Move development notes out of the README into AGENTS.md

The README is for someone deciding whether to install the app, so build commands,
module layout, signing and the migration internals do not belong in it.

AGENTS.md also collects the things that have already gone wrong here and are
invisible in the code: R8 stripping ML Kit's reflective constructors, dex refusing
commas in test method names, Robolectric double-starting Koin.

Author: anish-sahoo

AGENTS.md

@@ -0,0 +1,73 @@
+# Working in this repo
+
+Notes for anyone, human or otherwise, changing this codebase. Things the code
+itself does not say.
+
+## Layout
+
+    shared/       domain model, repositories, SQLDelight schema, most of the tests
+    composeApp/   Android app: UI, widget, notifications, camera, migration
+    config/       detekt configuration
+    store-assets/ Play listing assets, with the scripts that generate them
+
+`shared` is multiplatform-shaped but only Android is wired up. Nothing outside
+`androidMain` may depend on Android.
+
+## Commands
+
+    ./gradlew :composeApp:assembleDebug
+    ./gradlew ciCheck          # ktlint, detekt, Android Lint, unit tests, debug build
+    ./gradlew ciCheckDevice    # the above plus instrumented tests
+
+`ciCheck` and `.github/workflows/ci.yml` must stay in step. CI runs one task per
+job step so failures are attributable; adding a task to `ciCheck` means adding a
+step there too.
+
+Run the formatter and linter after changing code, and fix what they flag.
+
+## Conventions
+
+- ktlint is wired through the CLI, not the Gradle plugin. AGP 9 supplies its own
+  Kotlin plugin, so `org.jetbrains.kotlin.android` is never applied and
+  ktlint-gradle registers no source-set tasks. Style comes from `.editorconfig`.
+- American English throughout, including comments and strings. The pre-2.0 code
+  was British.
+- Radii come from `EdrShapes`. No one-off `RoundedCornerShape` values.
+- Comments explain why, not what. A rule or a workaround with no stated reason is
+  one nobody can safely delete later.
+
+## Things that have already gone wrong
+
+- **`LegacyImporter`** is the only path that can lose data users cannot get back.
+  It reads the 1.5 database and image cache on first launch, once, and leaves the
+  original files alone. Treat changes here as the highest-risk edits in the repo.
+- **R8 strips ML Kit's reflective constructors.** The failure is silent: the app
+  starts, logs `NoSuchMethodException` at WARN, and scanning never works. Keep
+  rules and their reasoning are in `composeApp/proguard-rules.pro`. A debug build
+  cannot show this, so exercise `assembleRelease` before shipping.
+- **Widget sizing** lives in `WidgetSizing.kt` as plain Kotlin, deliberately, so
+  it is testable without Glance. It still leaves dead space and drops its overflow
+  line at tall sizes.
+- **Schema defaults and `AppSettings()` must agree.** They silently disagreed
+  once; `SettingsDefaultsTest` is the guard.
+- **Instrumented test method names cannot contain commas.** Dex will not represent
+  them. JVM tests can keep backticked sentences.
+- **Robolectric boots the real `EdrApplication`** and Koin then refuses to start
+  twice. Use `@Config(application = Application::class)`.
+
+## Signing
+
+Release builds are signed only when `keystore.properties` exists in the project
+root, holding `storeFile`, `storePassword`, `keyAlias` and `keyPassword`. It is
+gitignored, along with `*.jks` and `*.keystore`, and must stay that way. Without
+it the build produces an unsigned artifact rather than failing configuration, so
+CI needs no secrets.
+
+Upload `mapping.txt` with every bundle or Play Console crash reports are
+unreadable.
+
+## Known gaps
+
+- The eight translations are machine generated and unreviewed.
+- OCR and the GenAI path have only ever run on an emulator.
+- Install-over-1.5 has never been tested through a real Play install.

README.md

@@ -11,8 +11,12 @@ and not after. Food, medicine, warranties, passports, anything with a date on it
 </a>
 </p>
 
-By Anish Sahoo, MIT licensed. Version 2.0 is a rewrite of the 2019-2022 Java app;
-that history is still in this repo, below the rewrite commit.
+## About
+
+Created by Anish Sahoo and released under the MIT license.
+
+Version 2.0 is a rewrite of the 2019-2022 Java app. That history is still in this
+repo, below the rewrite commit.
 
 ## Features
 
@@ -24,7 +28,8 @@ that history is still in this repo, below the rewrite commit.
 - Date formats picked from your region, changeable in settings
 - Eight languages, and colors that follow your wallpaper on Android 12+
 
-Everything is stored on device. No account, and the camera is only used when you scan.
+Everything is stored on device. There is no account, and the camera is used only
+when you scan.
 
 ## Technicalities
 
@@ -33,32 +38,10 @@ Everything is stored on device. No account, and the camera is only used when you
 - ML Kit Text Recognition, with the GenAI Prompt API where the device supports it
 - Glance for the widget, WorkManager for reminders
 - minSdk 31 (Android 12), targetSdk 36, JVM 21
-- Item photos live in `filesDir`, readable only by the app
-
-Layout:
-
-    shared/       domain model, repositories, SQLDelight schema, most of the tests
-    composeApp/   Android app: UI, widget, notifications, camera, migration
-    config/       detekt configuration
-    store-assets/ Play listing icon, feature graphic and screenshots, with generators
-
-## Building
-
-    ./gradlew :composeApp:assembleDebug
-    ./gradlew ciCheck          # ktlint, detekt, Android Lint, unit tests, debug build
-    ./gradlew ciCheckDevice    # the above plus instrumented tests
-
-`ciCheck` is what GitHub Actions runs, one step per gate.
-
-Release builds are signed only when a gitignored `keystore.properties` exists in the
-project root (`storeFile`, `storePassword`, `keyAlias`, `keyPassword`). Without it the
-build still produces an unsigned artifact rather than failing. Upload `mapping.txt`
-with the bundle or Play Console crash reports are unreadable.
-
-## Migrating from 1.5
+- Item photos live in the app's private storage, readable only by the app
 
-`LegacyImporter` reads the old app's SQLite database and image cache on first launch
-and imports both. It runs once, is idempotent, and leaves the old data in place. It is
-the only code path that can lose data users cannot get back, so it carries the most tests.
+Upgrading from 1.5 imports your existing items and photos automatically on first
+launch.
 
-Privacy policy in [PrivacyPolicy.md](PrivacyPolicy.md).
+Privacy policy in [PrivacyPolicy.md](PrivacyPolicy.md). Notes for contributors in
+[AGENTS.md](AGENTS.md).