feat(mobile): rework Session and Project headers for narrow viewports

Session header: breadcrumb (Projects > project) wrapped in
hidden sm:flex; active file path hidden on mobile; session name cap
max-w-[140px] sm:max-w-[280px]; padding px-3 sm:px-4. Mobile gets
just hamburger | session name | model pill.

Project header: px-3 sm:px-6, py-2 sm:py-3, heading text-base
sm:text-lg, project path hidden sm:block, "New session" button is
icon-only on mobile via <span className="hidden sm:inline">. Both
headers retain the safe-area-inset-top padding from v1.6.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/pages/Project.tsx

@@ -81,32 +81,32 @@ export function Project() {
   return (
     <div className="flex-1 flex flex-col">
       <header
-        className="border-b px-6 py-3 flex items-center justify-between gap-2"
+        className="border-b px-3 sm:px-6 py-2 sm:py-3 flex items-center justify-between gap-2"
-        style={{ paddingTop: 'max(0.75rem, env(safe-area-inset-top))' }}
+        style={{ paddingTop: 'max(0.5rem, env(safe-area-inset-top))' }}
       >
         <div className="flex items-center gap-2 min-w-0">
           {isMobile && (
             <button
               type="button"
               onClick={() => setDrawerOpen(true)}
-              className="inline-flex items-center justify-center -ml-2 min-w-[44px] min-h-[44px] rounded text-muted-foreground hover:bg-muted hover:text-foreground shrink-0"
+              className="inline-flex items-center justify-center -ml-1 min-w-[44px] min-h-[44px] rounded text-muted-foreground hover:bg-muted hover:text-foreground shrink-0"
               aria-label="Open sidebar"
             >
               <Menu className="size-5" />
             </button>
           )}
           <div className="min-w-0">
-            <h1 className="text-lg font-semibold tracking-tight truncate">
+            <h1 className="text-base sm:text-lg font-semibold tracking-tight truncate">
               {project?.name ?? '…'}
             </h1>
-            <div className="text-xs text-muted-foreground font-mono truncate">
+            <div className="text-xs text-muted-foreground font-mono truncate hidden sm:block">
               {project?.path}
             </div>
           </div>
         </div>
-        <Button onClick={handleNew} disabled={creating} className="shrink-0">
+        <Button onClick={handleNew} disabled={creating} className="shrink-0" aria-label="New session">
           <Plus />
-          New session
+          <span className="hidden sm:inline">New session</span>
         </Button>
       </header>
 

apps/web/src/pages/Session.tsx

@@ -87,33 +87,42 @@ export function Session() {
 
   return (
     <div className="flex-1 flex flex-col min-h-0">
-      <header className="border-b px-4 py-2 flex items-center gap-1.5 shrink-0 text-sm" style={{ paddingTop: 'max(0.5rem, env(safe-area-inset-top))' }}>
+      <header
+        className="border-b px-3 sm:px-4 py-2 flex items-center gap-1.5 shrink-0 text-sm"
+        style={{ paddingTop: 'max(0.5rem, env(safe-area-inset-top))' }}
+      >
         {isMobile && (
           <button
             type="button"
             onClick={() => setDrawerOpen(true)}
-            className="inline-flex items-center justify-center -ml-1 mr-1 min-w-[44px] min-h-[44px] rounded text-muted-foreground hover:bg-muted hover:text-foreground"
+            className="inline-flex items-center justify-center -ml-1 min-w-[44px] min-h-[44px] rounded text-muted-foreground hover:bg-muted hover:text-foreground shrink-0"
             aria-label="Open sidebar"
           >
             <Menu className="size-5" />
           </button>
         )}
-        <Link to="/" className="text-muted-foreground hover:text-foreground">
+
-          Projects
+        {/* Breadcrumb — desktop only */}
-        </Link>
+        <div className="hidden sm:flex items-center gap-1.5 min-w-0">
-        <ChevronRight className="size-3 text-muted-foreground/60" />
+          <Link to="/" className="text-muted-foreground hover:text-foreground shrink-0 text-xs">
-        {project ? (
+            Projects
-          <Link
-            to={`/project/${project.id}`}
-            className="text-muted-foreground hover:text-foreground truncate max-w-[200px]"
-            title={project.name}
-          >
-            {project.name}
           </Link>
-        ) : (
+          <ChevronRight className="size-3 text-muted-foreground/60 shrink-0" />
-          <span className="text-muted-foreground/60">…</span>
+          {project ? (
-        )}
+            <Link
-        <ChevronRight className="size-3 text-muted-foreground/60" />
+              to={`/project/${project.id}`}
+              className="text-muted-foreground hover:text-foreground truncate max-w-[200px]"
+              title={project.name}
+            >
+              {project.name}
+            </Link>
+          ) : (
+            <span className="text-muted-foreground/60">…</span>
+          )}
+          <ChevronRight className="size-3 text-muted-foreground/60 shrink-0" />
+        </div>
+
+        {/* Session name — always visible, truncated, editable */}
         {editingName ? (
           <input
             autoFocus
@@ -127,30 +136,34 @@ export function Session() {
                 setEditingName(false);
               }
             }}
-            className="bg-transparent border-b border-border px-1 py-0.5 text-sm font-medium outline-none focus:border-ring"
+            className="bg-transparent border-b border-border px-1 py-0.5 text-sm font-medium outline-none focus:border-ring min-w-0"
           />
         ) : (
           <button
             type="button"
-            className="text-sm font-medium hover:underline truncate max-w-[280px]"
+            className="text-sm font-medium hover:underline truncate max-w-[140px] sm:max-w-[280px] min-w-0"
             onClick={() => setEditingName(true)}
             title={session?.name ?? ''}
           >
             {session?.name ?? '…'}
           </button>
         )}
+
+        {/* Active file — desktop only */}
         {showActiveFile && active.activeFile && (
           <>
-            <span className="text-muted-foreground/40 mx-1">·</span>
+            <span className="text-muted-foreground/40 mx-1 hidden sm:inline">·</span>
             <span
-              className="text-xs font-mono text-muted-foreground truncate max-w-[320px]"
+              className="text-xs font-mono text-muted-foreground truncate max-w-[200px] hidden sm:inline"
               title={active.activeFile}
             >
               {active.activeFile}
             </span>
           </>
         )}
-        <div className="ml-auto">
+
+        {/* Model picker — right-aligned */}
+        <div className="ml-auto shrink-0">
           {session && (
             <div className="inline-flex items-center rounded-full bg-muted/40 hover:bg-muted/70 px-1">
               <ModelPicker