client/src/routes/player/Account.jsx

@@ -377,6 +377,15 @@ export default function Account() {
         <li>Type it below. It works once.</li>
       </ol>
 
+      {/* D392: core's "Link Steam" is a second way to make this link. Unlinking
+          Steam there removes only the sign-in (D393), so this page says where a
+          Rust link is removed. */}
+      <p className="sans dim" style={{ margin: '10px 0 0', fontSize: '0.86rem', maxWidth: '60ch' }}>
+        If this site offers Steam sign-in, linking Steam on your <a href="/account" className="link-accent">account
+        page</a> links that Steam account here too. Unlinking it there only stops you signing in with it; remove a
+        Rust link here.
+      </p>
+
       <LinkForm onLinked={reload} />
 
       {loading && <Loading />}

engagement-triggers.json

@@ -1,6 +1,6 @@
 {
   "_comment": "Generated freeze of module-rust's engagement contract (docs/modules/rust/PLAN.md §25). Regenerate with `npm run engagement:manifest` in server/. A renamed variable, a changed type or a widened ceiling breaks stored templates and rules, so the diff here is the review signal.",
-  "coreApi": "^1.15.0",
+  "coreApi": "^1.17.0",
   "triggers": [
     {
       "id": "rust.base.destroyed",

module.json

@@ -2,7 +2,7 @@
   "id": "rust",
   "name": "Rust",
   "version": "0.1.0",
-  "coreApi": "^1.15.0",
+  "coreApi": "^1.17.0",
   "server": "server/index.js",
   "client": { "entry": "client/dist/entry.js" },
   "schema": "server/db/schema.sql",

server/index.js

@@ -158,6 +158,16 @@ module.exports = function register(ctx, api) {
   api.onBoot(boot.onBoot)
   api.onShutdown(boot.onShutdown)
 
+  // Sign in with Steam (MODULE_API 1.17.0; PLAN_REDESIGNS §15). A Steam account
+  // linked on the site is a linked Rust player (D392): core asks before it writes
+  // the sign-in identity, and this module refuses a Steam id that is another
+  // account's Rust link (D396); once it is written, the Rust link is made. Both
+  // are in the links model beside `/link`'s own write, and neither runs at
+  // registration — core calls them from a signed-in user's link flow.
+  const links = require('./model/links/links.model') // eslint-disable-line global-require
+  api.onIdentityLinking(links.checkSteamSignin)
+  api.onIdentityLinked(links.linkFromSteamSignin)
+
   // The leases (PLAN.md §27, protocol 8): what an event may BORROW on a server
   // and must give back. Core's `core.lease` is the verb; these are the values it
   // may name and the four callables each ships. Every lease is targeted and the

server/model/links/links.model.js

@@ -286,6 +286,71 @@ async function unlinkFromGame(steamId) {
   return removed
 }
 
+// ── Steam's own sign-in as a second way to link (D392, D393, D396) ─────────
+//
+// Core's "Link Steam" (STEAM_SIGNIN.md) proves the account with Steam's OpenID
+// `check_authentication`, which is at least as strong as a code typed in game:
+// so a Steam account linked on the site IS a linked Rust player, beside `/link`.
+// Core asks this module twice through MODULE_API 1.17.0 — before it writes the
+// sign-in identity, and after. Unlinking Steam on the site removes only the
+// sign-in (D393), so there is no third call: the Rust link stays until it is
+// removed on the Rust page or by `/unlink` in game, exactly as one made by code.
+
+const STEAM_ID = /^\d{17}$/
+
+/**
+ * Core's pre-link check (`api.onIdentityLinking`). Refuses a Steam id that is
+ * already ANOTHER website account's Rust link (D396) — the same rule as D23 for
+ * a code, for the same reason: a link here is a privilege path, and moving it
+ * would hand that account's grants to whoever signed in. Core shows "already
+ * linked to another account" and nothing is written; staff remove the old link
+ * if the claim is real. Our own words go to core's log, never to the page.
+ */
+async function checkSteamSignin({ userId, provider, subject }) {
+  if (provider !== 'steam') return { ok: true }
+  const held = await db.getBySteamId(String(subject))
+  if (held && Number(held.userId) !== Number(userId)) {
+    return { ok: false, reason: 'in_use', message: `steam ${subject} is the Rust link of user ${held.userId}` }
+  }
+  return { ok: true }
+}
+
+/**
+ * Core's linked hook (`api.onIdentityLinked`): the Steam account becomes this
+ * user's Rust link (D392).
+ *
+ * The same write as `confirmOne`, with the PRIMARY KEY as the race guard: if
+ * somebody else's `/link` landed between core's check and this, the key refuses
+ * ours and their link stands — the sign-in identity core already wrote is only a
+ * way to sign in. `name` is the Steam persona name, which is what a Rust player is
+ * called in game until they rename. No `server_id`: no server minted anything.
+ */
+async function linkFromSteamSignin({ userId, provider, subject, displayName }) {
+  if (provider !== 'steam') return
+  const steamId = String(subject)
+  if (!STEAM_ID.test(steamId)) return
+
+  const held = await db.getBySteamId(steamId)
+  if (held) {
+    if (Number(held.userId) !== Number(userId)) {
+      log.warn('steam sign-in linked an id that is another user\'s Rust link; the Rust link stands', { steamId, userId })
+    }
+    return
+  }
+  try {
+    await db.insert({ steamId, userId, name: displayName || null, serverId: null })
+  } catch (err) {
+    if (err && (err.code === 'ER_DUP_ENTRY' || err.errno === 1062)) {
+      log.warn('steam sign-in link lost a race for this id; the other link stands', { steamId, userId })
+      return
+    }
+    throw err
+  }
+  log.info('steam account linked through steam sign-in', { steamId, userId })
+  linksChanged('rust account linked via steam sign-in')
+  engagement.linked({ userId, steamId, name: displayName || null })
+}
+
 /** The admin panel's read: every link this user holds, with per-server totals. */
 async function forAdmin(userId) {
   const links = await db.listForUserWithPlayer(userId)
@@ -326,5 +391,7 @@ module.exports = {
   unlinkOwned,
   unlinkAnyOwner,
   unlinkFromGame,
+  checkSteamSignin,
+  linkFromSteamSignin,
   forAdmin,
 }

server/test/_fakes.js

@@ -166,6 +166,9 @@ function fakeApi() {
     registerSlashCommands(commands) { once('registerSlashCommands'); record.slashCommands = commands },
     onBoot(fn) { once('onBoot'); record.hooks.onBoot = fn },
     onShutdown(fn) { once('onShutdown'); record.hooks.onShutdown = fn },
+    // MODULE_API 1.17.0 (Steam sign-in, PLAN_REDESIGNS §15).
+    onIdentityLinking(fn) { once('onIdentityLinking'); record.hooks.onIdentityLinking = fn },
+    onIdentityLinked(fn) { once('onIdentityLinked'); record.hooks.onIdentityLinked = fn },
   }
   api.record = record
   return api

server/test/entry.test.js

@@ -85,6 +85,13 @@ test('registers both lifecycle hooks', () => {
   assert.strictEqual(typeof api.record.hooks.onShutdown, 'function')
 })
 
+test('registers both identity hooks, so a Steam sign-in link is a Rust link (D392, D396)', () => {
+  const { api } = register()
+  const links = require('../model/links/links.model')
+  assert.strictEqual(api.record.hooks.onIdentityLinking, links.checkSteamSignin)
+  assert.strictEqual(api.record.hooks.onIdentityLinked, links.linkFromSteamSignin)
+})
+
 test('the manifest declares what the loader requires', () => {
   assert.match(manifest.id, /^[a-z][a-z0-9-]{1,31}$/)
   assert.match(manifest.version, /^\d+\.\d+\.\d+/)

server/test/links.test.js

@@ -429,3 +429,53 @@ test('a state read that fails asks everybody, which is slow and never wrong', as
   assert.equal((await links.redeem({ code: 'ZZZZZZ', userId: 4 })).reason, 'rejected')
   assert.equal(asked.length, 2)
 })
+
+
+// ── Steam's own sign-in as a second way to link (D392, D393, D396) ─────────
+
+const STEAM = '76561197960287930'
+
+test('core’s pre-link check refuses a Steam id that is another account’s Rust link (D396)', async () => {
+  withCore({ select: [[{ steamId: STEAM, userId: 9, username: 'bob' }]] })
+  const links = require('../model/links/links.model')
+  const answer = await links.checkSteamSignin({ userId: 4, provider: 'steam', subject: STEAM })
+  assert.equal(answer.ok, false)
+  assert.equal(answer.reason, 'in_use')
+})
+
+test('the pre-link check passes a free Steam id, one already yours, and every other provider', async () => {
+  withCore({ select: [[], [{ steamId: STEAM, userId: 4 }]] })
+  const links = require('../model/links/links.model')
+  assert.deepEqual(await links.checkSteamSignin({ userId: 4, provider: 'steam', subject: STEAM }), { ok: true })
+  assert.deepEqual(await links.checkSteamSignin({ userId: 4, provider: 'steam', subject: STEAM }), { ok: true })
+  assert.deepEqual(await links.checkSteamSignin({ userId: 4, provider: 'google', subject: 'x' }), { ok: true })
+})
+
+test('a Steam account linked on the site becomes a linked Rust player (D392)', async () => {
+  let inserted = null
+  const { ctx } = withCore({ select: [[]], onInsert: (params) => { inserted = params; return Promise.resolve({ affectedRows: 1 }) } })
+  const links = require('../model/links/links.model')
+  await links.linkFromSteamSignin({ userId: 4, provider: 'steam', subject: STEAM, displayName: 'CoolGuy99' })
+  assert.deepEqual(inserted, [STEAM, 4, 'CoolGuy99', null])
+  assert.equal(ctx.teams.reconcile.calls.length, 1)
+  assert.equal(ctx.events.emit.calls.length, 1, 'the player hears about the new link, as with /link')
+})
+
+test('the linked hook writes nothing for a link that is already there, or for another provider', async () => {
+  let inserts = 0
+  const { ctx } = withCore({ select: [[{ steamId: STEAM, userId: 4 }]], onInsert: () => { inserts += 1; return Promise.resolve({}) } })
+  const links = require('../model/links/links.model')
+  await links.linkFromSteamSignin({ userId: 4, provider: 'steam', subject: STEAM, displayName: 'x' })
+  await links.linkFromSteamSignin({ userId: 4, provider: 'discord', subject: '123', displayName: 'x' })
+  await links.linkFromSteamSignin({ userId: 4, provider: 'steam', subject: 'not-an-id', displayName: 'x' })
+  assert.equal(inserts, 0)
+  assert.equal(ctx.teams.reconcile.calls.length, 0)
+})
+
+test('a /link that lands between core’s check and the hook keeps its link; the hook does not throw', async () => {
+  const dup = Object.assign(new Error('dup'), { code: 'ER_DUP_ENTRY' })
+  const { ctx } = withCore({ select: [[]], onInsert: () => Promise.reject(dup) })
+  const links = require('../model/links/links.model')
+  await links.linkFromSteamSignin({ userId: 4, provider: 'steam', subject: STEAM, displayName: 'x' })
+  assert.equal(ctx.teams.reconcile.calls.length, 0)
+})