Startup box: server.run() prints app name, version and connect URL in a rounded unicode box on stderr. Shared termwidth module for ANSI-aware unicode display width and padding.

fastapi-vue/fastapi_vue/startupbox.py

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+"""Startup banner: a rounded unicode box printed to stderr (not via logging)."""
+
+import sys
+
+from .termwidth import display_width, pad_display
+
+
+def print_box(text: str) -> None:
+    """Print text in a rounded unicode box sized to its longest line.
+
+    The text is split on newlines as-is (not trimmed). Padding accounts
+    for ANSI colors and unicode display width (see termwidth.display_width).
+    """
+    lines = text.split("\n")
+    width = max(map(display_width, lines))
+    border = "─" * (width + 2)
+    out = [f"╭{border}╮"]
+    out.extend(f"│ {pad_display(line, width)} │" for line in lines)
+    out.append(f"╰{border}╯")
+    sys.stderr.write("\n".join(out) + "\n")