fix(cli): stream gateway logs in WebUI launcher

docs/cli-reference.md

@@ -139,7 +139,7 @@ Interactive mode exits with `exit`, `quit`, `/exit`, `/quit`, `:q`, or `Ctrl+D`.
 
 | Command | Description |
 |---|---|
-| `nanobot webui` | Create config/workspace if needed, enable the local WebUI channel after confirmation, start the gateway, and open `http://127.0.0.1:8765` |
+| `nanobot webui` | Create config/workspace if needed, enable the local WebUI channel after confirmation, start the gateway, open `http://127.0.0.1:8765`, and follow new gateway logs |
 | `nanobot webui --background` | Deprecated; prints the equivalent explicit `nanobot gateway --background` command and exits |
 | `nanobot webui --dev` | Start the gateway and Vite together at `http://127.0.0.1:5173`, with live frontend updates |
 | `nanobot webui --no-open` | Prepare and start the WebUI without opening a browser |

docs/webui.md

@@ -23,7 +23,9 @@ one is missing, starts or joins the same on-demand gateway used by the native
 TUI, and opens the browser. With a fresh config,
 it can open before a model is configured so you can finish setup in **Settings
 → Models**. The first-run path binds the WebUI to `127.0.0.1` by default, so
-it is not available from other devices on your LAN.
+it is not available from other devices on your LAN. While the launcher remains
+attached, it mirrors new log output from that exact gateway instance in the
+terminal without replaying older logs.
 
 After model setup, explicitly promote the shared gateway when you do not want to keep a client open:
 

nanobot/cli/webui_support.py

@@ -457,27 +457,54 @@ def _print_webui_foreground_lifecycle(*, attached: bool) -> None:
         console.print("[green]WebUI is attached to the shared gateway.[/green]")
     console.print("[dim]Closing the browser does not stop channels or automations.[/dim]")
     console.print(
-        "[dim]Press Ctrl+C to detach; the gateway stops only when the last local client exits.[/dim]"
+        "[dim]Following live gateway logs. Press Ctrl+C to detach; the gateway stops "
+        "only when the last local client exits.[/dim]"
     )
 
 
+def _read_new_gateway_logs(log_path: Path, offset: int) -> tuple[list[str], int]:
+    """Read gateway log lines appended after *offset*."""
+    try:
+        if log_path.stat().st_size < offset:
+            offset = 0
+        with log_path.open("r", encoding="utf-8", errors="replace") as handle:
+            handle.seek(offset)
+            lines = [line.rstrip("\r\n") for line in handle]
+            return lines, handle.tell()
+    except OSError:
+        return [], offset
+
+
 def _attach_to_background_gateway(
     runtime: "GatewayRuntime",
     *,
     poll_hook: Callable[[], None] | None = None,
     sleep: Callable[[float], None] = time.sleep,
 ) -> None:
-    """Keep a WebUI launcher attached without taking ownership of the gateway."""
+    """Keep the launcher attached and mirror this gateway's new log output."""
     _print_webui_foreground_lifecycle(attached=True)
+    status = runtime.status()
+    log_path = status.log_path
     try:
-        while runtime.status().running:
+        log_offset = log_path.stat().st_size
+    except OSError:
+        log_offset = 0
+    try:
+        while status.running:
+            lines, log_offset = _read_new_gateway_logs(log_path, log_offset)
+            for line in lines:
+                console.print(line, markup=False, highlight=False)
             if poll_hook is not None:
                 poll_hook()
             sleep(0.5)
+            status = runtime.status()
     except KeyboardInterrupt:
         console.print("\n[yellow]WebUI launcher detached.[/yellow]")
         return
 
+    lines, _ = _read_new_gateway_logs(log_path, log_offset)
+    for line in lines:
+        console.print(line, markup=False, highlight=False)
     console.print("[yellow]Gateway stopped.[/yellow]")
 
 

tests/cli/test_commands.py

@@ -2654,12 +2654,14 @@ def test_webui_foreground_attaches_to_existing_managed_gateway(monkeypatch, tmp_
     assert seen["lease_release_wait_for_stop"] is False
 
 
-def test_attach_to_background_gateway_detaches_on_ctrl_c(capsys) -> None:
+def test_attach_to_background_gateway_detaches_on_ctrl_c(capsys, tmp_path: Path) -> None:
     stopped = False
+    log_path = tmp_path / "gateway.log"
+    log_path.touch()
 
     class _FakeRuntime:
         def status(self):
-            return SimpleNamespace(running=True)
+            return SimpleNamespace(running=True, log_path=log_path)
 
         def stop(self):
             nonlocal stopped
@@ -2679,10 +2681,63 @@ def test_attach_to_background_gateway_detaches_on_ctrl_c(capsys) -> None:
     assert "WebUI launcher detached" in rendered
 
 
-def test_attach_to_background_gateway_checks_owned_sidecar() -> None:
+def test_attach_to_background_gateway_follows_only_new_logs(capsys, tmp_path: Path) -> None:
+    log_path = tmp_path / "gateway.log"
+    log_path.write_text("historical log\n", encoding="utf-8")
+    polls = 0
+
     class _FakeRuntime:
         def status(self):
-            return SimpleNamespace(running=True)
+            return SimpleNamespace(running=True, log_path=log_path)
+
+    def _append_then_interrupt(_seconds: float) -> None:
+        nonlocal polls
+        if polls == 0:
+            with log_path.open("a", encoding="utf-8") as handle:
+                handle.write("[websocket] live log\n")
+            polls += 1
+            return
+        raise KeyboardInterrupt
+
+    cli_webui_support._attach_to_background_gateway(
+        _FakeRuntime(),
+        sleep=_append_then_interrupt,
+    )
+
+    output = capsys.readouterr().out
+    assert "[websocket] live log" in output
+    assert "historical log" not in output
+
+
+def test_read_new_gateway_logs_recovers_after_truncation(tmp_path: Path) -> None:
+    log_path = tmp_path / "gateway.log"
+    log_path.write_text("a much longer historical log line\n", encoding="utf-8")
+    offset = log_path.stat().st_size
+    log_path.write_text("fresh log\n", encoding="utf-8")
+
+    lines, next_offset = cli_webui_support._read_new_gateway_logs(log_path, offset)
+
+    assert lines == ["fresh log"]
+    assert next_offset == log_path.stat().st_size
+
+
+def test_read_new_gateway_logs_tolerates_missing_file(tmp_path: Path) -> None:
+    lines, offset = cli_webui_support._read_new_gateway_logs(
+        tmp_path / "missing.log",
+        0,
+    )
+
+    assert lines == []
+    assert offset == 0
+
+
+def test_attach_to_background_gateway_checks_owned_sidecar(tmp_path: Path) -> None:
+    log_path = tmp_path / "gateway.log"
+    log_path.touch()
+
+    class _FakeRuntime:
+        def status(self):
+            return SimpleNamespace(running=True, log_path=log_path)
 
     def sidecar_exited() -> None:
         raise WebUIDevError("WebUI development server exited unexpectedly (code 23)")