Reason Me This

Shipped Blueprints

The blueprints that ship with the service, what each one covers, its calculations, and how to run and import it.

These blueprints ship with the service. They are supported rule sets, kept current, and every one is proven by its own worked examples. Read them as worked examples of everything in these guides.

Using One

In a blueprint, import one by name:

imports: [coc_7e_percentile]

From the CLI, run one by name, as you would one of your own definitions.

Call of Cthulhu 7th Edition

Written from the Keeper Rulebook’s rules.

Blueprint Covers Calculations Imports Cases
coc_7e_percentile the d100 roll the others share: success levels, and skill checks with bonus and penalty dice skill_check   13
coc_7e_investigator an investigator: derived values, occupation and skill allocation with every broken rule listed, the development phase, age deductions chosen by the player, and a ledger of sanity losses investigator, sanity_ledger, skills, development, age_adjustment, skill_base and the rows they run   52
coc_7e_encounters combat pieces (opposed melee rolls, damage and wounds, combat order) and creature sanity losses from a bestiary melee, damage, combat_order, encounters, sighting and more coc_7e_percentile 39
coc_7e_combat a whole fight, round by round, carrying every fighter’s hit points, wounds, ammunition and state, with firearms, outnumbering and CON rolls for the dying and the wounded fight, round, exchange, shot, reload, con_roll and more coc_7e_encounters 11
coc_7e_duel the same fight played by the engine from a seed until one side is down or a player must choose, and the odds across 200 fights simulate, odds and more coc_7e_combat 7
coc_7e_chase a chase along a track of locations, with speed rolls, movement actions, hazards and barriers, until the quarry is caught or gets away chase, chase_round, turn, move and more coc_7e_percentile 4

A skill check:

$ echo '{"skill": 60, "difficulty": "hard", "units": 1, "tens": [3], "bonus_dice": 0, "penalty_dice": 0}' |
    rmt run coc_7e_percentile
roll           31
success_level  regular
passes         false
can_push       true
dice_expected  1
problems

31 against a skill of 60 is a regular success, which fails a hard check and can be pushed.

The investigator and encounters blueprints were first built by agents using only the CLI, as a test of how discoverable it is.

Away from Games

Blueprint Covers Calculations Cases
electricity_bill smart meter reads priced by time-of-use window, rates and supply that change on a date, solar feed-in credits, and compare_plans to find the cheapest plan for the same reads bill, compare_plans, read_charge, supply_day 7
sales_commission a rep’s year from their deals: split, multi-year and discounted deal credit, SPIFFs, marginal tiers of attainment, a cap, clawbacks within 90 days, a plan change part way through the year, and a recoverable draw carried from quarter to quarter year, deal_credit, quarter, clawback, tier_slice 14 
$ echo '{"period_from":"2026-07-01","period_to":"2026-07-01","reads":[{"date":"2026-07-01","hour":2,"kwh":10}]}' |
    rmt run electricity_bill --calculation compare_plans
bills
  plan         days  usage_charge  feed_in_credit  supply_charge  total
  flat_rate    1     3             0               1.1            4.1
  time_of_use  1     1.5           0               1.2            2.7
cheapest  time_of_use

Ten kWh at 2am is off-peak, so time of use wins.

Where They Show Up

  • Imports: the service falls back to a shipped blueprint for an import name the workspace does not have.
  • The workbench: a blueprint’s page offers them to chain into a draft.