add more multiuser support

atlas/migrations/0108_multiusersession.py

@@ -0,0 +1,27 @@
+# Generated by Django 6.0.1 on 2026-06-16 11:53
+
+import django.db.models.deletion
+import uuid
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('atlas', '0107_caseprior_relation_type'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='MultiuserSession',
+            fields=[
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('name', models.CharField(blank=True, max_length=255)),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+                ('active_case', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='atlas.case')),
+                ('creator', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='created_multiuser_sessions', to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+    ]

atlas/models.py

@@ -3,6 +3,7 @@ import json
 import os
 import pathlib
 from typing import Tuple
+import uuid
 
 from django.http import Http404, HttpRequest
 from generic.mixins import AuthorMixin, QuestionMixin
@@ -879,6 +880,30 @@ class Case(models.Model, AuthorMixin, QuestionMixin):
         self._ordered_series_cache = ordered
         return ordered
 
+    def get_case_named_stacks(self):
+        stacks = []
+        for series in self.get_ordered_series():
+            series_images = list(series.get_images())
+            series_images_with_urls = [(img, f"{REMOTE_URL}{img.image.url}") for img in series_images]
+            images = [url for _, url in series_images_with_urls]
+            declared_groups = _build_declared_series_groups(series, series_images_with_urls)
+            stacks.append(
+                {
+                    "name": str(series),
+                    "imageIds": images,
+                    "seriesId": series.pk,
+                    "series": declared_groups,
+                }
+            )
+        results = [
+            {
+                "caseId": f"CASE-{self.pk}",
+                "studyId": "Current Case",
+                "stacks": stacks,
+            }
+        ]
+        return json.dumps(results)
+
     @staticmethod
     def _parse_dicom_date(value):
         if not value:
@@ -2949,4 +2974,15 @@ class PrerequisiteRequired(Exception):
 
     def __init__(self, message=None, *, prereq=None):
         super().__init__(message or "Prerequisite required")
-        self.prereq = prereq
+        self.prereq = prereq
+
+
+class MultiuserSession(models.Model):
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    name = models.CharField(max_length=255, blank=True)
+    creator = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="created_multiuser_sessions")
+    active_case = models.ForeignKey(Case, on_delete=models.SET_NULL, null=True, blank=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    def __str__(self):
+        return f"Session {self.name or str(self.id)[:8]} by {self.creator}"

atlas/templates/atlas/base.html

@@ -145,6 +145,9 @@
                         <li class="nav-item">
                             <a class="nav-link" href="{% url 'atlas:question_schema_overview' %}" title="View and edit question schemas"><i class="bi bi-journal-text me-1" aria-hidden="true"></i>Question Schemas</a>
                         </li>
+                        <li class="nav-item">
+                            <a class="nav-link" href="{% url 'atlas:multiuser_dashboard' %}" title="Multiuser case sync and review"><i class="bi bi-people me-1" aria-hidden="true"></i>Multiuser Sync</a>
+                        </li>
                         <li class="nav-item">
                             <a class="nav-link" href="{% url 'atlas:help' %}" title="View the atlas help pages"><i class="bi bi-question-circle me-1" aria-hidden="true"></i>Help</a>
                         </li>

atlas/templates/atlas/multiuser_dashboard.html

@@ -0,0 +1,148 @@
+{% extends 'atlas/base.html' %}
+
+{% block title %}
+    Multiuser Sync Portal - Atlas
+{% endblock %}
+
+{% block content %}
+<div class="container py-4">
+    <div class="row mb-4 align-items-center">
+        <div class="col">
+            <h1 class="h3 mb-1"><i class="bi bi-people-fill text-primary me-2"></i>Multiuser DICOM Portal</h1>
+            <p class="text-muted">Create or join real-time collaborative review sessions with synchronized DICOM viewports.</p>
+        </div>
+    </div>
+
+    <div class="row">
+        <!-- Sidebar: Start a new session -->
+        <div class="col-md-4 mb-4">
+            <div class="card shadow-sm border-secondary">
+                <div class="card-header bg-dark text-white fw-bold">
+                    <i class="bi bi-plus-circle me-1"></i> Start New Session
+                </div>
+                <div class="card-body">
+                    <form method="POST" action="{% url 'atlas:multiuser_create_session' %}">
+                        {% csrf_token %}
+                        <div class="mb-3">
+                            <label for="sessionName" class="form-label">Session Name / Topic (Optional)</label>
+                            <input type="text" class="form-control bg-dark text-white border-secondary" id="sessionName" name="name" placeholder="e.g. Case Review Cohort A" max_length="255">
+                        </div>
+                        <button type="submit" class="btn btn-primary w-100">
+                            <i class="bi bi-play-fill me-1"></i> Start Session
+                        </button>
+                    </form>
+                </div>
+            </div>
+        </div>
+
+        <!-- Main content: Sessions list -->
+        <div class="col-md-8">
+            <!-- My Sessions -->
+            <div class="card shadow-sm mb-4 bg-dark text-white border-secondary">
+                <div class="card-header bg-secondary text-white fw-bold">
+                    <i class="bi bi-person-fill-check me-1"></i> Sessions You Managed
+                </div>
+                <div class="card-body p-0">
+                    {% if my_sessions %}
+                        <div class="table-responsive">
+                            <table class="table table-dark table-striped table-hover mb-0 align-middle">
+                                <thead>
+                                    <tr>
+                                        <th>Name</th>
+                                        <th>Active Case</th>
+                                        <th>Created At</th>
+                                        <th class="text-end">Action</th>
+                                    </tr>
+                                </thead>
+                                <tbody>
+                                    {% for session in my_sessions %}
+                                        <tr>
+                                            <td>
+                                                <strong class="text-info">{{ session.name|default:"Unnamed Session" }}</strong>
+                                                <br>
+                                                <small class="text-muted font-monospace">{{ session.id }}</small>
+                                            </td>
+                                            <td>
+                                                {% if session.active_case %}
+                                                    <span class="badge bg-success">{{ session.active_case.title|default:"Case Loaded" }}</span>
+                                                {% else %}
+                                                    <span class="badge bg-secondary">No case active</span>
+                                                {% endif %}
+                                            </td>
+                                            <td>{{ session.created_at|date:"d M Y, H:i" }}</td>
+                                            <td class="text-end">
+                                                <a href="{% url 'atlas:multiuser_session_detail' session_id=session.id %}" class="btn btn-outline-info btn-sm">
+                                                    Enter Workspace <i class="bi bi-arrow-right-short"></i>
+                                                </a>
+                                            </td>
+                                        </tr>
+                                    {% endfor %}
+                                </tbody>
+                            </table>
+                        </div>
+                    {% else %}
+                        <div class="p-4 text-center text-muted">
+                            <i class="bi bi-inbox-fill fs-2 mb-2 d-block"></i>
+                            You haven't created any sessions yet.
+                        </div>
+                    {% endif %}
+                </div>
+            </div>
+
+            <!-- Active public sessions -->
+            <div class="card shadow-sm bg-dark text-white border-secondary">
+                <div class="card-header bg-secondary text-white fw-bold">
+                    <i class="bi bi-globe me-1"></i> Active Invited Sessions (Last 24 Hours)
+                </div>
+                <div class="card-body p-0">
+                    {% if active_sessions %}
+                        <div class="table-responsive">
+                            <table class="table table-dark table-striped table-hover mb-0 align-middle">
+                                <thead>
+                                    <tr>
+                                        <th>Name</th>
+                                        <th>Host</th>
+                                        <th>Active Case</th>
+                                        <th>Created At</th>
+                                        <th class="text-end">Action</th>
+                                    </tr>
+                                </thead>
+                                <tbody>
+                                    {% for session in active_sessions %}
+                                        <tr>
+                                            <td>
+                                                <strong class="text-info">{{ session.name|default:"Unnamed Session" }}</strong>
+                                                <br>
+                                                <small class="text-muted font-monospace">{{ session.id }}</small>
+                                            </td>
+                                            <td>{{ session.creator.get_full_name|default:session.creator.username }}</td>
+                                            <td>
+                                                {% if session.active_case %}
+                                                    <span class="badge bg-success">{{ session.active_case.title|default:"Case Loaded" }}</span>
+                                                {% else %}
+                                                    <span class="badge bg-secondary">No case active</span>
+                                                {% endif %}
+                                            </td>
+                                            <td>{{ session.created_at|date:"d M Y, H:i" }}</td>
+                                            <td class="text-end">
+                                                <a href="{% url 'atlas:multiuser_session_detail' session_id=session.id %}" class="btn btn-outline-info btn-sm">
+                                                    Join Session <i class="bi bi-arrow-right-short"></i>
+                                                </a>
+                                            </td>
+                                        </tr>
+                                    {% endfor %}
+                                </tbody>
+                            </table>
+                        </div>
+                    {% else %}
+                        <div class="p-4 text-center text-muted">
+                            <i class="bi bi-broadcast fs-2 mb-2 d-block"></i>
+                            No other active sessions found. Create a session to invite others!
+                        </div>
+                    {% endif %}
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
+{% endblock %}

atlas/templates/atlas/multiuser_session_detail.html

@@ -0,0 +1,204 @@
+{% extends 'atlas/base.html' %}
+{% load static %}
+{% load django_htmx %}
+
+{% block title %}
+    Multiuser Workspace - {{ session.name|default:"Session" }}
+{% endblock %}
+
+{% block content %}
+<div class="container-fluid py-3 px-4">
+    <!-- Session Header -->
+    <div class="row align-items-center mb-3">
+        <div class="col-md-6">
+            <div class="d-flex align-items-center gap-2">
+                <a href="{% url 'atlas:multiuser_dashboard' %}" class="btn btn-outline-secondary btn-sm" title="Back to Dashboard">
+                    <i class="bi bi-arrow-left"></i>
+                </a>
+                <h1 class="h4 mb-0 text-white">
+                    <i class="bi bi-people text-info me-2"></i>{{ session.name|default:"Unnamed Session" }}
+                </h1>
+                <span class="badge bg-secondary font-monospace small">{{ session.id|stringformat:".8s" }}</span>
+            </div>
+            <div class="small text-muted mt-1">
+                Managed by <strong>{{ session.creator.get_full_name|default:session.creator.username }}</strong>
+            </div>
+        </div>
+        
+        <!-- Invite Sharing Link Widget -->
+        <div class="col-md-6 mt-2 mt-md-0 d-flex justify-content-md-end">
+            <div class="input-group input-group-sm" style="max-width: 420px;">
+                <span class="input-group-text bg-secondary text-white border-secondary">
+                    <i class="bi bi-link-45deg"></i> Share Invite
+                </span>
+                <input type="text" id="inviteLinkInput" class="form-control bg-dark text-white border-secondary" readonly value="">
+                <button class="btn btn-info" type="button" id="copyLinkBtn" onclick="copyInviteLink()">
+                    <i class="bi bi-clipboard me-1"></i> Copy
+                </button>
+            </div>
+        </div>
+    </div>
+
+    <!-- Manager Control Bar -->
+    {% if is_manager %}
+        <div class="card bg-dark border-info text-white mb-4">
+            <div class="card-body py-2 px-3 d-flex align-items-center flex-wrap gap-3">
+                <div class="fw-semibold text-info small uppercase me-2">
+                    <i class="bi bi-gear-fill me-1 animate-spin"></i> Host Controls:
+                </div>
+                
+                <!-- Search Cases input -->
+                <div class="position-relative flex-grow-1" style="max-width: 480px;">
+                    <div class="input-group input-group-sm">
+                        <span class="input-group-text bg-secondary text-white border-secondary">
+                            <i class="bi bi-search"></i>
+                        </span>
+                        <input type="text" id="multiuserCaseSearch" class="form-control bg-dark text-white border-secondary" 
+                               placeholder="Search cases to load..."
+                               hx-get="{% url 'atlas:multiuser_search_cases' session_id=session.id %}"
+                               hx-trigger="input delay:300ms, focus"
+                               hx-target="#caseSearchDropdown"
+                               hx-swap="innerHTML"
+                               onfocus="document.getElementById('caseSearchDropdown').style.display='block'"
+                               autocomplete="off">
+                    </div>
+                    <!-- Autocomplete Dropdown list -->
+                    <div id="caseSearchDropdown" class="position-absolute w-100 mt-1" style="display: none; z-index: 10000;">
+                        <!-- Results injected by HTMX -->
+                    </div>
+                </div>
+                
+                <span class="text-muted small">|</span>
+                
+                <!-- Users Counter -->
+                <div class="small text-light">
+                    <i class="bi bi-person-fill text-success"></i> Connected Users: <span id="connectedUsersCount" class="badge bg-secondary">1</span>
+                </div>
+            </div>
+        </div>
+    {% else %}
+        <!-- Participant Status Bar -->
+        <div class="card bg-dark border-secondary text-white mb-4">
+            <div class="card-body py-2 px-3 d-flex align-items-center justify-content-between">
+                <div class="small text-muted">
+                    <i class="bi bi-broadcast text-warning me-1"></i> You are viewing this session in real-time. Viewport controls are synchronized.
+                </div>
+                <div class="small text-light">
+                    <i class="bi bi-person-fill text-success"></i> Connected Users: <span id="connectedUsersCountParticipant" class="badge bg-secondary">1</span>
+                </div>
+            </div>
+        </div>
+    {% endif %}
+
+    <!-- Main Workspace Area -->
+    <div id="multiuser-case-container" 
+         hx-get="{% url 'atlas:multiuser_case_content_partial' session_id=session.id %}" 
+         hx-trigger="load" 
+         hx-swap="innerHTML"
+    >
+        <div class="d-flex justify-content-center py-5">
+            <div class="spinner-border text-info" role="status">
+                <span class="visually-hidden">Loading case workspace...</span>
+            </div>
+        </div>
+    </div>
+</div>
+{% endblock %}
+
+{% block js %}
+<script type="text/javascript">
+    // Set invite link input on load
+    document.addEventListener("DOMContentLoaded", function() {
+        const inviteInput = document.getElementById("inviteLinkInput");
+        if (inviteInput) {
+            inviteInput.value = window.location.href;
+        }
+    });
+
+    // Copy to clipboard helper
+    function copyInviteLink() {
+        const inviteInput = document.getElementById("inviteLinkInput");
+        const copyBtn = document.getElementById("copyLinkBtn");
+        
+        inviteInput.select();
+        inviteInput.setSelectionRange(0, 99999); // For mobile devices
+        
+        navigator.clipboard.writeText(inviteInput.value).then(function() {
+            const origHTML = copyBtn.innerHTML;
+            copyBtn.innerHTML = '<i class="bi bi-check-lg me-1"></i> Copied!';
+            copyBtn.className = "btn btn-success";
+            setTimeout(function() {
+                copyBtn.innerHTML = origHTML;
+                copyBtn.className = "btn btn-info";
+            }, 2000);
+        }).catch(function(err) {
+            console.error('Could not copy link: ', err);
+        });
+    }
+
+    // Hide search autocomplete dropdown when clicking outside
+    document.addEventListener("click", function(e) {
+        const dropdown = document.getElementById("caseSearchDropdown");
+        const searchInput = document.getElementById("multiuserCaseSearch");
+        if (dropdown && searchInput && !dropdown.contains(e.target) && e.target !== searchInput) {
+            dropdown.style.display = "none";
+        }
+    });
+
+    // Session-level WebSocket to listen for control signals
+    (function() {
+        const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
+        const host = window.location.host || "localhost:8080";
+        const wsUrl = `${protocol}//${host}/ws/multiuser/{{ session.id }}/`;
+        
+        console.log("Connecting session WS to", wsUrl);
+        const socket = new WebSocket(wsUrl);
+        
+        socket.onmessage = function(event) {
+            try {
+                const data = JSON.parse(event.data);
+                console.log("Session WS event:", data.type, data);
+                
+                if (data.type === 'change_case') {
+                    console.log("Session host changed case to", data.case_id);
+                    // Fetch new case content via HTMX
+                    htmx.ajax('GET', "{% url 'atlas:multiuser_case_content_partial' session_id=session.id %}", {
+                        target: "#multiuser-case-container",
+                        swap: "innerHTML"
+                    });
+                } else if (data.type === 'room_status') {
+                    // Update user count
+                    const userCount = Object.keys(data.users || {}).length;
+                    const mgrCountBadge = document.getElementById("connectedUsersCount");
+                    const partCountBadge = document.getElementById("connectedUsersCountParticipant");
+                    
+                    if (mgrCountBadge) mgrCountBadge.textContent = userCount;
+                    if (partCountBadge) partCountBadge.textContent = userCount;
+                }
+            } catch (err) {
+                console.error("Error processing session WS message", err);
+            }
+        };
+        
+        socket.onclose = function(e) {
+            console.warn("Session WS closed. Reconnecting in 3s...", e);
+            setTimeout(arguments.callee, 3000);
+        };
+        
+        socket.onerror = function(err) {
+            console.error("Session WS error:", err);
+        };
+    })();
+</script>
+
+<style>
+    .animate-spin {
+        animation: spin 8s linear infinite;
+        display: inline-block;
+    }
+    @keyframes spin {
+        from { transform: rotate(0deg); }
+        to { transform: rotate(360deg); }
+    }
+</style>
+{% endblock %}

atlas/templates/atlas/partials/_multiuser_case_content.html

@@ -0,0 +1,74 @@
+<div class="row">
+    <!-- Left column: DICOM Viewer -->
+    <div class="col-lg-9 mb-4">
+        <div class="card bg-dark border-secondary">
+            <div class="card-header bg-secondary text-white d-flex align-items-center justify-content-between py-1 px-3">
+                <span class="fw-semibold"><i class="bi bi-display me-1"></i> Interactive DICOM Viewer</span>
+                <span class="badge bg-info">Case: {{ case.title|default:"Untitled Case" }}</span>
+            </div>
+            <div class="card-body p-0">
+                <div id="viewer-container" class="viewer-resizable-container" style="height: 70vh; min-height: 500px; max-height: 900px; position: relative; overflow: hidden; width: 100%;">
+                    <div id="main_viewer" class="dicom-viewer-root"
+                         data-auto-cache-stack="false"
+                         data-named-stacks='{{ named_stacks_json }}'
+                         data-multiuser-room="{{ session.id }}"
+                         data-username="{{ request.user.username }}"
+                         data-is-staff="{% if is_manager %}true{% else %}false{% endif %}"
+                         style="width: 100%; height: 100%;"
+                    ></div>
+                </div>
+            </div>
+        </div>
+    </div>
+
+    <!-- Right column: Case Details -->
+    <div class="col-lg-3">
+        <div class="card bg-dark border-secondary text-white shadow-sm mb-4">
+            <div class="card-header bg-secondary text-white fw-bold">
+                <i class="bi bi-info-circle-fill me-1"></i> Case Information
+            </div>
+            <div class="card-body">
+                <h5 class="text-info mb-2">{{ case.title|default:"Untitled Case" }}</h5>
+                <hr class="border-secondary mt-0">
+                
+                {% if case.description %}
+                    <div class="mb-3">
+                        <h6 class="text-muted mb-1 small uppercase fw-bold">Description</h6>
+                        <p class="mb-0 small">{{ case.description }}</p>
+                    </div>
+                {% endif %}
+                
+                {% if case.history %}
+                    <div class="mb-3">
+                        <h6 class="text-muted mb-1 small uppercase fw-bold">Patient History</h6>
+                        <p class="mb-0 small">{{ case.history|linebreaksbr }}</p>
+                    </div>
+                {% endif %}
+
+                {% if is_manager %}
+                    {% if case.discussion %}
+                        <div class="mb-3">
+                            <h6 class="text-warning mb-1 small uppercase fw-bold">Discussion (Host Only)</h6>
+                            <p class="mb-0 small text-light-emphasis">{{ case.discussion|linebreaksbr }}</p>
+                        </div>
+                    {% endif %}
+                    {% if case.report %}
+                        <div class="mb-3">
+                            <h6 class="text-warning mb-1 small uppercase fw-bold">Model Report (Host Only)</h6>
+                            <p class="mb-0 small text-light-emphasis">{{ case.report|linebreaksbr }}</p>
+                        </div>
+                    {% endif %}
+                {% endif %}
+            </div>
+        </div>
+    </div>
+</div>
+
+<script type="text/javascript">
+    if (typeof window.remountDicomViewer === "function") {
+        console.debug("Remounting DICOM viewer for case change");
+        window.remountDicomViewer('main_viewer');
+    } else {
+        console.warn("window.remountDicomViewer is not defined!");
+    }
+</script>

atlas/templates/atlas/partials/_multiuser_case_search_results.html

@@ -0,0 +1,28 @@
+<ul class="list-group bg-dark border-secondary shadow-lg" style="max-height: 300px; overflow-y: auto;">
+    {% for case in cases %}
+        <li class="list-group-item list-group-item-action bg-dark text-white border-secondary d-flex justify-content-between align-items-center py-2 px-3">
+            <div class="me-2 text-truncate">
+                <strong class="text-info d-block text-truncate">{{ case.title|default:"Untitled Case" }}</strong>
+                <span class="text-muted small">
+                    Authors: 
+                    {% for author in case.author.all %}
+                        {{ author.username }}{% if not forloop.last %}, {% endif %}
+                    {% empty %}
+                        Unknown
+                    {% endfor %}
+                </span>
+            </div>
+            <button class="btn btn-primary btn-sm flex-shrink-0"
+                    hx-post="{% url 'atlas:multiuser_load_case' session_id=session.id %}"
+                    hx-vals='{"case_id": "{{ case.pk }}"}'
+                    hx-target="#multiuser-case-container"
+                    hx-swap="innerHTML"
+                    onclick="document.getElementById('caseSearchDropdown').style.display='none'; document.getElementById('multiuserCaseSearch').value='';"
+            >
+                Load Case
+            </button>
+        </li>
+    {% empty %}
+        <li class="list-group-item bg-dark text-muted border-secondary py-2 px-3">No matching cases found</li>
+    {% endfor %}
+</ul>

atlas/templates/atlas/partials/_multiuser_empty_case.html

@@ -0,0 +1,12 @@
+<div class="card bg-dark border-secondary text-white text-center py-5 shadow-sm">
+    <div class="card-body py-5">
+        <i class="bi bi-display fs-1 text-muted mb-3 d-block"></i>
+        {% if is_manager %}
+            <h4 class="text-info">Ready to start review!</h4>
+            <p class="text-muted mb-4">Search and select a case above to load it into the session.</p>
+        {% else %}
+            <h4 class="text-info">Welcome to the session!</h4>
+            <p class="text-muted">Waiting for the session host to load a case...</p>
+        {% endif %}
+    </div>
+</div>

atlas/tests/test_multiuser.py

@@ -0,0 +1,103 @@
+import pytest
+from django.urls import reverse
+from atlas.models import Case, MultiuserSession
+from pytest_django.asserts import assertContains, assertRedirects
+
+@pytest.mark.django_db
+def test_multiuser_session_model_creation(create_user):
+    user = create_user
+    session = MultiuserSession.objects.create(
+        name="Test Sync Session",
+        creator=user
+    )
+    assert session.name == "Test Sync Session"
+    assert session.creator == user
+    assert session.active_case is None
+    assert str(session).startswith("Session Test Sync")
+
+@pytest.mark.django_db
+def test_multiuser_dashboard_view_anonymous_redirect(client):
+    response = client.get(reverse("atlas:multiuser_dashboard"))
+    assertRedirects(response, f"{reverse('login')}?next={reverse('atlas:multiuser_dashboard')}")
+
+@pytest.mark.django_db
+def test_multiuser_dashboard_lists_sessions(client, create_user):
+    user = create_user
+    session1 = MultiuserSession.objects.create(name="User Session 1", creator=user)
+    
+    other_user = create_user
+    session2 = MultiuserSession.objects.create(name="Other Session 2", creator=other_user)
+    
+    client.force_login(user)
+    response = client.get(reverse("atlas:multiuser_dashboard"))
+    assert response.status_code == 200
+    assertContains(response, "User Session 1")
+    assertContains(response, "Other Session 2")
+    assertContains(response, "Start New Session")
+
+@pytest.mark.django_db
+def test_multiuser_create_session_action(client, create_user):
+    client.force_login(create_user)
+    response = client.post(reverse("atlas:multiuser_create_session"), data={"name": "My New Session"})
+    
+    session = MultiuserSession.objects.get(name="My New Session")
+    assertRedirects(response, reverse("atlas:multiuser_session_detail", kwargs={"session_id": session.id}))
+
+@pytest.mark.django_db
+def test_multiuser_session_detail_manager_vs_participant(client, create_user):
+    manager = create_user
+    participant = create_user
+    session = MultiuserSession.objects.create(name="Collaboration Session", creator=manager)
+    
+    # Manager view
+    client.force_login(manager)
+    response = client.get(reverse("atlas:multiuser_session_detail", kwargs={"session_id": session.id}))
+    assert response.status_code == 200
+    assertContains(response, "Host Controls:")
+    assertContains(response, "Search cases to load...")
+    
+    # Participant view
+    client.force_login(participant)
+    response = client.get(reverse("atlas:multiuser_session_detail", kwargs={"session_id": session.id}))
+    assert response.status_code == 200
+    assert "Host Controls:" not in response.content.decode("utf-8")
+    assertContains(response, "You are viewing this session in real-time")
+
+@pytest.mark.django_db
+def test_multiuser_search_cases_permission(client, create_user):
+    manager = create_user
+    participant = create_user
+    session = MultiuserSession.objects.create(name="Search Session", creator=manager)
+    
+    # Participant cannot search
+    client.force_login(participant)
+    response = client.get(reverse("atlas:multiuser_search_cases", kwargs={"session_id": session.id}) + "?q=test")
+    assert response.status_code == 403
+    
+    # Manager can search
+    client.force_login(manager)
+    response = client.get(reverse("atlas:multiuser_search_cases", kwargs={"session_id": session.id}) + "?q=test")
+    assert response.status_code == 200
+
+@pytest.mark.django_db
+def test_multiuser_load_case_action(client, create_user, make_case):
+    manager = create_user
+    participant = create_user
+    session = MultiuserSession.objects.create(name="Load Case Session", creator=manager)
+    
+    case = make_case(title="Multiuser Dicom Case")
+    case.author.add(manager) # Grant access to manager
+    
+    # Participant cannot load
+    client.force_login(participant)
+    response = client.post(reverse("atlas:multiuser_load_case", kwargs={"session_id": session.id}), data={"case_id": case.pk})
+    assert response.status_code == 403
+    
+    # Manager loads case
+    client.force_login(manager)
+    response = client.post(reverse("atlas:multiuser_load_case", kwargs={"session_id": session.id}), data={"case_id": case.pk})
+    assert response.status_code == 200
+    
+    session.refresh_from_db()
+    assert session.active_case == case
+    assertContains(response, "Interactive DICOM Viewer")

atlas/urls.py

@@ -840,4 +840,11 @@ urlpatterns = [
         views.collection_supervision,
         name="collection_supervision",
     ),
+    # Multiuser DICOM Portal
+    path("multiuser/", views.multiuser_dashboard, name="multiuser_dashboard"),
+    path("multiuser/create/", views.multiuser_create_session, name="multiuser_create_session"),
+    path("multiuser/session/<uuid:session_id>/", views.multiuser_session_detail, name="multiuser_session_detail"),
+    path("multiuser/session/<uuid:session_id>/case-content/", views.multiuser_case_content_partial, name="multiuser_case_content_partial"),
+    path("multiuser/session/<uuid:session_id>/load-case/", views.multiuser_load_case, name="multiuser_load_case"),
+    path("multiuser/session/<uuid:session_id>/search-cases/", views.multiuser_search_cases, name="multiuser_search_cases"),
 ]

atlas/views.py

@@ -124,6 +124,7 @@ from .models import (
     CidReportAnswer,
     Condition,
     Differential,
+    MultiuserSession,
     PathologicalProcess,
     Presentation,
     QuestionSchema,
@@ -10477,3 +10478,122 @@ def collection_case_displaysetup(request, collection_id, case_number=None, case_
         "collection_length": case_count,
 
     })
+
+
+@login_required
+def multiuser_dashboard(request):
+    import datetime
+    from django.utils import timezone
+    
+    my_sessions = MultiuserSession.objects.filter(creator=request.user).order_by("-created_at")
+    recent_limit = timezone.now() - datetime.timedelta(hours=24)
+    active_sessions = MultiuserSession.objects.exclude(creator=request.user).filter(created_at__gte=recent_limit).order_by("-created_at")
+    
+    return render(request, "atlas/multiuser_dashboard.html", {
+        "my_sessions": my_sessions,
+        "active_sessions": active_sessions,
+    })
+
+
+@login_required
+def multiuser_create_session(request):
+    name = request.POST.get("name", "").strip()
+    session = MultiuserSession.objects.create(
+        name=name,
+        creator=request.user
+    )
+    return redirect("atlas:multiuser_session_detail", session_id=session.id)
+
+
+@login_required
+def multiuser_session_detail(request, session_id):
+    session = get_object_or_404(MultiuserSession, id=session_id)
+    is_manager = (request.user == session.creator)
+    
+    return render(request, "atlas/multiuser_session_detail.html", {
+        "session": session,
+        "is_manager": is_manager,
+        "active_case": session.active_case,
+    })
+
+
+@login_required
+def multiuser_search_cases(request, session_id):
+    from django.http import HttpResponseForbidden
+    session = get_object_or_404(MultiuserSession, id=session_id)
+    if request.user != session.creator and not request.user.is_staff:
+        return HttpResponseForbidden("Only the session manager can search cases.")
+    
+    q = request.GET.get("q", "").strip()
+    from .helpers import get_cases_available_to_user
+    qs = get_cases_available_to_user(request.user)
+    if q:
+        qs = qs.filter(title__icontains=q)
+    
+    cases = qs.order_by("title")[:15]
+    return render(request, "atlas/partials/_multiuser_case_search_results.html", {
+        "cases": cases,
+        "session": session,
+    })
+
+
+@login_required
+def multiuser_case_content_partial(request, session_id):
+    session = get_object_or_404(MultiuserSession, id=session_id)
+    case = session.active_case
+    
+    if not case:
+        return render(request, "atlas/partials/_multiuser_empty_case.html", {
+            "session": session,
+            "is_manager": (request.user == session.creator),
+        })
+    
+    named_stacks_json = case.get_case_named_stacks()
+    
+    return render(request, "atlas/partials/_multiuser_case_content.html", {
+        "session": session,
+        "case": case,
+        "named_stacks_json": named_stacks_json,
+        "is_manager": (request.user == session.creator),
+    })
+
+
+@login_required
+@require_POST
+def multiuser_load_case(request, session_id):
+    from django.http import HttpResponseForbidden
+    session = get_object_or_404(MultiuserSession, id=session_id)
+    if request.user != session.creator and not request.user.is_staff:
+        return HttpResponseForbidden("Only the session manager can load cases.")
+    
+    case_id = request.POST.get("case_id")
+    if not case_id:
+        return HttpResponse("No case selected", status=400)
+        
+    from .helpers import get_cases_available_to_user
+    case = get_object_or_404(get_cases_available_to_user(request.user), pk=case_id)
+    
+    session.active_case = case
+    session.save()
+    
+    # Broadcast to channels group
+    from channels.layers import get_channel_layer
+    from asgiref.sync import async_to_sync
+    
+    channel_layer = get_channel_layer()
+    if channel_layer:
+        async_to_sync(channel_layer.group_send)(
+            f"multiuser_{session.id}",
+            {
+                "type": "change_case",
+                "case_id": case.id
+            }
+        )
+    
+    named_stacks_json = case.get_case_named_stacks()
+    return render(request, "atlas/partials/_multiuser_case_content.html", {
+        "session": session,
+        "case": case,
+        "named_stacks_json": named_stacks_json,
+        "is_manager": True,
+    })

generic/consumers.py

@@ -2,21 +2,39 @@ import logging
 from channels.generic.websocket import AsyncJsonWebsocketConsumer
 from django.core.cache import cache
 from asgiref.sync import sync_to_async
+from channels.db import database_sync_to_async
+from django.core.exceptions import ValidationError
+from atlas.models import MultiuserSession
 
 logger = logging.getLogger(__name__)
 
 class MultiuserConsumer(AsyncJsonWebsocketConsumer):
+    @database_sync_to_async
+    def get_session(self, session_id):
+        try:
+            return MultiuserSession.objects.select_related('creator').get(id=session_id)
+        except (MultiuserSession.DoesNotExist, ValidationError):
+            return None
+
     async def connect(self):
         self.room_name = self.scope['url_route']['kwargs']['room_name']
         self.room_group_name = f'multiuser_{self.room_name}'
         self.user = self.scope.get('user')
 
+        # Get session from DB using self.room_name
+        session = await self.get_session(self.room_name)
+        if not session:
+            # Reject connection if session does not exist
+            await self.close()
+            return
+
         # Determine username and staff privilege
         if self.user and self.user.is_authenticated:
             self.username = self.user.username
-            self.is_staff = self.user.is_staff
+            # Manager is the creator or a site admin/staff
+            self.is_staff = (self.user == session.creator) or self.user.is_staff
         else:
-            self.username = 'Anonymous'
+            self.username = f"Guest_{self.channel_name[-4:]}"
             self.is_staff = False
 
         # Add to channels group
@@ -129,6 +147,12 @@ class MultiuserConsumer(AsyncJsonWebsocketConsumer):
             'controller_username': event['controller_username']
         })
 
+    async def change_case(self, event):
+        await self.send_json({
+            'type': 'change_case',
+            'case_id': event['case_id']
+        })
+
     # Cache state helpers (using sync_to_async for thread-safe Memcached/Redis interactions)
     def get_cache_key(self):
         return f"multiuser_room_{self.room_name}"

generic/routing.py

@@ -2,5 +2,5 @@ from django.urls import re_path
 from . import consumers
 
 websocket_urlpatterns = [
-    re_path(r'^ws/multiuser/(?P<room_name>\w+)/$', consumers.MultiuserConsumer.as_asgi()),
+    re_path(r'^ws/multiuser/(?P<room_name>[\w-]+)/$', consumers.MultiuserConsumer.as_asgi()),
 ]