diff --git a/.gitignore b/.gitignore
index a984e33e..21093e09 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@
 .hugo_build.lock
 __pycache__/
 node_modules/
+/forum/import/
diff --git a/Makefile b/Makefile
index eddd7b87..8844323c 100644
--- a/Makefile
+++ b/Makefile
@@ -7,10 +7,10 @@ PAGEFIND ?= npx -y pagefind@1
 DEPLOY_DIR ?= /run/user/$(shell id -u)/gvfs/smb-share:server=barbel-lescar,share=web/oldcomputers
 DEPLOY_URL ?= https://barbel.synology.me/oldcomputers/
 
-.PHONY: content build check serve deploy post
+.PHONY: content build check serve deploy post forum-up forum-import forum-down
 
 content:       ## regenerate content/ and static/media/ from the extraction repo
-	python3 $(OC)/scripts/05_hugo.py --target $(CURDIR)
+	python3 $(OC)/scripts/05_hugo.py --target $(CURDIR) $(if $(wildcard data/forum.json),--forum)
 
 build:         ## build the site and its search index into $(BUILD)/
 	rm -rf $(BUILD)
@@ -32,3 +32,17 @@ deploy: check  ## build, check, and copy $(BUILD)/ to DEPLOY_DIR (served at DEPL
 	mkdir -p "$(DEPLOY_DIR)"
 	rsync -r --size-only --info=stats1 $(BUILD)/media/ "$(DEPLOY_DIR)/media/"
 	rsync -rc --delete --exclude=/media/ --info=stats1 $(BUILD)/ "$(DEPLOY_DIR)/"
+
+# --- local test forum (Flarum in Docker, see forum/README.md) ---
+FORUM = docker compose -f forum/docker-compose.yml
+SITE_URL ?= http://localhost:1313
+
+forum-up:      ## start the test forum on http://localhost:8081 (admin / adminadmin)
+	$(FORUM) up -d --build
+
+forum-import:  ## export the archived comments and import them into the test forum
+	python3 $(OC)/scripts/06_forum.py --target $(CURDIR)
+	$(FORUM) exec -T flarum php flarum oc:import /import/machines.json --site-url=$(SITE_URL) --map=/import/forum.json
+
+forum-down:    ## stop the test forum (forum-db volume keeps its data)
+	$(FORUM) down
diff --git a/README.md b/README.md
index e83aeca8..405258ed 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,8 @@ Static rebuild of old-computers.com with [Hugo](https://gohugo.io/) (0.158 or ne
 | `static/media/` | generated (copied images and documents) |
 | `data/slugs.json` | generated, keeps URLs stable between runs — do not delete |
 | `content/post/` | written by hand: news posts, see below |
+| `data/forum.json` | machine → forum thread map, written by the forum import (absent = no forum) |
+| `forum/` | forum extension, local test stack, install notes |
 | `content/_index.md`, `layouts/`, `assets/`, `hugo.toml`, `tools/` | written by hand |
 | `build/`, `public/` | build output (`make build`, `hugo server`), not versioned |
 
@@ -39,6 +41,14 @@ sends to `/search/`, where results can be filtered by section. Content pages are
 visitor-comments tabs are not. `hugo server` has no index: use `make build` and serve `build/`
 to try the search locally.
 
+## Forum and comments
+
+A [Flarum](https://flarum.org/) forum can run next to the site and serve as its comment system:
+with `params.forum.url` set in `hugo.toml`, the menu gets a Forum entry and the Comments tab of
+each machine shows that machine's forum thread (archived comments first, new replies after).
+With the url empty the site has no forum and shows the archived comments as static text.
+Everything about the forum is in [`forum/README.md`](forum/README.md).
+
 ## Usage
 
     make content   # regenerate from ../oc (OC=path to use another location)
diff --git a/assets/css/main.css b/assets/css/main.css
index cba51ae4..ce219482 100644
--- a/assets/css/main.css
+++ b/assets/css/main.css
@@ -162,3 +162,5 @@ table { border-collapse: collapse; }
 .pager { display: flex; flex-wrap: wrap; justify-content: center; gap: 6px; margin: 24px 0 0; }
 .pager a, .pager .current { padding: 4px 10px; border: 1px solid var(--line); border-radius: 4px; text-decoration: none; background: var(--panel); }
 .pager .current { font-weight: 700; border-color: var(--accent); }
+
+.forum-thread { display: block; width: 100%; min-height: 400px; border: 0; }
diff --git a/assets/js/iframeResizer.min.js b/assets/js/iframeResizer.min.js
new file mode 100644
index 00000000..bd6c6422
--- /dev/null
+++ b/assets/js/iframeResizer.min.js
@@ -0,0 +1,21 @@
+/*! iFrame Resizer (iframeSizer.min.js ) - v4.4.5 - 2024-07-10
+ *  Desc: Force cross domain iframes to size to content.
+ *  Requires: iframeResizer.contentWindow.min.js to be loaded into the target frame.
+ *  Copyright: (c) 2024 David J. Bradshaw - dave@bradshaw.net
+ *  License: MIT
+ */
+console.info(`
+IFRAME-RESIZER
+
+Iframe-Resizer 5 is now available via the following two packages:
+
+ * @iframe-resizer/parent
+ * @iframe-resizer/child
+
+Additionally their are also new versions of iframe-resizer for React, Vue, and jQuery.
+
+Version 5 of iframe-resizer has been extensively rewritten to use modern browser APIs, which has enabled significantly better performance and greater accuracy in the detection of content resizing events.
+
+Please see https://iframe-resizer.com/upgrade for more details.
+`),function(d){var c,l,f,a,v,z,I,x,r,u,M,i,m,k;function g(){return window.MutationObserver||window.WebKitMutationObserver||window.MozMutationObserver}function F(e,n,i){e.addEventListener(n,i,!1)}function B(e,n,i){e.removeEventListener(n,i,!1)}function w(e){return z+"["+(n="Host page: "+(e=e),n=window.top!==window.self?window.parentIFrame&&window.parentIFrame.getId?window.parentIFrame.getId()+": "+e:"Nested host page: "+e:n)+"]";var n}function t(e){return M[e]?M[e].log:f}function R(e,n){o("log",e,n,t(e))}function O(e,n){o("info",e,n,t(e))}function E(e,n){o("warn",e,n,!0)}function o(e,n,i,t){!0===t&&"object"==typeof window.console&&console[e](w(n),i)}function n(e){function i(){t("Height"),t("Width"),P(function(){H(w),C(b),u("onResized",w)},w,"init")}function n(){var e=p.slice(I).split(":"),n=e[1]?parseInt(e[1],10):0,i=M[e[0]]&&M[e[0]].iframe,t=getComputedStyle(i);return{iframe:i,id:e[0],height:n+function(e){if("border-box"!==e.boxSizing)return 0;var n=e.paddingTop?parseInt(e.paddingTop,10):0,e=e.paddingBottom?parseInt(e.paddingBottom,10):0;return n+e}(t)+function(e){if("border-box"!==e.boxSizing)return 0;var n=e.borderTopWidth?parseInt(e.borderTopWidth,10):0,e=e.borderBottomWidth?parseInt(e.borderBottomWidth,10):0;return n+e}(t),width:e[2],type:e[3]}}function t(e){var n=Number(M[b]["max"+e]),i=Number(M[b]["min"+e]),e=e.toLowerCase(),t=Number(w[e]);R(b,"Checking "+e+" is in range "+i+"-"+n),t<i&&(t=i,R(b,"Set "+e+" to min value")),n<t&&(t=n,R(b,"Set "+e+" to max value")),w[e]=""+t}function o(){var t=e.origin,o=M[b]&&M[b].checkOrigin;if(o&&""+t!="null"&&!function(){if(o.constructor!==Array)return e=M[b]&&M[b].remoteHost,R(b,"Checking connection is from: "+e),t===e;var e,n=0,i=!1;for(R(b,"Checking connection is from allowed list of origins: "+o);n<o.length;n++)if(o[n]===t){i=!0;break}return i}())throw new Error("Unexpected message received from: "+t+" for "+w.iframe.id+". 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+//# sourceMappingURL=iframeResizer.map
\ No newline at end of file
diff --git a/forum/README.md b/forum/README.md
new file mode 100644
index 00000000..d7748780
--- /dev/null
+++ b/forum/README.md
@@ -0,0 +1,71 @@
+# Forum and comments (Flarum)
+
+The forum is a separate PHP application ([Flarum](https://flarum.org/) 2, PHP 8.3+, MariaDB or
+MySQL). It is not part of the static build: the site only links to it and shows its threads in a
+frame.
+
+| Path | Role |
+|---|---|
+| `extension/` | Flarum extension `oc/flarum-museum`: the `oc:import` command and the look of embedded threads |
+| `docker/`, `docker-compose.yml` | local test forum |
+| `import/` | not versioned: `machines.json` (export from the extraction repo) and `forum.json` (thread map) |
+
+## How comments work
+
+- `../oc/scripts/06_forum.py` writes `import/machines.json`: one entry per machine with its
+  archived comments, oldest first.
+- `php flarum oc:import` creates one discussion per machine: an opening post linking to the
+  museum page, then one post per archived comment, all by the user `Archive`, with the original
+  author and date at the top of each post and the original date as the post date. Discussions go
+  under three tags (Computers, Consoles, Pongs) that are hidden from "All discussions".
+- The command records what it imported (table `oc_threads`) and skips it on later runs, so it
+  can be run again when new machines arrive. It writes the map machine → discussion to
+  `forum.json`.
+- Copied to `../data/forum.json`, that map makes `make content` give every machine a Comments
+  tab pointing at its thread (`forum_thread` in the page front matter); the old comments are
+  then no longer written into the pages.
+- With `params.forum.url` set, the Comments tab shows `<forum>/embed/<id>` (Flarum's Embed
+  extension) in a frame that follows the height of the thread.
+
+## Local test
+
+    make forum-up        # http://localhost:8081, admin / adminadmin (first start takes a minute)
+    make forum-import    # export + import; safe to repeat
+
+To see it in the site, copy `forum/import/forum.json` to `data/forum.json`, run `make content`,
+and build with `HUGO_PARAMS_FORUM_URL=http://localhost:8081 hugo server`. Do not commit a
+`data/forum.json` made from the test forum: its thread numbers are not those of the real one.
+
+## Server install (outline)
+
+The forum must live **outside** the folder `make deploy` writes to (that folder is synchronised
+with deletion). On the test server: `web/oldcomputers-forum/`, next to `web/oldcomputers/`.
+
+1. PHP 8.3 or newer with curl, dom, fileinfo, gd, json, mbstring, openssl, pdo_mysql, tokenizer,
+   zip; an empty database and a user for it.
+2. `composer create-project flarum/flarum oldcomputers-forum "^2.0"`, then in that folder
+   `composer require flarum/embed "^2.0"`.
+3. Web server: requests that are not files go to `public/index.php`, and nothing outside `public/`
+   is served. Flarum ships rules for Apache (`public/.htaccess`) and nginx (`.nginx.conf`); a
+   sub-folder install is described in the Flarum documentation ("Customizing paths").
+4. Open the forum address and finish the installer (database, administrator account).
+5. Copy `extension/` to `packages/oc-museum/` in the forum folder, then:
+
+       composer config repositories.oc path "packages/*"
+       composer require "oc/flarum-museum:*@dev"
+       php flarum migrate
+       php flarum extension:enable flarum-tags
+       php flarum extension:enable flarum-embed
+       php flarum extension:enable oc-museum
+
+6. In the admin panel: e-mail settings (registration confirms addresses by e-mail), and a spam
+   filter extension. Schedule a database dump.
+7. Import: copy `import/machines.json` to the server and run
+
+       php flarum oc:import machines.json --site-url=https://example.org/oldcomputers --map=forum.json
+
+   then bring `forum.json` back as `data/forum.json`, set `params.forum.url`, `make content`,
+   `make deploy`.
+
+The forum and the site should share one domain: logging in from the embedded thread relies on
+the forum's cookie, which browsers restrict across domains.
diff --git a/forum/docker-compose.yml b/forum/docker-compose.yml
new file mode 100644
index 00000000..df1a4b14
--- /dev/null
+++ b/forum/docker-compose.yml
@@ -0,0 +1,24 @@
+# Local test forum on http://localhost:8081 (admin / adminadmin). Data in named volumes.
+services:
+  db:
+    image: mariadb:11
+    environment:
+      MARIADB_DATABASE: flarum
+      MARIADB_USER: flarum
+      MARIADB_PASSWORD: flarum
+      MARIADB_RANDOM_ROOT_PASSWORD: "1"
+    volumes:
+      - forum-db:/var/lib/mysql
+  flarum:
+    build: docker
+    depends_on: [db]
+    environment:
+      FORUM_URL: http://localhost:8081
+      ADMIN_PASSWORD: adminadmin
+    ports:
+      - "127.0.0.1:8081:80"
+    volumes:
+      - ./extension:/var/www/flarum/packages/oc-museum
+      - ./import:/import
+volumes:
+  forum-db:
diff --git a/forum/docker/Dockerfile b/forum/docker/Dockerfile
new file mode 100644
index 00000000..59720f69
--- /dev/null
+++ b/forum/docker/Dockerfile
@@ -0,0 +1,19 @@
+# Local test forum: Flarum 2 on Apache. Not the production install (see forum/README.md).
+FROM php:8.3-apache
+RUN apt-get update && apt-get install -y --no-install-recommends git unzip libzip-dev libpng-dev libjpeg-dev libfreetype6-dev \
+    && docker-php-ext-configure gd --with-jpeg --with-freetype \
+    && docker-php-ext-install pdo_mysql gd zip \
+    && a2enmod rewrite && rm -rf /var/lib/apt/lists/*
+COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
+ENV COMPOSER_ALLOW_SUPERUSER=1
+RUN composer create-project flarum/flarum /var/www/flarum "^2.0" --no-interaction --prefer-dist \
+    && cd /var/www/flarum && mkdir packages \
+    && composer require --no-interaction flarum/embed "^2.0" \
+    && composer config repositories.oc '{"type": "path", "url": "packages/*", "options": {"symlink": true}}' \
+    && chown -R www-data:www-data /var/www/flarum
+RUN sed -ri 's#/var/www/html#/var/www/flarum/public#g' /etc/apache2/sites-available/000-default.conf \
+    && printf '<Directory /var/www/flarum/public>\n  AllowOverride All\n  Require all granted\n</Directory>\n' > /etc/apache2/conf-enabled/flarum.conf
+COPY entrypoint.sh /entrypoint.sh
+WORKDIR /var/www/flarum
+ENTRYPOINT ["/entrypoint.sh"]
+CMD ["apache2-foreground"]
diff --git a/forum/docker/entrypoint.sh b/forum/docker/entrypoint.sh
new file mode 100755
index 00000000..4a524963
--- /dev/null
+++ b/forum/docker/entrypoint.sh
@@ -0,0 +1,33 @@
+#!/bin/sh
+# First start: install Flarum against the db service, enable the extensions the site relies on.
+set -e
+cd /var/www/flarum
+if [ ! -f config.php ]; then
+  until php -r 'new PDO("mysql:host=db;dbname=flarum", "flarum", "flarum");' >/dev/null 2>&1; do sleep 2; done
+  cat > /tmp/install.yml <<Y
+debug: true
+baseUrl: ${FORUM_URL}
+databaseConfiguration:
+  driver: mysql
+  host: db
+  port: 3306
+  database: flarum
+  username: flarum
+  password: flarum
+  prefix:
+adminUser:
+  username: admin
+  password: ${ADMIN_PASSWORD}
+  email: admin@example.com
+settings:
+  forum_title: Old-Computers.com forum
+Y
+  php flarum install --file=/tmp/install.yml
+fi
+# the museum extension is mounted from the repository (forum/extension)
+composer require --no-interaction "oc/flarum-museum:*@dev" >/dev/null 2>&1 || composer require --no-interaction "oc/flarum-museum:*@dev"
+php flarum migrate
+for ext in flarum-tags flarum-markdown flarum-embed oc-museum; do php flarum extension:enable "$ext" || true; done
+php flarum cache:clear
+chown -R www-data:www-data storage public/assets
+exec docker-php-entrypoint "$@"
diff --git a/forum/extension/composer.json b/forum/extension/composer.json
new file mode 100644
index 00000000..e2408f0a
--- /dev/null
+++ b/forum/extension/composer.json
@@ -0,0 +1,26 @@
+{
+    "name": "oc/flarum-museum",
+    "description": "Old-Computers.com museum integration: imports the archived visitor comments as discussions and styles the embedded threads.",
+    "type": "flarum-extension",
+    "license": "MIT",
+    "require": {
+        "flarum/core": "^2.0",
+        "flarum/tags": "^2.0",
+        "flarum/embed": "^2.0"
+    },
+    "autoload": {
+        "psr-4": {
+            "Oc\\Museum\\": "src/"
+        }
+    },
+    "extra": {
+        "flarum-extension": {
+            "title": "Old-Computers museum",
+            "icon": {
+                "name": "fas fa-landmark",
+                "backgroundColor": "#9a3412",
+                "color": "#fff"
+            }
+        }
+    }
+}
diff --git a/forum/extension/extend.php b/forum/extension/extend.php
new file mode 100644
index 00000000..6ab6ab9a
--- /dev/null
+++ b/forum/extension/extend.php
@@ -0,0 +1,11 @@
+<?php
+
+use Flarum\Extend;
+use Oc\Museum\Console\ImportCommand;
+
+return [
+    (new Extend\Console())->command(ImportCommand::class),
+
+    // threads shown inside the museum pages (flarum/embed) take the look of the static site
+    (new Extend\Frontend('embed'))->css(__DIR__.'/less/embed.less'),
+];
diff --git a/forum/extension/less/embed.less b/forum/extension/less/embed.less
new file mode 100644
index 00000000..58ff694d
--- /dev/null
+++ b/forum/extension/less/embed.less
@@ -0,0 +1,9 @@
+// Embedded thread, as shown in the Comments tab of the museum pages: full width, on the
+// light panel colour of the static site (--panel in its assets/css/main.css).
+@oc-accent: #9a3412;
+@oc-panel: #fffdf7;
+
+body, .App { background: @oc-panel; }
+.Page-content { max-width: none; }
+.Post-body a, .PostUser-name a, .Button--link { color: @oc-accent; }
+.Button--primary { background: @oc-accent; }
diff --git a/forum/extension/migrations/2026_10_11_000000_create_oc_threads_table.php b/forum/extension/migrations/2026_10_11_000000_create_oc_threads_table.php
new file mode 100644
index 00000000..bec470f1
--- /dev/null
+++ b/forum/extension/migrations/2026_10_11_000000_create_oc_threads_table.php
@@ -0,0 +1,10 @@
+<?php
+
+use Flarum\Database\Migration;
+use Illuminate\Database\Schema\Blueprint;
+
+// One discussion per museum machine; oc_id is the machine id of the original site.
+return Migration::createTable('oc_threads', function (Blueprint $table) {
+    $table->unsignedInteger('oc_id')->primary();
+    $table->unsignedInteger('discussion_id')->unique();
+});
diff --git a/forum/extension/src/Console/ImportCommand.php b/forum/extension/src/Console/ImportCommand.php
new file mode 100644
index 00000000..43ab153e
--- /dev/null
+++ b/forum/extension/src/Console/ImportCommand.php
@@ -0,0 +1,167 @@
+<?php
+
+namespace Oc\Museum\Console;
+
+use Carbon\Carbon;
+use Flarum\Console\AbstractCommand;
+use Flarum\Discussion\Discussion;
+use Flarum\Post\CommentPost;
+use Flarum\Tags\Tag;
+use Flarum\User\User;
+use Illuminate\Database\ConnectionInterface;
+use Illuminate\Support\Str;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputOption;
+
+/**
+ * Creates one discussion per museum machine from the file written by the extraction
+ * pipeline (oc/scripts/06_forum.py), with the archived visitor comments as its posts.
+ *
+ * Safe to run again: machines already imported (table oc_threads) are skipped.
+ */
+class ImportCommand extends AbstractCommand
+{
+    private const ARCHIVE_USER = 'Archive';
+    private const TAGS = [
+        'Computers' => ['#9a3412', 'fas fa-desktop'],
+        'Consoles' => ['#1d4ed8', 'fas fa-gamepad'],
+        'Pongs' => ['#15803d', 'fas fa-table-tennis-paddle-ball'],
+    ];
+
+    public function __construct(private ConnectionInterface $db)
+    {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        $this->setName('oc:import')
+            ->setDescription('Import the museum machines and their archived comments as discussions')
+            ->addArgument('file', InputArgument::REQUIRED, 'machines.json written by 06_forum.py')
+            ->addOption('site-url', null, InputOption::VALUE_REQUIRED, 'Address of the static site, e.g. https://example.org/oldcomputers', '')
+            ->addOption('map', null, InputOption::VALUE_REQUIRED, 'Where to write the machine -> discussion map (forum.json)');
+    }
+
+    protected function fire(): int
+    {
+        $machines = json_decode((string) file_get_contents($this->input->getArgument('file')), true);
+        if (! is_array($machines)) {
+            $this->error('Cannot read the import file.');
+
+            return 1;
+        }
+        $site = rtrim((string) $this->input->getOption('site-url'), '/');
+        $archive = $this->archiveUser();
+        $tags = $this->tags();
+        $done = $this->db->table('oc_threads')->pluck('discussion_id', 'oc_id');
+        $created = $posts = 0;
+
+        foreach ($machines as $machine) {
+            if (isset($done[$machine['oc_id']])) {
+                continue;
+            }
+            $this->db->transaction(function () use ($machine, $site, $archive, $tags, &$posts, &$done) {
+                $id = $this->importMachine($machine, $site, $archive, $tags[$machine['section']] ?? $tags['Computers']);
+                $this->db->table('oc_threads')->insert(['oc_id' => $machine['oc_id'], 'discussion_id' => $id]);
+                $done[$machine['oc_id']] = $id;
+                $posts += count($machine['comments']);
+            });
+            if (++$created % 50 === 0) {
+                $this->info("$created discussions…");
+            }
+        }
+
+        $archive->refreshCommentCount()->refreshDiscussionCount()->save();
+        foreach ($tags as $tag) {
+            $tag->discussion_count = $tag->discussions()->count();
+            $tag->refreshLastPostedDiscussion()->save();
+        }
+        if ($map = $this->input->getOption('map')) {
+            file_put_contents($map, json_encode($done, JSON_PRETTY_PRINT)."\n");
+        }
+        $this->info("$created discussions created with $posts archived comments; ".count($done).' machines mapped.');
+
+        return 0;
+    }
+
+    private function importMachine(array $machine, string $site, User $archive, Tag $tag): int
+    {
+        $comments = $machine['comments'];
+        // the thread opens just before its first comment (or now, when there is none)
+        $opened = $comments ? Carbon::parse($comments[0]['date'])->subMinute() : Carbon::now();
+        $page = $site.$machine['path'];
+
+        $discussion = Discussion::start($machine['title'], $archive);
+        $discussion->created_at = $opened;
+        $discussion->save();
+
+        $first = $this->post($discussion, $archive, $opened,
+            "Comments about the [{$machine['title']}]($page) page of the museum.\n\n"
+            .($comments ? 'The first messages below were left by visitors of the original site.' : 'Be the first to comment!'));
+        foreach ($comments as $comment) {
+            $header = '**'.$this->plain($comment['author']).'**'
+                .($comment['original_date'] ? ' — '.$this->plain($comment['original_date']) : '');
+            $this->post($discussion, $archive, Carbon::parse($comment['date']), $header."\n\n".$comment['text']);
+        }
+
+        $discussion->setFirstPost($first)->refreshCommentCount()->refreshLastPost()->refreshParticipantCount()->save();
+        $discussion->tags()->sync([$tag->id]);
+
+        return $discussion->id;
+    }
+
+    private function post(Discussion $discussion, User $user, Carbon $when, string $markdown): CommentPost
+    {
+        $post = new CommentPost();
+        $post->discussion_id = $discussion->id;
+        $post->user_id = $user->id;
+        $post->created_at = $when;
+        $post->type = CommentPost::$type;
+        // the pipeline writes hard line breaks as "\" + newline; the forum keeps plain newlines
+        $post->setContentAttribute(str_replace("\\\n", "\n", $markdown), $user);
+        $post->save();  // events raised by the model are not dispatched: no notifications
+
+        return $post;
+    }
+
+    private function plain(string $text): string
+    {
+        return preg_replace('/([\\\\*_`\[\]@])/', '\\\\$1', trim($text));
+    }
+
+    private function archiveUser(): User
+    {
+        $user = User::query()->where('username', self::ARCHIVE_USER)->first();
+        if (! $user) {
+            $user = new User();
+            $user->username = self::ARCHIVE_USER;
+            $user->email = 'archive@invalid.invalid';
+            $user->password = Str::random(40);  // nobody logs in as the archive
+            $user->is_email_confirmed = true;
+            $user->joined_at = Carbon::now();
+            $user->save();
+        }
+
+        return $user;
+    }
+
+    /** @return array<string, Tag> */
+    private function tags(): array
+    {
+        $tags = [];
+        $position = (int) Tag::query()->max('position');
+        foreach (self::TAGS as $name => [$color, $icon]) {
+            $tag = Tag::query()->where('slug', Str::slug($name))->first();
+            if (! $tag) {
+                // hidden from "All discussions": one thread per machine would bury the forum topics
+                $tag = Tag::build($name, Str::slug($name), "Comments on the $name pages of the museum", $color, $icon, true);
+                $tag->is_primary = true;
+                $tag->position = ++$position;
+                $tag->save();
+            }
+            $tags[$name] = $tag;
+        }
+
+        return $tags;
+    }
+}
diff --git a/hugo.toml b/hugo.toml
index c1c73cc7..37c412cd 100644
--- a/hugo.toml
+++ b/hugo.toml
@@ -19,6 +19,11 @@ capitalizeListTitles = false
   listPosts = 10
   description = "The Old-Computers.com museum of computers, consoles and pongs, rebuilt from the Wayback Machine archive."
 
+  # Forum (Flarum, see forum/README.md). Empty url = no forum: no menu entry, and machine pages
+  # show the archived comments as static text. With a url, the Comments tab shows the forum thread.
+  [params.forum]
+    url = ""
+
 [taxonomies]
   category = "categories"
   type = "types"
diff --git a/layouts/baseof.html b/layouts/baseof.html
index 6bb16208..21a88d1e 100644
--- a/layouts/baseof.html
+++ b/layouts/baseof.html
@@ -17,6 +17,7 @@
       {{ range site.Menus.main }}
       <a href="{{ .URL }}"{{ if or ($current.IsMenuCurrent .Menu .) ($current.HasMenuCurrent .Menu .) (eq $current.Section .Page.Section) }} class="active"{{ end }}>{{ .Name }}</a>
       {{ end }}
+      {{ with site.Params.forum.url }}<a href="{{ . }}">Forum</a>{{ end }}
     </nav>
     <form class="search" role="search" action="{{ "search/" | relURL }}" method="get">
       <input type="search" name="q" placeholder="Search…" aria-label="Search the site">
diff --git a/layouts/machine-tabs/single.html b/layouts/machine-tabs/single.html
index 2c7e89b5..4dbc40b9 100644
--- a/layouts/machine-tabs/single.html
+++ b/layouts/machine-tabs/single.html
@@ -33,6 +33,16 @@
       {{ end }}
     </div>
 
+  {{ else if and (eq $tab "comments") $p.forum_thread site.Params.forum.url }}
+    {{/* live comments: the machine's forum thread, shown in a frame sized to its content */}}
+    {{ $thread := printf "%s/embed/%d" (strings.TrimSuffix "/" site.Params.forum.url) (int $p.forum_thread) }}
+    <p class="note">The first comments were left by visitors of the original site. Log in to the forum to add yours. <a href="{{ replace $thread "/embed/" "/d/" }}">Open this discussion in the forum</a>.</p>
+    <iframe class="forum-thread" id="forum-thread" src="{{ $thread }}" title="Comments on {{ $m.Title }}" loading="lazy"></iframe>
+    {{ with resources.Get "js/iframeResizer.min.js" | fingerprint }}
+    <script src="{{ .RelPermalink }}"></script>
+    <script>iFrameResize({ checkOrigin: false, heightCalculationMethod: "lowestElement" }, "#forum-thread");</script>
+    {{ end }}
+
   {{ else if eq $tab "comments" }}
     <p class="note">Comments left by visitors of the original site. New comments are closed.</p>
     <ol class="comments">