diff --git a/packages/chat-ui/src/timeline.tsx b/packages/chat-ui/src/timeline.tsx
index a1761f062..e5dc43866 100644
--- a/packages/chat-ui/src/timeline.tsx
+++ b/packages/chat-ui/src/timeline.tsx
@@ -507,11 +507,7 @@ function TextBubble({
           />
         </button>
       )}
-      <div
-        className="chat-bubble"
-        data-own={isOwn}
-        data-pending={pendingStatus}
-      >
+      <div className="chat-bubble" data-pending={pendingStatus}>
         {showHeader ? (
           <div className="chat-bubble-head">
             {display !== undefined && (
@@ -1045,7 +1041,7 @@ function StreamingMessageGroup({
             isAgent={display.isAgent}
           />
         )}
-        <div className="chat-bubble" data-own="false">
+        <div className="chat-bubble">
           {display !== undefined && (
             <div className="chat-bubble-head">
               <span className="chat-bubble-sender">
diff --git a/packages/chat-ui/test/chat-bubble-flat.test.ts b/packages/chat-ui/test/chat-bubble-flat.test.ts
new file mode 100644
index 000000000..31fddce5a
--- /dev/null
+++ b/packages/chat-ui/test/chat-bubble-flat.test.ts
@@ -0,0 +1,42 @@
+// happy-dom does not apply stylesheets, so paint/chrome for `.chat-bubble`
+// is locked against CSS source (CL-6466: leftover bubble class, no chrome).
+import { describe, expect, test } from "bun:test";
+import { readFileSync } from "node:fs";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const css = readFileSync(
+  join(dirname(fileURLToPath(import.meta.url)), "../src/styles.css"),
+  "utf8",
+);
+
+function ruleBodies(selector: string): string[] {
+  const escaped = selector.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+  return [
+    ...css.matchAll(
+      new RegExp(`(?:^|\\n)\\s*${escaped}\\s*\\{([^}]+)\\}`, "g"),
+    ),
+  ].map((match) => match[1] ?? "");
+}
+
+describe("chat-bubble is visually flat", () => {
+  test(".chat-bubble has no border, fill, padding, or radius", () => {
+    const bodies = ruleBodies(".chat-bubble");
+    expect(bodies.length).toBeGreaterThan(0);
+    const body = bodies[0] ?? "";
+    expect(body).toMatch(/border:\s*0/);
+    expect(body).toMatch(/background:\s*transparent/);
+    expect(body).toMatch(/padding:\s*0/);
+    expect(body).toMatch(/border-radius:\s*0/);
+  });
+
+  test('.chat-bubble[data-own="true"] does not paint chrome', () => {
+    for (const body of ruleBodies('.chat-bubble[data-own="true"]')) {
+      expect(body).not.toMatch(/background\s*:/);
+      expect(body).not.toMatch(/border\s*:/);
+      expect(body).not.toMatch(/padding\s*:/);
+      expect(body).not.toMatch(/border-radius\s*:/);
+      expect(body).not.toMatch(/box-shadow\s*:/);
+    }
+  });
+});
diff --git a/packages/chat-ui/test/own-message-alignment.test.tsx b/packages/chat-ui/test/own-message-alignment.test.tsx
index d1ca6eec4..568400be0 100644
--- a/packages/chat-ui/test/own-message-alignment.test.tsx
+++ b/packages/chat-ui/test/own-message-alignment.test.tsx
@@ -61,7 +61,7 @@ describe("own-message alignment is per viewer, not per message", () => {
     const bubble = el.querySelector(".chat-bubble");
     expect(group?.getAttribute("data-own")).toBe("true");
     expect(row?.getAttribute("data-own")).toBe("true");
-    expect(bubble?.getAttribute("data-own")).toBe("true");
+    expect(bubble?.hasAttribute("data-own")).toBe(false);
   });
 
   test("the same message viewed by a different user renders left-aligned", async () => {
@@ -73,7 +73,7 @@ describe("own-message alignment is per viewer, not per message", () => {
     const bubble = el.querySelector(".chat-bubble");
     expect(group?.getAttribute("data-own")).toBe("false");
     expect(row?.getAttribute("data-own")).toBe("false");
-    expect(bubble?.getAttribute("data-own")).toBe("false");
+    expect(bubble?.hasAttribute("data-own")).toBe(false);
   });
 
   test("a system event line never gets own-message alignment, even when the current user caused it", async () => {
@@ -134,4 +134,48 @@ describe("own-message alignment is per viewer, not per message", () => {
       el.querySelector(".chat-message-group")?.getAttribute("data-own"),
     ).toBe("false");
   });
+
+  test("own-authored text plus tool activity plus a gen-UI block keeps tools and the block outside the bubble", async () => {
+    const items: MessageItem[] = [
+      {
+        id: "m1",
+        createdAt: "2026-01-01T00:00:00.000Z",
+        sender: { name: "Sawyer", address: "sawyer@agents.example" },
+        parts: [
+          { kind: "text", text: "ship it" },
+          {
+            kind: "tool-trace",
+            name: "search",
+            input: { q: "x" },
+            status: "success",
+          },
+          {
+            kind: "block",
+            block: {
+              type: "steps",
+              data: {
+                title: "Migration",
+                steps: [{ label: "Snapshot", state: "done" }],
+              },
+            },
+          },
+        ],
+      },
+    ];
+    const el = await mount(items, { principalId: "sawyer" });
+    const group = el.querySelector(".chat-message-group");
+    const row = el.querySelector(".chat-bubble-row");
+    const bubble = el.querySelector(".chat-bubble");
+    const tool = el.querySelector(".chat-tool-activity");
+    const block = el.querySelector(".chat-block");
+    expect(group?.getAttribute("data-own")).toBe("true");
+    expect(row?.getAttribute("data-own")).toBe("true");
+    expect(bubble?.hasAttribute("data-own")).toBe(false);
+    expect(tool).not.toBeNull();
+    expect(block).not.toBeNull();
+    expect(bubble?.contains(tool)).toBe(false);
+    expect(bubble?.contains(block)).toBe(false);
+    expect(group?.contains(tool)).toBe(true);
+    expect(group?.contains(block)).toBe(true);
+  });
 });
diff --git a/packages/chat/test/migrations.test.ts b/packages/chat/test/migrations.test.ts
index b9b9bd985..b39807782 100644
--- a/packages/chat/test/migrations.test.ts
+++ b/packages/chat/test/migrations.test.ts
@@ -40,6 +40,10 @@ const migrationNames = [
   "0017_message_client_ids",
   "0018_rename_channel_to_workbench",
   "0019_workbench_messages",
+  "0020_workbench_launch_current_run",
+  "0021_workbench_launch_prior_runs",
+  "0022_agent_turns",
+  "0023_drop_workbench_host_arm",
 ];
 
 describeIfDb("applyChatMigrations", () => {
@@ -91,7 +95,7 @@ describeIfDb("applyChatMigrations", () => {
       const tables = await sql.unsafe(
         `SELECT table_name FROM information_schema.tables ` +
           `WHERE table_schema = 'chat' AND table_name IN ` +
-          `('workbench_settings', 'workbench_read_state', 'workbench_launch', 'workbench_tenancy', 'chat_bench_settings', 'workbench_threads', 'workbench_thread_messages', 'message_reactions', 'pinned_messages', 'finalized_turn_write_claim', 'workbench_messages')`,
+          `('workbench_settings', 'workbench_read_state', 'workbench_launch', 'workbench_tenancy', 'chat_bench_settings', 'workbench_threads', 'workbench_thread_messages', 'message_reactions', 'pinned_messages', 'finalized_turn_write_claim', 'workbench_messages', 'agent_turns')`,
       );
       expect(tables.map((row) => String(row["table_name"])).sort()).toEqual(
         [
@@ -106,6 +110,7 @@ describeIfDb("applyChatMigrations", () => {
           "pinned_messages",
           "finalized_turn_write_claim",
           "workbench_messages",
+          "agent_turns",
         ].sort(),
       );