConfirmFuelEntryScreenState extends State<ConfirmFuelEntryScreen> {
   }
 
   Future<void> _pickDate() async {
+    // initialDate must fall within [firstDate, lastDate] or the picker
+    // throws — widen the bounds to cover _date in case a misread date from
+    // the receipt landed outside the normal 5-years-back-to-today window.
+    final today = DateTime.now();
+    final firstDate = _date.isBefore(today.subtract(const Duration(days: 365 * 5)))
+        ? _date
+        : today.subtract(const Duration(days: 365 * 5));
+    final lastDate = _date.isAfter(today) ? _date : today;
+
     final pickedDate = await showDatePicker(
       context: context,
       initialDate: _date,
-      firstDate: DateTime.now().subtract(const Duration(days: 365 * 5)),
-      lastDate: DateTime.now(),
+      firstDate: firstDate,
+      lastDate: lastDate,
     );
     if (pickedDate == null || !mounted) return;
 
@@ -99,7 +116,8 @@ class _ConfirmFuelEntryScreenState extends State<ConfirmFuelEntryScreen> {
 
     setState(() => _saving = true);
     try {
-      await context.read<AppState>().addFuelEntry(
+      final appState = context.read<AppState>();
+      await appState.addFuelEntry(
             vehicleId: widget.vehicleId,
             date: _date,
             gallons: double.parse(_gallonsController.text),
@@ -107,7 +125,31 @@ class _ConfirmFuelEntryScreenState extends State<ConfirmFuelEntryScreen> {
             totalCost: double.parse(_totalController.text),
             receiptImage: widget.imageFile,
           );
-      if (mounted) Navigator.of(context).pop();
+      if (!mounted) return;
+
+      // The entry is already committed by this point, so the ad isn't
+      // gating the save — it just fills the moment between saving and
+      // landing back on the list. Awaited rather than fired off, so the
+      // two don't race and the ad can't end up drawn over the Receipts
+      // tab after this screen has gone.
+      final adShown = await appState.maybeShowFuelSaveAd();
+      if (!mounted) return;
+
+      // Ask while this screen (and its context) is still fully alive,
+      // before popping — simpler than trying to show a dialog against a
+      // context whose widget is mid-removal. Held back when an ad just
+      // ran: one full-screen surface per save, and the reminder comes
+      // back around on the next save anyway.
+      var wantsBackupSetup = false;
+      if (!adShown && !appState.hasCloudBackupConfigured) {
+        wantsBackupSetup = await showBackupReminderDialog(context);
+        if (!mounted) return;
+      }
+
+      Navigator.of(context).pop();
+      if (wantsBackupSetup) {
+        unawaited(openCloudBackupSetup(context));
+      }
     } finally {
       if (mounted) setState(() => _saving = false);
     }
@@ -136,7 +178,7 @@ class _ConfirmFuelEntryScreenState extends State<ConfirmFuelEntryScreen> {
             GestureDetector(
               onTap: () => Navigator.of(context).push(
                 MaterialPageRoute(
-                  builder: (_) => ReceiptImageScreen(imagePath: widget.imageFile.path),
+                  builder: (_) => ReceiptImageScreen(localImagePath: widget.imageFile.path),
                 ),
               ),
               child: ClipRRect(

lib/screens/data_settings_screen.dart

@@ -0,0 +1,571 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:provider/provider.dart';
+
+import '../services/app_state.dart';
+import '../services/cloud/cloud_storage_provider.dart';
+import '../services/onboarding_keys.dart';
+import 'cloud_folder_browser_screen.dart';
+
+/// "Data" settings submenu, reached from [SettingsScreen]: cloud storage
+/// connection, the two photo-handling switches, and an Advanced section
+/// (stale sync lock timeout, plus the destructive purge actions — grouped
+/// there rather than given their own top-level "Danger Zone" so they sit
+/// behind the same disclosure as other rarely-touched settings).
+class DataSettingsScreen extends StatefulWidget {
+  const DataSettingsScreen({super.key});
+
+  @override
+  State<DataSettingsScreen> createState() => _DataSettingsScreenState();
+}
+
+class _DataSettingsScreenState extends State<DataSettingsScreen> {
+  static final _dateFormat = DateFormat.yMMMd();
+
+  bool _busy = false;
+  String? _error;
+
+  DateTime? _purgeRangeStart;
+  DateTime? _purgeRangeEnd;
+  String? _purgeRangeError;
+
+  Future<void> _connect(CloudProviderId id) async {
+    setState(() {
+      _busy = true;
+      _error = null;
+    });
+    try {
+      await context.read<AppState>().connectProvider(id);
+    } catch (e) {
+      setState(() => _error = 'Could not sign in: $e');
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  Future<void> _connectManual(CloudProviderId id, String providerName) async {
+    final credentials = await showDialog<_WebDavCredentials>(
+      context: context,
+      builder: (_) => _WebDavCredentialsDialog(providerName: providerName),
+    );
+    if (credentials == null || !mounted) return;
+
+    setState(() {
+      _busy = true;
+      _error = null;
+    });
+    try {
+      await context.read<AppState>().connectProviderWithCredentials(
+            id,
+            serverUrl: credentials.serverUrl,
+            username: credentials.username,
+            password: credentials.password,
+          );
+    } catch (e) {
+      setState(() => _error = 'Could not connect: $e');
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  Future<void> _disconnect() async {
+    setState(() => _busy = true);
+    try {
+      await context.read<AppState>().disconnectCloud();
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  void _chooseFolder() {
+    Navigator.of(context).push(
+      MaterialPageRoute(builder: (_) => const CloudFolderBrowserScreen()),
+    );
+  }
+
+  Future<void> _syncNow() async {
+    setState(() => _busy = true);
+    try {
+      await context.read<AppState>().syncNow();
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  /// The resting (non-syncing) Sync Now icon — badged with the same
+  /// play-triangle [CloudBackupActionButton] uses, for anyone who isn't on
+  /// an active ad-free purchase, since tapping this can trigger the
+  /// rewarded ad gate (see [AppState.syncNow]/`AdService.showGateAd`). Not
+  /// a live prediction of whether *this* tap specifically will show one —
+  /// same general "this leads to an ad-supported feature" disclosure the
+  /// icon-badge uses elsewhere, not an attempt to account for the open
+  /// gate window or the free-first-sync case.
+  Widget _syncNowIcon(BuildContext context, AppState appState) {
+    const icon = Icon(Icons.sync);
+    if (appState.adsCurrentlyDisabled) return icon;
+    final colors = Theme.of(context).colorScheme;
+    return Badge(
+      backgroundColor: colors.tertiary,
+      label: Icon(Icons.play_arrow, size: 8, color: colors.onTertiary),
+      child: icon,
+    );
+  }
+
+  /// Shared warning-dialog shell for both purge actions — [message] is the
+  /// caller's job to make specific and unambiguous, since this is the only
+  /// thing standing between the user and an unrecoverable delete.
+  Future<bool> _confirmPurge({required String title, required String message}) async {
+    final confirmed = await showDialog<bool>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: Text(title),
+        content: Text(message),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.of(dialogContext).pop(false),
+            child: const Text('Cancel'),
+          ),
+          TextButton(
+            style: TextButton.styleFrom(
+              foregroundColor: Theme.of(dialogContext).colorScheme.error,
+            ),
+            onPressed: () => Navigator.of(dialogContext).pop(true),
+            child: const Text('Delete'),
+          ),
+        ],
+      ),
+    );
+    return confirmed ?? false;
+  }
+
+  /// Extra context appended to a purge warning when a cloud account is
+  /// connected — a purely local delete would otherwise just get silently
+  /// re-imported from the remote copy on the very next sync, which isn't
+  /// obvious from the app's normal behavior.
+  String _cloudSyncCaveat(AppState appState) {
+    if (!appState.isCloudConnected) return '';
+    return '\n\nThis device is connected to ${appState.activeProvider!.displayName}. The '
+        'deletion will be pushed there on the next sync, same as any other delete.';
+  }
+
+  Future<void> _purgeAllData() async {
+    final appState = context.read<AppState>();
+    final confirmed = await _confirmPurge(
+      title: 'Purge all data?',
+      message: 'This permanently deletes every vehicle, fuel entry, and receipt photo on '
+          "this device — starting completely fresh. This can't be undone."
+          '${_cloudSyncCaveat(appState)}',
+    );
+    if (!confirmed || !mounted) return;
+
+    setState(() => _busy = true);
+    try {
+      await appState.purgeAllData();
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('All data purged.')),
+        );
+      }
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  Future<void> _pickPurgeRangeDate({required bool isStart}) async {
+    final now = DateTime.now();
+    final picked = await showDatePicker(
+      context: context,
+      initialDate: (isStart ? _purgeRangeStart : _purgeRangeEnd) ?? now,
+      firstDate: DateTime(2000),
+      lastDate: now,
+    );
+    if (picked == null) return;
+    setState(() {
+      _purgeRangeError = null;
+      if (isStart) {
+        _purgeRangeStart = picked;
+      } else {
+        _purgeRangeEnd = picked;
+      }
+    });
+  }
+
+  Future<void> _purgeDataInRange() async {
+    final start = _purgeRangeStart;
+    final end = _purgeRangeEnd;
+    if (start == null || end == null) return;
+    if (end.isBefore(start)) {
+      setState(() => _purgeRangeError = 'End date must be on or after the start date.');
+      return;
+    }
+
+    final appState = context.read<AppState>();
+    final confirmed = await _confirmPurge(
+      title: 'Purge data in range?',
+      message: 'This permanently deletes every fuel entry and receipt photo dated from '
+          '${_dateFormat.format(start)} to ${_dateFormat.format(end)}, across all '
+          "vehicles. Vehicles themselves aren't affected. This can't be undone."
+          '${_cloudSyncCaveat(appState)}',
+    );
+    if (!confirmed || !mounted) return;
+
+    setState(() => _busy = true);
+    try {
+      await appState.purgeFuelEntriesInRange(start, end);
+      if (mounted) {
+        setState(() {
+          _purgeRangeStart = null;
+          _purgeRangeEnd = null;
+          _purgeRangeError = null;
+        });
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('Fuel entries in range purged.')),
+        );
+      }
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final appState = context.watch<AppState>();
+
+    return Scaffold(
+      appBar: AppBar(title: const Text('Data')),
+      body: ListView(
+        padding: const EdgeInsets.all(16),
+        children: [
+          Card(
+            key: OnboardingKeys.cloudStorageCard,
+            child: Padding(
+              padding: const EdgeInsets.all(16),
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text('Cloud Storage', style: Theme.of(context).textTheme.titleMedium),
+                  const SizedBox(height: 8),
+                  if (!appState.isCloudConnected) ...[
+                    Text(
+                      'Connect a cloud storage account to share vehicles and fuel '
+                      'receipts with other people, and to keep a backup off this device.',
+                      style: Theme.of(context).textTheme.bodyMedium,
+                    ),
+                    const SizedBox(height: 12),
+                    if (_error != null) ...[
+                      Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
+                      const SizedBox(height: 8),
+                    ],
+                    Wrap(
+                      spacing: 8,
+                      runSpacing: 8,
+                      children: [
+                        for (final provider in appState.availableProviders)
+                          FilledButton.icon(
+                            onPressed: _busy
+                                ? null
+                                : () => provider is ManualCredentialCloudStorageProvider
+                                    ? _connectManual(provider.id, provider.displayName)
+                                    : _connect(provider.id),
+                            icon: const Icon(Icons.login),
+                            label: Text('Connect ${provider.displayName}'),
+                          ),
+                      ],
+                    ),
+                  ] else ...[
+                    Text('${appState.activeProvider!.displayName}: ${appState.cloudAccountLabel}'),
+                    const SizedBox(height: 4),
+                    Text(
+                      appState.cloudFolderPath == null
+                          ? 'No folder selected yet.'
+                          : 'Folder: ${appState.cloudFolderPath}',
+                      style: Theme.of(context).textTheme.bodySmall,
+                    ),
+                    const SizedBox(height: 12),
+                    Wrap(
+                      spacing: 8,
+                      runSpacing: 8,
+                      children: [
+                        OutlinedButton.icon(
+                          onPressed: _busy ? null : _chooseFolder,
+                          icon: const Icon(Icons.folder_open),
+                          label: Text(appState.cloudFolderPath == null
+                              ? 'Choose Folder'
+                              : 'Change Folder'),
+                        ),
+                        OutlinedButton.icon(
+                          onPressed: (_busy || appState.cloudFolderPath == null)
+                              ? null
+                              : _syncNow,
+                          icon: appState.isSyncing
+                              ? const SizedBox(
+                                  height: 16,
+                                  width: 16,
+                                  child: CircularProgressIndicator(strokeWidth: 2))
+                              : _syncNowIcon(context, appState),
+                          label: const Text('Sync Now'),
+                        ),
+                        TextButton.icon(
+                          onPressed: _busy ? null : _disconnect,
+                          icon: const Icon(Icons.logout),
+                          label: const Text('Disconnect'),
+                        ),
+                      ],
+                    ),
+                    const SizedBox(height: 8),
+                    if (appState.lastSyncedAt != null)
+                      Text(
+                        'Last synced ${DateFormat.yMMMd().add_jm().format(appState.lastSyncedAt!)}',
+                        style: Theme.of(context).textTheme.bodySmall,
+                      ),
+                    if (appState.lastSyncError != null)
+                      Padding(
+                        padding: const EdgeInsets.only(top: 4),
+                        child: Text(
+                          'Last sync failed: ${appState.lastSyncError}',
+                          style: TextStyle(color: Theme.of(context).colorScheme.error),
+                        ),
+                      ),
+                  ],
+                ],
+              ),
+            ),
+          ),
+          const SizedBox(height: 16),
+          Card(
+            child: SwitchListTile(
+              title: const Text('Keep photos on this phone after syncing'),
+              subtitle: const Text(
+                'Otherwise, a receipt photo is removed from this device once '
+                "it's safely uploaded to the cloud.",
+              ),
+              value: appState.keepReceiptPhotosLocally,
+              onChanged: (value) => context.read<AppState>().setKeepReceiptPhotosLocally(value),
+            ),
+          ),
+          const SizedBox(height: 16),
+          Card(
+            child: SwitchListTile(
+              title: const Text('Keep max quality images'),
+              subtitle: const Text(
+                'Otherwise, receipt photos are downscaled to a reasonable size '
+                'before storing — smaller cloud storage and faster syncs, with '
+                'no loss of legibility for a printed receipt.',
+              ),
+              value: appState.keepMaxQualityReceiptPhotos,
+              onChanged: (value) =>
+                  context.read<AppState>().setKeepMaxQualityReceiptPhotos(value),
+            ),
+          ),
+          const SizedBox(height: 16),
+          Card(
+            child: ExpansionTile(
+              title: const Text('Advanced'),
+              childrenPadding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
+              children: [
+                Align(
+                  alignment: Alignment.centerLeft,
+                  child: Text('Stale sync lock timeout', style: Theme.of(context).textTheme.titleSmall),
+                ),
+                const SizedBox(height: 4),
+                Text(
+                  "If another device disconnects mid-sync without releasing its lock, "
+                  "this is how long to wait before treating it as abandoned and clearing "
+                  "it so sync can continue.",
+                  style: Theme.of(context).textTheme.bodySmall,
+                ),
+                Slider(
+                  value: appState.staleLockMinutes.toDouble(),
+                  min: minStaleLockMinutes.toDouble(),
+                  max: maxStaleLockMinutes.toDouble(),
+                  divisions: maxStaleLockMinutes - minStaleLockMinutes,
+                  label: '${appState.staleLockMinutes} min',
+                  onChanged: (value) =>
+                      context.read<AppState>().setStaleLockMinutes(value.round()),
+                ),
+                Text('${appState.staleLockMinutes} minute(s)'),
+                const Divider(height: 32),
+                Text(
+                  'Danger Zone',
+                  style: Theme.of(context)
+                      .textTheme
+                      .titleMedium
+                      ?.copyWith(color: Theme.of(context).colorScheme.error),
+                ),
+                const SizedBox(height: 12),
+                Text('Purge All Data', style: Theme.of(context).textTheme.titleSmall),
+                const SizedBox(height: 4),
+                Text(
+                  'Deletes every vehicle, fuel entry, and receipt photo on this device '
+                  'and starts completely fresh.',
+                  style: Theme.of(context).textTheme.bodySmall,
+                ),
+                const SizedBox(height: 8),
+                SizedBox(
+                  width: double.infinity,
+                  child: OutlinedButton.icon(
+                    onPressed: _busy ? null : _purgeAllData,
+                    icon: Icon(Icons.delete_forever, color: Theme.of(context).colorScheme.error),
+                    label: Text(
+                      'Purge All Data',
+                      style: TextStyle(color: Theme.of(context).colorScheme.error),
+                    ),
+                    style: OutlinedButton.styleFrom(
+                      side: BorderSide(color: Theme.of(context).colorScheme.error),
+                    ),
+                  ),
+                ),
+                const Divider(height: 32),
+                Text('Purge Data by Date Range', style: Theme.of(context).textTheme.titleSmall),
+                const SizedBox(height: 4),
+                Text(
+                  'Deletes fuel entries and receipt photos dated within a range, across '
+                  'all vehicles. Vehicles themselves are kept.',
+                  style: Theme.of(context).textTheme.bodySmall,
+                ),
+                const SizedBox(height: 8),
+                Row(
+                  children: [
+                    Expanded(
+                      child: OutlinedButton(
+                        onPressed: _busy ? null : () => _pickPurgeRangeDate(isStart: true),
+                        child: Text(
+                          _purgeRangeStart == null
+                              ? 'Start date'
+                              : _dateFormat.format(_purgeRangeStart!),
+                        ),
+                      ),
+                    ),
+                    const SizedBox(width: 12),
+                    Expanded(
+                      child: OutlinedButton(
+                        onPressed: _busy ? null : () => _pickPurgeRangeDate(isStart: false),
+                        child: Text(
+                          _purgeRangeEnd == null ? 'End date' : _dateFormat.format(_purgeRangeEnd!),
+                        ),
+                      ),
+                    ),
+                  ],
+                ),
+                if (_purgeRangeError != null) ...[
+                  const SizedBox(height: 8),
+                  Text(
+                    _purgeRangeError!,
+                    style: TextStyle(color: Theme.of(context).colorScheme.error),
+                  ),
+                ],
+                const SizedBox(height: 8),
+                SizedBox(
+                  width: double.infinity,
+                  child: OutlinedButton.icon(
+                    onPressed: (_busy || _purgeRangeStart == null || _purgeRangeEnd == null)
+                        ? null
+                        : _purgeDataInRange,
+                    icon: Icon(Icons.delete_forever, color: Theme.of(context).colorScheme.error),
+                    label: Text(
+                      'Purge Range',
+                      style: TextStyle(color: Theme.of(context).colorScheme.error),
+                    ),
+                    style: OutlinedButton.styleFrom(
+                      side: BorderSide(color: Theme.of(context).colorScheme.error),
+                    ),
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _WebDavCredentials {
+  final String serverUrl;
+  final String username;
+  final String password;
+  _WebDavCredentials({required this.serverUrl, required this.username, required this.password});
+}
+
+/// Collects the server URL/username/password a [ManualCredentialCloudStorageProvider]
+/// needs, since (unlike the OAuth providers) there's no browser flow to
+/// gather these instead.
+class _WebDavCredentialsDialog extends StatefulWidget {
+  final String providerName;
+  const _WebDavCredentialsDialog({required this.providerName});
+
+  @override
+  State<_WebDavCredentialsDialog> createState() => _WebDavCredentialsDialogState();
+}
+
+class _WebDavCredentialsDialogState extends State<_WebDavCredentialsDialog> {
+  final _formKey = GlobalKey<FormState>();
+  final _serverController = TextEditingController();
+  final _usernameController = TextEditingController();
+  final _passwordController = TextEditingController();
+
+  @override
+  void dispose() {
+    _serverController.dispose();
+    _usernameController.dispose();
+    _passwordController.dispose();
+    super.dispose();
+  }
+
+  void _submit() {
+    if (!_formKey.currentState!.validate()) return;
+    Navigator.of(context).pop(_WebDavCredentials(
+      serverUrl: _serverController.text.trim(),
+      username: _usernameController.text.trim(),
+      password: _passwordController.text,
+    ));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AlertDialog(
+      title: Text('Connect ${widget.providerName}'),
+      content: Form(
+        key: _formKey,
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            TextFormField(
+              controller: _serverController,
+              decoration: const InputDecoration(
+                labelText: 'Server URL',
+                hintText: 'https://cloud.example.com/remote.php/dav/files/me/',
+              ),
+              keyboardType: TextInputType.url,
+              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
+            ),
+            const SizedBox(height: 12),
+            TextFormField(
+              controller: _usernameController,
+              decoration: const InputDecoration(labelText: 'Username'),
+              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
+            ),
+            const SizedBox(height: 12),
+            TextFormField(
+              controller: _passwordController,
+              decoration: const InputDecoration(labelText: 'Password'),
+              obscureText: true,
+              validator: (v) => (v == null || v.isEmpty) ? 'Required' : null,
+              onFieldSubmitted: (_) => _submit(),
+            ),
+          ],
+        ),
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(),
+          child: const Text('Cancel'),
+        ),
+        FilledButton(
+          onPressed: _submit,
+          child: const Text('Connect'),
+        ),
+      ],
+    );
+  }
+}

lib/screens/edit_fuel_entry_screen.dart

@@ -0,0 +1,203 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:provider/provider.dart';
+
+import '../models/fuel_entry.dart';
+import '../services/app_state.dart';
+import '../widgets/receipt_thumbnail.dart';
+
+/// Lets the user correct the *data* logged about a receipt (date, gallons,
+/// price/gal, total cost, and which vehicle it's attached to) — not the
+/// receipt photo itself, which is shown read-only up top (tap it to view
+/// full-screen, same as everywhere else it's shown) and can't be replaced
+/// from here.
+class EditFuelEntryScreen extends StatefulWidget {
+  final FuelEntry entry;
+
+  const EditFuelEntryScreen({super.key, required this.entry});
+
+  @override
+  State<EditFuelEntryScreen> createState() => _EditFuelEntryScreenState();
+}
+
+class _EditFuelEntryScreenState extends State<EditFuelEntryScreen> {
+  final _formKey = GlobalKey<FormState>();
+  late final TextEditingController _gallonsController;
+  late final TextEditingController _priceController;
+  late final TextEditingController _totalController;
+  late DateTime _date;
+  late String _vehicleId;
+  bool _saving = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _date = widget.entry.date;
+    _vehicleId = widget.entry.vehicleId;
+    _gallonsController = TextEditingController(text: widget.entry.gallons.toStringAsFixed(3));
+    _priceController = TextEditingController(text: widget.entry.pricePerGallon.toStringAsFixed(3));
+    _totalController = TextEditingController(text: widget.entry.totalCost.toStringAsFixed(2));
+  }
+
+  @override
+  void dispose() {
+    _gallonsController.dispose();
+    _priceController.dispose();
+    _totalController.dispose();
+    super.dispose();
+  }
+
+  void _calculateTotal() {
+    final gallons = double.tryParse(_gallonsController.text);
+    final price = double.tryParse(_priceController.text);
+    if (gallons != null && price != null) {
+      setState(() {
+        _totalController.text = (gallons * price).toStringAsFixed(2);
+      });
+    }
+  }
+
+  Future<void> _pickDate() async {
+    // initialDate must fall within [firstDate, lastDate] or the picker
+    // throws — widen the bounds to cover _date in case it's already
+    // outside the normal 5-years-back-to-today window.
+    final today = DateTime.now();
+    final firstDate = _date.isBefore(today.subtract(const Duration(days: 365 * 5)))
+        ? _date
+        : today.subtract(const Duration(days: 365 * 5));
+    final lastDate = _date.isAfter(today) ? _date : today;
+
+    final pickedDate = await showDatePicker(
+      context: context,
+      initialDate: _date,
+      firstDate: firstDate,
+      lastDate: lastDate,
+    );
+    if (pickedDate == null || !mounted) return;
+
+    final pickedTime = await showTimePicker(
+      context: context,
+      initialTime: TimeOfDay.fromDateTime(_date),
+    );
+    if (pickedTime == null) return;
+
+    setState(() {
+      _date = DateTime(
+        pickedDate.year,
+        pickedDate.month,
+        pickedDate.day,
+        pickedTime.hour,
+        pickedTime.minute,
+      );
+    });
+  }
+
+  Future<void> _save() async {
+    if (!_formKey.currentState!.validate()) return;
+
+    setState(() => _saving = true);
+    try {
+      await context.read<AppState>().updateFuelEntry(
+            entryId: widget.entry.id,
+            vehicleId: _vehicleId,
+            date: _date,
+            gallons: double.parse(_gallonsController.text),
+            pricePerGallon: double.parse(_priceController.text),
+            totalCost: double.parse(_totalController.text),
+          );
+      if (mounted) Navigator.of(context).pop();
+    } finally {
+      if (mounted) setState(() => _saving = false);
+    }
+  }
+
+  String? _requiredDecimal(String? value) {
+    if (value == null || value.trim().isEmpty) return 'Required';
+    if (double.tryParse(value) == null) return 'Enter a valid number';
+    return null;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final dateFormat = DateFormat.yMMMd().add_jm();
+    final vehicles = context.watch<AppState>().vehicles;
+
+    return Scaffold(
+      appBar: AppBar(title: const Text('Edit Fuel Entry')),
+      body: Form(
+        key: _formKey,
+        child: ListView(
+          padding: const EdgeInsets.all(16),
+          children: [
+            Center(
+              child: ReceiptThumbnail(entry: widget.entry, size: 180),
+            ),
+            const SizedBox(height: 8),
+            Text(
+              'Tap the photo to view it full-screen. The photo itself can\'t '
+              "be changed here — only the data below can.",
+              style: Theme.of(context).textTheme.bodySmall,
+              textAlign: TextAlign.center,
+            ),
+            const SizedBox(height: 16),
+            DropdownButtonFormField<String>(
+              initialValue: _vehicleId,
+              decoration: const InputDecoration(labelText: 'Vehicle'),
+              items: [
+                for (final vehicle in vehicles)
+                  DropdownMenuItem(value: vehicle.id, child: Text(vehicle.displayLabel)),
+              ],
+              onChanged: (value) {
+                if (value != null) setState(() => _vehicleId = value);
+              },
+            ),
+            const SizedBox(height: 8),
+            ListTile(
+              contentPadding: EdgeInsets.zero,
+              title: const Text('Date & time'),
+              subtitle: Text(dateFormat.format(_date)),
+              trailing: const Icon(Icons.edit_calendar_outlined),
+              onTap: _pickDate,
+            ),
+            const SizedBox(height: 8),
+            TextFormField(
+              controller: _gallonsController,
+              decoration: const InputDecoration(labelText: 'Gallons', suffixText: 'gal'),
+              keyboardType: const TextInputType.numberWithOptions(decimal: true),
+              validator: _requiredDecimal,
+            ),
+            const SizedBox(height: 12),
+            TextFormField(
+              controller: _priceController,
+              decoration: const InputDecoration(labelText: 'Price per gallon', prefixText: '\$'),
+              keyboardType: const TextInputType.numberWithOptions(decimal: true),
+              validator: _requiredDecimal,
+            ),
+            const SizedBox(height: 12),
+            TextFormField(
+              controller: _totalController,
+              decoration: InputDecoration(
+                labelText: 'Total cost',
+                prefixText: '\$',
+                suffixIcon: IconButton(
+                  icon: const Icon(Icons.calculate_outlined),
+                  tooltip: 'Calculate from gallons × price',
+                  onPressed: _calculateTotal,
+                ),
+              ),
+              keyboardType: const TextInputType.numberWithOptions(decimal: true),
+              validator: _requiredDecimal,
+            ),
+            const SizedBox(height: 24),
+            FilledButton(
+              onPressed: _saving ? null : _save,
+              child: _saving
+                  ? const SizedBox(height: 20, width: 20, child: CircularProgressIndicator(strokeWidth: 2))
+                  : const Text('Save Changes'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

lib/screens/faq_screen.dart

@@ -0,0 +1,178 @@
+import 'package:flutter/material.dart';
+
+class _FaqEntry {
+  final String question;
+  final String answer;
+  const _FaqEntry(this.question, this.answer);
+}
+
+class _FaqSection {
+  final String title;
+  final List<_FaqEntry> entries;
+  const _FaqSection(this.title, this.entries);
+}
+
+const _faqSections = <_FaqSection>[
+  _FaqSection('Missouri Motor Fuel Tax Refund', [
+    _FaqEntry(
+      'What is the Missouri Motor Fuel Tax Refund?',
+      'Missouri actually offers two separate fuel tax refunds — it\'s worth evaluating '
+          'both to see how you could benefit:\n\n'
+          '• Highway use — up to 12.5¢ per gallon.\n'
+          '• Non-highway use — up to 29.5¢ per gallon.\n\n'
+          "This app helps you collect and organize the receipts you'll need to claim "
+          "either one. This isn't tax advice — for guidance on which refund(s) fit your "
+          'situation, consult a tax professional. Rates and eligibility are set by '
+          'Missouri law, which can change at any time, so always confirm current details '
+          'with the Missouri Department of Revenue before filing.',
+    ),
+    _FaqEntry(
+      'Is this app affiliated with the Missouri Department of Revenue?',
+      "No. This is an independent tool for organizing your own receipts — it isn't run by, "
+          "endorsed by, or connected to the State of Missouri. It doesn't file anything on "
+          'your behalf.',
+    ),
+    _FaqEntry(
+      'How do I generate a report for my refund claim?',
+      "On the Reports tab, pick a date range to see your totals, then use Share or Print. "
+          "There's also a link to Missouri's official Motor Fuel Refund Claim form once "
+          "you're ready to file.",
+    ),
+  ]),
+  _FaqSection('Usage', [
+    _FaqEntry(
+      'How do I log a fuel purchase?',
+      "On the Receipts tab, tap the + button, snap a photo of the receipt, and the app "
+          'reads the date, gallons, and price automatically. Review (and correct, if '
+          'needed) the values before saving — every field stays editable both before and '
+          'after saving.',
+    ),
+    _FaqEntry(
+      'What if the app misreads my receipt?',
+      'Automatic reading is usually accurate but not perfect — correct any field yourself '
+          'before saving, or edit it afterward from the entry\'s detail page.',
+    ),
+    _FaqEntry(
+      "Found a receipt, VIN, or error the app couldn't handle?",
+      'Send it to ohbrer+ShowMeTheFuelRefund@gmail.com — example receipts or VINs that '
+          "didn't scan correctly, screenshots of error screens, or anything else that "
+          "didn't work as expected all help improve the app.",
+    ),
+    _FaqEntry(
+      'Do I need to add a vehicle before logging a receipt?',
+      'Yes — every fuel entry is linked to a vehicle. Add one on the Vehicles tab first '
+          "(you'll need its VIN).",
+    ),
+  ]),
+  _FaqSection('Data Safety', [
+    _FaqEntry(
+      'Is my data backed up?',
+      'Not by default — everything you log lives only on this device until you connect a '
+          'cloud storage account (Settings > Data). Once connected, a copy is kept there '
+          'too, in storage you control.',
+    ),
+    _FaqEntry(
+      'What cloud storage options are supported?',
+      'Google Drive, Dropbox, OneDrive, or your own WebDAV server (Nextcloud, ownCloud, or '
+          'any self-hosted WebDAV server).',
+    ),
+    _FaqEntry(
+      "What happens if I lose my phone, or reinstall the app?",
+      "If you never connected cloud storage, that data is gone — it only ever lived on "
+          "that device. If you had connected one, reconnect the same account on the new "
+          "device (or after reinstalling) and your vehicles, receipts, and photos sync back "
+          'down automatically.',
+    ),
+    _FaqEntry(
+      'How do I delete my data?',
+      'Settings > Data > Advanced has options to purge everything, or just fuel entries in '
+          "a specific date range. Both are permanent and can't be undone.",
+    ),
+  ]),
+  _FaqSection('Advertisements', [
+    _FaqEntry(
+      'Why do I sometimes see an ad?',
+      'Syncing your data to the cloud requires watching a short ad, to help support the '
+          "app — at most once every 5 minutes, so it won't show again if you sync "
+          'repeatedly in a short span.',
+    ),
+    _FaqEntry(
+      'How do I remove ads?',
+      '"Remove Ads for a Year" in Settings is a one-time purchase that disables ads for a '
+          "year from when you buy it. It doesn't auto-renew or charge you again "
+          "automatically — once the year's up, ads come back until you buy again.",
+    ),
+  ]),
+];
+
+/// A simple, static list of common questions grouped into sections —
+/// reached from [SettingsScreen] (and every tab's AppBar via
+/// [FaqActionButton]), the "back up your data" reminder, and the
+/// first-launch user agreement screen.
+class FaqScreen extends StatelessWidget {
+  /// If given, that question's entry starts expanded (and the rest
+  /// collapsed) instead of everything starting collapsed — used when a
+  /// link elsewhere in the app points at one specific answer, e.g. the
+  /// backup reminder dialog jumping straight to the backup question rather
+  /// than making the user hunt for it.
+  final String? initiallyExpandedQuestion;
+
+  const FaqScreen({super.key, this.initiallyExpandedQuestion});
+
+  @override
+  Widget build(BuildContext context) {
+    final textTheme = Theme.of(context).textTheme;
+
+    return Scaffold(
+      appBar: AppBar(title: const Text('FAQ')),
+      body: ListView(
+        padding: const EdgeInsets.all(16),
+        children: [
+          for (final section in _faqSections) ...[
+            Padding(
+              padding: const EdgeInsets.fromLTRB(4, 8, 4, 8),
+              child: Text(
+                section.title,
+                style: textTheme.titleMedium?.copyWith(fontWeight: FontWeight.w700),
+              ),
+            ),
+            for (final entry in section.entries)
+              Padding(
+                padding: const EdgeInsets.only(bottom: 12),
+                child: Card(
+                  child: ExpansionTile(
+                    title: Text(entry.question, style: textTheme.titleSmall),
+                    initiallyExpanded: entry.question == initiallyExpandedQuestion,
+                    childrenPadding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
+                    expandedCrossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      Text(entry.answer, style: textTheme.bodyMedium),
+                    ],
+                  ),
+                ),
+              ),
+            const SizedBox(height: 8),
+          ],
+        ],
+      ),
+    );
+  }
+}
+
+/// A "?" AppBar action that jumps straight to [FaqScreen] — added to every
+/// tab's AppBar (Receipts, Vehicles, Reports, Settings; see [MainShell])
+/// so help is reachable the same way no matter which screen the user's on.
+class FaqActionButton extends StatelessWidget {
+  const FaqActionButton({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return IconButton(
+      icon: const Icon(Icons.help_outline),
+      tooltip: 'FAQ',
+      onPressed: () => Navigator.of(context).push(
+        MaterialPageRoute(builder: (_) => const FaqScreen()),
+      ),
+    );
+  }
+}

lib/screens/home_screen.dart

@@ -3,10 +3,14 @@ import 'package:provider/provider.dart';
 
 import '../models/vehicle.dart';
 import '../services/app_state.dart';
+import '../services/onboarding_keys.dart';
+import '../widgets/cloud_backup_action_button.dart';
 import 'add_edit_vehicle_screen.dart';
-import 'settings_screen.dart';
+import 'faq_screen.dart';
 import 'vehicle_detail_screen.dart';
 
+/// The "Vehicles" tab body — Settings and Reports are reached via the
+/// bottom nav now (see [MainShell]), not from icons here.
 class HomeScreen extends StatelessWidget {
   const HomeScreen({super.key});
 
@@ -17,15 +21,19 @@ class HomeScreen extends StatelessWidget {
 
     return Scaffold(
       appBar: AppBar(
-        title: const Text('My Vehicles'),
+        title: const Text('Vehicles'),
+        actionsPadding: const EdgeInsets.only(right: 20),
         actions: [
           IconButton(
-            icon: const Icon(Icons.settings_outlined),
-            tooltip: 'Settings',
+            key: OnboardingKeys.vehiclesAddButton,
+            icon: const Icon(Icons.add),
+            tooltip: 'Add Vehicle',
             onPressed: () => Navigator.of(context).push(
-              MaterialPageRoute(builder: (_) => const SettingsScreen()),
+              MaterialPageRoute(builder: (_) => const AddEditVehicleScreen()),
             ),
           ),
+          const CloudBackupActionButton(),
+          const FaqActionButton(),
         ],
       ),
       body: vehicles.isEmpty
@@ -40,13 +48,6 @@ class HomeScreen extends StatelessWidget {
                 return _VehicleCard(vehicle: vehicle, totalGallons: gallons);
               },
             ),
-      floatingActionButton: FloatingActionButton.extended(
-        onPressed: () => Navigator.of(context).push(
-          MaterialPageRoute(builder: (_) => const AddEditVehicleScreen()),
-        ),
-        icon: const Icon(Icons.add),
-        label: const Text('Add Vehicle'),
-      ),
     );
   }
 }
@@ -59,22 +60,49 @@ class _VehicleCard extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final hasNickname = vehicle.nickname?.trim().isNotEmpty ?? false;
+    final gallonsLine = '${totalGallons.toStringAsFixed(3)} gallons logged';
+
     return Card(
       clipBehavior: Clip.antiAlias,
-      child: ListTile(
-        contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
-        leading: CircleAvatar(
-          child: Text(vehicle.make.isNotEmpty ? vehicle.make[0].toUpperCase() : '?'),
-        ),
-        title: Text('${vehicle.color} ${vehicle.make} ${vehicle.model}'),
-        subtitle: Text(
-          'Plate: ${vehicle.licensePlate}\n${totalGallons.toStringAsFixed(3)} gallons logged',
-        ),
-        isThreeLine: true,
-        trailing: const Icon(Icons.chevron_right),
+      child: InkWell(
         onTap: () => Navigator.of(context).push(
           MaterialPageRoute(builder: (_) => VehicleDetailScreen(vehicleId: vehicle.id)),
         ),
+        child: Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+          // Row cross-axis defaults to center, so the chevron sits
+          // vertically centered against the title+subtitle block even when
+          // the nickname line makes that block taller — ListTile's
+          // isThreeLine forces leading/trailing to the top instead, per
+          // Material spec, which is what pinned it to the top before.
+          child: Row(
+            children: [
+              const CircleAvatar(child: Icon(Icons.directions_car_outlined)),
+              const SizedBox(width: 16),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    Text(vehicle.displayLabel, style: Theme.of(context).textTheme.titleMedium),
+                    // Only repeat the VIN here when the title is already
+                    // showing the nickname instead — otherwise the title
+                    // (falling back to the VIN when there's no nickname)
+                    // would show it twice.
+                    Text(
+                      hasNickname ? 'VIN: ${vehicle.vin}\n$gallonsLine' : gallonsLine,
+                      style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                            color: Theme.of(context).colorScheme.onSurfaceVariant,
+                          ),
+                    ),
+                  ],
+                ),
+              ),
+              const Icon(Icons.chevron_right),
+            ],
+          ),
+        ),
       ),
     );
   }