feat(admin): new Django admin dashboard landing page

Replace the stock admin index (alphabetical app/model table) with an
Astro/React dashboard rendered via the existing custom-admin overlay.

Backend:
- custom_admin/index.py overrides admin.site.index, bucketing registered
  models into 9 workflow groups (+ Other catch-all so nothing is dropped),
  builds quick-action links (schedule builder, grants, submissions), and
  renders astro/landing.html with JSON-safe context.
- tests cover grouping, exhaustive coverage, catch-all, link resolution and
  JSON serializability.

Frontend (custom_admin Astro app):
- pages/landing.astro + components/landing/* (root, dashboard, group cards,
  quick actions, placeholder stat cards, collapsible all-models fallback).

Stats values are placeholders; wiring real data via /admin/graphql is a
follow-up. Spec in specs/django-admin-landing-page.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: marcoacierno

backend/custom_admin/admin.py

@@ -7,12 +7,15 @@
 from django.urls import path
 
 from custom_admin.audit import create_change_admin_log_entry
+from custom_admin.index import install as install_custom_index
 
 SITE_NAME = "PyCon Italia"
 
 admin.site.site_header = SITE_NAME
 admin.site.site_title = SITE_NAME
 
+install_custom_index()
+
 
 class CustomIndexLinks(admin.ModelAdmin):
     def get_index_links(self) -> list:

backend/custom_admin/index.py

@@ -0,0 +1,252 @@
+"""Custom Django admin index (landing page).
+
+Overrides ``admin.site.index`` to render a dashboard that organizes the
+registered models into workflow groups and exposes a few quick-action
+shortcuts, instead of the stock alphabetical app/model table.
+
+The grouping is driven by ``GROUPS`` below (keyed by model ``object_name``).
+Any registered model not listed falls through to an "Other" group, so no model
+is ever silently dropped -- a test enforces this.
+"""
+
+from django.contrib import admin
+from django.template.response import TemplateResponse
+from django.urls import NoReverseMatch, reverse
+
+INDEX_TEMPLATE = "astro/landing.html"
+
+# Ordered workflow groups. Keys are group titles; values are the model
+# ``object_name``s that belong to each group. Order here is the display order.
+GROUPS: dict[str, list[str]] = {
+    "Program": [
+        "Submission",
+        "SubmissionType",
+        "SubmissionTag",
+        "SubmissionComment",
+        "SubmissionConfirmPendingStatusProxy",
+        "Vote",
+        "RankSubmission",
+        "RankRequest",
+        "RankStat",
+        "UserReview",
+        "ReviewSession",
+        "Keynote",
+        "Event",
+    ],
+    "Schedule & Video": [
+        "ScheduleItem",
+        "ScheduleItemInvitation",
+        "Room",
+        "Day",
+        "ScheduleItemSentForVideoUpload",
+        "WetransferToS3TransferRequest",
+    ],
+    "Finance": [
+        "Grant",
+        "GrantReimbursement",
+        "GrantReimbursementCategory",
+        "GrantConfirmPendingStatusProxy",
+        "Invoice",
+        "Sender",
+        "Address",
+        "Item",
+        "BillingAddress",
+        "PretixPayment",
+        "StripeSubscriptionPayment",
+        "Membership",
+    ],
+    "Sponsors": [
+        "Sponsor",
+        "SponsorBenefit",
+        "SponsorLevel",
+        "SponsorSpecialOption",
+        "SponsorLead",
+    ],
+    "People": [
+        "User",
+        "Participant",
+        "AttendeeConferenceRole",
+        "BadgeScan",
+        "InvitationLetterRequest",
+        "InvitationLetterConferenceConfig",
+        "Organizer",
+        "Notification",
+        "VolunteerDevice",
+    ],
+    "Conference setup": [
+        "Conference",
+        "Topic",
+        "AudienceLevel",
+        "Deadline",
+        "ConferenceVoucher",
+        "ChecklistItem",
+        "Language",
+    ],
+    "Content & CMS": [
+        "Post",
+        "Page",
+        "GenericCopy",
+        "FAQ",
+        "Menu",
+        "MenuLink",
+        "JobListing",
+        "Subscription",
+    ],
+    "Comms": [
+        "EmailTemplate",
+        "SentEmail",
+    ],
+    "System": [
+        "APIToken",
+        "GoogleCloudOAuthCredential",
+        "File",
+    ],
+}
+
+OTHER_GROUP = "Other"
+
+
+def _model_to_group() -> dict[str, str]:
+    """Reverse map: model object_name -> group title."""
+    mapping = {}
+    for group, object_names in GROUPS.items():
+        for object_name in object_names:
+            mapping[object_name] = group
+    return mapping
+
+
+def _clean_model(model: dict, app: dict) -> dict:
+    """Produce a JSON-serializable model entry from Django's app_list dict.
+
+    Django's raw model dict carries the model class and lazy strings, neither of
+    which survive json.dumps -- so pick only the fields the frontend needs and
+    coerce names to plain strings.
+    """
+    return {
+        "name": str(model["name"]),
+        "object_name": model["object_name"],
+        "admin_url": model.get("admin_url"),
+        "add_url": model.get("add_url"),
+        "view_only": model.get("view_only", False),
+        "app_label": app["app_label"],
+        "app_name": str(app["name"]),
+    }
+
+
+def build_groups(app_list: list[dict]) -> list[dict]:
+    """Bucket the models from Django's ``app_list`` into workflow groups.
+
+    Returns an ordered list of ``{"title", "models"}`` dicts with serializable
+    model entries. Empty groups are omitted. Any model whose ``object_name``
+    isn't mapped lands in the Other group, so nothing is silently dropped.
+    """
+    model_to_group = _model_to_group()
+    buckets: dict[str, list[dict]] = {title: [] for title in GROUPS}
+    buckets[OTHER_GROUP] = []
+
+    for app in app_list:
+        for model in app["models"]:
+            group = model_to_group.get(model["object_name"], OTHER_GROUP)
+            buckets[group].append(_clean_model(model, app))
+
+    ordered_titles = [*GROUPS.keys(), OTHER_GROUP]
+    return [
+        {"title": title, "models": buckets[title]}
+        for title in ordered_titles
+        if buckets[title]
+    ]
+
+
+def build_all_apps(app_list: list[dict]) -> list[dict]:
+    """Serializable copy of Django's full app/model list (the fallback section)."""
+    return [
+        {
+            "app_label": app["app_label"],
+            "name": str(app["name"]),
+            "models": [_clean_model(model, app) for model in app["models"]],
+        }
+        for app in app_list
+    ]
+
+
+def build_quick_links(request) -> list[dict]:
+    """Curated shortcuts to common daily tasks.
+
+    Each link is ``{"title", "description", "url"}``. Links whose target can't
+    be resolved (e.g. a feature not wired in this deploy) are skipped.
+    """
+    links = []
+
+    # Schedule builder is per-conference; point at the most recent conference,
+    # falling back to the conference changelist.
+    schedule_url = _latest_schedule_builder_url() or _safe_reverse(
+        "admin:conferences_conference_changelist"
+    )
+    if schedule_url:
+        links.append(
+            {
+                "title": "Schedule builder",
+                "description": "Build the conference schedule",
+                "url": schedule_url,
+            }
+        )
+
+    grants_url = _safe_reverse("admin:grants_grant_changelist")
+    if grants_url:
+        links.append(
+            {
+                "title": "Review grants",
+                "description": "Review and update grant requests",
+                "url": grants_url,
+            }
+        )
+
+    submissions_url = _safe_reverse("admin:submissions_submission_changelist")
+    if submissions_url:
+        links.append(
+            {
+                "title": "Review submissions",
+                "description": "Review proposed talks",
+                "url": submissions_url,
+            }
+        )
+
+    return links
+
+
+def _safe_reverse(viewname, **kwargs):
+    try:
+        return reverse(viewname, **kwargs)
+    except NoReverseMatch:
+        return None
+
+
+def _latest_schedule_builder_url():
+    from conferences.models import Conference
+
+    conference = Conference.objects.order_by("-start").first()
+    if conference is None:
+        return None
+    return _safe_reverse("admin:schedule_builder", kwargs={"object_id": conference.pk})
+
+
+def custom_index(request, extra_context=None):
+    """Render the dashboard landing page in place of the stock admin index."""
+    app_list = admin.site.get_app_list(request)
+    context = {
+        **admin.site.each_context(request),
+        "title": admin.site.index_title,
+        "app_list": app_list,
+        "groups": build_groups(app_list),
+        "all_apps": build_all_apps(app_list),
+        "quick_links": build_quick_links(request),
+        "breadcrumbs": [],
+        **(extra_context or {}),
+    }
+    request.current_app = admin.site.name
+    return TemplateResponse(request, INDEX_TEMPLATE, context)
+
+
+def install():
+    """Replace the default admin site's index view with ``custom_index``."""
+    admin.site.index = custom_index

backend/custom_admin/src/components/landing/all-models.tsx

@@ -0,0 +1,46 @@
+import type { AdminApp } from "./types";
+
+type Props = {
+  apps: AdminApp[];
+};
+
+// Full stock app/model list, collapsed by default, for completeness and to keep
+// rarely-used models reachable even when they aren't featured in a group.
+export const AllModels = ({ apps }: Props) => {
+  if (apps.length === 0) {
+    return null;
+  }
+
+  return (
+    <details className="rounded-lg border border-gray-200 bg-white shadow-sm">
+      <summary className="cursor-pointer select-none px-4 py-3 font-medium text-gray-700">
+        All models
+      </summary>
+      <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-x-8 gap-y-4 px-4 pb-4">
+        {apps.map((app) => (
+          <div key={app.app_label}>
+            <div className="text-xs uppercase tracking-wide text-gray-500 mb-1">
+              {app.name}
+            </div>
+            <ul>
+              {app.models.map((model) => (
+                <li key={model.object_name} className="py-0.5">
+                  {model.admin_url ? (
+                    <a
+                      href={model.admin_url}
+                      className="text-[#417690] hover:underline"
+                    >
+                      {model.name}
+                    </a>
+                  ) : (
+                    <span className="text-gray-700">{model.name}</span>
+                  )}
+                </li>
+              ))}
+            </ul>
+          </div>
+        ))}
+      </div>
+    </details>
+  );
+};

backend/custom_admin/src/components/landing/dashboard.tsx

@@ -0,0 +1,55 @@
+import { useArgs } from "../shared/args";
+import { AllModels } from "./all-models";
+import { GroupCard } from "./group-card";
+import { QuickActions } from "./quick-actions";
+import { StatCard } from "./stat-card";
+import type { AdminApp, Group, QuickLink } from "./types";
+
+// Placeholder metrics. Real values are wired in a follow-up (T5) via the
+// /admin/graphql endpoint; the layout is sized for them now.
+const PLACEHOLDER_STATS = [
+  { label: "Submissions" },
+  { label: "Grants pending" },
+  { label: "Schedule items" },
+  { label: "Tickets sold" },
+];
+
+export const Dashboard = () => {
+  const {
+    groups = [],
+    quickLinks = [],
+    allApps = [],
+  } = useArgs() as {
+    groups: Group[];
+    quickLinks: QuickLink[];
+    allApps: AdminApp[];
+  };
+
+  return (
+    <div className="flex flex-col gap-8">
+      <section>
+        <h2 className="text-base font-medium text-gray-700 mb-3">Overview</h2>
+        <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
+          {PLACEHOLDER_STATS.map((stat) => (
+            <StatCard key={stat.label} label={stat.label} />
+          ))}
+        </div>
+      </section>
+
+      {quickLinks.length > 0 && <QuickActions links={quickLinks} />}
+
+      <section>
+        <h2 className="text-base font-medium text-gray-700 mb-3">
+          Manage by area
+        </h2>
+        <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-4">
+          {groups.map((group) => (
+            <GroupCard key={group.title} group={group} />
+          ))}
+        </div>
+      </section>
+
+      <AllModels apps={allApps} />
+    </div>
+  );
+};