RingBRP/tools/bestiary.mjs

/**
 * The bestiary as a document a GM can read before a session.
 *
 * There are forty-six creatures and, until this, no way to look at them. They live in
 * content.mjs, which is source code, and in the compendium, which shows one actor at a
 * time behind two clicks. A GM prepping a case cannot browse either, so in practice the
 * bestiary is whatever the GM happens to remember writing.
 *
 * Generated, never hand-written, for the reason the rules journal is generated from
 * rules.mjs: a reference that can disagree with the thing it references is worse than
 * no reference. Every number here is derived from the spec or read from the lethality
 * baseline, so the document cannot drift from the game.
 *
 *   node tools/bestiary.mjs           write docs/BESTIARY.md
 *   node tools/bestiary.mjs --check    fail if it is out of date (for the guards)
 *
 * The measured column comes from tools/lethality-baseline.json — the same frozen party
 * check-lethality uses — so a GM reading "2.1 of 4 down" is reading a number the build
 * refuses to let drift. It is a SOLO figure against one fixed party: read it to compare
 * creatures with each other, never as a prediction of your table. Encounter lethality
 * depends on how many there are and who the players brought, and `simulate --spread`
 * exists because that second one swings a fight by up to a hundred points.
 */
import { writeFile, readFile } from "node:fs/promises";
import { existsSync } from "node:fs";
import path from "node:path";
import { NPCS } from "./content.mjs";
import { hitPointsFor, majorWoundFor, locationsFor,
         resolveBands, defencePenaltyFor, DEFENCE_STEP } from "../rules.mjs";
import { buildCombatant } from "./simulate.mjs";
import { MONSTER_TAGS, carriesNothingManufactured } from "./make-portraits.mjs";

const ROOT = path.resolve(path.dirname(new URL(import.meta.url).pathname.replace(/^\/([A-Za-z]:)/, "$1")), "..");
const OUT = path.join(ROOT, "docs", "BESTIARY.md");
const BASELINE = path.join(ROOT, "tools", "lethality-baseline.json");
const FOCUS = path.join(ROOT, "tools", "focus-baseline.json");
const CHECK = process.argv.includes("--check");

const base = existsSync(BASELINE)
  ? JSON.parse(await readFile(BASELINE, "utf8"))
  : { creatures: {}, party: [], runs: 0, seed: 0 };

/* R-261. The focus-fire numbers below are READ, not restated: check-focus re-measures
   them on every build and check-bestiary refuses a page that has fallen behind them. The
   three previous attempts to say this in prose were wrong twice. */
const focus = existsSync(FOCUS)
  ? JSON.parse(await readFile(FOCUS, "utf8"))
  : { creatures: {}, runs: 0, seeds: [] };

/* ---------------------------------------------------------------- shaping */

const TAG_ORDER = ["FOLKLORE", "HORROR", "FORWARD", ""];
const TAG_TITLE = {
  FOLKLORE: "Folklore",
  HORROR: "Horror",
  FORWARD: "The far side",
  "": "Uncategorised"
};
const TAG_BLURB = {
  FOLKLORE: "Older than the department and largely uninterested in it. Most of these are "
    + "arrangements rather than fights, and the arrangement is nearly always cheaper.",
  HORROR: "The department's own. Every one is a piece of administration that kept going "
    + "after the reason for it stopped.",
  FORWARD: "The far side, and what it sends. This is where the non-human anatomies are: "
    + "a Vesh has no head to shoot off, a Cadence has no vital at all.",
  "": "People, mostly — contractors, locals, and the ones who were already here."
};

const tagOf = spec => (String(spec.role ?? "").match(/^([A-Z]{3,})\b/) ?? [, ""])[1] ?? "";
const essenceOf = spec => String(spec.role ?? "").replace(/^[A-Z]{3,}[^.]*\.\s*/, "").trim() || String(spec.role ?? "");

/** The POWER line is the mechanic a GM needs in front of them; the rest is staging. */
function powerOf(spec) {
  const m = String(spec.tactics ?? "").match(/POWER:\s*([A-Z][A-Z '’-]*)\.\s*([^]*?)(?=\s*(?:POWER:|$))/);
  if (!m) return null;
  let body = m[2].trim().replace(/\s+/g, " ");
  // Trim to the first two sentences: the rule, and the qualification on it.
  const parts = body.split(/(?<=[.!?])\s+/);
  return { name: m[1].trim(), rule: parts.slice(0, 2).join(" ") };
}

/* Keyed by BODY PLAN rather than species, because what a GM needs at the table is
   where the thing can be hit — and a bear is not a species, it is a shape. */
const SPECIES_NOTE = {
  vesh: "**Vesh** — no head, so no killing shot; the sensory ridge is the vital and is hit on 3 of 20.",
  cadence: "**Cadence** — five bodies, no vital, no head. Cannot be dropped; each body lost costs it −10% to everything.",
  quadruped: "**Four-legged** — four legs, no arms. The forequarters are the vital and take the most hits at range; the neck is worth aiming at and the head is hard to reach (1 face in melee).",
  winged: "**Four-legged, winged** — as the four-legged, plus wings. **Disable either wing and it cannot fly**, which is the fight the players can win. Wings are 6 faces of 20 at range and 2 in melee, and carry no hide at all. Once it is grounded the hide halves everywhere except the chest, which it keeps turned towards you.",
  baseline: null
};

function rowFor(spec) {
  const c = buildCombatant(spec, { side: "enemy" });
  const arm = c.arms[0];
  const measured = base.creatures[spec.key] ?? null;
  return {
    spec, c, arm, measured,
    tag: tagOf(spec),
    essence: essenceOf(spec),
    power: powerOf(spec),
    hp: hitPointsFor(spec.ch.con, spec.ch.siz),
    locs: locationsFor(spec.species ?? "baseline").length
  };
}

const rows = NPCS.map(rowFor);
const danger = r => r.measured ? r.measured.down : -1;

/* Which of them are the wrong shape.
 *
 * Counting "baseline creatures that carry a category tag" was the first attempt and it
 * over-counted badly: the locum and the predecessor are tagged HORROR and are both
 * shaped exactly like a man in a lanyard. The structural test is the one mj-queue uses —
 * a monster is a thing that was issued nothing by anybody and fights with its own body —
 * which catches the black dog and the case file and leaves the people alone. */
const unmodelled = rows.filter(r =>
  (r.spec.species ?? "baseline") === "baseline"
  && MONSTER_TAGS.includes(r.tag)
  && carriesNothingManufactured(r.spec));

/* ---------------------------------------------------------------- document */

const esc = s => String(s).replace(/\|/g, "\\|");
const pad2 = n => n.toFixed(2);

let md = `# THE CUSTODIANS — bestiary\n\n`
  + `*Generated by \`tools/bestiary.mjs\`. Do not edit: every number is derived from the\n`
  + `statblock or read from the lethality baseline, so this cannot disagree with the game.*\n\n`
  + `${rows.length} creatures. ${rows.filter(r => (r.spec.species ?? "baseline") !== "baseline").length} of them are not human-shaped.\n\n`;

/* --- the one-page table, which is the part that gets printed --- */

md += `## At a glance\n\n`
  + `Sorted by how much of a four-agent party each one puts on the floor, alone. `
  + `**Solo figures against one fixed party** — compare creatures with each other, never `
  + `read them as a prediction of your table. See the note at the foot.\n\n`
  + `| | Creature | Essence | SIZ | Arm | HP | Attack | Down of 4 |\n`
  + `|---|---|---|---|---|---|---|---|\n`;

for (const r of [...rows].sort((a, b) => danger(b) - danger(a))) {
  const sp = (r.spec.species ?? "baseline");
  const mark = sp === "vesh" ? "V" : sp === "cadence" ? "C" : "";
  md += `| ${mark} | **${esc(r.spec.name)}** | ${esc(r.essence)} | ${r.spec.ch.siz} | `
     + `${Number(r.spec.naturalArmour) || 0} | ${r.hp} | ${esc(r.arm?.w.name ?? "—")} ${r.arm?.rating ?? 0}% | `
     + `${r.measured ? pad2(r.measured.down) : "—"} |\n`;
}

md += `\n**V** = Vesh, **C** = Cadence. Everything else is baseline-human anatomy, including\n`
  + `several things that are plainly not human-shaped — see the note at the foot.\n\n---\n\n`;

/* --- how a defence is spent, which decides what order the party shoots in --- */
function focusParagraph() {
  const rows = Object.values(focus.creatures ?? {}).filter(r => r.gain !== undefined);
  if (!rows.length) return "";
  const mean = a => a.reduce((x, y) => x + y, 0) / a.length;
  const pairs = rows.filter(r => r.n === 2), packs = rows.filter(r => r.n >= 3);
  const helped = rows.filter(r => r.gain > 0).length;
  const clear  = rows.filter(r => r.gain > r.noise).length;
  const best   = rows.reduce((a, b) => (b.gain > a.gain ? b : a));
  const bestKey = Object.keys(focus.creatures).find(k => focus.creatures[k] === best);
  const bestName = (NPCS.find(n => n.key === bestKey) ?? {}).name ?? bestKey;
  const every = helped === rows.length && clear === rows.length;
  return `**What you can do is kill them one at a time.** Against a pack, every agent putting\n`
    + `their attacks into the same creature beats spreading them \u2014 in ${every ? "**every one**" : `${helped}`} of the\n`
    + `${rows.length} fights in this book whose outcome was ever in doubt${every ? ", without exception" : ""}, and by more\n`
    + `than the measurement\u2019s own noise ${every ? "each time" : `in ${clear} of them`}. It is worth about\n`
    + `**${mean(pairs.map(r => r.gain)).toFixed(0)} points** of win rate against a pair and\n`
    + `**${mean(packs.map(r => r.gain)).toFixed(0)} points** against three or more; the best case in the book is\n`
    + `${best.n} \u00d7 ${esc(bestName)}, which goes ${best.spread.toFixed(1)}% to ${best.focus.toFixed(1)}%. Most of that is not the ladder\n`
    + `above: a creature that is dead stops attacking, and one on half its hit points does not\n`
    + `attack any less. Held at a fixed pack size the dodge ladder is worth a point or two.\n\n`
    + `*(${focus.runs} fights \u00d7 ${(focus.seeds ?? []).length} seeds per arm, re-measured by \`check-focus\` on every build.)*\n\n`;
}

{
  const dodgeOf = spec => (spec.skills ?? []).find(k => k.fam === "dodge")?.val ?? 0;
  const effAfter = (rating, used) =>
    resolveBands(rating, { situational: defencePenaltyFor(used) }).effective;
  // How many LANDING hits it takes before the thing is defending at the 1% floor.
  const stripsIn = rating => {
    for (let used = 0; used < 8; used++) if (effAfter(rating, used) <= 1) return used;
    return 8;
  };

  const all = rows.map(r => ({ name: r.spec.name, d: dodgeOf(r.spec) })).filter(x => x.d > 0);
  const sorted = [...all].sort((a, b) => a.d - b.d);
  const median = sorted[Math.floor(sorted.length / 2)].d;
  const ladder = [0, 1, 2].map(u => effAfter(median, u));
  const spread = {};
  for (const x of all) spread[stripsIn(x.d)] = (spread[stripsIn(x.d)] ?? 0) + 1;
  const hardest = [...all].sort((a, b) => b.d - a.d).slice(0, 5);

  md += `## Shooting at something that moves\n\n`
    + `A creature's Dodge is not a percentage it has all round. Every defence it spends\n`
    + `costs it **${Math.abs(DEFENCE_STEP)} points** on the next one, and the whole thing resets when the\n`
    + `round does. The median dodge in this book is ${median}%, which goes `
    + `${ladder.map(v => `**${v}%**`).join(" → ")}\n`
    + `and is down to the floor after ${stripsIn(median)} landing hits.\n\n`
    + `Across ${all.length} creatures: `
    + Object.keys(spread).sort().map(k => `**${spread[k]}** are stripped by ${k} landing hit${k === "1" ? "" : "s"}`).join(", ")
    + `.\n\n`
    + `Two things follow:\n\n`
    + `- **Only a hit spends a defence.** A miss strips nothing, so a round in which the\n`
    + `  party misses twice is one where the creature meets the third shot at full value.\n`
    + `- **Each landing hit makes the next one easier**, in the same round only. The second\n`
    + `  agent to connect is worth more than the first, and against the heavy dodgers below\n`
    + `  the third is worth more still.\n\n`
    + `**What you cannot do is choose who goes first.** Reaction is re-rolled every round, so\n`
    + `over a fight every agent takes the opening slot about equally often, and there is no\n`
    + `rule for holding an action. Arranging the party so its best weapon fires last was\n`
    + `measured in the simulator and came to nothing distinguishable from noise.\n\n`
    + focusParagraph()
    + `The ones that take the most stripping:\n\n`
    + hardest.map(x => `- **${esc(x.name)}** — dodge ${x.d}%, ${stripsIn(x.d)} landing hits to strip\n`).join("")
    + `\nIt runs the other way too: agents defend on the same ladder, which is why a second\n`
    + `attacker in a round is worth so much more than the first, and why anything that gets\n`
    + `two attacks in before the party acts is far more dangerous than its statblock reads.\n\n---\n\n`;
}

/* --- the entries themselves --- */

for (const tag of TAG_ORDER) {
  const group = rows.filter(r => r.tag === tag).sort((a, b) => danger(b) - danger(a));
  if (!group.length) continue;
  md += `## ${TAG_TITLE[tag]}\n\n${TAG_BLURB[tag]}\n\n`;
  for (const r of group) {
    const sp = r.spec.bodyPlan ?? r.spec.species ?? "baseline";
    md += `### ${r.spec.name}\n\n`
       + `*${esc(r.essence)}*\n\n`;
    if (SPECIES_NOTE[sp]) md += `> ${SPECIES_NOTE[sp]}\n\n`;
    md += `| STR | CON | SIZ | INT | POW | DEX | Armour | HP | Major wound | Locations |\n`
       + `|---|---|---|---|---|---|---|---|---|---|\n`
       + `| ${r.spec.ch.str} | ${r.spec.ch.con} | ${r.spec.ch.siz} | ${r.spec.ch.int} | `
       + `${r.spec.ch.pow} | ${r.spec.ch.dex} | ${Number(r.spec.naturalArmour) || 0} | ${r.hp} | `
       + `${majorWoundFor(r.hp)} | ${r.locs} |\n\n`;
    md += `**Attacks with** ${r.arm ? `${r.arm.w.name} at ${r.arm.rating}%, ${r.arm.w.dmg}` : "nothing"}`
       + `${r.c.dodge ? ` · **dodges** ${r.c.dodge}%` : ""}\n\n`;
    if (r.power) md += `**${r.power.name}.** ${esc(r.power.rule)}\n\n`;
    if (r.measured) {
      md += `*Measured alone against the frozen party: ${pad2(r.measured.down)} of 4 down, `
         + `${r.measured.wipe}% wiped, ${r.measured.rounds} rounds.*\n\n`;
    }
  }
  md += `---\n\n`;
}

/* --- the caveats, which matter more than the numbers --- */

md += `## Reading the measured column\n\n`
  + `Every figure comes from \`tools/lethality-baseline.json\`, measured over ${base.runs} runs\n`
  + `at seed ${base.seed}${base.seedMode === "per-creature"
      ? ", one sequence derived per creature so no two share a draw," : ","}\n`
  + `against a frozen party of ${base.party.length}: ${base.party.map(k => k.replace(/^pc_/, "")).join(", ")}.\n`
  + `\`check-lethality\` refuses the build if any of them drifts, so these cannot go stale.\n\n`
  + `**They are solo figures and they are not a prediction.** Two things move them hard:\n\n`
  + `- **How many there are.** One Keeper is nothing; six are a 36% chance of a wiped party.\n`
  + `- **Who the players brought.** This is the big one. The same fight measured across every\n`
  + `  party the duty roster can field runs from 0% to 100% wiped — Okonkwo alone is worth\n`
  + `  forty-three points. Run \`node tools/simulate.mjs --creature <key> --count N --spread\`\n`
  + `  before you decide a fight is survivable.\n\n`
  + `The harness models banding, graded defences, hit locations, major wounds and the dying\n`
  + `clock. It does **not** model bleeding, panic, Coherence, cover, range bands or fire\n`
  + `modes, and every one of those makes a fight worse for whoever is losing. Read all of it\n`
  + `as a floor.\n\n`
  + `## A known gap\n\n`
  + `${unmodelled.length} creatures fight with nothing but their own bodies and still carry\n`
  + `baseline-human anatomy. Some of those are people and that is fine. Several plainly are\n`
  + `not — a black dog, a case file that eats the cases filed next to it, a machine that has\n`
  + `decided it is the site — and all of them are hit-located as people, so you can shoot the\n`
  + `barghest in the left arm and open the carrion file's chest.\n\n`
  + `The machinery to fix it exists, works, and is measured: see any Vesh or Cadence entry\n`
  + `above. What is missing is the anatomy tables for the shapes those creatures actually\n`
  + `are — a quadruped, an immobile object, a swarm — and the statblocks to go with them.\n\n`
  + `*Private convention play materials — not for sale or distribution.*\n`;

/* ---------------------------------------------------------------- write */

if (CHECK) {
  const existing = existsSync(OUT) ? await readFile(OUT, "utf8") : "";
  if (existing !== md) {
    console.error("bestiary: FAILED — docs/BESTIARY.md is out of date. Run `npm run bestiary`.");
    process.exit(1);
  }
  console.log(`bestiary: OK — ${rows.length} creatures, document current`);
  process.exit(0);
}

await writeFile(OUT, md, "utf8");
console.log(`bestiary: wrote ${path.relative(ROOT, OUT)} — ${rows.length} creatures across `
  + `${TAG_ORDER.filter(t => rows.some(r => r.tag === t)).length} groupings, `
  + `${rows.filter(r => r.measured).length} with measured lethality`);