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/termwidth.py

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+"""Terminal display width calculation for unicode and ANSI-colored text."""
+
+import re
+import unicodedata
+
+ANSI_ESCAPE_RE = re.compile(r"\x1b\[[0-9;:]*[A-Za-z]")
+
+
+def _is_wide(char: str) -> bool:
+    """Return True for characters rendered as two terminal columns."""
+    if unicodedata.east_asian_width(char) in {"F", "W"}:
+        return True
+    cp = ord(char)
+    return unicodedata.category(char) == "So" and (
+        0x2600 <= cp <= 0x27BF or 0x1F300 <= cp <= 0x1F9FF or 0x1FA00 <= cp <= 0x1FAFF
+    )
+
+
+def display_width(text: str) -> int:
+    """Calculate the display width of a string in terminal columns.
+
+    ANSI escape codes are ignored. Wide characters (East Asian F/W and
+    emoji) count as two columns, combining marks and format characters
+    (e.g. emoji variation selectors) as zero.
+    """
+    plain = ANSI_ESCAPE_RE.sub("", text)
+    width = 0
+    for char in plain:
+        if unicodedata.category(char) in {"Mn", "Mc", "Me", "Cf"}:
+            continue
+        width += 2 if _is_wide(char) else 1
+    return width
+
+
+def pad_display(text: str, width: int) -> str:
+    """Pad text with trailing spaces to the given display width (no truncation)."""
+    return text + " " * max(width - display_width(text), 0)