First files upload.

app.py

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+import subprocess
+from flask import Flask, render_template_string, request
+
+app = Flask(__name__)
+
+HTML_TEMPLATE = """
+<!DOCTYPE html>
+<html>
+<head>
+    <title>IPv6 Subnet Calculator</title>
+    <style>
+        body { font-family: monospace; background: #1e1e2e; color: #cdd6f4; padding: 20px; }
+        input, button { padding: 10px; font-size: 16px; border-radius: 4px; border: none; }
+        input { width: 350px; background: #313244; color: #fff; }
+        button { background: #89b4fa; color: #11111b; cursor: pointer; font-weight: bold; }
+        pre { background: #181825; padding: 15px; border-radius: 6px; border: 1px solid #45475a; }
+    </style>
+</head>
+<body>
+    <h2>IPv6 Subnet Calculator (sipcalc Wrapper)</h2>
+    <form method="POST">
+        <input type="text" name="ipv6" placeholder="2001:db8:85a3::8a2e:370:7334/64" value="{{ query }}">
+        <button type="submit">Calculate</button>
+    </form>
+    {% if output %}
+    <h3>Results:</h3>
+    <pre>{{ output }}</pre>
+    {% endif %}
+</body>
+</html>
+"""
+
+@app.route("/", methods=["GET", "POST"])
+def index():
+    output = ""
+    query = ""
+    if request.method == "POST":
+        query = request.form.get("ipv6", "").strip()
+        if query:
+            try:
+                # Run sipcalc CLI command securely
+                result = subprocess.run(
+                    ["sipcalc", query], capture_output=True, text=True, timeout=5
+                )
+                output = result.stdout if result.returncode == 0 else result.stderr
+            except Exception as e:
+                output = str(e)
+    return render_template_string(HTML_TEMPLATE, query=query, output=output)
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", port=5000)