# `Srd`
[🔗](https://github.com/autodidaddict/agentic-realms/tree/main/packages/srd_5e/blob/main/lib/srd.ex#L1)

Tabletop RPG rules resolution modeled on the SRD 5.2.

Three layers fit together: `Srd.Content` loads SRD items and data, `Srd.Dice`
rolls, and `Srd.Rules` resolves a completed roll into an outcome.

## A combat round

```elixir
alias Srd.Content.{Weapons, Armors}
alias Srd.Dice
alias Srd.Rules.{Initiative, Attack, Damage, Hitpoints, DeathSaves}

# Order the combatants. The caller rolls each initiative and captures the roll.
Initiative.order([
  {"knight", Dice.Rolls.initiative(2)},
  {"orc", Dice.Rolls.initiative(1)}
])
#=> [{"orc", %Srd.Dice.Roll{...}}, {"knight", %Srd.Dice.Roll{...}}]   # highest first

# The knight attacks the orc with a longsword, against its chain-mail AC.
longsword = Weapons.get("longsword")          # 1d8 slashing, versatile 1d10
orc_ac = Armors.get("chain-mail").base_ac     # 16

attack = Dice.Rolls.attack(5)                 # 1d20 + attack bonus
result = Attack.resolve(attack, target_ac: orc_ac)
#=> %Srd.Rules.Attack{hit?: true, critical?: false, natural: 14, total: 19, target_ac: 16}

# On a hit, roll the weapon's damage (parsed from content) and apply defenses.
if result.hit? do
  damage = Dice.roll(longsword.damage)
  dealt = Damage.resolve(damage, longsword.damage_type)
  #=> %Srd.Rules.Damage{type: :slashing, raw: 4, final: 4}

  # Apply to the orc's hit points. The outcome drives what happens next.
  Hitpoints.new(15, 15) |> Hitpoints.damage(dealt.final)
  #=> %Srd.Rules.Hitpoints{hp: 11, max_hp: 15, temp_hp: 0, outcome: :ok}
end
```

When `Hitpoints` reports `:downed`, the caller starts death saves; a hit taken
while at 0 hit points is a failure it routes in.

```elixir
down = Hitpoints.new(4, 15) |> Hitpoints.damage(4)
down.outcome
#=> :downed

DeathSaves.new() |> DeathSaves.record_save(Dice.Rolls.death_save())
#=> %Srd.Rules.DeathSaves{successes: 1, failures: 0, status: :dying}
```

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*Consult [api-reference.md](api-reference.md) for complete listing*