kaizen-app/CLAUDE.md

Kaizen App

Architecture map for the native Android client. Source of truth for any agent or human picking up this codebase.

Goal

Make the native Android app (kaizen-app) a valid daily-driver that talks to the Kaizen backend (kaizen). One binary, deployment-agnostic: one uniform Authorization: Bearer <token> contract, same against the official server or any self-host. Design constraint (hard): backend complexity stays invisible to the user.

Repos (absolute paths)

• Backend (Next.js 16, Drizzle, Postgres): /Users/brunodeanoz/Kaizen/kaizen — git remote origin = git@git.kryptomrx.de:krypto/kaizen.git, branch main. Read its CLAUDE.md first; it is the architecture map.
• Android app (Kotlin, Jetpack Compose, package dev.kaizen.app): /Users/brunodeanoz/Kaizen/kaizen-app — built/run from Windows Android Studio on a real S25 Ultra; everything else (backend, Postgres, Docker) runs on the dev Mac + dedicated servers.
• Note: /Users/brunodeanoz/Kaizen itself is NOT a git repo. Only kaizen and kaizen-app are separate git repos.

Platform strategy

• Android: Kotlin + Jetpack Compose (native, no WebView)
• iOS (planned): Swift + SwiftUI + SwiftData (native, separate codebase)
• No KMP — each platform uses its native stack for best feel

The API contract the app uses (source of truth — verify, don't guess)

• Auth: every request carries Authorization: Bearer kzn_.... Backend resolves via requireActiveUserOrToken (lib/auth/guard.ts).
• Token acquisition: in-app login (POST {baseUrl}/api/v1/auth/token with { email, password, name }). Consumer "Sign in" pattern — no copy-paste.
• Chat: POST {baseUrl}/api/v1/chat — { model, messages: [{ role, content }], reasoningEffort?, preferThroughput? }. Response is text/plain chunked stream (NOT SSE). Parsed by StreamConsumer.Incremental in net/StreamConsumer.kt.
• Sentinels (lib/chat/constants.ts): \x00 USAGE, \x01 REASONING, \x02 SOURCES, \x03 TOOL, \x04 QUERY. App currently strips all sentinels and renders only visible content.
• Models: GET {baseUrl}/api/v1/models → { models: [{ id, name?, provider? }] }.
• Conversations: GET /api/v1/conversations → { conversations, hasMore }. POST /api/v1/conversations → create. GET /api/v1/conversations/[id] → { messages }. POST /api/v1/conversations/[id]/messages → persist. POST /api/v1/conversations/[id]/title → auto-title.
• Identity: GET /api/v1/me → { id, email, name, role, defaultModel }.
• Capability handshake: GET /api/v1/meta → { app, apiVersion, features } (unauth).
• Upload: POST /api/v1/upload — multipart file → { url, kind, name, mimeType, size, fileId }.

App architecture

Package structure (app/src/main/java/dev/kaizen/app/)

auth/           LoginScreen
chat/           ChatScreen, ChatViewModel, Sidebar, ChatComponents, ChatModels,
                ModelSheet, Markdown, Background
db/             Room offline cache: KaizenDatabase, Entities, DAOs,
                Repositories, Converters, Mappers
haptics/        Phase-aware haptics
net/            KaizenApi (HTTP), SecureStore (encrypted prefs),
                SessionViewModel, ServerConfig, StreamConsumer
settings/       SettingsScreen, SettingsViewModel, SettingsComponents
ui/
  theme/        Color (P3), Theme (multi-theme), Type, Oklab, Dither
  theme/themes/ AccentScheme, AmberTheme, BlauTheme, MonoTheme, AuroraTheme, ThemeRegistry
  shape/        SquircleShape (superellipse), KaizenShapes (token system)
  effect/       GlassSurface (frosted glass), Shadow (multi-layer stack)
  motion/       Motion (easing curves, spring specs, duration tokens)
  sensor/       TiltState (gyro/accel parallax, lifecycle-aware)

Key components

• KaizenApi (net/KaizenApi.kt) — singleton object, all HTTP calls via OkHttp. Streaming chat returns Flow<String> with incremental sentinel-stripping.
• StreamConsumer (net/StreamConsumer.kt) — O(chunk-size) incremental parser, each character visited exactly once across the entire stream.
• SessionViewModel (net/SessionViewModel.kt) — Compose snapshot state for auth session. Holds ServerConfig (baseUrl, token, model, email, speed). Persisted in EncryptedSharedPreferences via SecureStore.
• ChatViewModel (chat/ChatViewModel.kt) — owns Room database instance + repositories. Created in MainActivity, passed to ChatScreen.
• ChatScreen (chat/ChatScreen.kt) — main composable, orchestrates sidebar, messages, streaming, file uploads.

Design System v2 (ui/) — added 2026-06-21

Full spec: DESIGN.md. Branch: feature/design-system-v2.

Six pillars (load-bearing — if any regress, the design regresses):

1. P3 color pipeline — all tokens in DisplayP3 color space (Color.kt). window.colorMode = COLOR_MODE_HDR (API 34+) / COLOR_MODE_WIDE_COLOR_GAMUT (API 26+) in MainActivity. No Color(0xFF…) for brand colors outside Color.kt.
2. Squircle shapes — iOS-style superellipse with G2 continuity (ui/shape/Squircle.kt). Token system KaizenShapes.{xs,sm,md,lg,xl,pill,circle}. Replaces all RoundedCornerShape.
3. GlassSurface — frosted-glass composable (gradient tint + specular border + inner highlight + multi-layer shadow). Android has no backdrop-filter; glass effect works via semi-transparent tint over the blob layer. Opacity tiers per component in GlassTiers.
4. Multi-layer shadows — ShadowStack with 2–4 overlapping layers (KaizenShadows.level0..4). Dark mode multiplies alphas ×1.8. Replaces all Modifier.shadow().
5. 4-theme system — Amber/Blau/Mono/Aurora. Each theme = KaizenAccentScheme (primary + 4 blob colors). Neutrals are theme-independent. LocalKaizenAccent CompositionLocal. Theme selection wired end-to-end: SettingsViewModel.selectedTheme → MainActivity → KaizenTheme(themeId=...). No server sync (web stores in localStorage, app stores locally). Appearance (Light/Dark/System) also wired end-to-end.
6. Sensor-reactive motion — rememberTiltState() provides smoothed tilt Offset(-1..1). Uses TYPE_GAME_ROTATION_VECTOR (fused, no drift). Auto-disables on battery saver, reduced motion, background, extreme tilt.

Motion tokens (ui/motion/Motion.kt): EaseSpring (overshoot), EaseSmooth (expo-out), EaseEmphasized (M3), SpringSnappy/Default/Gentle. All durations centralised in Durations object.

Migration status: All UI components migrated to the design system. Sidebar, ChatInput, ChatScreen, LoginScreen, ModelSheet, SettingsCard, SettingsScreen use GlassSurface + KaizenShapes + kaizenShadow. Only Markdown code-block shapes remain as RoundedCornerShape (intentionally rectangular for code).

KaizenOrb (chat/Background.kt) uses rememberTiltState() from ui/sensor/ instead of inline sensor code. Breath animation uses Durations.ORB_BREATH / ORB_BREATH_STREAMING from ui/motion/.

Typography — Inter Variable (res/font/inter_variable.ttf, 859 KB, SIL OFL). Full type scale from DESIGN.md §8: displayLarge (32sp/W600) through labelSmall (11sp/W500). All 9 weight axes registered (W100–W900). Negative tracking at display sizes, positive at label sizes. @OptIn(ExperimentalTextApi::class) for FontVariation.Settings.

Oklab (ui/theme/Oklab.kt) — Double-precision matrix math for accurate sRGB↔Oklab round-trips. Used by theme picker's Oklab gradient swatches and generateGradientStops(). Forward LMS matrix corrected to Björn Ottosson reference.

Internationalization (i18n)

• de (default), en — same as web (messages/de.json, messages/en.json).
• Strings: res/values/strings.xml (de) + res/values-en/strings.xml (en).
• All UI strings use stringResource(R.string.xxx) in @Composable functions, or context.getString(R.string.xxx) in non-composable contexts (error handlers, coroutines).
• Date/time: DateTimeFormatter with Locale.getDefault().
• Greeting: time-of-day-based (Morgen/Tag/Abend → Morning/Afternoon/Evening), boundaries 5/12/18.
• ChatModels: Suggestion.labelRes/promptRes and ChatMode.labelRes are resource IDs (Int), not hardcoded strings.
• ModePillsRow: selected state is Int (resource ID), not String.

Settings persistence + server sync

• SettingsViewModel takes SecureStore — theme, appearance, username, locale survive app restart.
• Theme selection persisted as KaizenThemeId.value string ("amber"/"blue"/"mono"/"aurora").
• Appearance persisted as AppAppearance.name ("Light"/"Dark"/"System").
• On login + on each foreground: KaizenApi.fetchMe() → MeResponse(name, email, defaultModel) populates SettingsViewModel name/email.
• Language selector in Settings: System / Deutsch / English. Stored as locale in SecureStore. Note: currently only stores the preference; runtime locale switching (AppCompatDelegate.setApplicationLocales) needs wiring in MainActivity on next iteration.
• No server-side theme storage — web uses localStorage, app uses SecureStore. Both are client-local.

Offline-first cache layer (Room) — added 2026-06-21

Architecture decision document: OFFLINE_CACHE_ADD.md.

Principle: Read-cache, not sync engine. Server is source of truth. No offline-queue, no conflict resolution.

Stack: Room 2.8.4 + KSP 2.2.10-2.0.2. room-ktx merged into room-runtime since Room 2.7 (no separate dep needed). exportSchema = false, fallbackToDestructiveMigration() — it's a cache, not a DB. On schema changes the SQLite is wiped; cache rebuilds on next server fetch.

Schema:

• conversations — id, title, locked, pinned, updatedAt, cachedAt
• messages — id, conversationId (FK CASCADE), role, content, attachments (JSON via TypeConverter), sortOrder

Data flow:

App start    → Room (instant) → UI shows cached data
             → Background: server fetch → Room update → Flow emits → UI updates
Chat open    → Room (instant) → Background: server fetch → Room update
Send message → in-memory during streaming → Room flush after stream ends

Streaming hybrid model: During active streaming, messages are mutated in-memory (60x/s). Room is NOT written during streaming — that would be absurd I/O. After stream completion, user + assistant messages are upserted into Room. This avoids SQLite lock contention while keeping the cache fresh.

Files:

• db/Entities.kt — ConversationEntity, MessageEntity
• db/ConversationDao.kt — observeAll() (Flow), replaceAll() (transaction: deleteAll + upsertAll, avoids SQLite 999-variable limit), lastCachedAt()
• db/MessageDao.kt — observeByConversation(), getByConversation(), upsertAll(), deleteByConversation()
• db/KaizenDatabase.kt — singleton via companion object (double-checked locking), thread-safe
• db/ConversationRepository.kt — observeAll() (Flow of ConversationSummary), refresh() (server → Room)
• db/MessageRepository.kt — observeMessages(), getCached(), fetchAndCache(), cacheMessages()
• db/Converters.kt — List<Attachment> ↔ JSON string via kotlinx.serialization
• db/Mappers.kt — ConversationSummary ↔ ConversationEntity, StoredMessage ↔ MessageEntity

AGP 9.x compat: android.disallowKotlinSourceSets=false in gradle.properties (KSP issue #2729).

What's DONE and verified

Backend — all complete, deployed, tested

All backend work for the app is done. pnpm test:run green (774+), tsc + lint clean.

• api_tokens table + SHA-256 hash storage (never raw). Migration 0024.
• Bearer auth path (getTokenSession / requireActiveUserOrToken in lib/auth/guard.ts).
• Token mint endpoint POST /api/v1/auth/token — unauthenticated, Argon2id verify, anti-enumeration, rate-limited.
• GET /api/v1/me — identity + defaultModel for native clients.
• GET /api/v1/models — Bearer-authed, returns filtered model catalog.
• /api/v1/conversations — thin re-exports of canonical handlers, Bearer-authed.
• GET /api/v1/meta — capability handshake.
• App-devices card (components/settings/app-tokens-card.tsx) — see/revoke signed-in devices on /settings/security.
• API versioning — /api/v1/ for outward contract, additive-only within v1. Web-internal endpoints stay unversioned.

App — shipped features (on-device verified on S25 Ultra)

All committed on main. Compile-verified on Mac (./gradlew :app:compileDebugKotlin clean).

Commit	Feature
44c17b6	In-app login (email+password → POST /api/v1/auth/token), EncryptedSharedPreferences, real streaming via StreamConsumer.Incremental, ServerConfig persistence
aa0a97b	Dither overlay to kill 8-bit sRGB banding on orb + mesh gradients
d2f269f	Model + speed picker (top pill → bottom sheet), response-speed segment, favorites, provider badges
ea5e625	Sidebar wired to real conversations, persistence (create/save/load/auto-title), date-grouped history
7399c73	Model sheet redesign with OpenRouter/Vertex badging, offline-first caching
d81c6ff	Robust JSON parsing (malformed response handling)
827a2f3	Streaming performance, error handling
423abc0	Specific error diagnostics — FetchResult<T> replaces null-returns; error banner shows exact cause (HTTP status, DNS, SSL, timeout, JSON parsing) instead of generic "Verbindung zum Server fehlgeschlagen"
4616ef2	Markdown rendering with syntax-highlighted code blocks — native Compose renderer: headings, bold/italic, inline code, fenced code blocks with keyword highlighting (15+ languages), ordered/unordered lists, streaming cursor integration
d8dcb25	Attachment support — display, upload, and send files — parse + render message attachments from loaded conversations (images inline via OkHttp + in-memory cache, other kinds as icon chips); + button wired to Android file picker with upload to /api/v1/upload, progress chips, send attachments with chat requests + persist in saved messages. Also: Markdown horizontal rules, blockquotes, links, code block copy button
9759d47	Offline-first cache layer (Room) — sidebar + messages load instantly from SQLite cache, background refresh syncs with server, streaming hybrid model (in-memory during stream, Room flush after), ChatViewModel, repositories, mappers, TypeConverters, unit tests

Earlier UI/feel work (Phase 0 prototype → feel-first):

• Liquid glass styling, floating panels, glassmorphic sidebar
• KaizenOrb with 3D sphere rendering, streaming animation
• Mesh gradient background with dithered blobs
• Phase-aware haptics (click → thinkingStart → responseStart → responseEnd)
• Tablet/landscape optimization (width capping)
• Dynamic keyboard handling (suggestion pills hide, spacer shrinks)
• Settings screen with SettingsViewModel

Bug fixed this session (2026-06-19/20)

"Verbindung zum Server fehlgeschlagen" on S25 — root cause was server running an old build without the v1/conversations route (404) and without Bearer auth on models (401). Fix was git pull && docker compose -f docker-compose.prod.yml up -d --build on the server. Additionally, the error diagnostics were improved (see 423abc0) so future issues show the exact cause in the UI banner instead of a generic message.

What's NOT done yet (app, priority order)

1. Remaining visual/UX gaps (daily-drive blockers)

These are what separate "prototype" from "daily-driver":

• Markdown rendering during streaming — currently renders live but performance with long code blocks during high-speed streaming needs real-device verification
• Code block copy button — tap-to-copy on fenced code blocks (clipboard + haptic feedback)
• Horizontal rule / blockquote rendering — --- and > quote not yet parsed
• Table rendering — Markdown tables render as raw text
• Link rendering — styled visually, not yet clickable (tap-to-open pending)

2. Conversation management from the app

• Conversation rename/delete from the sidebar (currently read-only)
• Conversation pin/unpin from the sidebar
• In-app unlock for locked conversations (currently skipped with "Gesperrter Chat" label)

3. Security hardening

• Auto-logout on 401 — if the token is rejected, route to login screen instead of showing error banner
• Server version check — call /api/v1/meta after login to detect server skew and warn cleanly
• Biometric lock (BiometricPrompt + KeyStore binding) — see LATER.md §1C
• FLAG_SECURE on sensitive screens — see LATER.md §1B

4. Features for parity with the web

• Attachments — image/file upload, attachment preview in messages, display in loaded conversations (camera capture still TODO)
• Reasoning/thinking display — parse \x01 sentinel, show collapsible thinking block
• Web search sources — parse \x02/\x04 sentinels, render source cards
• Tool call display — parse \x03 sentinel, show live tool steps
• Native passkey login (WebAuthn/FIDO2 on Android)
• WebSocket streaming (replace chunked HTTP for lower latency on mobile)
• Usage/cost display
• User context / KI-Profil

5. App distribution

• Push notifications (FCM)
• Play Store / F-Droid listing
• Auto-update mechanism

6. Offline-cache enhancements (future iterations, see OFFLINE_CACHE_ADD.md §11)

• Stale-check enforcement — use cachedAt to trigger background refresh when older than N minutes
• Offline-queue for sends — queue messages locally, send when network returns (needs conflict resolution)
• Incremental sync — only fetch changed conversations (needs server-side since parameter)
• Media cache — cache images/files locally (Coil or custom disk cache)
• Full-text search — FTS4/FTS5 over cached messages (Room supports this natively)
• Attachment queries — "show me all chats with images/PDFs" via Room DB

Dependencies

# gradle/libs.versions.toml (key versions)
agp = "9.2.1"
kotlin = "2.2.10"
ksp = "2.2.10-2.0.2"
room = "2.8.4"
composeBom = "2026.02.01"
okhttp = "4.12.0"
kotlinxSerialization = "1.7.3"
securityCrypto = "1.1.0-alpha06"

Tests

Unit tests (app/src/test/): JVM-only, no emulator needed.

• SettingsViewModelTest — state transitions, default values, theme selection, name updates
• StreamConsumerTest — incremental parser, sentinel stripping, edge cases
• OklabTest — 2 pre-existing failures (round-trip color drift > 0.01 tolerance, unrelated to backend wiring, likely too-tight tolerance or headless float precision)
• MappersTest — ConversationSummary ↔ ConversationEntity, StoredMessage ↔ MessageEntity, round-trip integrity, attachment preservation
• ConvertersTest — List<Attachment> ↔ JSON round-trips, malformed JSON returns empty list, unknown fields tolerance via ignoreUnknownKeys
• ColorPipelineTest — all tokens in DisplayP3, approximate value ranges, no pure black/white in neutrals
• SquircleShapeTest — KaizenShapes token existence/distinctness, SquircleShape toString
• ThemeRegistryTest — 4 themes present, forId lookup, fromString parsing + fallback, distinct blob colors
• ShadowStackTest — layer counts per level, alpha range validation, blur/alpha progression

Pre-existing issues (not from this work)

• OklabTest has 2 headless failures (testColorToOklabAndBack, testGradientGeneration — round-trip color drift > 0.01 tolerance). Unrelated to backend wiring; likely too-tight tolerance or headless float precision.

Constraints & gotchas

• Local dev Mac has no RustFS (storage on server only); upload/storage flows fail locally with ECONNREFUSED :9000.
• Live OpenRouter key is encrypted in the DB (api_keys), .env.local is stale.
• Never hand-write migrations or fake timestamps — use pnpm db:generate. Always git pull before docker build on prod.
• App philosophy: the real driver is feel, not features; native Compose (no WebView). Backend complexity stays invisible.
• Deploy gotcha (learned 2026-06-19): git pull BEFORE docker compose up --build, else the image bakes stale code and the app gets 404/401 against endpoints that exist in the repo but aren't in the running build.
• Headless compile on Mac: JAVA_HOME=/opt/homebrew/opt/openjdk@21/libexec/openjdk.jdk/Contents/Home ./gradlew :app:compileDebugKotlin — JDK 21 via Homebrew, Android SDK at /opt/homebrew/share/android-commandlinetools.
• AGP 9.x + KSP: requires android.disallowKotlinSourceSets=false in gradle.properties.
• Room is a cache: fallbackToDestructiveMigration() means the SQLite DB is wiped on schema changes. No data loss — server is source of truth, cache rebuilds on next fetch.