diff --git a/CHANGELOG.md b/CHANGELOG.md
index fb9c4627..6f115637 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,14 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- **Mobile drawer shows the dashboard link and extension nav-actions again.** On narrow screens (≤800px) the sidebar drawer was hiding the dashboard link and any extension-added nav-action icons, so you couldn't reach them on mobile. They now mirror into the drawer and stay in sync as they appear/disappear. Thanks @rodboev. (#5605, #5583)
+- **Inline Mermaid diagrams no longer collapse to zero height on mobile.** An inline diagram could render invisibly on narrow screens before its SVG laid out; it now has a min-height on mobile (scoped so the lightbox and desktop are unaffected). Thanks @nankingjing. (#5560, #5525)
+- **Steer file uploads no longer leak their progress across sessions.** When you steer a live turn with an attachment and switch to another conversation mid-upload, the progress bar and composer status now stay scoped to the session that owns the upload (and the steer indicator shows your original text). Thanks @ruizanthony. (#5630)
+- **The chat message header scales with your text-size preference.** The model name, icon, TPS badge, and timestamp in the assistant header were ignoring the font-size setting, so they looked disproportionately small at large/xlarge text; they now scale with the body. Thanks @nankingjing. (#5633)
+- **The three-panel desktop layout keeps the conversation readable when you resize.** With the sidebar and workspace panel both open, shrinking the window used to crush the center conversation; it now has a readable floor and the side rails yield first (desktop ≥901px; the workspace panel still fully collapses when closed). Thanks @rodboev. (#5594, #5545)
+
 ### Changed
 
 - **The busy-time send behavior is now called "Default message mode," and new installs default to Steer.** The Settings → Preferences control formerly labeled "Busy input mode" is renamed to "Default message mode," and a fresh install now defaults to **Steer** (inject a mid-turn correction without interrupting) instead of Queue. Your existing choice is preserved — if you ever saved settings, your current mode (Queue/Interrupt/Steer) is migrated as-is and unchanged; only never-configured installs pick up the new Steer default. The saved preference still survives a reload or a brief server outage (the localStorage mirror from the previous release is intact). Thanks @rodboev. (#5162, #5145)
diff --git a/static/commands.js b/static/commands.js
index 51f66037..c1d6dc54 100644
--- a/static/commands.js
+++ b/static/commands.js
@@ -1431,10 +1431,24 @@ function _steerOwnerIsCurrent(ownerSid){
   return !!(ownerSid&&typeof S!=='undefined'&&S.session&&S.session.session_id===ownerSid);
 }
 
+function _steerSetComposerStatusForOwner(ownerSid,text){
+  if(_steerOwnerIsCurrent(ownerSid)&&typeof setComposerStatus==='function')setComposerStatus(text);
+}
+
 function _steerRestoreText(originalMsg, explicitSteer){
   return explicitSteer?`/steer ${originalMsg}`:originalMsg;
 }
 
+function _steerIndicatorText(originalMsg, filesSnapshot){
+  const text=String(originalMsg||'').trim();
+  if(text)return text;
+  const names=(Array.isArray(filesSnapshot)?filesSnapshot:[])
+    .map(f=>f&&(f.name||f.filename||f.path||''))
+    .map(v=>String(v||'').trim())
+    .filter(Boolean);
+  return names.length?`Attached files: ${names.join(', ')}`:'Attached files';
+}
+
 async function _steerPersistDraftForOwner(ownerSid, originalMsg, explicitSteer, filesSnapshot){
   if(!ownerSid||typeof _saveComposerDraftNow!=='function')return;
   await _saveComposerDraftNow(ownerSid,_steerRestoreText(originalMsg,explicitSteer),filesSnapshot);
@@ -1463,14 +1477,14 @@ async function _steerTextWithPendingFiles(msg, ownerSid, filesSnapshot){
   if(_steerUploadCache&&_steerUploadCache.sid===ownerSid&&_steerUploadCache.sig===sig&&Array.isArray(_steerUploadCache.paths)&&_steerUploadCache.paths.length){
     paths=_steerUploadCache.paths;
   }else{
-    if(typeof setComposerStatus==='function')setComposerStatus(t('uploading')||'Uploading…');
+    _steerSetComposerStatusForOwner(ownerSid,t('uploading')||'Uploading…');
     let uploaded=[];
     try{
       // Keep File objects staged until /api/chat/steer confirms acceptance. If
       // steer falls back, the draft and chips stay available for Queue/Interrupt.
       uploaded=await uploadPendingFiles({clearPending:false,sessionId:ownerSid,files:pendingFiles});
     }finally{
-      if(typeof setComposerStatus==='function')setComposerStatus('');
+      _steerSetComposerStatusForOwner(ownerSid,'');
     }
     paths=_steerUploadedAttachmentPaths(uploaded);
     if(paths.length) _steerUploadCache={sid:ownerSid,sig,paths};
@@ -1500,7 +1514,7 @@ async function _trySteer(msg, explicitSteer){
     }else{
       await _steerPersistDraftForOwner(ownerSid,originalMsg,explicitSteer,pendingFilesSnapshot);
     }
-    if(typeof setComposerStatus==='function')setComposerStatus('');
+    _steerSetComposerStatusForOwner(ownerSid,'');
     showToast(`${t('upload_failed')}${e&&e.message?e.message:e}`,3500);
     return false;
   }
@@ -1546,7 +1560,7 @@ async function _trySteer(msg, explicitSteer){
         const _remaining=S.pendingFiles.filter(f=>!_delivered.has(f));
         if(_remaining.length!==S.pendingFiles.length){S.pendingFiles=_remaining;if(typeof renderTray==='function')renderTray();}
       }
-      _showSteerIndicator(steerText);
+      _showSteerIndicator(_steerIndicatorText(originalMsg,pendingFilesSnapshot));
     }
     showToast(t('cmd_steer_delivered'),2500);
     return true;
diff --git a/static/sessions.js b/static/sessions.js
index ce8185e0..3abfe84e 100644
--- a/static/sessions.js
+++ b/static/sessions.js
@@ -1322,6 +1322,7 @@ async function loadSession(sid){
   // Mark this session as the in-flight load. Subsequent loadSession() calls
   // will overwrite this; stale awaits use the mismatch to bail out (#1060).
   _loadingSessionId = sid;
+  if(currentSid!==sid&&typeof _uploadPendingFilesSyncProgressForSession==='function')_uploadPendingFilesSyncProgressForSession(sid);
   // Reset scroll state for fresh session navigation — the reader expects to
   // land at the bottom of the new transcript, not wherever a stale unpin flag
   // from a prior session or a stray touch event during loading would place them.
diff --git a/static/style.css b/static/style.css
index 4fbea1c0..c5d0e6e3 100644
--- a/static/style.css
+++ b/static/style.css
@@ -72,6 +72,23 @@
   :root[data-font-size="large"] .msg-body table { font-size: 14px; }
   :root[data-font-size="xlarge"] .msg-body table { font-size: 16px; }
 
+  /* Chat message role header (model name / icon / TPS / timestamp) */
+  :root[data-font-size="small"] .msg-role { font-size: 10px; }
+  :root[data-font-size="large"] .msg-role { font-size: 13px; }
+  :root[data-font-size="xlarge"] .msg-role { font-size: 15px; }
+  :root[data-font-size="small"] .role-icon { width: 18px; height: 18px; font-size: 8px; }
+  :root[data-font-size="large"] .role-icon { width: 22px; height: 22px; font-size: 10px; }
+  :root[data-font-size="xlarge"] .role-icon { width: 24px; height: 24px; font-size: 11px; }
+  :root[data-font-size="small"] .msg-role-name { font-size: 11px; }
+  :root[data-font-size="large"] .msg-role-name { font-size: 14px; }
+  :root[data-font-size="xlarge"] .msg-role-name { font-size: 16px; }
+  :root[data-font-size="small"] .msg-tps-inline { font-size: 9.5px; }
+  :root[data-font-size="large"] .msg-tps-inline { font-size: 12.5px; }
+  :root[data-font-size="xlarge"] .msg-tps-inline { font-size: 14.5px; }
+  :root[data-font-size="small"] .msg-role .msg-time { font-size: 9px; }
+  :root[data-font-size="large"] .msg-role .msg-time { font-size: 12px; }
+  :root[data-font-size="xlarge"] .msg-role .msg-time { font-size: 14px; }
+
   /* Composer textarea (default is 16px in stylesheet) */
   :root[data-font-size="small"] #msg { font-size: 14px; }
   :root[data-font-size="large"] #msg { font-size: 18px; }
@@ -2104,7 +2121,7 @@
    (see line ~681). The rail rule is no longer needed. */
   .rail .nav-tab.active::before{content:'';position:absolute;left:-6px;top:50%;bottom:auto;transform:translateY(-50%);width:3px;height:16px;background:var(--accent);border-radius:0 2px 2px 0;}
   .dashboard-link{position:relative;}
-  .dashboard-link-visible{display:flex!important;}
+  .dashboard-link-visible,.nav-action-visible{display:flex!important;}
   .dashboard-external-badge{position:absolute;right:5px;top:5px;width:9px;height:9px;border-radius:2px;border:1px solid var(--accent);background:var(--sidebar);box-shadow:0 0 0 2px var(--sidebar);opacity:.95;}
   .dashboard-external-badge::after{content:'';position:absolute;right:-2px;top:-2px;width:5px;height:5px;border-top:1.5px solid var(--accent);border-right:1.5px solid var(--accent);}
   .sidebar-nav .dashboard-external-badge{right:8px;top:7px;width:8px;height:8px;}
@@ -2399,6 +2416,9 @@
   .mermaid-viewer-viewport{position:relative;overflow:hidden;max-width:100%;border:1px solid var(--border);border-radius:8px;background:var(--code-bg);cursor:grab;touch-action:none;user-select:none;-webkit-user-select:none;}
   .mermaid-viewer-viewport.is-panning{cursor:grabbing;}
   .mermaid-viewer--inline .mermaid-viewer-viewport{width:100%;max-height:70vh;}
+  @media (max-width: 640px){
+    .mermaid-viewer--inline .mermaid-viewer-viewport{min-height:min(200px,70vh);}
+  }
   .mermaid-viewer--lightbox .mermaid-viewer-viewport{max-width:90vw;max-height:90vh;border:none;box-shadow:0 8px 48px rgba(0,0,0,.6);}
   .mermaid-viewer-canvas{position:absolute;left:0;top:0;transform-origin:0 0;will-change:transform;}
   .mermaid-viewer-svg{display:block;width:100%;height:100%;}
@@ -2892,10 +2912,14 @@
   .pwa-sidebar-edge-guard{display:none;}
 
   @media(min-width:901px){
-    html[data-workspace-panel="closed"] .rightpanel{width:0 !important;opacity:0;transform:translateX(14px);border-left-color:transparent;pointer-events:none;}
-    .layout.workspace-panel-collapsed .rightpanel{width:0 !important;opacity:0;transform:translateX(14px);border-left-color:transparent;pointer-events:none;}
+    html[data-workspace-panel="closed"] .rightpanel{width:0 !important;min-width:0 !important;opacity:0;transform:translateX(14px);border-left-color:transparent;pointer-events:none;}
+    .layout.workspace-panel-collapsed .rightpanel{width:0 !important;min-width:0 !important;opacity:0;transform:translateX(14px);border-left-color:transparent;pointer-events:none;}
     html[data-workspace-panel="closed"] .workspace-panel-edge-toggle{display:inline-flex;opacity:1;pointer-events:auto;transform:translateY(-50%);}
     html[data-workspace-panel="open"] .workspace-panel-edge-toggle{display:none;}
+    /* Keep the center readable before the rails hit their resize floor. */
+    .main{flex:1 1 420px;min-width:420px;}
+    .sidebar{flex-shrink:1;min-width:180px;}
+    .rightpanel{flex-shrink:1;min-width:180px;}
   }
 
   /* Sidebar collapse breakpoint matches `_isDesktopWidth()` (min-width:641px) so
@@ -3100,8 +3124,7 @@
     .sidebar-nav .nav-tab svg{width:20px;height:20px;}
     .sidebar-nav .nav-tab.active{background:var(--accent-bg);}
     .sidebar-nav .nav-tab.active::before{left:-4px;top:50%;bottom:auto;transform:translateY(-50%);width:3px;height:16px;border-radius:0 2px 2px 0;}
-    .sidebar-nav .dashboard-link,
-    .sidebar-nav .dashboard-link.dashboard-link-visible{display:none!important;}
+    .sidebar-nav .dashboard-link:not(.nav-action-visible),.sidebar-nav [data-nav-action-mirror]:not(.nav-action-visible){display:none!important;}
     .sidebar .panel-view{height:100%;margin-left:52px;}
     .sidebar .panel-head{padding-right:52px;}
     .mobile-sidebar-close{display:inline-flex!important;position:absolute;right:4px;top:calc(4px + var(--app-titlebar-safe-top));width:44px;height:44px;z-index:4;background:var(--surface);border:1px solid var(--border);}
@@ -5876,6 +5899,7 @@ main.main > #mainPlugin{display:none;}
 /* Quieter, always-visible role header (smaller avatar, always-visible timestamp) */
 .msg-role { font-size: 11px; font-weight: 500; margin-bottom: 6px; opacity: .8; letter-spacing: 0; }
 .msg-role:hover { opacity: 1; }
+.msg-role-name { font-size: 12px; }
 .role-icon { width: 20px; height: 20px; font-size: 9px; }
 .msg-tps-inline {
   display: inline-flex;
diff --git a/static/ui.js b/static/ui.js
index 68c2c523..352caf47 100644
--- a/static/ui.js
+++ b/static/ui.js
@@ -1458,12 +1458,82 @@ function _dashboardBrowserUrl(status){
   const displayHost=browserHost.includes(':')&&!browserHost.startsWith('[')?'['+browserHost+']':browserHost;
   return source.protocol+'//'+displayHost+':'+status.port;
 }
+function _stripInlineEventHandlers(node){
+  if(!node)return;
+  const strip=el=>{
+    Array.from(el.attributes||[]).forEach(attr=>{
+      if(attr.name&&attr.name.toLowerCase().startsWith('on'))el.removeAttribute(attr.name);
+    });
+    if('onclick' in el)el.onclick=null;
+    Array.from(el.children||[]).forEach(strip);
+  };
+  strip(node);
+}
+function _syncNavActionMirrors(){
+  const rail=document.querySelector('.rail');
+  const sidebar=document.querySelector('.sidebar-nav');
+  if(!rail||!sidebar)return;
+  const sources=Array.from(rail.querySelectorAll('.nav-tab:not([data-panel]):not([data-dashboard-link])')).filter(source=>source.id);
+  const mirrors=Array.from(sidebar.querySelectorAll('[data-nav-action-mirror]'));
+  const sourceIds=new Set(sources.map(source=>source.id));
+  mirrors.forEach(mirror=>{
+    if(!sourceIds.has(mirror.getAttribute('data-nav-action-mirror')))mirror.remove();
+  });
+  sources.forEach(source=>{
+    const sourceVisible=(()=>{
+      if(source.hidden||source.getAttribute('aria-hidden')==='true')return false;
+      if(source.classList.contains('nav-tab-hidden'))return false;
+      if(source.style&&(source.style.display==='none'||source.style.visibility==='hidden'))return false;
+      if(typeof window!=='undefined'&&typeof window.getComputedStyle==='function'){
+        const computed=window.getComputedStyle(source);
+        if(computed&&(computed.display==='none'||computed.visibility==='hidden'))return false;
+      }
+      return true;
+    })();
+    let mirror=mirrors.find(el=>el.getAttribute('data-nav-action-mirror')===source.id);
+    if(!mirror){
+      mirror=source.cloneNode(true);
+      _stripInlineEventHandlers(mirror);
+      mirror.id=source.id+'Mobile';
+      mirror.classList.remove('rail-btn');
+      mirror.classList.add('has-tooltip--bottom');
+      mirror.setAttribute('data-nav-action-mirror',source.id);
+      mirror.addEventListener('click',e=>{
+        e.preventDefault();
+        if(mirror._navActionSource)mirror._navActionSource.click();
+        if(typeof closeMobileSidebar==='function')closeMobileSidebar();
+      });
+      const anchor=sidebar.querySelector('.dashboard-link,[data-dashboard-link]')||sidebar.querySelector('[data-panel="logs"]');
+      sidebar.insertBefore(mirror,anchor||null);
+    }else{
+      mirror.innerHTML=source.innerHTML;
+      _stripInlineEventHandlers(mirror);
+    }
+    mirror._navActionSource=source;
+    mirror.classList.toggle('nav-action-visible',sourceVisible);
+    const label=source.getAttribute('data-tooltip')||source.getAttribute('aria-label')||'';
+    if(label)mirror.setAttribute('data-label',label);
+  });
+}
+function _initNavActionMirrors(){
+  _syncNavActionMirrors();
+  const rail=document.querySelector('.rail');
+  if(rail&&window.MutationObserver)new MutationObserver(_syncNavActionMirrors).observe(rail,{
+    childList:true,
+    subtree:true,
+    attributes:true,
+    attributeFilter:['class','style','hidden','aria-hidden','data-tooltip','aria-label'],
+  });
+}
+if(document.readyState==='loading')document.addEventListener('DOMContentLoaded',_initNavActionMirrors,{once:true});
+else _initNavActionMirrors();
 function _applyDashboardStatus(status){
   const running=!!(status&&status.running);
   const url=running?_dashboardBrowserUrl(status):'';
   const warning=running&&!_dashboardIsBrowserLoopback()?t('dashboard_loopback_warning'):'';
   document.querySelectorAll('[data-dashboard-link]').forEach(btn=>{
     btn.classList.toggle('dashboard-link-visible',running);
+    btn.classList.toggle('nav-action-visible',running);
     btn.style.display=running?'':'none';
     btn.dataset.dashboardUrl=url;
     const tipText=warning||t('tab_dashboard');
@@ -9540,7 +9610,7 @@ function isTpsDisplayEnabled(){
 function _assistantRoleHtml(tsTitle='', tpsText=''){
   const _bn=assistantDisplayName();
   const tps=(isTpsDisplayEnabled()&&tpsText)?`<span class="msg-tps-inline" title="Tokens per second">${esc(tpsText)}</span>`:'';
-  return `<div class="msg-role assistant" ${tsTitle?`title="${esc(tsTitle)}"`:''}><div class="role-icon assistant">${esc(_bn.charAt(0).toUpperCase())}</div><span style="font-size:12px">${esc(_bn)}</span>${tps}</div>`;
+  return `<div class="msg-role assistant" ${tsTitle?`title="${esc(tsTitle)}"`:''}><div class="role-icon assistant">${esc(_bn.charAt(0).toUpperCase())}</div><span class="msg-role-name">${esc(_bn)}</span>${tps}</div>`;
 }
 function _setAssistantTurnTps(turn, tpsText=''){
   if(!turn) return;
@@ -17965,9 +18035,50 @@ function addFiles(files){
   }
   renderTray();
 }
+const _uploadPendingFilesProgressBySession=new Map();
 function _uploadPendingFilesCurrentSession(sessionId){
   return !!(!sessionId||(S.session&&S.session.session_id===sessionId));
 }
+function _uploadPendingFilesHideProgressBar(){
+  const bar=$('uploadBar');const barWrap=$('uploadBarWrap');
+  if(!bar||!barWrap)return;
+  barWrap.classList.remove('active');
+  bar.style.width='0%';
+  if(barWrap.dataset)delete barWrap.dataset.uploadSessionId;
+}
+function _uploadPendingFilesShowProgressBar(owner,percent){
+  const bar=$('uploadBar');const barWrap=$('uploadBarWrap');
+  if(!bar||!barWrap)return;
+  if(barWrap.dataset)barWrap.dataset.uploadSessionId=owner;
+  barWrap.classList.add('active');
+  bar.style.width=`${Math.max(0,Math.min(100,Number(percent)||0))}%`;
+}
+function _uploadPendingFilesSyncProgressForSession(sessionId){
+  const owner=String(sessionId||'');
+  const state=owner?_uploadPendingFilesProgressBySession.get(owner):null;
+  if(state){_uploadPendingFilesShowProgressBar(owner,state.percent);return;}
+  _uploadPendingFilesHideProgressBar();
+}
+function _uploadPendingFilesUpdateProgress(sessionId,percent){
+  const bar=$('uploadBar');const barWrap=$('uploadBarWrap');
+  if(!bar||!barWrap)return;
+  const owner=String(sessionId||'');
+  const activeForOwner=barWrap.dataset&&barWrap.dataset.uploadSessionId===owner;
+  if(percent===null){
+    if(owner)_uploadPendingFilesProgressBySession.delete(owner);
+    if(activeForOwner){
+      _uploadPendingFilesHideProgressBar();
+    }
+    return;
+  }
+  const clamped=Math.max(0,Math.min(100,Number(percent)||0));
+  if(owner)_uploadPendingFilesProgressBySession.set(owner,{percent:clamped});
+  if(!_uploadPendingFilesCurrentSession(sessionId)){
+    if(activeForOwner)_uploadPendingFilesHideProgressBar();
+    return;
+  }
+  _uploadPendingFilesShowProgressBar(owner,clamped);
+}
 async function uploadPendingFiles(options={}){
   const opts=options||{};
   const pendingFiles=Array.isArray(opts.files)?opts.files.filter(Boolean):[...(S.pendingFiles||[])];
@@ -17975,8 +18086,7 @@ async function uploadPendingFiles(options={}){
   if(!pendingFiles.length||!sessionId)return[];
   const clearPending=!(opts&&opts.clearPending===false);
   const names=[];let failures=0;
-  const bar=$('uploadBar');const barWrap=$('uploadBarWrap');
-  barWrap.classList.add('active');bar.style.width='0%';
+  _uploadPendingFilesUpdateProgress(sessionId,0);
   const total=pendingFiles.length;
   for(let i=0;i<total;i++){
     const f=pendingFiles[i];
@@ -17998,9 +18108,9 @@ async function uploadPendingFiles(options={}){
         names.push({name: data.filename, path: data.path, mime: data.mime, size: data.size, is_image: !!data.is_image});
       }
     }catch(e){failures++;setStatus(`\u274c ${t('upload_failed')}${f.name} \u2014 ${e.message}`);}
-    bar.style.width=`${Math.round((i+1)/total*100)}%`;
+    _uploadPendingFilesUpdateProgress(sessionId,Math.round((i+1)/total*100));
   }
-  barWrap.classList.remove('active');bar.style.width='0%';
+  _uploadPendingFilesUpdateProgress(sessionId,null);
   if(clearPending&&_uploadPendingFilesCurrentSession(sessionId)){S.pendingFiles=[];renderTray();}
   else if(typeof renderTray==='function'&&_uploadPendingFilesCurrentSession(sessionId))renderTray();
   if(failures===total&&total>0)throw new Error(t('all_uploads_failed',total));
diff --git a/tests/helpers.py b/tests/helpers.py
new file mode 100644
index 00000000..1325bf48
--- /dev/null
+++ b/tests/helpers.py
@@ -0,0 +1,9 @@
+"""Shared test helpers for static source assertions."""
+
+
+def source_between(src: str, start_marker: str, end_marker: str) -> str:
+    start = src.find(start_marker)
+    assert start >= 0, f"{start_marker} not found"
+    end = src.find(end_marker, start)
+    assert end > start, f"{end_marker} not found after {start_marker}"
+    return src[start:end]
diff --git a/tests/test_1062_busy_input_modes.py b/tests/test_1062_busy_input_modes.py
index eb45f40b..80204a1c 100644
--- a/tests/test_1062_busy_input_modes.py
+++ b/tests/test_1062_busy_input_modes.py
@@ -11,6 +11,8 @@ Issue: #720 (configurable busy-input behaviour)
 """
 from pathlib import Path
 
+from tests.helpers import source_between as _source_between
+
 ROOT = Path(__file__).parent.parent
 CONFIG_PY = (ROOT / "api" / "config.py").read_text(encoding="utf-8")
 COMMANDS_JS = (ROOT / "static" / "commands.js").read_text(encoding="utf-8")
@@ -22,14 +24,6 @@ INDEX_HTML = (ROOT / "static" / "index.html").read_text(encoding="utf-8")
 I18N_JS = (ROOT / "static" / "i18n.js").read_text(encoding="utf-8")
 
 
-def _source_between(src, start_marker, end_marker):
-    start = src.find(start_marker)
-    assert start >= 0, f"{start_marker} not found"
-    end = src.find(end_marker, start)
-    assert end > start, f"{end_marker} not found after {start_marker}"
-    return src[start:end]
-
-
 # ── Backend: setting registration + enum validation ─────────────────────
 
 class TestBusyInputModeSetting:
diff --git a/tests/test_dashboard_link_ui.py b/tests/test_dashboard_link_ui.py
index 9c9dcfbc..8fc4c91c 100644
--- a/tests/test_dashboard_link_ui.py
+++ b/tests/test_dashboard_link_ui.py
@@ -385,7 +385,7 @@ def test_dashboard_settings_controls_live_in_system_panel():
 
 
 def test_dashboard_frontend_uses_browser_url_without_requiring_probe_port():
-    match = re.search(r"function _dashboardBrowserUrl\(status\).*?\n}\nfunction _applyDashboardStatus", UI_JS, re.DOTALL)
+    match = re.search(r"function _dashboardBrowserUrl\(status\).*?\n}\nfunction _syncNavActionMirrors", UI_JS, re.DOTALL)
     assert match is not None
     helper = match.group(0)
     assert "status.browser_url||status.url" in helper
@@ -393,7 +393,7 @@ def test_dashboard_frontend_uses_browser_url_without_requiring_probe_port():
     assert helper.index("status.browser_url||status.url") < helper.index("!status.port")
 
 
-def test_mobile_dashboard_link_is_scoped_hidden_in_narrow_viewport_css():
+def test_mobile_dashboard_link_uses_shared_visible_action_class():
     match = re.search(
         r"@media\(max-width:640px\)\{([\s\S]*?)\n\s*}\s*\n\s*@media \(hover:none\)",
         STYLE_CSS,
@@ -401,11 +401,219 @@ def test_mobile_dashboard_link_is_scoped_hidden_in_narrow_viewport_css():
     )
     assert match is not None
     mobile_css = match.group(1)
-    assert re.search(
-        r"\.sidebar-nav\s+\.dashboard-link,\s*\.sidebar-nav\s+\.dashboard-link\.dashboard-link-visible\s*\{\s*display\s*:\s*none\s*!important\s*;\s*}",
-        mobile_css,
-        re.DOTALL,
+    assert re.search(r"\.dashboard-link-visible,\s*\.nav-action-visible\{display:flex!important;\}", STYLE_CSS)
+    assert ".sidebar-nav .dashboard-link:not(.nav-action-visible)" in mobile_css
+    assert ".sidebar-nav [data-nav-action-mirror]:not(.nav-action-visible){display:none!important;}" in mobile_css
+    assert ".sidebar-nav .dashboard-link.dashboard-link-visible{display:none!important;}" not in mobile_css
+    assert ".sidebar-nav .dashboard-link:not(.dashboard-link-visible){display:none!important;}" not in mobile_css
+
+
+@requires_node
+def test_extension_rail_actions_are_mirrored_to_mobile_nav():
+    driver = textwrap.dedent(
+        """\
+        const fs = require('fs');
+        const src = fs.readFileSync(process.argv[2], 'utf8');
+
+        function extractFn(name) {
+          const start = src.indexOf(`function ${name}(`);
+          if (start < 0) throw new Error(`${name}() not found`);
+          let i = src.indexOf('{', start);
+          let depth = 0;
+          for (; i < src.length; i++) {
+            if (src[i] === '{') depth += 1;
+            if (src[i] === '}') {
+              depth -= 1;
+              if (depth === 0) return src.slice(start, i + 1);
+            }
+          }
+          throw new Error(`could not extract ${name}`);
+        }
+
+        class El {
+          constructor(tag) {
+            this.tagName = tag;
+            this.children = [];
+            this._attrs = {};
+            this.dataset = {};
+            this.innerHTML = '';
+            this.id = '';
+            this.onclick = null;
+            this.parentNode = null;
+            this._handlers = {};
+            this.classList = {
+              _set: new Set(),
+              add: (...classes) => classes.forEach(c => this.classList._set.add(c)),
+              remove: (...classes) => classes.forEach(c => this.classList._set.delete(c)),
+              contains: c => this.classList._set.has(c),
+              toggle: (cls, force) => {
+                if (force === undefined) {
+                  if (this.classList._set.has(cls)) {
+                    this.classList._set.delete(cls);
+                    return false;
+                  }
+                  this.classList._set.add(cls);
+                  return true;
+                }
+                if (force) this.classList._set.add(cls);
+                else this.classList._set.delete(cls);
+                return !!force;
+              },
+            };
+          }
+          appendChild(child) { child.parentNode = this; this.children.push(child); return child; }
+          insertBefore(child, anchor) {
+            const idx = anchor ? this.children.indexOf(anchor) : -1;
+            child.parentNode = this;
+            if (idx >= 0) this.children.splice(idx, 0, child);
+            else this.children.push(child);
+            return child;
+          }
+          remove() {
+            if (!this.parentNode) return;
+            const idx = this.parentNode.children.indexOf(this);
+            if (idx >= 0) this.parentNode.children.splice(idx, 1);
+            this.parentNode = null;
+          }
+          setAttribute(name, value) {
+            this._attrs[name] = String(value);
+            if (name.startsWith('data-')) this.dataset[name.slice(5).replace(/-([a-z])/g, (_, c) => c.toUpperCase())] = String(value);
+          }
+          removeAttribute(name) {
+            delete this._attrs[name];
+            if (name.startsWith('data-')) delete this.dataset[name.slice(5).replace(/-([a-z])/g, (_, c) => c.toUpperCase())];
+          }
+          get attributes() { return Object.entries(this._attrs).map(([name, value]) => ({ name, value })); }
+          getAttribute(name) { return Object.prototype.hasOwnProperty.call(this._attrs, name) ? this._attrs[name] : null; }
+          hasAttribute(name) { return Object.prototype.hasOwnProperty.call(this._attrs, name); }
+          addEventListener(name, fn) { this._handlers[name] = fn; }
+          click() { if (this._handlers.click) this._handlers.click({ preventDefault() {} }); }
+          cloneNode() {
+            const clone = new El(this.tagName);
+            clone.id = this.id;
+            clone.innerHTML = this.innerHTML;
+            clone.onclick = this.onclick;
+            this.classList._set.forEach(c => clone.classList.add(c));
+            Object.entries(this._attrs).forEach(([k, v]) => clone.setAttribute(k, v));
+            return clone;
+          }
+          querySelectorAll(sel) {
+            if (sel === '.nav-tab:not([data-panel]):not([data-dashboard-link])') {
+              return this.children.filter(el => el.classList.contains('nav-tab') && !el.hasAttribute('data-panel') && !el.hasAttribute('data-dashboard-link'));
+            }
+            if (sel === '[data-nav-action-mirror]') {
+              return this.children.filter(el => el.hasAttribute('data-nav-action-mirror'));
+            }
+            return [];
+          }
+          querySelector(sel) {
+            if (sel.startsWith('[data-nav-action-mirror="')) {
+              const id = sel.slice(25, -2);
+              return this.children.find(el => el.getAttribute('data-nav-action-mirror') === id) || null;
+            }
+            if (sel === '.dashboard-link,[data-dashboard-link]') return this.children.find(el => el.classList.contains('dashboard-link') || el.hasAttribute('data-dashboard-link')) || null;
+            if (sel === '[data-panel="logs"]') return this.children.find(el => el.getAttribute('data-panel') === 'logs') || null;
+            return null;
+          }
+        }
+
+        const rail = new El('nav');
+        const sidebar = new El('div');
+        const source = new El('button');
+        const dashboard = new El('button');
+        let clicked = 0;
+        let sidebarClosed = 0;
+        source.id = 'hwxThemeCreatorRailBtn';
+        source.classList.add('rail-btn', 'nav-tab', 'has-tooltip');
+        source.setAttribute('data-tooltip', 'Theme Creator');
+        source.setAttribute('onclick', 'clicked += 100;');
+        source.onclick = () => { clicked += 100; };
+        source.innerHTML = '<svg></svg>';
+        source.click = () => { clicked += 1; };
+        dashboard.classList.add('dashboard-link');
+        sidebar.appendChild(dashboard);
+        let observerCallback = null;
+        let observedRail = null;
+        let observedOptions = null;
+
+        global.document = {
+          readyState: 'complete',
+          querySelector(sel) {
+            if (sel === '.rail') return rail;
+            if (sel === '.sidebar-nav') return sidebar;
+            return null;
+          },
+        };
+        global.closeMobileSidebar = () => { sidebarClosed += 1; };
+        global.window = {
+          getComputedStyle(el) {
+            return {
+              display: el.hidden || (el.style && el.style.display === 'none') ? 'none' : '',
+              visibility: (el.style && el.style.visibility) || '',
+            };
+          },
+        };
+        global.MutationObserver = window.MutationObserver = class {
+          constructor(callback) { observerCallback = callback; }
+          observe(target, options) { observedRail = target; observedOptions = options; }
+        };
+
+        const helpers = Function(extractFn('_stripInlineEventHandlers') + '\\n' + extractFn('_syncNavActionMirrors') + '\\n' + extractFn('_initNavActionMirrors') + '; return { _initNavActionMirrors };')();
+        helpers._initNavActionMirrors();
+        rail.appendChild(source);
+        observerCallback();
+        const mirror = sidebar.children.find(el => el.getAttribute('data-nav-action-mirror') === 'hwxThemeCreatorRailBtn');
+        source.hidden = true;
+        observerCallback();
+        const mirrorHiddenWhenSourceHidden = !mirror.classList.contains('nav-action-visible');
+        source.hidden = false;
+        observerCallback();
+        mirror.click();
+        const mirrorBeforeDashboard = sidebar.children[0] === mirror;
+        source.remove();
+        observerCallback();
+        console.log(JSON.stringify({
+          observerArmed: observedRail === rail,
+          observerAttributes: !!(observedOptions && observedOptions.attributes),
+          observerSubtree: !!(observedOptions && observedOptions.subtree),
+          sourceVisible: source.classList.contains('nav-action-visible'),
+          mirrorVisible: mirror.classList.contains('nav-action-visible'),
+          mirrorHiddenWhenSourceHidden,
+          mirrorRailClass: mirror.classList.contains('rail-btn'),
+          mirrorLabel: mirror.getAttribute('data-label'),
+          mirrorOnclickAttribute: mirror.getAttribute('onclick'),
+          mirrorOnclickProperty: mirror.onclick === null,
+          mirrorBeforeDashboard,
+          mirrorRemoved: !sidebar.children.some(el => el.getAttribute('data-nav-action-mirror') === 'hwxThemeCreatorRailBtn'),
+          clicked,
+          sidebarClosed,
+        }));
+        """
     )
+    with tempfile.NamedTemporaryFile("w", suffix=".js", delete=False, encoding="utf-8") as handle:
+        handle.write(driver)
+        path = handle.name
+    try:
+        result = subprocess.run([NODE, path, str(UI_PATH)], text=True, capture_output=True, timeout=15, check=True)
+        out = json.loads(result.stdout)
+    finally:
+        pathlib.Path(path).unlink(missing_ok=True)
+    assert out == {
+        "observerArmed": True,
+        "observerAttributes": True,
+        "observerSubtree": True,
+        "sourceVisible": False,
+        "mirrorVisible": True,
+        "mirrorHiddenWhenSourceHidden": True,
+        "mirrorRailClass": False,
+        "mirrorLabel": "Theme Creator",
+        "mirrorOnclickAttribute": None,
+        "mirrorOnclickProperty": True,
+        "mirrorBeforeDashboard": True,
+        "mirrorRemoved": True,
+        "clicked": 1,
+        "sidebarClosed": 1,
+    }
 
 
 def test_desktop_dashboard_link_button_stays_in_desktop_nav():
@@ -431,6 +639,7 @@ def test_dashboard_dropdown_save_resyncs_chip_state():
     assert out["statusCalls"] >= 1
     assert all(
         "dashboard-link-visible" not in state["classes"]
+        and "nav-action-visible" not in state["classes"]
         and state["display"] == "none"
         for state in out["buttonStates"]
     )
@@ -448,6 +657,7 @@ def test_dashboard_chip_save_keeps_buttons_refreshed():
     assert out["statusCalls"] >= 1
     assert all(
         "dashboard-link-visible" in state["classes"]
+        and "nav-action-visible" in state["classes"]
         and state["display"] != "none"
         for state in out["buttonStates"]
     )
@@ -471,6 +681,7 @@ def test_stale_dashboard_load_does_not_overwrite_newer_save():
     assert out["statusCalls"] == 1
     assert all(
         "dashboard-link-visible" in state["classes"]
+        and "nav-action-visible" in state["classes"]
         and state["display"] != "none"
         for state in out["buttonStates"]
     )
diff --git a/tests/test_issue5545_three_panel_layout.py b/tests/test_issue5545_three_panel_layout.py
new file mode 100644
index 00000000..cd7fd255
--- /dev/null
+++ b/tests/test_issue5545_three_panel_layout.py
@@ -0,0 +1,134 @@
+"""
+Issue #5545 three-panel desktop layout regression checks.
+
+These tests stay source-level so they can verify the declared CSS contract
+without needing a browser or rendered layout.
+"""
+
+import pathlib
+import re
+
+REPO = pathlib.Path(__file__).parent.parent
+CSS = (REPO / "static" / "style.css").read_text(encoding="utf-8")
+BOOT_JS = (REPO / "static" / "boot.js").read_text(encoding="utf-8")
+
+
+def _media_blocks(kind):
+    pattern = re.compile(rf"@media\s*\(\s*{kind}\s*:\s*(\d+)px\s*\)\s*\{{")
+    blocks = []
+    for match in pattern.finditer(CSS):
+        width_px = int(match.group(1))
+        open_brace = match.end() - 1
+        depth = 0
+        for idx in range(open_brace, len(CSS)):
+            if CSS[idx] == "{":
+                depth += 1
+            elif CSS[idx] == "}":
+                depth -= 1
+                if depth == 0:
+                    blocks.append((width_px, CSS[open_brace + 1:idx]))
+                    break
+    return blocks
+
+
+def _normalize_css(css):
+    return re.sub(r"\s+", "", css)
+
+
+def _media_block(kind, width_px, needle):
+    normalized_needle = _normalize_css(needle)
+    for current_width, block in _media_blocks(kind):
+        if current_width == width_px and normalized_needle in _normalize_css(block):
+            return block
+    raise AssertionError(f"Missing @media({kind}:{width_px}px) block containing {needle!r}")
+
+
+def _strip_css_comments(css):
+    return re.sub(r"/\*.*?\*/", "", css, flags=re.DOTALL)
+
+
+def _rule_body(css, selector):
+    for match in re.finditer(r"([^{}]+)\{([^{}]*)\}", _strip_css_comments(css)):
+        selectors = {part.strip() for part in match.group(1).split(",")}
+        if selector in selectors:
+            return match.group(2)
+    raise AssertionError(f"Missing CSS rule for {selector}")
+
+
+def _declarations(rule_body):
+    declarations = {}
+    for item in rule_body.split(";"):
+        if ":" not in item:
+            continue
+        prop, value = item.split(":", 1)
+        declarations[prop.strip()] = re.sub(r"\s+", " ", value.strip())
+    return declarations
+
+
+def test_desktop_three_panel_contract_gives_main_readable_floor():
+    desktop = _media_block("min-width", 901, ".main{flex:1 1 420px;min-width:420px;}")
+    main = _declarations(_rule_body(desktop, ".main"))
+
+    assert main.get("flex") == "1 1 420px"
+    assert main.get("min-width") == "420px"
+
+
+def test_desktop_side_rails_can_shrink_to_resize_minima():
+    desktop = _media_block("min-width", 901, ".sidebar{flex-shrink:1;min-width:180px;}")
+    sidebar = _declarations(_rule_body(desktop, ".sidebar"))
+    rightpanel = _declarations(_rule_body(desktop, ".rightpanel"))
+    closed_rightpanel = _declarations(
+        _rule_body(desktop, 'html[data-workspace-panel="closed"] .rightpanel')
+    )
+    collapsed_rightpanel = _declarations(
+        _rule_body(desktop, ".layout.workspace-panel-collapsed .rightpanel")
+    )
+
+    assert re.search(r"\bSIDEBAR_MIN\s*=\s*180\b", BOOT_JS)
+    assert re.search(r"\bPANEL_MIN\s*=\s*180\b", BOOT_JS)
+    assert sidebar.get("flex-shrink") == "1"
+    assert sidebar.get("min-width") == "180px"
+    assert rightpanel.get("flex-shrink") == "1"
+    assert rightpanel.get("min-width") == "180px"
+    assert closed_rightpanel.get("width") == "0 !important"
+    assert closed_rightpanel.get("min-width") == "0 !important"
+    assert collapsed_rightpanel.get("width") == "0 !important"
+    assert collapsed_rightpanel.get("min-width") == "0 !important"
+
+
+def test_compact_breakpoint_900px_remains_hidden_right_panel_boundary():
+    assert "@media(max-width:900px)" in CSS or "@media (max-width: 900px)" in CSS
+
+    compact = _media_block("max-width", 900, ".rightpanel{display:none}")
+    rightpanel = _declarations(_rule_body(compact, ".rightpanel"))
+    workspace_toggle = _declarations(_rule_body(compact, ".workspace-toggle-btn"))
+    mobile_files = _declarations(_rule_body(compact, ".mobile-files-btn"))
+
+    assert rightpanel.get("display") == "none"
+    assert workspace_toggle.get("display") == "inline-flex!important"
+    assert mobile_files.get("display") == "inline-flex!important"
+
+
+def test_mobile_slide_over_breakpoint_640px_remains_intact():
+    assert "@media(max-width:640px)" in CSS or "@media (max-width: 640px)" in CSS
+
+    mobile = _media_block("max-width", 640, ".rightpanel.mobile-open")
+    rightpanel = _declarations(_rule_body(mobile, ".rightpanel"))
+    rightpanel_open = _declarations(_rule_body(mobile, ".rightpanel.mobile-open"))
+
+    assert rightpanel.get("display") == "flex!important"
+    assert rightpanel.get("position") == "fixed"
+    assert rightpanel.get("right") == "calc(-1 * var(--mobile-rightpanel-width))!important"
+    assert rightpanel.get("width") == "var(--mobile-rightpanel-width)!important"
+    assert rightpanel.get("box-shadow") == "none!important"
+    assert rightpanel_open.get("right") == "0!important"
+
+
+def test_no_unmatched_desktop_hide_breakpoint_above_900():
+    hidden_widths = []
+    for width_px, block in _media_blocks("max-width"):
+        if re.search(r"\.rightpanel\s*\{\s*display\s*:\s*none", block):
+            hidden_widths.append(width_px)
+
+    assert 900 in hidden_widths
+    assert all(width_px <= 900 for width_px in hidden_widths)
diff --git a/tests/test_real_steer.py b/tests/test_real_steer.py
index bfbf73a6..7546e66c 100644
--- a/tests/test_real_steer.py
+++ b/tests/test_real_steer.py
@@ -23,6 +23,8 @@ from unittest.mock import MagicMock, patch
 
 import pytest
 
+from tests.helpers import source_between as _source_between
+
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
 
 
@@ -81,14 +83,6 @@ def _captured_status(handler):
     return calls[-1][0][0]
 
 
-def _source_between(src, start_marker, end_marker):
-    start = src.find(start_marker)
-    assert start >= 0, f"{start_marker} not found"
-    end = src.find(end_marker, start)
-    assert end > start, f"{end_marker} not found after {start_marker}"
-    return src[start:end]
-
-
 # ── Backend: the /api/chat/steer endpoint ─────────────────────────────────
 
 class TestHandleChatSteerHappyPath:
@@ -327,6 +321,119 @@ class TestFrontendWiring:
             "post-await tray/DOM mutations must be guarded by the captured owner session"
         )
 
+    def test_file_steer_upload_status_and_indicator_are_owner_scoped(self):
+        steer_helpers = _source_between(
+            self.cmds,
+            "function _steerOwnerIsCurrent",
+            "\nasync function cmdTitle",
+        )
+        try_body = _source_between(self.cmds, "async function _trySteer(", "\nasync function cmdTitle")
+        assert "function _steerSetComposerStatusForOwner" in steer_helpers
+        assert "_steerSetComposerStatusForOwner(ownerSid,t('uploading')||'Uploading…')" in steer_helpers
+        assert "_steerSetComposerStatusForOwner(ownerSid,'')" in steer_helpers
+        assert "function _steerIndicatorText" in steer_helpers
+        assert "_showSteerIndicator(_steerIndicatorText(originalMsg,pendingFilesSnapshot))" in try_body, (
+            "visible steer indicator must use original text or a file-only display label, not attachment tool instructions"
+        )
+        assert "_showSteerIndicator(steerText)" not in try_body
+
+    def test_file_steer_indicator_omits_attachment_tool_note(self):
+        import json
+        import shutil
+        import subprocess
+        import textwrap
+
+        node = shutil.which("node")
+        if not node:  # pragma: no cover
+            pytest.skip("node not available")
+        assert node is not None
+
+        steer_src = _source_between(
+            self.cmds,
+            "function _steerUploadedAttachmentPaths",
+            "\nasync function cmdTitle",
+        )
+        script = textwrap.dedent(
+            f"""
+            const assert = require('assert');
+            let S = {{session:{{session_id:'A'}}, pendingFiles:[{{name:'a.pdf'}}]}};
+            let apiPayload = null;
+            let indicatorText = null;
+            function t(k){{return k;}}
+            function $(id){{return {{value:'', classList:{{add(){{}}, remove(){{}}}}, style:{{}}}};}}
+            function setComposerStatus(){{}}
+            function showToast(){{}}
+            function renderTray(){{}}
+            function _showSteerIndicator(text){{indicatorText = text;}}
+            function _showSteerRecovery(){{}}
+            function _clearComposerDraft(){{}}
+            async function uploadPendingFiles(){{return [{{path:'/tmp/a.pdf'}}];}}
+            async function api(url, options){{
+              assert.strictEqual(url, '/api/chat/steer');
+              apiPayload = JSON.parse(options.body);
+              return {{accepted:true}};
+            }}
+            eval({json.dumps(steer_src)});
+            (async()=>{{
+              const delivered = await _trySteer('hint', false);
+              assert.strictEqual(delivered, true);
+              assert.strictEqual(indicatorText, 'hint');
+              assert.ok(apiPayload.text.includes('[Attached files for this steer: /tmp/a.pdf]'));
+              assert.ok(!indicatorText.includes('Attached files'));
+              assert.ok(!indicatorText.includes('file tools/read_file'));
+            }})().catch(err=>{{console.error(err); process.exit(1);}});
+            """
+        )
+        subprocess.run([node, "-e", script], check=True, capture_output=True, text=True)
+
+    def test_attachment_only_steer_indicator_uses_file_label(self):
+        import json
+        import shutil
+        import subprocess
+        import textwrap
+
+        node = shutil.which("node")
+        if not node:  # pragma: no cover
+            pytest.skip("node not available")
+        assert node is not None
+
+        steer_src = _source_between(
+            self.cmds,
+            "function _steerUploadedAttachmentPaths",
+            "\nasync function cmdTitle",
+        )
+        script = textwrap.dedent(
+            f"""
+            const assert = require('assert');
+            let S = {{session:{{session_id:'A'}}, pendingFiles:[{{name:'a.pdf'}}]}};
+            let apiPayload = null;
+            let indicatorText = null;
+            function t(k){{return k;}}
+            function $(id){{return {{value:'', classList:{{add(){{}}, remove(){{}}}}, style:{{}}}};}}
+            function setComposerStatus(){{}}
+            function showToast(){{}}
+            function renderTray(){{}}
+            function _showSteerIndicator(text){{indicatorText = text;}}
+            function _showSteerRecovery(){{}}
+            function _clearComposerDraft(){{}}
+            async function uploadPendingFiles(){{return [{{path:'/tmp/a.pdf'}}];}}
+            async function api(url, options){{
+              assert.strictEqual(url, '/api/chat/steer');
+              apiPayload = JSON.parse(options.body);
+              return {{accepted:true}};
+            }}
+            eval({json.dumps(steer_src)});
+            (async()=>{{
+              const delivered = await _trySteer('', false);
+              assert.strictEqual(delivered, true);
+              assert.strictEqual(indicatorText, 'Attached files: a.pdf');
+              assert.ok(apiPayload.text.includes('[Attached files for this steer: /tmp/a.pdf]'));
+              assert.ok(!indicatorText.includes('file tools/read_file'));
+            }})().catch(err=>{{console.error(err); process.exit(1);}});
+            """
+        )
+        subprocess.run([node, "-e", script], check=True, capture_output=True, text=True)
+
     def test_file_steer_targets_captured_session_when_user_switches_mid_upload(self):
         import json
         import shutil
@@ -411,6 +518,94 @@ class TestFrontendWiring:
         assert "if(clearPending&&_uploadPendingFilesCurrentSession(sessionId)){S.pendingFiles=[];renderTray();}" in ui
         assert "else if(typeof renderTray==='function'&&_uploadPendingFilesCurrentSession(sessionId))renderTray();" in ui
 
+    def test_upload_pending_files_progress_bar_is_session_scoped(self):
+        ui = (Path(__file__).parent.parent / "static" / "ui.js").read_text(encoding="utf-8")
+        progress_helper = _source_between(
+            ui,
+            "const _uploadPendingFilesProgressBySession",
+            "\nasync function uploadPendingFiles",
+        )
+        upload_body = ui[ui.index("async function uploadPendingFiles") :]
+        sessions = (Path(__file__).parent.parent / "static" / "sessions.js").read_text(encoding="utf-8")
+        load_body = _source_between(sessions, "async function loadSession", "\nfunction _isMessagingSession")
+        assert "_uploadPendingFilesSyncProgressForSession(sid)" in load_body
+        assert "_uploadPendingFilesProgressBySession.set(owner,{percent:clamped})" in progress_helper
+        assert "function _uploadPendingFilesSyncProgressForSession" in progress_helper
+        assert "if(!_uploadPendingFilesCurrentSession(sessionId)){" in progress_helper
+        assert "barWrap.dataset.uploadSessionId=owner" in progress_helper
+        assert "activeForOwner" in progress_helper
+        assert "barWrap.classList.remove('active')" in progress_helper
+        assert "_uploadPendingFilesUpdateProgress(sessionId,0)" in upload_body
+        assert "_uploadPendingFilesUpdateProgress(sessionId,Math.round((i+1)/total*100))" in upload_body
+        assert "_uploadPendingFilesUpdateProgress(sessionId,null)" in upload_body
+        assert "barWrap.classList.add('active');bar.style.width='0%';" not in upload_body
+        assert "barWrap.classList.remove('active');bar.style.width='0%';" not in upload_body
+
+    def test_upload_progress_bar_hides_on_switch_and_reappears_on_owner_return(self):
+        import json
+        import shutil
+        import subprocess
+        import textwrap
+
+        node = shutil.which("node")
+        if not node:  # pragma: no cover
+            pytest.skip("node not available")
+        assert node is not None
+
+        ui = (Path(__file__).parent.parent / "static" / "ui.js").read_text(encoding="utf-8")
+        progress_src = _source_between(
+            ui,
+            "const _uploadPendingFilesProgressBySession",
+            "\nasync function uploadPendingFiles",
+        )
+        script = textwrap.dedent(
+            f"""
+            const assert = require('assert');
+            let S = {{session:{{session_id:'A'}}}};
+            const bar = {{style:{{width:''}}}};
+            const barWrap = {{
+              dataset: {{}},
+              active: false,
+              classList: {{
+                add(cls){{ if(cls === 'active') barWrap.active = true; }},
+                remove(cls){{ if(cls === 'active') barWrap.active = false; }},
+              }},
+            }};
+            function $(id){{
+              if(id === 'uploadBar') return bar;
+              if(id === 'uploadBarWrap') return barWrap;
+              return null;
+            }}
+            eval({json.dumps(progress_src)});
+            _uploadPendingFilesUpdateProgress('A', 0);
+            assert.strictEqual(barWrap.active, true);
+            assert.strictEqual(bar.style.width, '0%');
+            assert.strictEqual(barWrap.dataset.uploadSessionId, 'A');
+
+            S.session = {{session_id:'B'}};
+            _uploadPendingFilesSyncProgressForSession('B');
+            assert.strictEqual(barWrap.active, false);
+            assert.strictEqual(bar.style.width, '0%');
+            assert.strictEqual(barWrap.dataset.uploadSessionId, undefined);
+
+            _uploadPendingFilesUpdateProgress('A', 50);
+            assert.strictEqual(barWrap.active, false);
+            assert.strictEqual(bar.style.width, '0%');
+
+            S.session = {{session_id:'A'}};
+            _uploadPendingFilesSyncProgressForSession('A');
+            assert.strictEqual(barWrap.active, true);
+            assert.strictEqual(bar.style.width, '50%');
+            assert.strictEqual(barWrap.dataset.uploadSessionId, 'A');
+
+            _uploadPendingFilesUpdateProgress('A', null);
+            assert.strictEqual(barWrap.active, false);
+            assert.strictEqual(bar.style.width, '0%');
+            assert.strictEqual(barWrap.dataset.uploadSessionId, undefined);
+            """
+        )
+        subprocess.run([node, "-e", script], check=True, capture_output=True, text=True)
+
     def test_pending_steer_leftover_listener(self):
         """Frontend must listen for pending_steer_leftover SSE events and queue them."""
         idx = self.msgs.find("addEventListener('pending_steer_leftover'")