feat: add scroll-to-top button and improve pagination handling

- Implemented a scroll-to-top button in the viewer UI for better navigation.
- Added styles for the scroll-to-top button in viewer.html and viewer-template.html.
- Created a new ScrollToTop component to manage visibility and scrolling behavior.
- Updated Feed component to include the ScrollToTop component.
- Enhanced pagination logic in usePagination hook to prevent stale closures and improve performance.
- Modified SDKAgent to include additional observation fields for better data handling.

plugin/ui/viewer.html

@@ -871,6 +871,49 @@
         background-position: -200% 0;
       }
     }
+
+    /* Scroll to top button */
+    .scroll-to-top {
+      position: fixed;
+      bottom: 24px;
+      right: 24px;
+      width: 48px;
+      height: 48px;
+      background: var(--color-bg-button);
+      color: var(--color-text-button);
+      border: none;
+      border-radius: 24px;
+      cursor: pointer;
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+      transition: all 0.2s ease;
+      z-index: 50;
+      animation: fadeInUp 0.3s ease-out;
+    }
+
+    .scroll-to-top:hover {
+      background: var(--color-bg-button-hover);
+      transform: translateY(-2px);
+      box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
+    }
+
+    .scroll-to-top:active {
+      background: var(--color-bg-button-active);
+      transform: translateY(0);
+    }
+
+    @keyframes fadeInUp {
+      from {
+        opacity: 0;
+        transform: translateY(10px);
+      }
+      to {
+        opacity: 1;
+        transform: translateY(0);
+      }
+    }
   </style>
 </head>
 

src/services/worker/SDKAgent.ts

@@ -198,10 +198,17 @@ export class SDKAgent {
           type: 'new_observation',
           observation: {
             id: obsId,
+            sdk_session_id: session.sdkSessionId,
             session_id: session.claudeSessionId,
             type: obs.type,
             title: obs.title,
             subtitle: obs.subtitle,
+            text: obs.text || null,
+            narrative: null,
+            facts: JSON.stringify(obs.facts || []),
+            concepts: JSON.stringify(obs.concepts || []),
+            files_read: JSON.stringify(obs.files || []),
+            files_modified: JSON.stringify([]),
             project: session.project,
             prompt_number: session.lastPromptNumber,
             created_at_epoch: createdAtEpoch

src/ui/viewer-template.html

@@ -871,6 +871,49 @@
         background-position: -200% 0;
       }
     }
+
+    /* Scroll to top button */
+    .scroll-to-top {
+      position: fixed;
+      bottom: 24px;
+      right: 24px;
+      width: 48px;
+      height: 48px;
+      background: var(--color-bg-button);
+      color: var(--color-text-button);
+      border: none;
+      border-radius: 24px;
+      cursor: pointer;
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+      transition: all 0.2s ease;
+      z-index: 50;
+      animation: fadeInUp 0.3s ease-out;
+    }
+
+    .scroll-to-top:hover {
+      background: var(--color-bg-button-hover);
+      transform: translateY(-2px);
+      box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
+    }
+
+    .scroll-to-top:active {
+      background: var(--color-bg-button-active);
+      transform: translateY(0);
+    }
+
+    @keyframes fadeInUp {
+      from {
+        opacity: 0;
+        transform: translateY(10px);
+      }
+      to {
+        opacity: 1;
+        transform: translateY(0);
+      }
+    }
   </style>
 </head>
 

src/ui/viewer/App.tsx

@@ -72,12 +72,13 @@ export function App() {
     } catch (error) {
       console.error('Failed to load more data:', error);
     }
-  }, [pagination]);
+  }, [pagination.observations, pagination.summaries, pagination.prompts]);
 
-  // Load first page when filter changes or pagination handlers update
+  // Load first page only when filter changes
   useEffect(() => {
     handleLoadMore();
-  }, [currentFilter, handleLoadMore]);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [currentFilter]); // Only re-run when filter changes, not when handleLoadMore changes
 
   return (
     <div className="container">

src/ui/viewer/components/Feed.tsx

@@ -3,6 +3,7 @@ import { Observation, Summary, UserPrompt, FeedItem } from '../types';
 import { ObservationCard } from './ObservationCard';
 import { SummaryCard } from './SummaryCard';
 import { PromptCard } from './PromptCard';
+import { ScrollToTop } from './ScrollToTop';
 import { UI } from '../constants/ui';
 
 interface FeedProps {
@@ -16,6 +17,7 @@ interface FeedProps {
 
 export function Feed({ observations, summaries, prompts, onLoadMore, isLoading, hasMore }: FeedProps) {
   const loadMoreRef = useRef<HTMLDivElement>(null);
+  const feedRef = useRef<HTMLDivElement>(null);
   const onLoadMoreRef = useRef(onLoadMore);
 
   // Keep the callback ref up to date
@@ -59,7 +61,8 @@ export function Feed({ observations, summaries, prompts, onLoadMore, isLoading,
   }, [observations, summaries, prompts]);
 
   return (
-    <div className="feed">
+    <div className="feed" ref={feedRef}>
+      <ScrollToTop targetRef={feedRef} />
       <div className="feed-content">
         {items.map(item => {
           const key = `${item.itemType}-${item.id}`;

src/ui/viewer/components/ScrollToTop.tsx

@@ -0,0 +1,57 @@
+import React, { useState, useEffect } from 'react';
+
+interface ScrollToTopProps {
+  targetRef: React.RefObject<HTMLDivElement>;
+}
+
+export function ScrollToTop({ targetRef }: ScrollToTopProps) {
+  const [isVisible, setIsVisible] = useState(false);
+
+  useEffect(() => {
+    const handleScroll = () => {
+      const target = targetRef.current;
+      if (target) {
+        setIsVisible(target.scrollTop > 300);
+      }
+    };
+
+    const target = targetRef.current;
+    if (target) {
+      target.addEventListener('scroll', handleScroll);
+      return () => target.removeEventListener('scroll', handleScroll);
+    }
+  }, []); // Empty deps - only set up listener once on mount
+
+  const scrollToTop = () => {
+    const target = targetRef.current;
+    if (target) {
+      target.scrollTo({
+        top: 0,
+        behavior: 'smooth'
+      });
+    }
+  };
+
+  if (!isVisible) return null;
+
+  return (
+    <button
+      onClick={scrollToTop}
+      className="scroll-to-top"
+      aria-label="Scroll to top"
+    >
+      <svg
+        width="20"
+        height="20"
+        viewBox="0 0 24 24"
+        fill="none"
+        stroke="currentColor"
+        strokeWidth="2"
+        strokeLinecap="round"
+        strokeLinejoin="round"
+      >
+        <polyline points="18 15 12 9 6 15"></polyline>
+      </svg>
+    </button>
+  );
+}

src/ui/viewer/hooks/usePagination.ts

@@ -1,4 +1,4 @@
-import { useState, useEffect, useCallback } from 'react';
+import { useState, useEffect, useCallback, useRef } from 'react';
 import { Observation, Summary, UserPrompt } from '../types';
 import { UI } from '../constants/ui';
 import { API_ENDPOINTS } from '../constants/api';
@@ -21,6 +21,18 @@ function usePaginationFor(endpoint: string, dataType: DataType, currentFilter: s
   });
   const [offset, setOffset] = useState(0);
 
+  // Use refs to avoid stale closures and prevent infinite loops
+  const stateRef = useRef(state);
+  const offsetRef = useRef(offset);
+
+  useEffect(() => {
+    stateRef.current = state;
+  }, [state]);
+
+  useEffect(() => {
+    offsetRef.current = offset;
+  }, [offset]);
+
   // Reset pagination when filter changes
   useEffect(() => {
     setOffset(0);
@@ -34,17 +46,17 @@ function usePaginationFor(endpoint: string, dataType: DataType, currentFilter: s
    * Load more items from the API
    */
   const loadMore = useCallback(async (): Promise<DataItem[]> => {
-    // Prevent concurrent requests using state
-    if (state.isLoading || !state.hasMore) {
+    // Prevent concurrent requests using ref (always current)
+    if (stateRef.current.isLoading || !stateRef.current.hasMore) {
       return [];
     }
 
     setState(prev => ({ ...prev, isLoading: true }));
 
     try {
-      // Build query params
+      // Build query params using ref (always current)
       const params = new URLSearchParams({
-        offset: offset.toString(),
+        offset: offsetRef.current.toString(),
         limit: UI.PAGINATION_PAGE_SIZE.toString()
       });
 
@@ -74,7 +86,7 @@ function usePaginationFor(endpoint: string, dataType: DataType, currentFilter: s
       setState(prev => ({ ...prev, isLoading: false }));
       return [];
     }
-  }, [offset, state.hasMore, state.isLoading, currentFilter, endpoint, dataType]);
+  }, [currentFilter, endpoint, dataType]); // Only stable values - no state/offset deps
 
   return {
     ...state,