feature:chat

Screen States

ChatScreenState enum: LANDING | LOADING | ACTIVE

Landing: no conversation selected, shows greeting + model icon + optional conversation starters
Loading: spinner while fetching messages for a conversation
Active: message list + streaming content + input area

Sealed interface: ChatRoute : NavKey with typed route classes
Routes: NewChat (landing), Chat(conversationId: String? = null), PromptsLibrary, PromptEditor(groupId: String? = null) (all @Serializable)
Feature entries registered via EntryProviderScope<NavKey>.chatEntries()
When a new conversation starts from the landing page, pendingNavigationConversationId triggers navigation to Chat(id) after the first stream completes (data persisted to Room), keeping NewChat in the back stack
navigateToChat() replaces the current chat entry on the NavBackStack when switching between chats so back returns to NewChat

Messages stored flat, linked by parentMessageId (root = NO_PARENT UUID)
MessageTree.kt builds tree via buildActiveMessagePath(messages, activeBranches)
activeBranches: Map<String, Int> tracks which sibling is displayed per parent
switchBranch(parentMessageId, siblingIndex) updates branch selection and rebuilds display list
Editing a user message creates a new sibling (new branch); regenerating an AI message also creates a sibling

ContentPartRenderer dispatches by ContentPart.type:
- text -> MarkdownContent (custom regex parser with LaTeX support)
- think -> collapsible thinking block
- tool_call -> StreamingToolCallCard (expandable, shows args/output)
- image_file / image_url -> inline AsyncImage, tap opens FullscreenImageViewer
- error -> red-styled error display
CodeBlock renders fenced code with syntax highlighting, language badge, and copy button (3s checkmark)
LaTeX: LatexBlock (block math) and LatexInline (inline math) via AndroidMath native rendering
- Supports $$...$$, \[...\] (block) and $...$ , $...$ (inline)
- $...$ requires heuristic check (looksLikeLatex()) to avoid false positives on dollar amounts
- Falls back to monospace text if AndroidMath can't parse the expression

ChatViewModel.sendMessage() calls ChatRepository.startChat() which returns Flow<StreamEvent>
Two-phase: POST /api/agents/chat -> streamId, then GET SSE stream
streamingBuffer: StringBuilder accumulates text deltas
Tool calls tracked in activeToolCalls list (start -> complete lifecycle)
stopGeneration() cancels stream job and calls chatRepository.abortChat()
onPause()/onResume() handle app backgrounding: checks stream status, resumes if still active

Component	Purpose
`ChatInput`	Auto-growing text field, send/stop button, file attach, voice
`MessageBubble`	Icon + content column + action bar + sibling nav
`MessageList`	LazyColumn of MessageBubbles with scroll-to-bottom FAB
`ModelSelectorSheet`	Bottom sheet: search + endpoint-grouped model list
`ModelSelectorButton`	Header chip showing current model
`SiblingNavigator`	"1/3" with chevrons for branch switching
`LandingContent`	Greeting, entity icon, conversation starters
`StreamingIndicator`	Blinking cursor during active generation
`PresetPicker`	Preset selection menu
`SavePresetDialog`	Dialog to name and save current config as preset

PromptsLibraryScreen and PromptDetailScreen live in chat/prompts/
PromptsViewModel loads prompt groups from PromptRepository
handlePromptMention() on ChatViewModel inserts prompt command text at @ position

ChatInputToolbar renders toggles for enabled tools (web search, code interpreter, file search)
Tool state tracked as Set<String> in ChatUiState.enabledTools
ToolsDropdownMenu provides overflow for additional tool options
Toolbar wired into ChatInput above the text field

ImageGenCard renders DALL-E / image generation results (spinner while generating, AsyncImage when done)
LogContentCard renders expandable log output blocks with monospace text
Both dispatched from ContentPartRenderer — tool calls with name containing dall route to ImageGenCard

ArtifactDetector parses remark-directive format :::artifact{identifier="id" type="..." title="..."} with backtick-fenced content; groupArtifactVersions() groups by identifier
Supported types: text/html, image/svg+xml, application/vnd.react, application/vnd.mermaid, text/markdown/text/md, text/plain, application/vnd.code-html
MermaidWebContent renders Mermaid diagrams via CDN mermaid.js with zoom controls and dark theme
MarkdownWebContent renders Markdown via CDN marked.js + highlight.js with GFM and syntax highlighting
HTML/React/SVG templates include Tailwind CDN, theme CSS vars, and error handling
React template preprocesses import/export statements for browser-compatible execution
ArtifactPanel supports fullscreen Dialog mode, version switching, loading indicator, and WebView error overlay
ArtifactButton shows type-specific icons and subtitle (e.g. "Mermaid Diagram", "React Component")
ContentPartRenderer wires groupArtifactVersions() to pass version lists to ArtifactButton/ArtifactPanel
ArtifactVersionNav provides prev/next arrows with "v2/3" indicator
ArtifactDownloadHelper shares artifacts via FileProvider temp file + system share sheet. Maps 25+ language extensions including .mmd for Mermaid. Sanitizes filenames to 100 chars
Gotcha: FileProvider authority must match app's declared authority in AndroidManifest

VideoContentPlayer uses ExoPlayer (media3) — 16:9 aspect ratio Card, lifecycle-aware release
AudioContentPlayer uses MediaPlayer — play/pause + seekbar, 250ms polling for progress
AudioContentPlayerFromBytes variant writes bytes to temp file for MediaPlayer
Gotcha: Both players must release resources on dispose — use DisposableEffect

Thumbs-down opens FeedbackCommentDialog before submitting; thumbs-up fires immediately
Comment is optional — empty string is a valid submission
Toggling off an existing thumbs-down (already selected) calls onFeedback(null) directly, skipping the dialog

MessageTimestamp shows relative/absolute time, toggled on tap
Parses multiple ISO 8601 format variants; falls back gracefully on invalid input
Integrated into MessageBubble action row