feat(floating-ai): step 8 — page interactions (all variants)

Register AI sections across all content pages with dual-anchor scroll
tracking, cross-page navigation via [SECTION:xxx] tags, and right-margin
positioning for the notes editor.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/renderer/components/ai/FloatingChat.tsx

@@ -1,10 +1,11 @@
 import { useCallback, useEffect, useMemo, useRef } from 'react';
 import { createPortal } from 'react-dom';
 import { AnimatePresence, motion } from 'framer-motion';
-import { useRouterState } from '@tanstack/react-router';
+import { useNavigate, useRouterState } from '@tanstack/react-router';
 import { X, ArrowUp } from 'lucide-react';
 import {
   useFloatingChat,
+  computeDualAnchor,
   CHAT_WIDTH,
   CHAT_HEIGHT,
   PADDING,
@@ -14,9 +15,22 @@ import { ChatMarkdown } from '@/components/ai/AIChatPanel';
 import { Skeleton } from '@/components/ui/skeleton';
 import { trpc } from '@/lib/trpc';
 
+/** Map section IDs to their routes for cross-page navigation */
+const SECTION_ROUTES: Record<string, string> = {
+  'project-summary': 'project',
+  'project-timeline': 'project',
+  'project-tasks': 'project',
+  'project-notes': 'project',
+  'tasks-overview': '/tasks',
+  'tasks-list': '/tasks',
+  'timeline-chart': '/timeline',
+  'note-editor': 'note',
+};
+
 function FloatingChatInner() {
-  const { state, sections, close, setMorphTarget } = useFloatingChat();
+  const { state, sections, close, setMorphTarget, moveToSection, updatePosition, setPendingSection } = useFloatingChat();
   const utils = trpc.useUtils();
+  const navigate = useNavigate();
   const routerState = useRouterState();
   const prevPathRef = useRef(routerState.location.pathname);
 
@@ -33,6 +47,32 @@ function FloatingChatInner() {
     [activeSection?.projectId, activeSection?.label],
   );
 
+  // Handle [SECTION:xxx] tags from AI responses
+  const handleSectionTag = useCallback((sectionId: string) => {
+    // Same-page: section is already registered
+    const targetSection = sections.get(sectionId);
+    if (targetSection) {
+      moveToSection(sectionId);
+      targetSection.ref.current?.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
+      return;
+    }
+
+    // Cross-page: section not registered, navigate to its route
+    const route = SECTION_ROUTES[sectionId];
+    if (!route) return;
+
+    setPendingSection({ sectionId });
+
+    if (route === 'project' && state.projectId) {
+      // Navigate to the project page (stay on same project)
+      // Project sections re-register on mount and pendingSection will auto-open
+      void navigate({ to: '/projects/$projectId', params: { projectId: state.projectId } });
+    } else if (route.startsWith('/')) {
+      void navigate({ to: route });
+    }
+    // 'note' type requires noteId — skip cross-page for now
+  }, [sections, moveToSection, setPendingSection, state.projectId, navigate]);
+
   const {
     messages,
     input,
@@ -41,7 +81,7 @@ function FloatingChatInner() {
     streamingContent,
     handleSend,
     clearMessages,
-  } = useAIChat(chatContext);
+  } = useAIChat(chatContext, { onSectionTag: handleSectionTag });
 
   const containerRef = useRef<HTMLDivElement>(null);
 
@@ -59,15 +99,15 @@ function FloatingChatInner() {
     return () => document.removeEventListener('keydown', handler);
   }, [state.isOpen, close]);
 
-  // ---- Close on route change ----
+  // ---- Close on route change (unless cross-page navigation pending) ----
 
   useEffect(() => {
     const currentPath = routerState.location.pathname;
-    if (prevPathRef.current !== currentPath && state.isOpen) {
+    if (prevPathRef.current !== currentPath && state.isOpen && !state.pendingSection) {
       close();
     }
     prevPathRef.current = currentPath;
-  }, [routerState.location.pathname, state.isOpen, close]);
+  }, [routerState.location.pathname, state.isOpen, state.pendingSection, close]);
 
   // ---- Clear messages on close ----
 
@@ -123,6 +163,51 @@ function FloatingChatInner() {
     return () => window.removeEventListener('resize', handler);
   }, [state.isOpen, state.position.x, state.position.y]);
 
+  // ---- Scroll tracking: dual-anchor repositioning ----
+
+  useEffect(() => {
+    if (!state.isOpen || !state.activeSectionId) return;
+    const section = sections.get(state.activeSectionId);
+    if (!section || section.anchorMode === 'right-margin') return;
+
+    const el = section.ref.current;
+    if (!el) return;
+
+    // Find scrollable ancestor
+    let scrollParent: HTMLElement | null = el.parentElement;
+    while (scrollParent) {
+      const style = getComputedStyle(scrollParent);
+      if (style.overflow === 'auto' || style.overflow === 'scroll' ||
+          style.overflowY === 'auto' || style.overflowY === 'scroll') {
+        break;
+      }
+      // Also check for Radix ScrollArea viewport
+      if (scrollParent.hasAttribute('data-radix-scroll-area-viewport')) break;
+      scrollParent = scrollParent.parentElement;
+    }
+
+    if (!scrollParent) return;
+
+    let rafId: number | null = null;
+    const handleScroll = () => {
+      if (rafId !== null) return;
+      rafId = requestAnimationFrame(() => {
+        rafId = null;
+        const newPos = computeDualAnchor(section);
+        if (newPos) {
+          updatePosition(newPos);
+        }
+        // null = fully off-screen → freeze (do nothing)
+      });
+    };
+
+    scrollParent.addEventListener('scroll', handleScroll, { passive: true });
+    return () => {
+      scrollParent.removeEventListener('scroll', handleScroll);
+      if (rafId !== null) cancelAnimationFrame(rafId);
+    };
+  }, [state.isOpen, state.activeSectionId, sections, updatePosition]);
+
   // ---- Auto-scroll messages ----
 
   const scrollRef = useRef<HTMLDivElement>(null);