Optional modules — what to delete, and what breaks when you do

The template ships an app that records things: a Room database, photos, backup export and restore, and reminders. Most of that is machinery with a data-loss story attached, and an app that does not need a piece of it should delete it before the first upload, while deleting is free.

Why before, and not “later, if it turns out unused”. Nothing is shipped yet, so a table deleted today comes back at version 1 if a feature ever needs it. Ship an unused items table and remove it later, and that removal is a destructive migration against real installs — the exact failure ADR-0001 exists to prevent. The same asymmetry holds for permissions: one declared today is a Data safety answer you will have to keep defending.

The first app built from this template stored settings rather than records and deleted everything below except the preferences on day one. It took 69 files, and five things around the code broke that nothing had said depended on the code. This page is that strip written down, so the next one is a checklist rather than a discovery.

How to decide

The test is shape, not subject matter.

A fixed set is plain DataStore keys, however many members it has: four schedule options are settings, and seven per-day windows are fourteen settings.
A small list the user makes is JSON under one DataStore key, read whole and written whole. Its migration story is the decoder’s tolerance: unknown keys ignored, a default on every field added later, and one unreadable entry dropped rather than the whole list. The template’s AppBackupAgent leaves the store out of backups; once Auto Backup takes over (Backup export/restore below) the list reaches the user’s next phone with every other key, which is right for anything that is really a setting. The first app built from this template keeps its saved presets this way rather than bring Room back.
A table is for querying, relations or partial writes — records found by a field, joined to other records, or too many to rewrite whole. Only then Room, and ADR-0001 comes with it.

The modules

Each row lists what to delete together. Delete a module, then build, then run ./gradlew test lint and the scripts in the last column — they are what tells you the strip is finished rather than the compiler. Lint fails on every resource the deleted code was the last to use (UnusedResources is an error, because resource shrinking would strip it from the bundle), so remove those in every language.

Room database and the schema gate

data/AppDatabase.kt, ItemDao.kt, ItemEntity.kt, ItemRepository.kt, Converters.kt, Migrations.kt, SchemaGate.kt, DatabasePreserve.kt, BackgroundSchemaGuard.kt and, if the reminders stay, ReminderSweep’s call to it
ui/wipe/SchemaMismatchScreen.kt and its schema_mismatch_* strings, both variants’ ui/wipe/SchemaMismatchContinue.kt and its debug string, the wipe guard’s call in MainApplication
app/schemas/, test/…/data/SchemaGateTest.kt, androidTest/…/data/ItemDaoTest.kt, MigrationTest.kt
Gradle: the ksp plugin and ksp {} block, the three Room dependencies, room.testing, and the androidTest schema-assets line in androidComponents
What adapts on its own: scripts/project.py reads HAS_DATABASE off data/AppDatabase.kt, so schema-gate.py passes with “no database, nothing to gate”, doze-capture.sh stops pulling a file that is not there, and the mismatch suite leaves edge-to-edge.py and screenshots.py.
What does not: docs/DOD.md’s standing schema gate — mark it parked, keep the five points verbatim, and say it comes back the day a feature adds a table. ADR-0001 gets a dated amendment, not a rewrite (docs/adr/0000-template.md).

Photos (the media pipeline)

media/MediaFiles.kt, androidTest/…/media/MediaFilesTest.kt, res/xml/file_paths.xml and the FileProvider in the manifest
Gradle: coil.compose, both exifinterface lines
The items editor’s picker and its item_pick_image string, if the placeholder domain stays
scripts/aab-permissions.py: nothing to remove — the photo path declares no permission — but CAMERA stays in FORBIDDEN, because a dependency that merges it changes the listing.
The privacy policy’s Photos and camera bullets, and play-app-content.md’s Data safety point 2.
ADR-0002 gets its amendment.

Backup export/restore, and the custom `BackupAgent`

data/backup/, ui/backup/, test/…/data/backup/, AppBackupAgent.kt and its manifest attributes; scripts/upgrade-diff.py, which reads those backups
Settings’ Backup row (onOpenBackup, the Backup route, settings_backup) and the backup_* strings
If nothing else shares a file: ui/common/Share.kt, ShareBook.kt and ShareBookTest.kt, androidTest/…/ui/common/ShareChosenCallbackTest.kt, MainActivity.onResume’s revokeUnpickedShare(), ManifestWiringTest’s share case, the ShareChosenReceiver entry and the two SEND entries in the manifest’s <queries>, and the privacy policy’s sentences on sharing
kotlinx.serialization stays: Navigation 3 serialises every NavKey.
Platform Auto Backup takes over, with android:dataExtractionRules if anything must stay on the phone. ⚠ Every DataStore key is then backed up, whether you meant it to be or not — exclusions are per file, and the preferences store is one file — so every key lands on the user’s next phone with no code of yours involved. Ask what each key means there: a setting is welcome, live state is not (“the service should be running”, “a deadline is armed”). Judge live state at the read, against something the platform never backs up — PackageInfo.firstInstallTime is one. The first app built from this template met this in its restore test: a restored “running” flag was acted on by a boot receiver on a phone that had never granted the permission it assumed.
ADR-0005 gets its amendment.

Reminders and WorkManager

This one is a pure deletion: outside work/, only MainApplication and Settings’ Reminders section use it, and both are listed below. startActivitySafely lives in ui/common/Intents.kt and the background schema check in data/BackgroundSchemaGuard.kt because other code needs them after the reminders are gone.

work/ReminderSweep.kt, BootReceiver.kt, PackageReplacedReceiver.kt, ReceiverWork.kt, ExactAlarms.kt, ReminderChannels.kt, its test and the channel_reminders_* strings; NotificationPermission.kt if nothing else posts; Autostart.kt, BatteryExemption.kt and the com.miui.securitycenter <queries> entry if nothing else runs in the background
res/drawable/ic_notification.xml and res/raw/keep.xml, if nothing else posts
androidTest/…/ManifestWiringTest.kt’s boot, update and boot-permission cases, or the whole file if the share case has gone with the backup
app/proguard-rules.pro’s Workers, across versions note; .gitignore’s /doze-*/ and scripts/doze-capture.sh, which captures an overnight sweep
Manifest: SCHEDULE_EXACT_ALARM, RECEIVE_BOOT_COMPLETED, the receivers, and the androidx.startup tools:node="remove" for WorkManager’s initializer (the provider itself stays — emoji2 registers there)
MainApplication’s Configuration.Provider and ensureSweepEnqueued call; Gradle’s work.runtime and work.testing
⚠ WorkManager merges three permissions your source never declares — WAKE_LOCK, ACCESS_NETWORK_STATE, FOREGROUND_SERVICE — and RECEIVE_BOOT_COMPLETED for good measure. If you keep a boot receiver but drop WorkManager, declare RECEIVE_BOOT_COMPLETED yourself first, or the receiver stops being called with nothing to say so. ACCESS_NETWORK_STATE on an app with no INTERNET is a line a Play reviewer can ask about, and the tip merges it too: removing WorkManager removes the question only if the tip goes as well.
scripts/aab-permissions.py’s EXPECTED rows for all of the above, in the same commit — except ACCESS_NETWORK_STATE while the tip stays, which then belongs to billing alone: keep the row, and its line in play-app-content.md, and name billing as the only owner.
scripts/device-gate.py’s reminder checks, if nothing schedules: ALARM_TAG and the alarm reads (app_alarms, armed, disarmed), the channel pair (channel_importance, set_channel), the --reboot arm (wait_for_unlock, reboot_and_wait), and the exact-alarm line. Keep the autostart half while anything else runs in the background.
Settings’ Reminders section, and the ask and banner behind it — the SwitchRow, the rememberNotificationPermissionAsk call, the resumed re-read of notificationsAllowed, the WarningBanner, and every settings_reminders* string, plus AppPreferences.remindersEnabled, Keys.REMINDERS_ENABLED and its place in Keys.SETTINGS, and the reminder lines in AppPreferencesTest. That whole block is PLAN.md rule 4 worked through for one ask; it is the shape to copy for your first ask, so read it before deleting it.
“reminders” in settings_restore_hint and settings_restore_confirm_body, in every language, or Restore defaults promises to reset something that is gone.
ADR-0003 gets its amendment.

The tip (Play Billing)

Every line it adds is deleted outright, along with the imports that leave unused; the two edits are marked.

tip/, test/…/tip/; ui/support/SupportViewModel.kt and TipSection.kt, and the tip argument the Support entry passes in Navigation.kt
The one-time ask: ui/home/TipAskCard.kt; HomeScreen’s onOpenSupport parameter and its showTipAsk item; the onOpenSupport the Home entry passes in Navigation.kt; in HomeViewModel, showTipAsk, the preferences, tipJar and installedAt parameters and their arguments in Factory, the withTipAsk line, the init block and answerTipAsk
AppPreferences.tipAsked / markTipAsked, Keys.TIP_ASKED and its place in Keys.KEPT, and the tip lines in AppPreferencesTest
AppContainer.tipJar and installedAt (applicationScope keeps its @Suppress("unused") for this day); settleTipsOnEveryForeground and its call in MainApplication
The home_tip_ask_* and support_tip* strings, in every language — scripts/sync-support.py leaves the latter out of the shared block for an app with no tip/, so later syncs keep them out
Gradle: billing.ktx, androidx.lifecycle.process and licensee’s allowUrl for Google’s terms in app/build.gradle.kts; the billing version and the billing-ktx and androidx-lifecycle-process aliases in libs.versions.toml
Manifest: the INTERNET tools:node="remove" and its comment — harmless once billing is gone, but it then removes nothing and reads as a reason that no longer exists
scripts/aab-permissions.py: the BILLING row and its comment, and the datatransport comment above ACCESS_NETWORK_STATE. Edit that row’s note back to WorkManager alone, or delete the row if WorkManager has already gone.
play-app-content.md: the BILLING row and the datatransport paragraph under What the artifact carries; the tip paragraph under Content rating, which leaves the all-No answer; Data safety point 4 and its Would change bullet; and The tip. Edit the ACCESS_NETWORK_STATE row back to WorkManager alone. Keep A payment-link tip: an app that drops the billing tip is the one most likely to try a link next.
The privacy policy’s billing-library sentence under The app collects nothing, its billing bullet and its tip paragraph
CLAUDE.md’s Play Billing row in Stack and tip/ line in Layout; CONTEXT.md’s Tip row
RELEASING.md’s Selling the tip; the tip section of DOD.md
ADR-0007 gets its amendment.

The placeholder domain

ui/items/, the items routes in Navigation.kt / NavigationKeys.kt, and the tab_items, item_*, items_*, action_save, action_edit and action_delete strings
⚠ The tip’s one ask lives on the items screen and counts items as its measure of use. Move TipAskCard.kt and its items_tip_ask_* strings to your home screen and give tipAskDue your own measure, or the ask goes with them
debug/…/data/SampleData.kt, debug/…/debug/SeedReceiver.kt, the debug manifest’s receiver, and the seed rows in DebugSettings.kt with their debug_seed and debug_wipe strings — or keep the seeding seam and point it at your own data
scripts/edge-to-edge.py’s SCENES, TAB_BAR, HOME_TAB and SEED_WALK: they walk the template’s screens. Rewrite them against yours the same week — until then the nightly job boots ten emulators to walk screens that do not exist and reports a red everyone learns to ignore.

Around the code

Five places the strip reaches that no compiler will point at:

scripts/aab-permissions.py — EXPECTED must be exactly what the artifact carries. Run it against a local bundleRelease (or bundleDebug); a stale row fails the release upload, after the tag, which is where the first app built from this template found it.
CI’s instrumented job fails on zero tests. If the strip deletes every androidTest, write one real device test — the thing the app must never get wrong is a good first one — or delete the job.
CLAUDE.md — the stack table, the house rules that name deleted code, and the layout block.
docs/privacy-policy.md and docs/play-app-content.md, together, in the same commit.
The ADRs — each module above names the one that gets a dated amendment. Never delete an ADR: the reasoning is what the next feature that wants the module back will need.