diff --git a/CLI/cmux.swift b/CLI/cmux.swift
index 0f9246cf7bbf..c4877c71addb 100644
--- a/CLI/cmux.swift
+++ b/CLI/cmux.swift
@@ -1945,6 +1945,37 @@ struct CMUXCLI {
             let payload = try client.sendV2(method: "workspace.rename", params: params)
             printV2Payload(payload, jsonOutput: jsonOutput, idFormat: idFormat, fallbackText: v2OKSummary(payload, idFormat: idFormat, kinds: ["workspace"]))
 
+        case "set-workspace-color":
+            let (wsArg, rem0) = parseOption(commandArgs, name: "--workspace")
+            let workspaceArg = wsArg ?? (windowId == nil ? ProcessInfo.processInfo.environment["CMUX_WORKSPACE_ID"] : nil)
+            let trailing = Array(rem0.dropFirst(rem0.first == "--" ? 1 : 0))
+            guard trailing.count == 1 else {
+                throw CLIError(message: trailing.isEmpty
+                    ? "set-workspace-color requires a hex color (e.g. \"#C0392B\")"
+                    : "set-workspace-color: unexpected arguments: \(trailing.dropFirst().joined(separator: " "))")
+            }
+            let color = trailing[0].trimmingCharacters(in: .whitespacesAndNewlines)
+            let body = color.hasPrefix("#") ? String(color.dropFirst()) : color
+            guard body.count == 6, UInt64(body, radix: 16) != nil else {
+                throw CLIError(message: "set-workspace-color: invalid hex color \"\(color)\" (expected #RRGGBB)")
+            }
+            let wsId = try resolveWorkspaceId(workspaceArg, client: client)
+            let params: [String: Any] = ["workspace_id": wsId, "color": color]
+            let payload = try client.sendV2(method: "workspace.set_color", params: params)
+            printV2Payload(payload, jsonOutput: jsonOutput, idFormat: idFormat, fallbackText: v2OKSummary(payload, idFormat: idFormat, kinds: ["workspace"]))
+
+        case "clear-workspace-color":
+            let (wsArg, rem0) = parseOption(commandArgs, name: "--workspace")
+            let workspaceArg = wsArg ?? (windowId == nil ? ProcessInfo.processInfo.environment["CMUX_WORKSPACE_ID"] : nil)
+            let trailing = rem0.filter { $0 != "--" }
+            guard trailing.isEmpty else {
+                throw CLIError(message: "clear-workspace-color: unexpected arguments: \(trailing.joined(separator: " "))")
+            }
+            let wsId = try resolveWorkspaceId(workspaceArg, client: client)
+            let params: [String: Any] = ["workspace_id": wsId]
+            let payload = try client.sendV2(method: "workspace.clear_color", params: params)
+            printV2Payload(payload, jsonOutput: jsonOutput, idFormat: idFormat, fallbackText: v2OKSummary(payload, idFormat: idFormat, kinds: ["workspace"]))
+
         case "current-workspace":
             let response = try sendV1Command("current_workspace", client: client)
             if jsonOutput {
@@ -6545,6 +6576,32 @@ struct CMUXCLI {
               cmux rename-workspace "backend logs"
               cmux rename-window --workspace workspace:2 "agent run"
             """
+        case "set-workspace-color":
+            return """
+            Usage: cmux set-workspace-color [--workspace <id|ref|index>] <hex>
+
+            Set the tab color for a workspace. Defaults to the current workspace.
+
+            Flags:
+              --workspace <id|ref|index>   Workspace to color (default: current/$CMUX_WORKSPACE_ID)
+
+            Example:
+              cmux set-workspace-color "#C0392B"
+              cmux set-workspace-color --workspace workspace:2 "#2D1B69"
+            """
+        case "clear-workspace-color":
+            return """
+            Usage: cmux clear-workspace-color [--workspace <id|ref|index>]
+
+            Remove the custom tab color from a workspace.
+
+            Flags:
+              --workspace <id|ref|index>   Workspace to clear color from (default: current/$CMUX_WORKSPACE_ID)
+
+            Example:
+              cmux clear-workspace-color
+              cmux clear-workspace-color --workspace workspace:2
+            """
         case "current-workspace":
             return """
             Usage: cmux current-workspace
@@ -11159,6 +11216,8 @@ struct CMUXCLI {
           select-workspace --workspace <id|ref>
           rename-workspace [--workspace <id|ref>] <title>
           rename-window [--workspace <id|ref>] <title>
+          set-workspace-color [--workspace <id|ref|index>] <hex>
+          clear-workspace-color [--workspace <id|ref|index>]
           current-workspace
           read-screen [--workspace <id|ref>] [--surface <id|ref>] [--scrollback] [--lines <n>]
           send [--workspace <id|ref>] [--surface <id|ref>] <text>
diff --git a/Sources/TerminalController.swift b/Sources/TerminalController.swift
index 063358504754..6bc1d4d7f24b 100644
--- a/Sources/TerminalController.swift
+++ b/Sources/TerminalController.swift
@@ -2065,6 +2065,10 @@ class TerminalController {
             return v2Result(id: id, self.v2WorkspaceReorder(params: params))
         case "workspace.rename":
             return v2Result(id: id, self.v2WorkspaceRename(params: params))
+        case "workspace.set_color":
+            return v2Result(id: id, self.v2WorkspaceSetColor(params: params))
+        case "workspace.clear_color":
+            return v2Result(id: id, self.v2WorkspaceClearColor(params: params))
         case "workspace.action":
             return v2Result(id: id, self.v2WorkspaceAction(params: params))
         case "workspace.next":
@@ -2441,6 +2445,8 @@ class TerminalController {
             "workspace.move_to_window",
             "workspace.reorder",
             "workspace.rename",
+            "workspace.set_color",
+            "workspace.clear_color",
             "workspace.action",
             "workspace.next",
             "workspace.previous",
@@ -3598,6 +3604,77 @@ class TerminalController {
             "title": title
         ])
     }
+    private func v2WorkspaceSetColor(params: [String: Any]) -> V2CallResult {
+        guard let tabManager = v2ResolveTabManager(params: params) else {
+            return .err(code: "unavailable", message: "TabManager not available", data: nil)
+        }
+        guard let workspaceId = v2UUID(params, "workspace_id") else {
+            return .err(code: "invalid_params", message: "Missing or invalid workspace_id", data: nil)
+        }
+        guard let colorRaw = v2String(params, "color"),
+              !colorRaw.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty else {
+            return .err(code: "invalid_params", message: "Missing or invalid color", data: nil)
+        }
+
+        let trimmed = colorRaw.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard let color = WorkspaceTabColorSettings.normalizedHex(trimmed) else {
+            return .err(code: "invalid_params", message: "Invalid hex color \"\(trimmed)\" (expected #RRGGBB)", data: nil)
+        }
+        var applied = false
+        v2MainSync {
+            guard tabManager.tabs.contains(where: { $0.id == workspaceId }) else { return }
+            tabManager.setTabColor(tabId: workspaceId, color: color)
+            applied = true
+        }
+
+        guard applied else {
+            return .err(code: "not_found", message: "Workspace not found", data: [
+                "workspace_id": workspaceId.uuidString,
+                "workspace_ref": v2Ref(kind: .workspace, uuid: workspaceId)
+            ])
+        }
+
+        let windowId = v2ResolveWindowId(tabManager: tabManager)
+        return .ok([
+            "workspace_id": workspaceId.uuidString,
+            "workspace_ref": v2Ref(kind: .workspace, uuid: workspaceId),
+            "window_id": v2OrNull(windowId?.uuidString),
+            "window_ref": v2Ref(kind: .window, uuid: windowId),
+            "color": color
+        ])
+    }
+
+    private func v2WorkspaceClearColor(params: [String: Any]) -> V2CallResult {
+        guard let tabManager = v2ResolveTabManager(params: params) else {
+            return .err(code: "unavailable", message: "TabManager not available", data: nil)
+        }
+        guard let workspaceId = v2UUID(params, "workspace_id") else {
+            return .err(code: "invalid_params", message: "Missing or invalid workspace_id", data: nil)
+        }
+
+        var cleared = false
+        v2MainSync {
+            guard tabManager.tabs.contains(where: { $0.id == workspaceId }) else { return }
+            tabManager.setTabColor(tabId: workspaceId, color: nil)
+            cleared = true
+        }
+
+        guard cleared else {
+            return .err(code: "not_found", message: "Workspace not found", data: [
+                "workspace_id": workspaceId.uuidString,
+                "workspace_ref": v2Ref(kind: .workspace, uuid: workspaceId)
+            ])
+        }
+
+        let windowId = v2ResolveWindowId(tabManager: tabManager)
+        return .ok([
+            "workspace_id": workspaceId.uuidString,
+            "workspace_ref": v2Ref(kind: .workspace, uuid: workspaceId),
+            "window_id": v2OrNull(windowId?.uuidString),
+            "window_ref": v2Ref(kind: .window, uuid: windowId),
+        ])
+    }
+
     private func v2WorkspaceNext(params: [String: Any]) -> V2CallResult {
         guard let tabManager = v2ResolveTabManager(params: params) else {
             return .err(code: "unavailable", message: "TabManager not available", data: nil)