diff --git a/scripts/wikiGen.js b/scripts/wikiGen.js
new file mode 100644
index 0000000..232bd25
--- /dev/null
+++ b/scripts/wikiGen.js
@@ -0,0 +1,303 @@
+#!/usr/bin/env node
+'use strict';
+
+/**
+ * wikiGen.js — shared wiki auto-generation helper for every EVOLV node.
+ *
+ * Two subcommands:
+ *
+ *   node wikiGen.js contract  <commands-module>     [--write <wiki-path>]
+ *   node wikiGen.js datamodel <specificClass-module> [--write <wiki-path>]
+ *
+ * `contract` walks the descriptor array exported by `src/commands/index.js`
+ * and emits a markdown table mapping canonical topic → aliases → payload
+ * schema → effect description.
+ *
+ * `datamodel` instantiates the domain with a minimal stub config, calls
+ * `getOutput()` once, and emits a markdown table of (key, type, sample value).
+ * If construction fails (because the domain needs a live runtime that isn't
+ * trivially stubbable), the script falls back to a hand-curated partial at
+ * `<repo>/wiki/_partial-datamodel.md.template` instead of crashing.
+ *
+ * When `--write <wiki-path>` is given, the output is spliced between the
+ * matching `<!-- BEGIN AUTOGEN: <marker> -->` / `<!-- END AUTOGEN: ... -->`
+ * markers in that file. Otherwise it prints to stdout.
+ *
+ * See `.claude/refactor/WIKI_TEMPLATE.md` (sections 5 and 8) and CONTRACTS.md
+ * for the canonical topic naming and registry shape this script consumes.
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+// ── CLI parsing ────────────────────────────────────────────────────────────
+
+function parseArgs(argv) {
+  const [, , subcmd, target, ...rest] = argv;
+  const opts = { subcmd, target, write: null };
+  for (let i = 0; i < rest.length; i++) {
+    if (rest[i] === '--write' && rest[i + 1]) {
+      opts.write = rest[i + 1];
+      i++;
+    }
+  }
+  return opts;
+}
+
+function usage() {
+  process.stderr.write([
+    'Usage:',
+    '  node wikiGen.js contract  <path-to-commands/index.js>     [--write <wiki-path>]',
+    '  node wikiGen.js datamodel <path-to-specificClass.js>      [--write <wiki-path>]',
+    '',
+  ].join('\n'));
+}
+
+// ── Shared helpers ─────────────────────────────────────────────────────────
+
+function resolveAbs(p) {
+  return path.isAbsolute(p) ? p : path.resolve(process.cwd(), p);
+}
+
+function describeSchema(schema) {
+  if (!schema) return '_unspecified_';
+  const t = schema.type;
+  if (!t) return '_unspecified_';
+  if (t === 'any')    return '`any`';
+  if (t === 'object') {
+    const props = schema.properties || {};
+    const keys = Object.keys(props);
+    if (!keys.length) return '`object`';
+    const parts = keys.map((k) => {
+      const subType = props[k]?.type ?? 'any';
+      return `${k}:${subType}`;
+    });
+    return '`{ ' + parts.join(', ') + ' }`';
+  }
+  return '`' + t + '`';
+}
+
+function topicEffectFallback(topic) {
+  // Try to derive a short, plain-English effect from the canonical topic
+  // when the descriptor doesn't carry a description field. Keep it terse —
+  // a maintainer can override by adding `description` to the descriptor.
+  const prefixes = {
+    'set.':    'Replaces the named state value with the supplied payload.',
+    'cmd.':    'Triggers an action / sequence — not idempotent.',
+    'data.':   'Pushes a value into the node\'s measurement stream.',
+    'query.':  'Read-only query; node replies on the same msg.',
+    'child.':  'Parent/child plumbing — registers or unregisters a child node.',
+  };
+  for (const [pfx, line] of Object.entries(prefixes)) {
+    if (topic.startsWith(pfx)) return line;
+  }
+  return '_(see handler)_';
+}
+
+function spliceAutogen(filePath, marker, body) {
+  const begin = `<!-- BEGIN AUTOGEN: ${marker} -->`;
+  const end   = `<!-- END AUTOGEN: ${marker} -->`;
+  if (!fs.existsSync(filePath)) {
+    throw new Error(`wikiGen: --write target '${filePath}' does not exist`);
+  }
+  const src = fs.readFileSync(filePath, 'utf8');
+  const bIdx = src.indexOf(begin);
+  const eIdx = src.indexOf(end);
+  if (bIdx < 0 || eIdx < 0 || eIdx < bIdx) {
+    throw new Error(`wikiGen: markers '${marker}' not found in ${filePath}`);
+  }
+  const before = src.slice(0, bIdx + begin.length);
+  const after  = src.slice(eIdx);
+  const out = before + '\n\n' + body.trimEnd() + '\n\n' + after;
+  fs.writeFileSync(filePath, out, 'utf8');
+}
+
+// ── Subcommand: contract ───────────────────────────────────────────────────
+
+function renderContract(commandsPath) {
+  const abs = resolveAbs(commandsPath);
+  // eslint-disable-next-line import/no-dynamic-require, global-require
+  const registry = require(abs);
+  if (!Array.isArray(registry)) {
+    throw new Error(`wikiGen contract: ${abs} does not export an array of descriptors`);
+  }
+
+  const lines = [];
+  lines.push('| Canonical topic | Aliases | Payload | Effect |');
+  lines.push('|---|---|---|---|');
+  for (const d of registry) {
+    const topic = '`' + d.topic + '`';
+    const aliases = (d.aliases && d.aliases.length)
+      ? d.aliases.map((a) => '`' + a + '`').join(', ')
+      : '_(none)_';
+    const payload = describeSchema(d.payloadSchema);
+    const effect = d.description ? String(d.description) : topicEffectFallback(d.topic);
+    lines.push(`| ${topic} | ${aliases} | ${payload} | ${effect} |`);
+  }
+  return lines.join('\n');
+}
+
+// ── Subcommand: datamodel ──────────────────────────────────────────────────
+
+function inferSampleType(v) {
+  if (v === null) return 'null';
+  if (Array.isArray(v)) return 'array';
+  return typeof v;
+}
+
+function trySampleValue(v) {
+  if (v === null || v === undefined) return '`null`';
+  const t = typeof v;
+  if (t === 'number' || t === 'boolean') return '`' + String(v) + '`';
+  if (t === 'string') return '`"' + v + '"`';
+  if (Array.isArray(v)) return '`[…]`';
+  if (t === 'object') return '`{…}`';
+  return '`' + String(v) + '`';
+}
+
+// Heuristic unit map for top-level snapshot keys that aren't structured as
+// MeasurementContainer keys (e.g. `heightBasin`, `surfaceArea`). Best-effort
+// — the canonical place for unit semantics is the node's config schema; the
+// table below is just enough to keep the auto-generated data-model readable.
+const FLAT_KEY_UNITS = {
+  heightBasin:     'm',
+  basinHeight:     'm',
+  inflowLevel:     'm',
+  outflowLevel:    'm',
+  overflowLevel:   'm',
+  startLevel:      'm',
+  stopLevel:       'm',
+  minLevel:        'm',
+  maxLevel:        'm',
+  surfaceArea:     'm2',
+  volEmptyBasin:   'm3',
+  maxVol:          'm3',
+  maxVolAtOverflow:'m3',
+  minVol:          'm3',
+  minVolAtInflow:  'm3',
+  minVolAtOutflow: 'm3',
+  percControl:     '%',
+  timeleft:        's',
+};
+
+function inferUnitFromKey(key) {
+  // MeasurementContainer-shaped keys take precedence: `{type}.{variant}.{position}.{childId}`.
+  const parts = key.split('.');
+  if (parts.length >= 3) {
+    const type = parts[0];
+    const map = {
+      flow:           'm3/s',
+      pressure:       'Pa',
+      power:          'W',
+      temperature:    'K',
+      level:          'm',
+      volume:         'm3',
+      volumePercent:  '%',
+      netFlowRate:    'm3/s',
+    };
+    if (map[type]) return map[type];
+  }
+  return FLAT_KEY_UNITS[key] || '—';
+}
+
+function renderDatamodel(specificClassPath) {
+  const abs = resolveAbs(specificClassPath);
+  // eslint-disable-next-line import/no-dynamic-require, global-require
+  const Domain = require(abs);
+
+  // Minimum viable stub config — the BaseDomain pipeline pulls per-key
+  // defaults from the JSON schema, so this only needs to supply the bits
+  // that BaseDomain reads from `userConfig` directly.
+  const stubConfig = {
+    general: {
+      name: `wikiGen-${Domain.name || 'domain'}`,
+      id: `wikiGen-${Domain.name || 'domain'}-id`,
+      logging: { enabled: false, logLevel: 'error' },
+    },
+  };
+
+  // Look for a hand-curated fallback alongside the wiki. Path is
+  // `<node>/wiki/_partial-datamodel.md.template` relative to the
+  // *commands*-or-specificClass file's repo root.
+  const repoRoot = findRepoRoot(abs);
+  const fallback = repoRoot
+    ? path.join(repoRoot, 'wiki', '_partial-datamodel.md.template')
+    : null;
+
+  let out;
+  try {
+    const instance = new Domain(stubConfig);
+    out = instance.getOutput ? instance.getOutput() : null;
+    if (!out || typeof out !== 'object') {
+      throw new Error('getOutput() returned a non-object');
+    }
+  } catch (err) {
+    process.stderr.write(`wikiGen datamodel: live instantiation failed: ${err.message}\n`);
+    if (fallback && fs.existsSync(fallback)) {
+      process.stderr.write(`wikiGen datamodel: using hand-curated fallback ${fallback}\n`);
+      return fs.readFileSync(fallback, 'utf8').trimEnd();
+    }
+    process.stderr.write('wikiGen datamodel: no hand-curated fallback found — emitting placeholder\n');
+    return [
+      '| Key | Type | Unit | Sample |',
+      '|---|---|---|---|',
+      `| _live instantiation failed; provide ${fallback ? `\`wiki/_partial-datamodel.md.template\`` : 'a hand-curated template'}_ | — | — | — |`,
+    ].join('\n');
+  }
+
+  const lines = [];
+  lines.push('| Key | Type | Unit | Sample |');
+  lines.push('|---|---|---|---|');
+  for (const k of Object.keys(out).sort()) {
+    const v = out[k];
+    lines.push(`| \`${k}\` | ${inferSampleType(v)} | ${inferUnitFromKey(k)} | ${trySampleValue(v)} |`);
+  }
+  return lines.join('\n');
+}
+
+function findRepoRoot(startPath) {
+  let dir = path.dirname(startPath);
+  for (let i = 0; i < 8; i++) {
+    if (fs.existsSync(path.join(dir, 'package.json'))) return dir;
+    const parent = path.dirname(dir);
+    if (parent === dir) return null;
+    dir = parent;
+  }
+  return null;
+}
+
+// ── Entry point ────────────────────────────────────────────────────────────
+
+function main() {
+  const opts = parseArgs(process.argv);
+  if (!opts.subcmd || !opts.target) {
+    usage();
+    process.exit(1);
+  }
+
+  let body;
+  let marker;
+  if (opts.subcmd === 'contract') {
+    body = renderContract(opts.target);
+    marker = 'topic-contract';
+  } else if (opts.subcmd === 'datamodel') {
+    body = renderDatamodel(opts.target);
+    marker = 'data-model';
+  } else {
+    usage();
+    process.exit(1);
+  }
+
+  if (opts.write) {
+    spliceAutogen(resolveAbs(opts.write), marker, body);
+    process.stderr.write(`wikiGen: wrote ${marker} block into ${opts.write}\n`);
+  } else {
+    process.stdout.write(body + '\n');
+  }
+}
+
+if (require.main === module) {
+  main();
+}
+
+module.exports = { renderContract, renderDatamodel, spliceAutogen, describeSchema };