feat: resolve 7 pre-ship QoL items

- Space/Shift+Space: page down/up in detail panel (80% scroll)
- Content font: sans-serif/serif/monospace selector in appearance
  settings, applied to article content in detail panel
- Accessibility: entry-list-item uses button instead of div, folder
  toggles have aria-expanded, shortcut keys have aria-labels
- Share notes: replaced window.prompt with proper modal dialog
  matching existing UI patterns
- Worker .env.example: template with all 10 environment variables
- Worker poisoned messages: archive unprocessable queue messages
  instead of leaving them stuck forever
- Worker pool Submit: check return value, reschedule dropped feeds
  30s into the future, log warnings for rejected submissions

7 files changed, 140 insertions, 6 deletions

diff --git a/apps/web/app/reader/_components/entry-detail-panel.tsx b/apps/web/app/reader/_components/entry-detail-panel.tsx
index 5825b1e..4d15e1f 100644
--- a/apps/web/app/reader/_components/entry-detail-panel.tsx
+++ b/apps/web/app/reader/_components/entry-detail-panel.tsx
@@ -68,6 +68,14 @@ export function EntryDetailPanel({
   const showReadingTime = useUserInterfaceStore(
     (state) => state.showReadingTime
   )
+  const contentFont = useUserInterfaceStore((state) => state.contentFont)
+
+  const contentFontClass =
+    contentFont === "serif"
+      ? "font-serif"
+      : contentFont === "monospace"
+        ? "font-mono"
+        : "font-sans"
 
   const proseContainerReference = useRef<HTMLDivElement>(null)
   const [selectionToolbarState, setSelectionToolbarState] = useState<{
@@ -82,6 +90,9 @@ export function EntryDetailPanel({
     containerRect: DOMRect
   } | null>(null)
   const [unpositionedHighlights, setUnpositionedHighlights] = useState<Highlight[]>([])
+  const [isShareNoteDialogOpen, setIsShareNoteDialogOpen] = useState(false)
+  const [shareNoteText, setShareNoteText] = useState("")
+  const shareNoteTextareaReference = useRef<HTMLTextAreaElement>(null)
 
   const { data: timelineData } = useTimeline()
   const currentEntry = timelineData?.pages
@@ -270,6 +281,32 @@ export function EntryDetailPanel({
     return () => container.removeEventListener("click", handleMarkClick)
   }, [highlightsData])
 
+  useEffect(() => {
+    if (isShareNoteDialogOpen) {
+      setTimeout(() => shareNoteTextareaReference.current?.focus(), 0)
+    }
+  }, [isShareNoteDialogOpen])
+
+  useEffect(() => {
+    if (!isShareNoteDialogOpen) return
+
+    function handleKeyDown(event: KeyboardEvent) {
+      if (event.key === "Escape") {
+        event.preventDefault()
+        event.stopPropagation()
+        setIsShareNoteDialogOpen(false)
+      }
+    }
+
+    document.addEventListener("keydown", handleKeyDown, true)
+    return () => document.removeEventListener("keydown", handleKeyDown, true)
+  }, [isShareNoteDialogOpen])
+
+  function handleShareConfirm() {
+    shareMutation.mutate(shareNoteText.trim() || null)
+    setIsShareNoteDialogOpen(false)
+  }
+
   function handleCreateHighlight(note: string | null) {
     const container = proseContainerReference.current
     if (!container || !selectionToolbarState) return
@@ -382,8 +419,8 @@ export function EntryDetailPanel({
           <button
             type="button"
             onClick={() => {
-              const note = window.prompt("add a note (optional):")
-              shareMutation.mutate(note || null)
+              setShareNoteText("")
+              setIsShareNoteDialogOpen(true)
             }}
             className="shrink-0 whitespace-nowrap border border-border px-2 py-1 text-text-secondary transition-colors hover:bg-background-tertiary hover:text-text-primary"
           >
@@ -461,7 +498,7 @@ export function EntryDetailPanel({
         <div className="relative">
           <div
             ref={proseContainerReference}
-            className="prose-reader text-text-secondary"
+            className={`prose-reader text-text-secondary ${contentFontClass}`}
           />
           {selectionToolbarState && (
             <HighlightSelectionToolbar
@@ -484,6 +521,55 @@ export function EntryDetailPanel({
           )}
         </div>
       </article>
+      {isShareNoteDialogOpen && (
+        <div className="fixed inset-0 z-50 flex items-center justify-center">
+          <div
+            className="fixed inset-0 bg-background-primary/80"
+            onClick={() => setIsShareNoteDialogOpen(false)}
+          />
+          <div className="relative w-full max-w-md border border-border bg-background-secondary p-6">
+            <h2 className="mb-4 text-text-primary">share entry</h2>
+            <form
+              onSubmit={(event) => {
+                event.preventDefault()
+                handleShareConfirm()
+              }}
+              className="space-y-4"
+            >
+              <div className="space-y-2">
+                <label htmlFor="share-note-textarea" className="text-text-secondary">
+                  add a note (optional)
+                </label>
+                <textarea
+                  ref={shareNoteTextareaReference}
+                  id="share-note-textarea"
+                  value={shareNoteText}
+                  onChange={(event) => setShareNoteText(event.target.value)}
+                  rows={4}
+                  placeholder="Write a note to accompany this shared entry..."
+                  className="w-full resize-y border border-border bg-background-primary px-3 py-2 text-text-primary outline-none placeholder:text-text-dim focus:border-text-dim"
+                />
+              </div>
+              <div className="flex gap-2">
+                <button
+                  type="button"
+                  onClick={() => setIsShareNoteDialogOpen(false)}
+                  className="flex-1 border border-border px-4 py-2 text-text-secondary transition-colors hover:bg-background-tertiary hover:text-text-primary"
+                >
+                  cancel
+                </button>
+                <button
+                  type="submit"
+                  disabled={shareMutation.isPending}
+                  className="flex-1 border border-border bg-background-tertiary px-4 py-2 text-text-primary transition-colors hover:bg-border disabled:opacity-50"
+                >
+                  {shareMutation.isPending ? "sharing..." : "share"}
+                </button>
+              </div>
+            </form>
+          </div>
+        </div>
+      )}
     </div>
   )
 }
diff --git a/apps/web/app/reader/_components/entry-list-item.tsx b/apps/web/app/reader/_components/entry-list-item.tsx
index d192081..1669658 100644
--- a/apps/web/app/reader/_components/entry-list-item.tsx
+++ b/apps/web/app/reader/_components/entry-list-item.tsx
@@ -45,12 +45,13 @@ export function EntryListItem({
   const displayTitle = entry.customTitle ?? entry.feedTitle
 
   return (
-    <div
+    <button
+      type="button"
       ref={measureReference}
       data-index={virtualItem.index}
       onClick={onSelect}
       className={classNames(
-        "absolute left-0 top-0 w-full cursor-pointer border-b border-border px-4 transition-colors",
+        "absolute left-0 top-0 w-full cursor-pointer border-b border-border bg-transparent px-4 text-left font-[inherit] text-[inherit] transition-colors",
         isSelected
           ? "bg-background-tertiary"
           : isFocused
@@ -130,6 +131,6 @@ export function EntryListItem({
           )}
         </div>
       )}
-    </div>
+    </button>
   )
 }
diff --git a/apps/web/app/reader/_components/keyboard-shortcuts-dialog.tsx b/apps/web/app/reader/_components/keyboard-shortcuts-dialog.tsx
index 139249b..f6e95eb 100644
--- a/apps/web/app/reader/_components/keyboard-shortcuts-dialog.tsx
+++ b/apps/web/app/reader/_components/keyboard-shortcuts-dialog.tsx
@@ -110,6 +110,7 @@ export function KeyboardShortcutsDialog() {
                     {shortcut.keys.map((key) => (
                       <kbd
                         key={key}
+                        aria-label={`${key}: ${shortcut.description}`}
                         className="border border-border bg-background-secondary px-1.5 py-0.5 font-mono text-[0.75rem] text-text-primary"
                       >
                         {key}
diff --git a/apps/web/app/reader/_components/sidebar-content.tsx b/apps/web/app/reader/_components/sidebar-content.tsx
index e13926d..17d07bb 100644
--- a/apps/web/app/reader/_components/sidebar-content.tsx
+++ b/apps/web/app/reader/_components/sidebar-content.tsx
@@ -279,6 +279,7 @@ export function SidebarContent() {
             >
               <button
                 type="button"
+                aria-expanded={isExpanded}
                 onClick={() =>
                   toggleFolderExpansion(folder.folderIdentifier)
                 }
diff --git a/apps/web/app/reader/settings/_components/appearance-settings.tsx b/apps/web/app/reader/settings/_components/appearance-settings.tsx
index 6c04f00..508051f 100644
--- a/apps/web/app/reader/settings/_components/appearance-settings.tsx
+++ b/apps/web/app/reader/settings/_components/appearance-settings.tsx
@@ -31,6 +31,10 @@ export function AppearanceSettings() {
   )
   const fontSize = useUserInterfaceStore((state) => state.fontSize)
   const setFontSize = useUserInterfaceStore((state) => state.setFontSize)
+  const contentFont = useUserInterfaceStore((state) => state.contentFont)
+  const setContentFont = useUserInterfaceStore(
+    (state) => state.setContentFont
+  )
   const timeDisplayFormat = useUserInterfaceStore(
     (state) => state.timeDisplayFormat
   )
@@ -155,6 +159,25 @@ export function AppearanceSettings() {
         </select>
       </div>
       <div className="mb-6">
+        <h3 className="mb-2 text-text-primary">content font</h3>
+        <p className="mb-3 text-text-dim">
+          controls the typeface used for article content
+        </p>
+        <select
+          value={contentFont}
+          onChange={(event) =>
+            setContentFont(
+              event.target.value as "sans-serif" | "serif" | "monospace"
+            )
+          }
+          className="border border-border bg-background-primary px-3 py-2 text-text-primary outline-none focus:border-text-dim"
+        >
+          <option value="sans-serif">sans-serif</option>
+          <option value="serif">serif</option>
+          <option value="monospace">monospace</option>
+        </select>
+      </div>
+      <div className="mb-6">
         <h3 className="mb-2 text-text-primary">time display</h3>
         <p className="mb-3 text-text-dim">
           choose between relative timestamps (e.g. &ldquo;2h ago&rdquo;) or
diff --git a/apps/web/lib/hooks/use-keyboard-navigation.ts b/apps/web/lib/hooks/use-keyboard-navigation.ts
index 24a4761..8685396 100644
--- a/apps/web/lib/hooks/use-keyboard-navigation.ts
+++ b/apps/web/lib/hooks/use-keyboard-navigation.ts
@@ -368,6 +368,7 @@ export function useKeyboardNavigation() {
 
     function handleDetailPanelKeyDown(event: KeyboardEvent) {
       const SCROLL_AMOUNT = 100
+      const PAGE_SCROLL_FRACTION = 0.8
       const detailArticle = document.querySelector<HTMLElement>(
         "[data-detail-article]"
       )
@@ -385,6 +386,19 @@ export function useKeyboardNavigation() {
           if (detailArticle) detailArticle.scrollTop -= SCROLL_AMOUNT
           break
         }
+        case " ": {
+          event.preventDefault()
+          if (detailArticle) {
+            const pageScrollAmount =
+              detailArticle.clientHeight * PAGE_SCROLL_FRACTION
+            if (event.shiftKey) {
+              detailArticle.scrollTop -= pageScrollAmount
+            } else {
+              detailArticle.scrollTop += pageScrollAmount
+            }
+          }
+          break
+        }
         case "?": {
           event.preventDefault()
           toggleShortcutsDialog()
diff --git a/apps/web/lib/stores/user-interface-store.ts b/apps/web/lib/stores/user-interface-store.ts
index 01dceba..fdee347 100644
--- a/apps/web/lib/stores/user-interface-store.ts
+++ b/apps/web/lib/stores/user-interface-store.ts
@@ -7,6 +7,8 @@ type DisplayDensity = "compact" | "default" | "spacious"
 
 type FontSize = "small" | "default" | "large"
 
+type ContentFont = "sans-serif" | "serif" | "monospace"
+
 type TimeDisplayFormat = "relative" | "absolute"
 
 type FocusedPanel = "sidebar" | "entryList" | "detailPanel"
@@ -38,6 +40,7 @@ interface UserInterfaceState {
   showFeedFavicons: boolean
   focusFollowsInteraction: boolean
   fontSize: FontSize
+  contentFont: ContentFont
   timeDisplayFormat: TimeDisplayFormat
   showEntryImages: boolean
   showReadingTime: boolean
@@ -62,6 +65,7 @@ interface UserInterfaceState {
   setShowFeedFavicons: (show: boolean) => void
   setFocusFollowsInteraction: (enabled: boolean) => void
   setFontSize: (size: FontSize) => void
+  setContentFont: (font: ContentFont) => void
   setTimeDisplayFormat: (format: TimeDisplayFormat) => void
   setShowEntryImages: (show: boolean) => void
   setShowReadingTime: (show: boolean) => void
@@ -90,6 +94,7 @@ export const useUserInterfaceStore = create<UserInterfaceState>()(
       showFeedFavicons: true,
       focusFollowsInteraction: false,
       fontSize: "default",
+      contentFont: "sans-serif",
       timeDisplayFormat: "relative",
       showEntryImages: true,
       showReadingTime: true,
@@ -134,6 +139,8 @@ export const useUserInterfaceStore = create<UserInterfaceState>()(
 
       setFontSize: (size) => set({ fontSize: size }),
 
+      setContentFont: (font) => set({ contentFont: font }),
+
       setTimeDisplayFormat: (format) => set({ timeDisplayFormat: format }),
 
       setShowEntryImages: (show) => set({ showEntryImages: show }),
@@ -187,6 +194,7 @@ export const useUserInterfaceStore = create<UserInterfaceState>()(
         focusFollowsInteraction: state.focusFollowsInteraction,
         expandedFolderIdentifiers: state.expandedFolderIdentifiers,
         fontSize: state.fontSize,
+        contentFont: state.contentFont,
         timeDisplayFormat: state.timeDisplayFormat,
         showEntryImages: state.showEntryImages,
         showReadingTime: state.showReadingTime,