fix(canvas/mobile): WCAG 2.4.7 focus-visible rings on all mobile interactive buttons

Adds focus-visible:ring-2 to keyboard-navigable buttons across all mobile
components that previously relied on inline styles only:

- MobileChat.tsx: Back, More, tab-switch, Retry, Remove file, Attach, Send
- MobileHome.tsx: Spawn FAB
- MobileSpawn.tsx: Close, template select, tier select, Spawn agent
- MobileMe.tsx: Accent swatches, Theme/Density segmented controls
- MobileDetail.tsx: Back, More, tab-switch, Open chat CTA
- MobileComms.tsx: filter chips
- components.tsx: AgentCard, FilterChips

Tailwind focus-visible utilities applied alongside existing inline styles;
no visual change for mouse users.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

canvas/src/components/mobile/MobileChat.tsx

@@ -339,6 +339,7 @@ export function MobileChat({
             type="button"
             onClick={onBack}
             aria-label="Back"
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               width: 36,
               height: 36,
@@ -385,6 +386,7 @@ export function MobileChat({
           <button
             type="button"
             aria-label="More"
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               width: 36,
               height: 36,
@@ -415,6 +417,7 @@ export function MobileChat({
                 key={t.id}
                 type="button"
                 onClick={() => setTab(t.id)}
+                className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
                 style={{
                   padding: "4px 0 8px",
                   border: "none",
@@ -478,6 +481,7 @@ export function MobileChat({
               onClick={() => {
                 loadInitial();
               }}
+              className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
               style={{
                 padding: "6px 14px",
                 borderRadius: 14,
@@ -619,6 +623,7 @@ export function MobileChat({
                   type="button"
                   onClick={() => removePendingFile(i)}
                   aria-label={`Remove ${f.name}`}
+                  className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
                   style={{
                     border: "none",
                     background: "transparent",
@@ -659,6 +664,7 @@ export function MobileChat({
             onClick={() => fileInputRef.current?.click()}
             disabled={!reachable || sending || uploading}
             aria-label="Attach"
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               width: 32,
               height: 32,
@@ -719,6 +725,7 @@ export function MobileChat({
             onClick={send}
             disabled={(!draft.trim() && pendingFiles.length === 0) || !reachable || sending || uploading}
             aria-label="Send"
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               width: 36,
               height: 36,

canvas/src/components/mobile/MobileComms.tsx

@@ -218,6 +218,7 @@ export function MobileComms({ dark }: { dark: boolean }) {
               key={o.id}
               type="button"
               onClick={() => setFilter(o.id)}
+              className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
               style={{
                 display: "inline-flex",
                 alignItems: "center",

canvas/src/components/mobile/MobileDetail.tsx

@@ -83,11 +83,12 @@ export function MobileDetail({
             type="button"
             onClick={onBack}
             aria-label="Back"
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={iconButtonStyle(p, dark)}
           >
             {Icons.back({ size: 18 })}
           </button>
-          <button type="button" aria-label="More" style={iconButtonStyle(p, dark)}>
+          <button type="button" aria-label="More" className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none" style={iconButtonStyle(p, dark)}>
             {Icons.more({ size: 18 })}
           </button>
         </div>
@@ -183,6 +184,7 @@ export function MobileDetail({
               key={t.id}
               type="button"
               onClick={() => setTab(t.id)}
+              className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
               style={{
                 padding: "8px 14px",
                 borderRadius: 999,
@@ -215,6 +217,7 @@ export function MobileDetail({
           type="button"
           onClick={onChat}
           data-testid="mobile-chat-cta"
+          className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
           style={{
             width: "100%",
             height: 52,

canvas/src/components/mobile/MobileHome.tsx

@@ -183,6 +183,7 @@ export function MobileHome({
         type="button"
         onClick={onSpawn}
         aria-label="Spawn new agent"
+        className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
         style={{
           position: "absolute",
           right: 24,

canvas/src/components/mobile/MobileMe.tsx

@@ -83,6 +83,7 @@ export function MobileMe({
                   type="button"
                   onClick={() => setAccent(c)}
                   aria-label={`Set accent ${c}`}
+                  className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
                   style={{
                     width: 36,
                     height: 36,
@@ -173,6 +174,7 @@ function SegmentedRow({
             key={o.id}
             type="button"
             onClick={() => onChange(o.id)}
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               flex: 1,
               padding: "10px 8px",

canvas/src/components/mobile/MobileSpawn.tsx

@@ -148,6 +148,7 @@ export function MobileSpawn({ dark, onClose }: { dark: boolean; onClose: () => v
             type="button"
             onClick={onClose}
             aria-label="Close"
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               width: 32,
               height: 32,
@@ -214,6 +215,7 @@ export function MobileSpawn({ dark, onClose }: { dark: boolean; onClose: () => v
                       setTplId(t.id);
                       setTier(tCode);
                     }}
+                    className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
                     style={{
                       background: on
                         ? dark
@@ -330,6 +332,7 @@ export function MobileSpawn({ dark, onClose }: { dark: boolean; onClose: () => v
                 key={t}
                 type="button"
                 onClick={() => setTier(t)}
+                className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
                 style={{
                   flex: 1,
                   padding: "10px 8px",
@@ -377,6 +380,7 @@ export function MobileSpawn({ dark, onClose }: { dark: boolean; onClose: () => v
             type="button"
             onClick={handleSpawn}
             disabled={busy || !tplId || templates.length === 0}
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               width: "100%",
               height: 52,

canvas/src/components/mobile/components.tsx

@@ -292,6 +292,7 @@ export function AgentCard({
       data-testid="workspace-card"
       aria-label={`${agent.name}, status: ${agent.status}, tier ${agent.tier}${agent.remote ? ", remote" : ""}`}
       onClick={onClick}
+      className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
       style={{
         display: "block",
         width: "100%",
@@ -445,6 +446,7 @@ export function FilterChips({
             type="button"
             aria-checked={on}
             onClick={() => onChange(o.id)}
+            className="focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:outline-none"
             style={{
               display: "inline-flex",
               alignItems: "center",