diff --git a/mobile/App.js b/mobile/App.js
index cf70493..4dd3f21 100644
--- a/mobile/App.js
+++ b/mobile/App.js
@@ -2,7 +2,7 @@
 // browser behind it keeps its tabs of WebViews, address bar, and the shared
 // suggestion engine from core/.
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
-import { ActivityIndicator, BackHandler, Keyboard, PanResponder, Platform, Pressable, Text, TextInput, View, useWindowDimensions } from "react-native";
+import { AccessibilityInfo, ActivityIndicator, BackHandler, Keyboard, PanResponder, Platform, Pressable, Text, TextInput, View, useWindowDimensions } from "react-native";
 import { StatusBar } from "expo-status-bar";
 import { SafeAreaProvider, SafeAreaView } from "react-native-safe-area-context";
 
@@ -217,6 +217,7 @@ function Browser({ services }) {
   // recorded as a capture card. No screen change; a note with Undo shows.
   const showToast = (t) => {
     clearTimeout(toastTimer.current);
+    AccessibilityInfo.announceForAccessibility?.(t.text); // VoiceOver reads the note; TalkBack uses the live region
     setToast(t);
     toastTimer.current = setTimeout(() => setToast(null), 6000);
   };
@@ -397,8 +398,8 @@ function Browser({ services }) {
       {/* Address bar, with suggestions from history and Wikipedia while typing */}
       <View style={{ zIndex: 20, elevation: 20 }}>
       <View style={{ flexDirection: "row", alignItems: "center", gap: 6, padding: 8, borderBottomWidth: 1, borderColor: colors.line }} {...addressPan.panHandlers}>
-        <Button label="‹" small onPress={() => refs.current.get(activeId)?.goBack()} style={!active?.canGoBack && { opacity: 0.4 }} />
-        <Button label="›" small onPress={() => refs.current.get(activeId)?.goForward()} style={!active?.canGoForward && { opacity: 0.4 }} />
+        <Button label="‹" a11yLabel="Back" small onPress={() => refs.current.get(activeId)?.goBack()} style={!active?.canGoBack && { opacity: 0.4 }} />
+        <Button label="›" a11yLabel="Forward" small onPress={() => refs.current.get(activeId)?.goForward()} style={!active?.canGoForward && { opacity: 0.4 }} />
         <TextInput
           style={[ui.input, { flex: 1, paddingVertical: 6 }]}
           value={editing ? address : active?.url || ""}
@@ -432,7 +433,7 @@ function Browser({ services }) {
           }}
         />
         {/* Tap: tab list. Press and hold: new tab. */}
-        <Button label={String(tabs.length)} small onPress={() => setSheet("tabs")} onLongPress={() => addTab(HOME_URL)} />
+        <Button label={String(tabs.length)} a11yLabel={`${tabs.length} ${tabs.length === 1 ? "tab" : "tabs"}, open the tab list`} a11yHint="Press and hold for a new tab" small onPress={() => setSheet("tabs")} onLongPress={() => addTab(HOME_URL)} />
       </View>
       {editing ? (
         <AddressSuggestions
@@ -484,7 +485,13 @@ function Browser({ services }) {
               />
               {showMosaic && !isActive ? (
                 // Tap an inactive tile to make it the active tab; then it takes touches.
-                <Pressable style={{ position: "absolute", left: 0, right: 0, top: 0, bottom: 0 }} onPress={() => switchTo(t.id)} />
+                <Pressable
+                  style={{ position: "absolute", left: 0, right: 0, top: 0, bottom: 0 }}
+                  onPress={() => switchTo(t.id)}
+                  accessibilityRole="button"
+                  accessibilityLabel={`Mosaic tile ${tile + 1}: ${t.title || t.url || "new tab"}`}
+                  accessibilityHint="Makes this the active tab"
+                />
               ) : null}
             </View>
           );
@@ -494,10 +501,10 @@ function Browser({ services }) {
       {/* Bottom bar */}
       <View style={{ flexDirection: "row", gap: 6, padding: 8, borderTopWidth: 1, borderColor: colors.line, alignItems: "center" }}>
         <Button label={`Suggest${state.results.length ? ` (${state.results.length})` : ""}`} active={state.busy} onPress={() => setSheet("suggest")} />
-        <Button label="Capture" onPress={capture} />
+        <Button label="Capture" a11yHint="Saves this page, the selected text and a thumbnail into the trail" onPress={capture} />
         <Button label="Mosaic" active={mosaic} onPress={() => setMosaic(!mosaic)} />
         <Button label="Trail" onPress={() => setHome(true)} />
-        <Button label="⚙︎" onPress={() => setSheet("settings")} />
+        <Button label="⚙︎" a11yLabel="Settings" onPress={() => setSheet("settings")} />
         <Text style={[ui.help, { flex: 1 }]} numberOfLines={1}>
           {state.busy ? "Searching…" : ""}
         </Text>
@@ -539,7 +546,7 @@ function Browser({ services }) {
       <SettingsSheet visible={sheet === "settings"} onClose={() => setSheet(null)} services={services} />
 
       {toast && !home ? (
-        <View style={{ position: "absolute", left: 12, right: 12, bottom: 70, zIndex: 40, elevation: 40, flexDirection: "row", alignItems: "center", gap: 8, backgroundColor: colors.bg3, borderWidth: 1, borderColor: colors.line, borderRadius: 10, padding: 10 }}>
+        <View accessibilityLiveRegion="polite" style={{ position: "absolute", left: 12, right: 12, bottom: 70, zIndex: 40, elevation: 40, flexDirection: "row", alignItems: "center", gap: 8, backgroundColor: colors.bg3, borderWidth: 1, borderColor: colors.line, borderRadius: 10, padding: 10 }}>
           <Text style={{ color: colors.text, flex: 1 }} numberOfLines={2}>
             {toast.text}
           </Text>
diff --git a/mobile/README.md b/mobile/README.md
index 1826ccd..02ab091 100644
--- a/mobile/README.md
+++ b/mobile/README.md
@@ -9,6 +9,7 @@ Phase 5 groundwork. A React Native (Expo SDK 58, React Native 0.88) app that reu
 - **Open a `.trail.md`** (CM3): Open file → the file opens read only, on Replay: the sender's note, Start here, the steps with captions (Back, Next, tap a step); the Canvas tab dims cards not reached yet and follows the step. Save as new trail makes an editable copy, "<name> · <sender>", and goes to its timeline. Open on desktop hands the file to the share sheet (AirDrop it to your Mac)
 - **Share** (CM4, CM5): a note, Start here, the timeline on or off, your name; file name and size; "Share file…" opens the phone's share sheet with the `.trail.md`. Sign-in and payment pages are never put in the file
 - **Capture** (M18, bottom bar): one tap saves the page into the trail being recorded: address, title, DOI or PMID if the page has one, the time with the time zone, the selected text (or the last text you selected on the page) and a thumbnail. It becomes a capture card linked "captured from" the page's card, as on desktop. A note says where it went, with Undo. Sign-in and payment pages are never captured. The card's preview shows the thumbnail and Open DOI / PubMed. Shared files carry the quote and the "Captured from … · DOI …" line, not the thumbnail
+- **Screen readers** (M25): every button, tab, card, Mosaic tile, keyword and result has a spoken label and role; sheet titles and timeline sessions are headings; Timeline / Canvas / Replay are tabs. Gestures have screen-reader actions: next and previous trail on the switcher, hide on a keyword, close on a tab row. The capture note is announced. Every grid has a list: the Timeline for the canvas, the tab list for Mosaic
 - Pages you read on the phone go into the current trail's timeline as phone visits (timeline only, as decided in doc 25); cards are placed on desktop. Old research sessions are copied into trails on the first start
 - Tabs, each a WebView kept loaded; address bar with back and forward; tab switcher
 - Mosaic on every screen (Mosaic button in the bottom bar): all tabs in a grid on tablets and phones in landscape; up to 4 tiles on a phone in portrait (the active tab plus the 3 most recent others)
diff --git a/mobile/src/components/AddressSuggestions.js b/mobile/src/components/AddressSuggestions.js
index 25f8808..5547fee 100644
--- a/mobile/src/components/AddressSuggestions.js
+++ b/mobile/src/components/AddressSuggestions.js
@@ -64,7 +64,7 @@ export default function AddressSuggestions({ query, history, bookmarks, getText,
       {/* "handled": tapping a row does not first close the keyboard and the list. */}
       <ScrollView keyboardShouldPersistTaps="handled">
         {rows.map((r) => (
-          <Pressable key={r.key} onPress={() => onPick(r.url)} style={{ paddingHorizontal: 12, paddingVertical: 9, borderTopWidth: 1, borderColor: colors.line }}>
+          <Pressable key={r.key} onPress={() => onPick(r.url)} accessibilityRole="button" accessibilityLabel={`${r.history ? "From history: " : ""}${r.label}`} style={{ paddingHorizontal: 12, paddingVertical: 9, borderTopWidth: 1, borderColor: colors.line }}>
             <Text style={{ color: colors.text, fontSize: 14 }} numberOfLines={1}>
               {r.history ? "🕘 " : ""}
               {r.label}
diff --git a/mobile/src/components/Button.js b/mobile/src/components/Button.js
index 7703af0..e5e7ae7 100644
--- a/mobile/src/components/Button.js
+++ b/mobile/src/components/Button.js
@@ -1,11 +1,16 @@
 import { Pressable, Text } from "react-native";
 import { colors, ui } from "../theme";
 
-export default function Button({ label, onPress, onLongPress, active, style, small }) {
+// a11yLabel: what a screen reader says when the label is a symbol (‹, ⚙︎, +).
+export default function Button({ label, onPress, onLongPress, active, style, small, a11yLabel, a11yHint }) {
   return (
     <Pressable
       onPress={onPress}
       onLongPress={onLongPress}
+      accessibilityRole="button"
+      accessibilityLabel={a11yLabel || String(label)}
+      accessibilityHint={a11yHint}
+      accessibilityState={active !== undefined ? { selected: Boolean(active) } : undefined}
       style={({ pressed }) => [ui.button, small && { paddingVertical: 4, paddingHorizontal: 8 }, active && { borderColor: colors.accent }, pressed && { opacity: 0.6 }, style]}
     >
       <Text style={[ui.buttonText, active && { color: colors.accent }, small && { fontSize: 12 }]}>{label}</Text>
diff --git a/mobile/src/components/Sheet.js b/mobile/src/components/Sheet.js
index a6d76cf..39d5c06 100644
--- a/mobile/src/components/Sheet.js
+++ b/mobile/src/components/Sheet.js
@@ -12,7 +12,7 @@ export default function Sheet({ visible, title, kicker, onClose, children, scrol
         <View style={{ flexDirection: "row", alignItems: "center", justifyContent: "space-between", padding: 14, paddingBottom: 6 }}>
           <View>
             {kicker ? <Text style={[ui.kicker, { marginTop: 0 }]}>{kicker}</Text> : null}
-            <Text style={ui.title}>{title}</Text>
+            <Text style={ui.title} accessibilityRole="header">{title}</Text>
           </View>
           <Button label="Close" onPress={onClose} small />
         </View>
diff --git a/mobile/src/components/SuggestionsSheet.js b/mobile/src/components/SuggestionsSheet.js
index 22208e0..2d62301 100644
--- a/mobile/src/components/SuggestionsSheet.js
+++ b/mobile/src/components/SuggestionsSheet.js
@@ -21,12 +21,22 @@ export default function SuggestionsSheet({ visible, onClose, state, controller,
       <Text style={ui.help}>Tap a keyword to pin it. Press and hold to hide it.</Text>
       <View style={{ flexDirection: "row", flexWrap: "wrap", marginTop: 8 }}>
         {pins.map((k) => (
-          <Pressable key={"p" + k} style={[ui.chip, { borderColor: colors.accent }]} onPress={() => controller.togglePin(k)}>
+          <Pressable key={"p" + k} style={[ui.chip, { borderColor: colors.accent }]} onPress={() => controller.togglePin(k)} accessibilityRole="button" accessibilityLabel={`${k}, pinned`} accessibilityHint="Unpins this keyword">
             <Text style={[ui.chipText, { color: colors.accent }]}>📌 {k}</Text>
           </Pressable>
         ))}
         {auto.map((k) => (
-          <Pressable key={"a" + k} style={ui.chip} onPress={() => controller.togglePin(k)} onLongPress={() => controller.hide(k)}>
+          <Pressable
+            key={"a" + k}
+            style={ui.chip}
+            onPress={() => controller.togglePin(k)}
+            onLongPress={() => controller.hide(k)}
+            accessibilityRole="button"
+            accessibilityLabel={k}
+            accessibilityHint="Pins this keyword. Actions: hide it"
+            accessibilityActions={[{ name: "hide", label: "Hide keyword" }]}
+            onAccessibilityAction={(e) => e.nativeEvent.actionName === "hide" && controller.hide(k)}
+          >
             <Text style={ui.chipText}>{k}</Text>
           </Pressable>
         ))}
@@ -52,7 +62,7 @@ export default function SuggestionsSheet({ visible, onClose, state, controller,
               {r.source}
               {r.query ? <Text style={{ color: colors.mute, textTransform: "none" }}> · {r.query}</Text> : null}
             </Text>
-            <Pressable onPress={() => controller.dismiss(r.url)} hitSlop={10}>
+            <Pressable onPress={() => controller.dismiss(r.url)} hitSlop={10} accessibilityRole="button" accessibilityLabel={`Dismiss ${r.title}`}>
               <Text style={{ color: colors.mute }}>×</Text>
             </Pressable>
           </View>
diff --git a/mobile/src/components/TabsSheet.js b/mobile/src/components/TabsSheet.js
index bb8688e..1c88338 100644
--- a/mobile/src/components/TabsSheet.js
+++ b/mobile/src/components/TabsSheet.js
@@ -18,6 +18,10 @@ export default function TabsSheet({ visible, onClose, tabs, activeId, onActivate
         <SwipeRow key={t.id} onSwipe={() => onCloseTab(t.id)}>
           <Pressable
             onPress={() => onActivate(t.id)}
+            accessibilityRole="button"
+            accessibilityLabel={`${t.title || "New tab"}${t.id === activeId ? ", current tab" : ""}`}
+            accessibilityActions={[{ name: "close", label: "Close tab" }]}
+            onAccessibilityAction={(e) => e.nativeEvent.actionName === "close" && onCloseTab(t.id)}
             style={{ flexDirection: "row", alignItems: "center", borderTopWidth: 1, borderColor: colors.line, paddingVertical: 10 }}
           >
             <View style={{ flex: 1 }}>
@@ -26,7 +30,7 @@ export default function TabsSheet({ visible, onClose, tabs, activeId, onActivate
               </Text>
               <Text style={ui.help} numberOfLines={1}>{t.pausedByLimit ? "⏸ Paused (4 tabs already playing) · " : ""}{t.sysPauses ? `Paused by the system ${t.sysPauses}× and restarted · ` : ""}{t.url}</Text>
             </View>
-            <Pressable onPress={() => onCloseTab(t.id)} hitSlop={10} style={{ paddingHorizontal: 8 }}>
+            <Pressable onPress={() => onCloseTab(t.id)} hitSlop={10} style={{ paddingHorizontal: 8 }} accessibilityRole="button" accessibilityLabel={`Close ${t.title || "tab"}`}>
               <Text style={{ color: colors.mute, fontSize: 18 }}>×</Text>
             </Pressable>
           </Pressable>
@@ -38,7 +42,7 @@ export default function TabsSheet({ visible, onClose, tabs, activeId, onActivate
           {bookmarks.search("", 100).length === 0 ? <Text style={ui.help}>No bookmarks yet. Tap ☆ next to the address bar to add the page you are on.</Text> : null}
           {bookmarks.search("", 100).map((b) => (
             <SwipeRow key={"b" + b.url} label="Remove" onSwipe={() => onRemoveBookmark(b.url)}>
-              <Pressable onPress={() => onOpenBookmark(b.url)} style={{ borderTopWidth: 1, borderColor: colors.line, paddingVertical: 10 }}>
+              <Pressable onPress={() => onOpenBookmark(b.url)} accessibilityRole="link" style={{ borderTopWidth: 1, borderColor: colors.line, paddingVertical: 10 }}>
                 <Text style={{ color: colors.text, fontWeight: "600" }} numberOfLines={1}>★ {b.title || b.url}</Text>
                 <Text style={ui.help} numberOfLines={1}>{b.url}</Text>
               </Pressable>
diff --git a/mobile/src/components/TrailCanvas.js b/mobile/src/components/TrailCanvas.js
index 1602abe..8a9b363 100644
--- a/mobile/src/components/TrailCanvas.js
+++ b/mobile/src/components/TrailCanvas.js
@@ -124,6 +124,8 @@ export default function TrailCanvas({ snap, onCard, shown = null, focus = null }
                 <Pressable
                   key={c.id}
                   onPress={() => onCard?.(c)}
+                  accessibilityRole="button"
+                  accessibilityLabel={`${start ? "Start here. " : ""}${f.kicker}: ${f.title}${f.text ? `. ${f.text}` : ""}`}
                   style={{ position: "absolute", left: c.x, top: c.y, width: c.w, height: c.h, borderRadius: 10, borderWidth: focus === c.id || start ? 3 : 1, borderColor: focus === c.id ? colors.accent : start ? colors.ok : colors.line, backgroundColor: colors.bg3, padding: 14, opacity: dim(c.id) ? 0.2 : 1, overflow: "hidden" }}
                 >
                   <Text style={{ color: colors.accent, fontSize: 13, letterSpacing: 1, textTransform: "uppercase" }} numberOfLines={1}>
@@ -152,9 +154,9 @@ export default function TrailCanvas({ snap, onCard, shown = null, focus = null }
       {view && size && !empty ? <Minimap snap={snap} bounds={bounds} view={view} size={size} onJump={(wx, wy) => setView(M.centreOn(view, wx, wy, size.w, size.h))} /> : null}
       {view && size && !empty ? (
         <View style={{ position: "absolute", left: 10, bottom: 10, flexDirection: "row", gap: 6 }}>
-          <Button label="Fit" small onPress={fit} />
-          <Button label="−" small onPress={() => setView(M.zoomAt(view, 1 / 1.4, size.w / 2, size.h / 2))} />
-          <Button label="+" small onPress={() => setView(M.zoomAt(view, 1.4, size.w / 2, size.h / 2))} />
+          <Button label="Fit" a11yLabel="Fit the whole trail" small onPress={fit} />
+          <Button label="−" a11yLabel="Zoom out" small onPress={() => setView(M.zoomAt(view, 1 / 1.4, size.w / 2, size.h / 2))} />
+          <Button label="+" a11yLabel="Zoom in" small onPress={() => setView(M.zoomAt(view, 1.4, size.w / 2, size.h / 2))} />
         </View>
       ) : null}
     </View>
@@ -172,6 +174,9 @@ function Minimap({ snap, bounds, view, size, onJump }) {
   const vp = at(vx, vy);
   return (
     <Pressable
+      accessibilityRole="button"
+      accessibilityLabel="Minimap"
+      accessibilityHint="Moves the canvas to where you tap. The Timeline tab lists every card."
       onPress={(e) => onJump(bounds.x + (e.nativeEvent.locationX - ox) / k, bounds.y + (e.nativeEvent.locationY - oy) / k)}
       style={{ position: "absolute", right: 10, bottom: 10, width: MINI_W, height: MINI_H, backgroundColor: "rgba(26,26,26,0.92)", borderRadius: 8, borderWidth: 1, borderColor: colors.line, overflow: "hidden" }}
     >
diff --git a/mobile/src/components/TrailHome.js b/mobile/src/components/TrailHome.js
index 48b029c..a6b541a 100644
--- a/mobile/src/components/TrailHome.js
+++ b/mobile/src/components/TrailHome.js
@@ -121,7 +121,21 @@ export default function TrailHome({ services, controller, onBrowse, onOpenUrl, o
     <View style={{ flex: 1, backgroundColor: colors.bg2 }}>
       {/* Trail switcher: initials, name, last visit, dots; Share next to it. */}
       <View style={{ flexDirection: "row", alignItems: "center", gap: 10, paddingHorizontal: 14, paddingTop: 10, paddingBottom: 6 }} {...swipe.panHandlers}>
-        <Pressable onPress={() => setMenu(true)} style={{ flexDirection: "row", alignItems: "center", gap: 10, flex: 1 }} accessibilityRole="button" accessibilityLabel="Trails">
+        <Pressable
+          onPress={() => setMenu(true)}
+          style={{ flexDirection: "row", alignItems: "center", gap: 10, flex: 1 }}
+          accessibilityRole="button"
+          accessibilityLabel={`Trail: ${snap?.trail.name || "Trail"}${readonly ? `, from ${snap.trail.from || "someone"}, read only` : ""}`}
+          accessibilityHint="Opens the list of trails"
+          accessibilityActions={[
+            { name: "next", label: "Next trail" },
+            { name: "previous", label: "Previous trail" },
+          ]}
+          onAccessibilityAction={(e) => {
+            const next = list[index + (e.nativeEvent.actionName === "next" ? 1 : -1)];
+            if (next) show(next.id);
+          }}
+        >
           <View style={{ width: 34, height: 34, borderRadius: 17, backgroundColor: readonly ? "#2a3a2a" : "#2a3350", alignItems: "center", justifyContent: "center" }}>
             <Text style={{ color: colors.text, fontWeight: "700", fontSize: 13 }}>{snap?.trail.mono || "?"}</Text>
           </View>
@@ -135,12 +149,12 @@ export default function TrailHome({ services, controller, onBrowse, onOpenUrl, o
             </Text>
           </View>
         </Pressable>
-        <Button label="Share" small onPress={() => (readonly ? openOnDesktop() : setSharing(true))} />
+        <Button label="Share" a11yLabel={readonly ? "Share this file" : "Share this trail as a file"} small onPress={() => (readonly ? openOnDesktop() : setSharing(true))} />
       </View>
       {list.length > 1 ? (
         <View style={{ flexDirection: "row", justifyContent: "center", gap: 6, paddingBottom: 6 }}>
           {list.slice(0, MAX_DOTS).map((t) => (
-            <Pressable key={t.id} onPress={() => show(t.id)} hitSlop={6}>
+            <Pressable key={t.id} onPress={() => show(t.id)} hitSlop={6} accessibilityRole="button" accessibilityLabel={`Trail: ${t.name}`} accessibilityState={{ selected: t.id === id }}>
               <View style={{ width: 7, height: 7, borderRadius: 4, backgroundColor: t.id === id ? colors.accent : colors.line }} />
             </Pressable>
           ))}
@@ -170,7 +184,7 @@ export default function TrailHome({ services, controller, onBrowse, onOpenUrl, o
 
       <View style={{ flexDirection: "row", marginHorizontal: 14, borderWidth: 1, borderColor: colors.line, borderRadius: 8, overflow: "hidden" }}>
         {tabs.map(([k, label]) => (
-          <Pressable key={k} onPress={() => setTab(k)} style={{ flex: 1, paddingVertical: 7, alignItems: "center", backgroundColor: tab === k ? colors.bg3 : "transparent" }}>
+          <Pressable key={k} onPress={() => setTab(k)} accessibilityRole="tab" accessibilityState={{ selected: tab === k }} accessibilityLabel={label} style={{ flex: 1, paddingVertical: 7, alignItems: "center", backgroundColor: tab === k ? colors.bg3 : "transparent" }}>
             <Text style={{ color: tab === k ? colors.accent : colors.mute, fontSize: 13, fontWeight: "600" }}>{label}</Text>
           </Pressable>
         ))}
diff --git a/mobile/src/components/TrailTimeline.js b/mobile/src/components/TrailTimeline.js
index 8aa7231..440dace 100644
--- a/mobile/src/components/TrailTimeline.js
+++ b/mobile/src/components/TrailTimeline.js
@@ -21,11 +21,14 @@ export default function TrailTimeline({ snap, header, onItem }) {
         </View>
       }
       renderItem={({ item }) => {
-        if (item.head) return <Text style={ui.kicker}>{item.head}</Text>;
+        if (item.head) return <Text style={ui.kicker} accessibilityRole="header">{item.head}</Text>;
         const face = item.card ? M.cardFace(item.card) : null;
         return (
           <Pressable
             onPress={() => onItem(item)}
+            accessibilityRole="button"
+            accessibilityLabel={[item.time, face ? `${face.kicker}: ${face.title}` : item.title, face?.text || item.sub].filter(Boolean).join(". ")}
+            accessibilityHint={item.card ? "Opens the card's preview" : "Opens the page"}
             style={({ pressed }) => ({ flexDirection: "row", gap: 10, paddingVertical: 10, borderTopWidth: 1, borderColor: colors.line, opacity: pressed ? 0.6 : 1 })}
           >
             <Text style={[ui.help, { width: 42 }]}>{item.time}</Text>