docs(kit): re-pin to core 1.21.0 and teach report targets

ci/core-ref.json moves from 7bd93b8 (1.20.0) to f13b8fe (1.21.0,
website#233, report, block and hide). Chapter 2 gains a section on
registerReportTargets, registerGameIdentities and ctx.safety, and its call
count becomes twenty-three. template/module.json's coreApi becomes ^1.21.0
for the equality check; the template declares none of the new members.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

book/02-website-module.md

@@ -147,7 +147,7 @@ statement of your dependencies, and it makes a test double for it — see
 
 ## What you register
 
-Twenty-one calls, all synchronous and all listed in [§2.4][api]: fifteen
+Twenty-three calls, all synchronous and all listed in [§2.4][api]: seventeen
 registrations, the two lifecycle hooks, the two identity-link hooks, the demo's
 seed hook, and the account-deletion hook. Five of the
 registrations are the event system's, and [chapter 5](05-events.md) has those. What
@@ -571,6 +571,46 @@ api.onUserDeleting(async ({ userId, deletedBy }) => {}) // deletedBy: 'self' | '
   needs `coreApi` `^1.20.0`, because an older core has no `api.onUserDeleting`, and
   calling a missing function throws during `register()`.
 
+### When members report, hide or block what your game shows
+
+If your module shows what players wrote, such as chat from the game, members can
+report it, hide it for themselves, and block whoever wrote it, and staff can hide
+it for everyone (`MODULE_API_VERSION` 1.21.0, [`USER_SAFETY.md`][safety]). Core
+keeps the Reports queue and each member's blocks and hides. You keep the content,
+and you tell core three things about it:
+
+```js
+api.registerReportTargets([{ id: 'mygame.chat', label: 'Chat line', snapshot, hide, unhide }])
+api.registerGameIdentities([{ kind: 'steam', label: 'Steam account', ownersOf }])
+// and, from your own per-reader routes: ctx.safety.forViewer(userId), ctx.safety.staffAmong(userIds)
+```
+
+- **`snapshot({ targetId, viewer })` answers for that reader, and `null` covers two
+  cases.** An item that is gone and an item they could not have seen get the same
+  `null`, so core gives them the same 404. Otherwise a report or a block would tell
+  anybody who said line 4410 on a server whose player list is hidden from them. Run
+  the same visibility check your page runs.
+- **Name the author by their site account when they have one.** `author.userId` is
+  the linked account and `author.identity` is the game id. `ownersOf(ids)` answers
+  which ids are linked. A block then lands on the account, and only an unlinked id
+  is blocked as itself. Core rewrites that block as an account block once the id
+  links, so you never have to.
+- **Filter on the server, in your query.** A route that shows the content to
+  signed-in readers calls `ctx.safety.forViewer(userId)` and leaves out what that
+  reader blocked or hid. Do it in the `WHERE` clause, so a page of 100 is still 100
+  long, and keep the route per-viewer (`Cache-Control: private`), or a shared cache
+  hands one reader's filter to the next. If your page offers *Block*, mark each item
+  with whether it can be blocked. Use `ctx.safety.staffAmong` for that, because
+  staff cannot be blocked.
+- **Hide for everyone is a flag you keep.** `hide` is called from core's queue.
+  Leave the item out for everyone but staff, and show it to staff marked, with an
+  undo where it lives. Core never calls `unhide` itself.
+- **Each call has 5 s.** A module that does not answer is a 503 to the member,
+  never a silent success. Declaring any of it needs `coreApi` `^1.21.0`.
+
+Module-Rust's `server/safety.js` is a complete worked example: chat lines, Steam
+ids and the feed's own filter.
+
 ### On a public demo site
 
 A site can run as a public demo (`MODULE_API_VERSION` 1.18.0). Anybody signs in with
@@ -939,3 +979,4 @@ the next chapter is for.
 
 [api]: https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/website/MODULE_API.md
 [acceptance]: https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/modules/kit-acceptance.md
+[safety]: https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/website/USER_SAFETY.md

ci/core-ref.json

@@ -1,10 +1,20 @@
 {
   "repo": "https://gitea.whitlocktech.com/RunicGateway/website.git",
   "branch": "main",
-  "ref": "7bd93b8bb0da734a642587f256d10c523ca39bea",
+  "ref": "f13b8fe1fec9dc330a985430b8bd4f67c9ec26c5",
   "why": [
     "The core this kit is written against, pinned to a commit rather than a branch.",
     "",
+    "2026-10-30: moved from 7bd93b8 (1.20.0) to f13b8fe (1.21.0, website#233,",
+    "report, block and hide, USER_SAFETY.md). Chapter 2 was read again:",
+    "- 1.21.0: api.registerReportTargets, api.registerGameIdentities and",
+    "  ctx.safety.forViewer / staffAmong (chapter 2 gains a section, and its call",
+    "  count becomes twenty-three).",
+    "website#233 is the only core change in the window. The template declares",
+    "none of the new members, so nothing it does changed meaning; module.json's",
+    "coreApi becomes ^1.21.0 for the equality check. The real core run was",
+    "repeated at this ref, with the template as the only module in the directory.",
+    "",
     "2026-10-30: moved from 69998ec (1.19.0) to 7bd93b8 (1.20.0, website#232,",
     "account deletion, ACCOUNT_DELETION.md). Chapter 2 was read again:",
     "- 1.20.0: api.onUserDeleting (chapter 2 gains a section, and its call count",

template/module.json

@@ -2,7 +2,7 @@
   "id": "examplegame",
   "name": "Example Game",
   "version": "0.1.0",
-  "coreApi": "^1.20.0",
+  "coreApi": "^1.21.0",
   "server": "server/index.js",
   "client": { "entry": "client/dist/entry.js" },
   "schema": "server/db/schema.sql",