feat(lanes): Antigravity lanes, release exited panes, fresh Codex starts

- antigravity: a third lane tool running Antigravity's `agy` CLI. `-i`
  carries the first prompt, `--continue` resumes; `agy` has no model,
  effort or permission flag, and `--dangerously-skip-permissions` is never
  emitted. No pipeline, no agents install, and no AI Router (native only,
  else EUNSUPPORTED). Add lane gains an Antigravity choice and the binary
  probe maps it to `agy`.
- UI: the lane card no longer renders a frame holding only a "Codex" chip,
  and the prompt box names the lane's CLI ("Ask Codex anything…"), via
  LANE_TOOL_LABEL.
- runs: a pane that exits is released on a 10 s server beat
  (healAllRunIds, DASHBOARD_RUN_HEAL_MS). Codex and Antigravity fire no
  hook, so their lanes stayed "running" until something re-read them.
- codex: Start no longer sends resumeLast — only "Resume last session"
  continues the previous thread.

server/__tests__/lane-agents.test.js

@@ -116,15 +116,17 @@ describe("installAgents", () => {
     assert.ok(fs.existsSync(path.join(cwd, ".claude", "agents")));
   });
 
-  it("installs nothing for a codex lane — no .claude/agents/, no AGENTS.md", async () => {
-    const cwd = makeRepoDir();
-    const lane = lanesLib.createLane({ title: "cx", cwd, kind: "managed", tool: "codex" });
+  for (const tool of ["codex", "antigravity"]) {
+    it(`installs nothing for a ${tool} lane — no .claude/agents/, no AGENTS.md`, async () => {
+      const cwd = makeRepoDir();
+      const lane = lanesLib.createLane({ title: "cx", cwd, kind: "managed", tool });
 
-    const result = await installAgents(lane);
-    assert.deepEqual(result.installed, []);
-    assert.equal(fs.existsSync(path.join(cwd, ".claude", "agents")), false);
-    assert.equal(fs.existsSync(path.join(cwd, "AGENTS.md")), false);
-  });
+      const result = await installAgents(lane);
+      assert.deepEqual(result.installed, []);
+      assert.equal(fs.existsSync(path.join(cwd, ".claude", "agents")), false);
+      assert.equal(fs.existsSync(path.join(cwd, "AGENTS.md")), false);
+    });
+  }
 });
 
 describe("codex pipeline cleanup", () => {

server/__tests__/lane-lifecycle.test.js

@@ -1302,4 +1302,20 @@ describe("lane ensure, start mode, lane_id and releasing a finished run", () =>
       restorePath();
     }
   });
+
+  it("healAllRunIds releases a lane whose pane exited, with no read to trigger it", async () => {
+    // A codex/antigravity pane fires no hook on exit, so nothing re-reads its
+    // lane; the server's periodic sweep is what has to notice.
+    const lanesLib = require("../lib/lanes");
+    const { healAllRunIds } = require("../routes/lanes");
+    const lane = await adoptedLane("heal-all-sweep");
+    // No tmux session by this name exists on the suite's private server.
+    lanesLib.updateLane(lane.id, { run_id: `agenthub-lane-${lane.id}`, status: "running" });
+
+    healAllRunIds();
+
+    const after = lanesLib.getLane(lane.id);
+    assert.equal(after.run_id, null);
+    assert.equal(after.status, "idle");
+  });
 });

server/__tests__/pty-run.test.js

@@ -398,6 +398,27 @@ describe("pty-run", () => {
     assert.ok(!call.some((a) => String(a).startsWith("--dangerously-bypass")));
   });
 
+  it("spawnRun runs `agy` for an antigravity lane, dropping flags it has no use for", () => {
+    const call = captureNewSession(() =>
+      pty.spawnRun({
+        laneId: 13,
+        cwd: "/tmp/repo",
+        tool: "antigravity",
+        model: "opus",
+        effort: "high",
+        permissionMode: "bypassPermissions",
+        initialPrompt: "hello",
+      })
+    );
+    assert.deepEqual(paneArgv(call), ["agy", "-i", "hello"]);
+
+    tmux.__reset();
+    const last = captureNewSession(() =>
+      pty.spawnRun({ laneId: 14, cwd: "/tmp/repo", tool: "antigravity", resumeLast: true })
+    );
+    assert.deepEqual(paneArgv(last), ["agy", "--continue"]);
+  });
+
   // `dashboard_runs.mode` is NOT NULL and recordRun swallows insert errors, so a
   // null there persisted nothing at all while every call still looked fine: the
   // runs modal rendered a row with no cwd, model, prompt or start time, and a

server/__tests__/router-apply.test.js

@@ -233,6 +233,24 @@ describe("router-apply — the written file must survive a lane reset", () => {
   });
 });
 
+describe("router-apply — Antigravity lane", () => {
+  const agyLane = () => ({ id: 9, cwd: LANE_CWD, tool: "antigravity" });
+
+  it("accepts native and writes nothing", () => {
+    assert.equal(applyRouterToLane(agyLane(), "native").file, null);
+    assert.equal(fs.existsSync(SETTINGS), false);
+  });
+
+  it("refuses a real router instead of writing Claude's settings file", () => {
+    const { name } = saveNineRouter();
+    assert.throws(
+      () => applyRouterToLane(agyLane(), name),
+      (err) => err.code === "EUNSUPPORTED"
+    );
+    assert.equal(fs.existsSync(SETTINGS), false);
+  });
+});
+
 describe("router-apply — Codex lane", () => {
   it("writes a profile layer file, never the base config", () => {
     const base = path.join(process.env.CODEX_HOME, "config.toml");