refactor(contextual): drop 'floating' branch from useAIChat and useChatStream

UIChatContext is now 'global' | 'project' only. Floating domain
signal, scope field, and onDomainSignal callback removed. ChatInputBox
no longer defines floating variant. TaskBriefChat migrated to contextual mode.

src/renderer/components/ai/ChatInputBox.tsx

@@ -9,7 +9,7 @@ export interface ChatInputBoxHandle {
   focus: () => void;
 }
 
-type ChatInputBoxVariant = 'panel' | 'floating' | 'comment';
+type ChatInputBoxVariant = 'panel' | 'comment';
 
 interface ChatInputBoxProps {
   cacheKey: string;
@@ -27,12 +27,6 @@ const VARIANT_STYLES = {
     button: 'flex h-8 w-8 shrink-0 items-center justify-center rounded-lg bg-primary text-primary-foreground shadow-sm transition-all hover:bg-primary/90 active:scale-95 disabled:opacity-40 disabled:cursor-not-allowed disabled:active:scale-100',
     iconSize: 16,
   },
-  floating: {
-    container: 'flex items-center gap-2 px-3 py-2.5',
-    textarea: 'flex-1 resize-none bg-transparent text-sm placeholder:text-muted-foreground/60 outline-none max-h-20 overflow-y-auto',
-    button: 'flex h-7 w-7 shrink-0 items-center justify-center rounded-xl bg-primary text-primary-foreground shadow-sm transition-all hover:bg-primary/90 active:scale-95 disabled:opacity-30 disabled:cursor-not-allowed',
-    iconSize: 14,
-  },
   comment: {
     container: 'flex items-center gap-2 px-3 py-2',
     textarea: 'flex-1 resize-none bg-transparent text-sm placeholder:text-muted-foreground outline-none max-h-32 overflow-y-auto',
@@ -49,7 +43,7 @@ export const ChatInputBox = forwardRef<ChatInputBoxHandle, ChatInputBoxProps>(
     const valueRef = useRef(value);
     valueRef.current = value;
 
-    // Re-init when the cache key changes (context switches in FloatingChat).
+    // Re-init when the cache key changes (context switches).
     const prevKeyRef = useRef(cacheKey);
     useEffect(() => {
       if (prevKeyRef.current !== cacheKey) {

src/renderer/components/brief/TaskBriefChat.tsx

@@ -177,7 +177,7 @@ export function TaskBriefChat({ taskId, projectId, initialBriefing, onBriefingRe
         message: trimmed,
         conversationHistory,
         sessionId,
-        mode: 'floating',
+        mode: 'contextual',
         scope: { type: 'task', id: taskId },
         briefMode: true,
         briefingContext: briefingText || undefined,

src/renderer/hooks/useAIChat.ts

@@ -1,33 +1,16 @@
 import { useState, useCallback, useRef, useEffect, useMemo } from 'react';
 import { trpc } from '@/lib/trpc';
 
-export type FloatingDomainSignal =
-  | 'tasks'
-  | 'notes'
-  | 'timelines'
-  | 'projects'
-  | {
-      type: 'task' | 'timeline' | 'project' | 'note' | 'node';
-      id?: string | null;
-      section?: 'task' | 'timeline' | 'note' | null;
-    };
-
 // ---------------------------------------------------------------------------
 // Types
 // ---------------------------------------------------------------------------
 
 /**
  * Renderer-only context describing where the user is in the UI.
- * Retained for call-site compatibility; mode/scope fields support v3 routing.
  */
 export interface UIChatContext {
-  type: 'global' | 'project' | 'floating';
+  type: 'global' | 'project';
   projectId?: string;
-  /** For floating mode — the entity scope to pass to the backend. */
-  scope?: {
-    type: 'task' | 'project' | 'note' | 'timeline';
-    id?: string;
-  };
 }
 
 export interface ChatMessage {
@@ -47,10 +30,6 @@ interface UseAIChatReturn {
   cacheKey: string;
 }
 
-interface UseAIChatOptions {
-  onDomainSignal?: (domain: FloatingDomainSignal) => void;
-}
-
 interface CachedChatState {
   messages: ChatMessage[];
   /** Written by ChatInputBox; read on mount to restore draft. Not written by this hook. */
@@ -62,11 +41,7 @@ const chatSessionCache = new Map<string, CachedChatState>();
 
 function getContextCacheKey(ctx: UIChatContext): string {
   if (ctx.type === 'global') return 'global';
-  if (ctx.type === 'project') return `project:${ctx.projectId ?? ''}`;
-
-  // Floating chat should keep a single continuous session while the panel is open,
-  // even when route/section context changes due floating-domain navigation.
-  return 'floating';
+  return `project:${ctx.projectId ?? ''}`;
 }
 
 // ---------------------------------------------------------------------------
@@ -121,10 +96,10 @@ export function parseMutationsToEntityTags(mutations: unknown[] | undefined): st
 // Hook
 // ---------------------------------------------------------------------------
 
-export function useAIChat(defaultContext: UIChatContext, options?: UseAIChatOptions): UseAIChatReturn {
+export function useAIChat(defaultContext: UIChatContext): UseAIChatReturn {
   const contextCacheKey = useMemo(
     () => getContextCacheKey(defaultContext),
-    [defaultContext.type, defaultContext.projectId, defaultContext.scope?.type, defaultContext.scope?.id],
+    [defaultContext.type, defaultContext.projectId],
   );
 
   const [messages, setMessages] = useState<ChatMessage[]>(
@@ -148,9 +123,6 @@ export function useAIChat(defaultContext: UIChatContext, options?: UseAIChatOpti
   messagesRef.current = messages;
   const sessionIdRef = useRef(sessionId);
   sessionIdRef.current = sessionId;
-  const onDomainSignalRef = useRef(options?.onDomainSignal);
-  onDomainSignalRef.current = options?.onDomainSignal;
-
   // Keep local state aligned when the chat context changes in-place.
   useEffect(() => {
     const cached = chatSessionCache.get(contextCacheKey);
@@ -234,9 +206,6 @@ export function useAIChat(defaultContext: UIChatContext, options?: UseAIChatOpti
             break;
           }
 
-          case 'floating_domain':
-            onDomainSignalRef.current?.(event.domain);
-            break;
         }
       });
 
@@ -246,17 +215,12 @@ export function useAIChat(defaultContext: UIChatContext, options?: UseAIChatOpti
         content: m.content,
       }));
 
-      const isFloating = ctx.type === 'floating';
-
       chatMutationRef.current.mutate(
         {
           requestId,
           message: trimmed,
           conversationHistory,
           sessionId: sessionIdRef.current,
-          ...(isFloating && ctx.scope
-            ? { mode: 'floating' as const, scope: ctx.scope }
-            : {}),
         },
         {
           onSuccess: (data) => {

src/renderer/hooks/useChatStream.ts

@@ -14,15 +14,12 @@ export interface UseChatStreamArgs {
   onAssistantMessage: (msg: ChatMessage) => void;
   /** Called when the request fails. */
   onError: (msg: ChatMessage) => void;
-  /** Optional: legacy floating_domain pivot signal. Kept until M6 removes floating. */
-  onDomainSignal?: (domain: unknown) => void;
 }
 
 export function useChatStream({
   sessionId,
   onAssistantMessage,
   onError,
-  onDomainSignal,
 }: UseChatStreamArgs) {
   const [isStreaming, setIsStreaming] = useState(false);
   const [streamingContent, setStreamingContent] = useState('');
@@ -30,9 +27,6 @@ export function useChatStream({
   const mutation = trpc.ai.chat.useMutation();
   const mutationRef = useRef(mutation);
   mutationRef.current = mutation;
-  const domainRef = useRef(onDomainSignal);
-  domainRef.current = onDomainSignal;
-
   const send = useCallback(
     (args: {
       message: string;
@@ -67,9 +61,6 @@ export function useChatStream({
             unsubscribe();
             break;
           }
-          case 'floating_domain':
-            domainRef.current?.(event.domain);
-            break;
         }
       });