Wrap canvas tab bar and make Start-session button icon-only

src/Client/CanvasPane.fs

@@ -51,6 +51,18 @@ let private shareIcon =
         ]
     ]
 
+/// The Start-session glyph (a filled play triangle), styled like `shareIcon` (`btn-icon`, 24×24,
+/// `currentColor`) so the icon-only launch button matches the Share and Archive buttons.
+let private playIcon =
+    Svg.svg [
+        svg.className "btn-icon"
+        svg.viewBox (0, 0, 24, 24)
+        svg.fill "currentColor"
+        svg.children [
+            Svg.path [ svg.d "M8 5v14l11-7z" ]
+        ]
+    ]
+
 /// Render the liveness dot only for AgentDocs. A SystemView (e.g. the beads dashboard) is
 /// server-generated and has no owner session, so liveness is meaningless and the dot is omitted.
 let private livenessDotFor (bridgeLiveness: Map<string, BridgeLiveness>) (doc: CanvasDoc) =
@@ -296,7 +308,7 @@ let view (state: CanvasPaneState) (focusedDoc: (WorktreeStatus * CanvasDoc) opti
                                 prop.className "canvas-launch-btn"
                                 prop.onClick (fun _ -> launchSession ())
                                 prop.title "Start a session to work on the selected canvas doc"
-                                prop.text "▶ Start session"
+                                prop.children [ playIcon ]
                             ]
                         match activeDoc with
                         | Some d when d.Kind = AgentDoc ->

src/Client/index.html

@@ -591,7 +591,7 @@
         .canvas-tab-bar {
             display: flex;
             justify-content: space-between;
-            align-items: center;
+            align-items: flex-start;
             padding: 4px 8px;
             background: #181825;
             border-bottom: 1px solid #313244;
@@ -600,7 +600,7 @@
         .canvas-tab-group {
             display: flex;
             gap: 2px;
-            overflow-x: auto;
+            flex-wrap: wrap;
             flex: 1;
             min-width: 0;
         }
@@ -640,10 +640,11 @@
             flex-shrink: 0;
             background: none; border: 1px solid #45475a; border-radius: 4px;
             color: #a6adc8; cursor: pointer;
-            padding: 2px 8px; font-size: 0.75em; font-family: inherit;
+            padding: 2px 6px; display: flex; align-items: center;
             transition: color 0.15s, border-color 0.15s, opacity 0.15s;
             opacity: 0.6;
         }
+        .canvas-launch-btn .btn-icon { width: 14px; height: 14px; }
         .canvas-launch-btn:hover { color: #a6e3a1; border-color: #a6e3a1; opacity: 1; }
         .canvas-pos-btn, .canvas-size-btn {
             background: #313244; border: 1px solid #45475a; border-radius: 4px;

src/Tests/CanvasPhase4Tests.fs

@@ -180,8 +180,8 @@ type CanvasPhase4Tests() =
             let! count = launchBtn.CountAsync()
             Assert.That(count, Is.EqualTo(1), "Start session button should be visible when no bridge is alive")
 
-            let! text = launchBtn.TextContentAsync()
-            Assert.That(text, Does.Contain("Start session"), "Button should say 'Start session'")
+            let! title = launchBtn.GetAttributeAsync("title")
+            Assert.That(title, Does.Contain("Start a session"), "Button tooltip should describe starting a session")
         }
 
     [<Test>]