diff --git a/src/main/services/team/TeamConfigReader.ts b/src/main/services/team/TeamConfigReader.ts
index 3f6a830c..d1de9a24 100644
--- a/src/main/services/team/TeamConfigReader.ts
+++ b/src/main/services/team/TeamConfigReader.ts
@@ -8,6 +8,7 @@ import { getTeamFsWorkerClient } from './TeamFsWorkerClient';
 import { TeamMembersMetaStore } from './TeamMembersMetaStore';
 
 import type { TeamConfig, TeamMember, TeamSummary, TeamSummaryMember } from '@shared/types';
+import { createCliAutoSuffixNameGuard } from '@shared/utils/teamMemberName';
 
 const logger = createLogger('Service:TeamConfigReader');
 
@@ -244,6 +245,15 @@ export class TeamConfigReader {
         }
       }
 
+      // Defense: drop CLI auto-suffixed duplicates (alice-2) when base name exists.
+      const allNames = Array.from(memberMap.values()).map((m) => m.name);
+      const keepName = createCliAutoSuffixNameGuard(allNames);
+      for (const [key, member] of Array.from(memberMap.entries())) {
+        if (!keepName(member.name)) {
+          memberMap.delete(key);
+        }
+      }
+
       const members = Array.from(memberMap.values());
       const summary: TeamSummary = {
         teamName,
diff --git a/src/main/services/team/TeamMemberResolver.ts b/src/main/services/team/TeamMemberResolver.ts
index 313f3349..d2e5a42d 100644
--- a/src/main/services/team/TeamMemberResolver.ts
+++ b/src/main/services/team/TeamMemberResolver.ts
@@ -6,6 +6,8 @@ import type {
   TeamTaskWithKanban,
 } from '@shared/types';
 
+import { createCliAutoSuffixNameGuard } from '@shared/utils/teamMemberName';
+
 export class TeamMemberResolver {
   resolveMembers(
     config: TeamConfig,
@@ -78,6 +80,14 @@ export class TeamMemberResolver {
     // (recipient of SendMessage to "user"). It's not a real AI teammate.
     names.delete('user');
 
+    // Defense: hide CLI auto-suffixed duplicates (alice-2) when base name (alice) exists.
+    const keepName = createCliAutoSuffixNameGuard(names);
+    for (const name of Array.from(names)) {
+      if (!keepName(name)) {
+        names.delete(name);
+      }
+    }
+
     const members: ResolvedTeamMember[] = [];
     for (const name of names) {
       const ownedTasks = tasks.filter((task) => task.owner === name);
diff --git a/src/main/services/team/TeamMembersMetaStore.ts b/src/main/services/team/TeamMembersMetaStore.ts
index 66ff8f43..1fb221ff 100644
--- a/src/main/services/team/TeamMembersMetaStore.ts
+++ b/src/main/services/team/TeamMembersMetaStore.ts
@@ -7,6 +7,8 @@ import { atomicWriteAsync } from './atomicWrite';
 
 import type { TeamMember } from '@shared/types';
 
+import { createCliAutoSuffixNameGuard } from '@shared/utils/teamMemberName';
+
 interface TeamMembersMetaFile {
   version: 1;
   members: TeamMember[];
@@ -90,6 +92,15 @@ export class TeamMembersMetaStore {
       deduped.set(normalized.name, normalized);
     }
 
+    // Defense: drop CLI auto-suffixed duplicates (alice-2) when base name exists.
+    const allNames = Array.from(deduped.keys());
+    const keepName = createCliAutoSuffixNameGuard(allNames);
+    for (const name of allNames) {
+      if (!keepName(name)) {
+        deduped.delete(name);
+      }
+    }
+
     return Array.from(deduped.values()).sort((a, b) => a.name.localeCompare(b.name));
   }
 
@@ -103,6 +114,15 @@ export class TeamMembersMetaStore {
       deduped.set(normalized.name, normalized);
     }
 
+    // Defense: drop CLI auto-suffixed duplicates (alice-2) when base name exists.
+    const allNames = Array.from(deduped.keys());
+    const keepName = createCliAutoSuffixNameGuard(allNames);
+    for (const name of allNames) {
+      if (!keepName(name)) {
+        deduped.delete(name);
+      }
+    }
+
     const payload: TeamMembersMetaFile = {
       version: 1,
       members: Array.from(deduped.values()).sort((a, b) => a.name.localeCompare(b.name)),
diff --git a/src/renderer/components/layout/SortableTab.tsx b/src/renderer/components/layout/SortableTab.tsx
index 84dd9f36..bf366be6 100644
--- a/src/renderer/components/layout/SortableTab.tsx
+++ b/src/renderer/components/layout/SortableTab.tsx
@@ -125,11 +125,7 @@ export const SortableTab = ({
       role="tab"
       tabIndex={0}
       aria-selected={isActive}
-      className={
-        isTeamTab
-          ? 'group flex min-w-0 max-w-[200px] shrink-0 cursor-grab flex-col rounded-md'
-          : 'group flex min-w-0 max-w-[200px] shrink-0 cursor-grab items-center gap-2 rounded-md px-3 py-1.5'
-      }
+      className="group flex min-w-0 max-w-[200px] shrink-0 cursor-grab items-center gap-2 rounded-md px-3 py-1.5"
       style={style}
       onClick={(e) => onTabClick(tab.id, e)}
       onMouseDown={(e) => onMouseDown(tab.id, e)}
@@ -143,32 +139,18 @@ export const SortableTab = ({
         }
       }}
     >
-      <div className={isTeamTab ? 'flex min-w-0 items-center gap-2 px-3 pb-0.5 pt-1' : 'contents'}>
-        <Icon className="size-4 shrink-0" />
-        {tab.fromSearch && (
-          <span title="Opened from search">
-            <Search className="size-3 shrink-0 text-amber-400" />
-          </span>
-        )}
-        {isPinned && (
-          <span title="Pinned session">
-            <Pin className="size-3 shrink-0 text-blue-400" />
-          </span>
-        )}
-        <span className="truncate text-sm">{tab.label}</span>
-        <button
-          className="flex size-4 shrink-0 items-center justify-center rounded-sm opacity-0 transition-opacity group-hover:opacity-100"
-          style={{ backgroundColor: 'transparent' }}
-          onClick={(e) => {
-            e.stopPropagation();
-            onClose(tab.id);
-          }}
-          onPointerDown={(e) => e.stopPropagation()}
-          title="Close tab"
-        >
-          <X className="size-3" />
-        </button>
-      </div>
+      <Icon className="size-4 shrink-0" />
+      {tab.fromSearch && (
+        <span title="Opened from search">
+          <Search className="size-3 shrink-0 text-amber-400" />
+        </span>
+      )}
+      {isPinned && (
+        <span title="Pinned session">
+          <Pin className="size-3 shrink-0 text-blue-400" />
+        </span>
+      )}
+      <span className="truncate text-sm">{tab.label}</span>
       {isTeamTab && (
         <TeamTabSectionNav
           teamName={tab.teamName!}
@@ -182,6 +164,18 @@ export const SortableTab = ({
           }}
         />
       )}
+      <button
+        className="flex size-4 shrink-0 items-center justify-center rounded-sm opacity-0 transition-opacity group-hover:opacity-100"
+        style={{ backgroundColor: 'transparent' }}
+        onClick={(e) => {
+          e.stopPropagation();
+          onClose(tab.id);
+        }}
+        onPointerDown={(e) => e.stopPropagation()}
+        title="Close tab"
+      >
+        <X className="size-3" />
+      </button>
     </div>
   );
 };
diff --git a/src/renderer/components/layout/TabBar.tsx b/src/renderer/components/layout/TabBar.tsx
index 4efd68ef..74b5f215 100644
--- a/src/renderer/components/layout/TabBar.tsx
+++ b/src/renderer/components/layout/TabBar.tsx
@@ -309,7 +309,7 @@ export const TabBar = ({ paneId }: TabBarProps): React.JSX.Element => {
             outline: isDroppableOver ? '1px dashed var(--color-accent, #6366f1)' : 'none',
             outlineOffset: '-1px',
             overflowX: 'auto',
-            overflowY: 'clip',
+            overflowY: 'hidden',
           } as React.CSSProperties
         }
       >
diff --git a/src/renderer/components/layout/TeamTabSectionNav.tsx b/src/renderer/components/layout/TeamTabSectionNav.tsx
index 913fe1ce..c43125ff 100644
--- a/src/renderer/components/layout/TeamTabSectionNav.tsx
+++ b/src/renderer/components/layout/TeamTabSectionNav.tsx
@@ -71,11 +71,11 @@ export const TeamTabSectionNav = ({
   }, [open]);
 
   return (
-    <div className="w-full" onPointerDown={(e) => e.stopPropagation()}>
+    <div className="shrink-0" onPointerDown={(e) => e.stopPropagation()}>
       <button
         ref={buttonRef}
         type="button"
-        className="flex h-3.5 w-full items-center justify-center text-[var(--color-text-muted)] transition-colors hover:text-[var(--color-text-secondary)]"
+        className="flex size-4 items-center justify-center rounded-sm text-[var(--color-text-muted)] transition-colors hover:text-[var(--color-text-secondary)]"
         onClick={(e) => {
           e.stopPropagation();
           setOpen((prev) => !prev);
diff --git a/src/renderer/components/team/activity/ActivityItem.tsx b/src/renderer/components/team/activity/ActivityItem.tsx
index fe1e9eeb..0b472ef5 100644
--- a/src/renderer/components/team/activity/ActivityItem.tsx
+++ b/src/renderer/components/team/activity/ActivityItem.tsx
@@ -284,6 +284,7 @@ export const ActivityItem = ({
 
   const isHeaderClickable = Boolean(systemLabel);
   const isUserSent = message.source === 'user_sent';
+  const isSystemMessage = message.from === 'system';
 
   return (
     <article
@@ -293,17 +294,23 @@ export const ActivityItem = ({
         backgroundColor:
           rateLimited || isApiError
             ? 'var(--tool-result-error-bg)'
-            : zebraShade
-              ? CARD_BG_ZEBRA
-              : CARD_BG,
+            : isSystemMessage
+              ? 'var(--system-activity-bg)'
+              : zebraShade
+                ? CARD_BG_ZEBRA
+                : CARD_BG,
         border:
           rateLimited || isApiError
             ? '1px solid var(--tool-result-error-border)'
-            : CARD_BORDER_STYLE,
+            : isSystemMessage
+              ? '1px solid var(--system-activity-border)'
+              : CARD_BORDER_STYLE,
         borderLeft:
           rateLimited || isApiError
             ? '3px solid var(--tool-result-error-text)'
-            : `3px solid ${colors.border}`,
+            : isSystemMessage
+              ? '3px solid var(--system-activity-accent)'
+              : `3px solid ${colors.border}`,
       }}
     >
       {/* Header — div with role=button (cannot use <button> due to nested buttons inside) */}
@@ -345,7 +352,7 @@ export const ActivityItem = ({
         <MemberBadge
           name={message.from}
           color={memberColor ?? message.color}
-          hideAvatar={message.from === 'user'}
+          hideAvatar={message.from === 'user' || message.from === 'system'}
           onClick={onMemberNameClick}
         />
 
diff --git a/src/renderer/index.css b/src/renderer/index.css
index 1e18c1ca..563130fa 100644
--- a/src/renderer/index.css
+++ b/src/renderer/index.css
@@ -182,6 +182,11 @@
   --card-text-lighter: #e2e8f0;
   --card-separator: #2a2c38;
 
+  /* System activity messages */
+  --system-activity-bg: rgba(59, 130, 246, 0.06);
+  --system-activity-border: rgba(59, 130, 246, 0.12);
+  --system-activity-accent: rgba(96, 165, 250, 0.5);
+
   /* Assessment severity colors (badges, health indicators) */
   --assess-good: #4ade80;
   --assess-warning: #fbbf24;
@@ -404,6 +409,11 @@
   --card-text-lighter: #2a2925;
   --card-separator: #d5d3cf;
 
+  /* System activity messages */
+  --system-activity-bg: rgba(59, 130, 246, 0.06);
+  --system-activity-border: rgba(59, 130, 246, 0.15);
+  --system-activity-accent: rgba(37, 99, 235, 0.5);
+
   /* Sticky Context button - transparent glass */
   --context-btn-bg: rgba(0, 0, 0, 0.06);
   --context-btn-bg-hover: rgba(0, 0, 0, 0.1);
diff --git a/src/shared/utils/teamMemberName.ts b/src/shared/utils/teamMemberName.ts
new file mode 100644
index 00000000..9252d6eb
--- /dev/null
+++ b/src/shared/utils/teamMemberName.ts
@@ -0,0 +1,41 @@
+export function parseNumericSuffixName(
+  name: string
+): { base: string; suffix: number } | null {
+  const trimmed = name.trim();
+  if (!trimmed) return null;
+  const match = trimmed.match(/^(.+)-(\d+)$/);
+  if (!match?.[1] || !match[2]) return null;
+  const suffix = Number(match[2]);
+  if (!Number.isFinite(suffix)) return null;
+  return { base: match[1], suffix };
+}
+
+/**
+ * Claude CLI auto-suffixes teammate names when a name already exists in config.json
+ * (e.g. "alice" → "alice-2"). We treat "-2+" as an auto-suffix only when the base
+ * name also exists among the current set of names.
+ *
+ * Important: do NOT treat "-1" as auto-suffix; it's commonly intentional ("dev-1").
+ */
+export function createCliAutoSuffixNameGuard(allNames: Iterable<string>): (name: string) => boolean {
+  const trimmed: string[] = [];
+  const seen = new Set<string>();
+  for (const n of allNames) {
+    if (typeof n !== 'string') continue;
+    const t = n.trim();
+    if (!t) continue;
+    if (seen.has(t)) continue;
+    seen.add(t);
+    trimmed.push(t);
+  }
+
+  const allLower = new Set(trimmed.map((n) => n.toLowerCase()));
+
+  return (name: string): boolean => {
+    const info = parseNumericSuffixName(name);
+    if (!info) return true;
+    if (info.suffix < 2) return true;
+    return !allLower.has(info.base.toLowerCase());
+  };
+}
+