Valvelet

A terminal runway calculator. It answers one question: when does the money run out?

Given your current cash, expected incomes, fixed costs, and lifestyle scenarios, Valvelet simulates your financial future and tells you the death day -- the date your balance hits zero.

Compare multiple lifestyle scenarios side by side to see how your choices affect your runway.

Screenshots

Chart -- Balance over time with death day markers

Death Day -- When each scenario runs out

Metrics -- Burn rates and income breakdown per scenario

Requirements

• Python 3.10+
• Textual
• textual-plotext

pip install textual textual-plotext

Usage

python valvelet.py

Edit the XML files in dat/ with your own numbers, then press r to reload.

Key	Action
r	Reload XML data and re-simulate
q	Quit

Data Files

All data lives in dat/ as hand-editable XML.

balance.xml

Your current cash and the date it was measured.

<balance currency="JPY">
  <current as-of="2026-02-19">500000</current>
</balance>

income.xml

Expected future incomes. Each entry has a frequency (monthly, weekly, daily, or once) and a date range (<to> is optional for ongoing income).

<income>
  <entry frequency="monthly">
    <source>Freelance client A</source>
    <amount>200000</amount>
    <from>2026-01-01</from>
  </entry>
  <entry frequency="monthly">
    <source>Side project</source>
    <amount>30000</amount>
    <from>2026-01-01</from>
    <to>2026-06-30</to>
  </entry>
</income>

fixed_costs.xml

Monthly fixed costs that apply regardless of lifestyle (rent, utilities, etc.).

<fixed-costs>
  <cost>
    <name>Rent</name>
    <amount>85000</amount>
  </cost>
  <cost>
    <name>Electricity</name>
    <amount>8000</amount>
  </cost>
</fixed-costs>

scenarios.xml

Lifestyle spending patterns. Each scenario contains activities with a cost per occurrence and a frequency (days per week, 0-7, decimals ok).

<scenarios>
  <scenario>
    <name>Social lifestyle</name>
    <activity>
      <name>Cafe</name>
      <cost>800</cost>
      <days-per-week>5</days-per-week>
    </activity>
    <activity>
      <name>Restaurant</name>
      <cost>1200</cost>
      <days-per-week>4</days-per-week>
    </activity>
    <activity>
      <name>Shotbar</name>
      <cost>3000</cost>
      <days-per-week>2</days-per-week>
    </activity>
  </scenario>
  <scenario>
    <name>Minimal lifestyle</name>
    <activity>
      <name>Grocery</name>
      <cost>1000</cost>
      <days-per-week>3</days-per-week>
    </activity>
  </scenario>
</scenarios>

Expected daily cost per scenario = sum of (cost * days_per_week / 7).

Tabs

The app has three tabs:

• Chart -- Line chart of balance over time for all scenarios. Death days are marked with vertical lines.
• Death Day -- When each scenario runs out, sorted by earliest death first.
• Metrics -- Daily burn, monthly burn, daily income, net daily, and death day per scenario.

License

MIT