vscode-dashboard-webviews

name	vscode-dashboard-webviews
description	Patterns for building dashboard webviews with tabs and visualizations
domain	vscode-extension-ui
confidence	high
source	manual

Context

VS Code dashboard webviews require specific patterns for tab navigation, data visualization, and lifecycle management. This skill captures the architecture established for SquadUI's dashboard feature.

Patterns

Single Webview with Tab Navigation

Use a single webview panel that hosts multiple tabs rather than separate webviews for related features:

export class SquadDashboardWebview {
    private panel: vscode.WebviewPanel | undefined;
    
    constructor(extensionUri: vscode.Uri, dataProvider: DataProvider) {
        this.extensionUri = extensionUri;
        this.dataProvider = dataProvider;
    }
    
    async show(): Promise<void> {
        if (this.panel) {
            this.panel.reveal(vscode.ViewColumn.One);
            await this.updateContent();
        } else {
            this.createPanel();
            await this.updateContent();
        }
    }
}

Why: Reduces activation cost, natural grouping for related insights, avoids panel proliferation.

Webview Configuration

this.panel = vscode.window.createWebviewPanel(
    'squadui.dashboard',
    'Squad Dashboard',
    vscode.ViewColumn.One,
    {
        enableScripts: true,              // Required for tab navigation JS
        retainContextWhenHidden: true,    // Preserve tab state
        localResourceRoots: [this.extensionUri],
    }
);

Data Pipeline Architecture

Separate concerns: Service → Builder → Template

OrchestrationLogService + DataProvider
    ↓
DashboardDataBuilder (transforms raw logs → chart data)
    ↓
htmlTemplate.ts (renders HTML with embedded data)

Builder Pattern:

export class DashboardDataBuilder {
    buildDashboardData(
        logEntries: LogEntry[],
        members: Member[],
        tasks: Task[]
    ): DashboardData {
        return {
            velocity: {
                timeline: this.buildVelocityTimeline(tasks),
                heatmap: this.buildActivityHeatmap(members, logEntries),
            },
            activity: { /* ... */ },
            decisions: { /* ... */ },
        };
    }
}

Lightweight Visualization

Avoid chart libraries. Use HTML5 Canvas + CSS Grid for simple visualizations:

// Line chart with Canvas
function renderVelocityChart() {
    const canvas = document.getElementById('velocity-chart');
    const ctx = canvas.getContext('2d');
    
    // Draw axes
    ctx.strokeStyle = 'var(--vscode-panel-border)';
    ctx.moveTo(padding, padding);
    ctx.lineTo(padding, padding + height);
    ctx.stroke();
    
    // Draw line
    ctx.strokeStyle = 'var(--vscode-charts-blue)';
    timeline.forEach((point, i) => {
        const x = padding + i * stepX;
        const y = padding + height - (point.value / maxValue) * height;
        i === 0 ? ctx.moveTo(x, y) : ctx.lineTo(x, y);
    });
    ctx.stroke();
}

// Heatmap with CSS Grid
<div class="heatmap-grid">
    ${heatmap.map(point => `
        <div class="heatmap-cell">
            <div class="member-name">${point.member}</div>
            <div class="activity-bar">
                <div class="activity-fill" style="width: ${point.activityLevel * 100}%"></div>
            </div>
        </div>
    `).join('')}
</div>

Status-Based Visual Styling

Use color coding and borders to indicate state at-a-glance:

.task-item.done {
    background-color: rgba(40, 167, 69, 0.15);
    border-left: 3px solid var(--vscode-charts-green);
}
.task-item.in-progress {
    background-color: rgba(255, 193, 7, 0.15);
    border-left: 3px solid var(--vscode-charts-orange);
}

const isDone = task.endDate !== null;
const statusClass = isDone ? 'done' : 'in-progress';
tasksHtml += `<li class="task-item ${statusClass}">...</li>`;

Color Palette:

• Green: Done/completed (var(--vscode-charts-green))
• Amber/Orange: In progress (var(--vscode-charts-orange))
• Blue: Charts/data visualization (var(--vscode-charts-blue))

CSS Tooltips

Pure CSS tooltips for hover details (no JS needed):

.task-item .tooltip {
    visibility: hidden;
    position: absolute;
    z-index: 1000;
    bottom: 125%;
    left: 12px;
    min-width: 250px;
    background-color: var(--vscode-editorWidget-background);
    border: 1px solid var(--vscode-editorWidget-border);
    padding: 10px;
    opacity: 0;
    transition: opacity 0.2s;
}
.task-item:hover .tooltip {
    visibility: visible;
    opacity: 1;
}

<li class="task-item" title="Task name">
    <span>Task name</span>
    <div class="tooltip">
        <div class="tooltip-title">Task name</div>
        <div class="tooltip-meta">Status: Completed</div>
    </div>
</li>

Why CSS tooltips: Lighter than JS-based solutions, no postMessage overhead, theme-aware via CSS variables.

Tab Navigation (Client-Side)

Use vanilla JS for tab switching — no frameworks needed:

document.querySelectorAll('.tab').forEach(tab => {
    tab.addEventListener('click', () => {
        const targetTab = tab.dataset.tab;
        
        // Update buttons
        document.querySelectorAll('.tab').forEach(t => t.classList.remove('active'));
        tab.classList.add('active');
        
        // Update content
        document.querySelectorAll('.tab-content').forEach(c => c.classList.remove('active'));
        document.getElementById(targetTab + '-tab').classList.add('active');
    });
});

Data Embedding

Serialize data as JSON in HTML template:

export function getDashboardHtml(data: DashboardData): string {
    const velocityDataJson = JSON.stringify(data.velocity);
    
    return `
    <script>
        const velocityData = ${velocityDataJson};
        renderVelocityChart();
    </script>
    `;
}

Security: CSP allows script-src 'unsafe-inline' for inline scripts. Data is server-controlled, not user input.

File Structure

src/views/
  SquadDashboardWebview.ts      ← Main webview class
  dashboard/                     ← Dashboard-specific logic
    DashboardDataBuilder.ts      ← Data transformation
    htmlTemplate.ts              ← HTML generation

Status Bar Integration

Wire status bar to open dashboard:

this.statusBarItem.command = 'squadui.openDashboard';

User clicks status bar → dashboard opens → sees visualizations.

Examples

Building a Heatmap

buildActivityHeatmap(members: Member[], logs: LogEntry[]): HeatmapPoint[] {
    const participationCount = new Map<string, number>();
    let maxParticipation = 0;
    
    for (const entry of logs) {
        for (const participant of entry.participants) {
            const count = (participationCount.get(participant) ?? 0) + 1;
            participationCount.set(participant, count);
            maxParticipation = Math.max(maxParticipation, count);
        }
    }
    
    // Normalize to 0.0-1.0 scale
    return members.map(member => ({
        member: member.name,
        activityLevel: maxParticipation > 0 
            ? (participationCount.get(member.name) ?? 0) / maxParticipation 
            : 0,
    }));
}

Timeline Chart (30 days, fill gaps)

buildVelocityTimeline(tasks: Task[]): DataPoint[] {
    const now = new Date();
    const thirtyDaysAgo = new Date(now.getTime() - 30 * 24 * 60 * 60 * 1000);
    
    const tasksByDate = new Map<string, number>();
    for (const task of tasks.filter(t => t.status === 'completed')) {
        const dateKey = task.completedAt.toISOString().split('T')[0];
        tasksByDate.set(dateKey, (tasksByDate.get(dateKey) ?? 0) + 1);
    }
    
    // Fill in missing dates with 0 counts
    const timeline: DataPoint[] = [];
    for (let d = new Date(thirtyDaysAgo); d <= now; d.setDate(d.getDate() + 1)) {
        const dateKey = d.toISOString().split('T')[0];
        timeline.push({
            date: dateKey,
            completedTasks: tasksByDate.get(dateKey) ?? 0,
        });
    }
    
    return timeline;
}

Anti-Patterns

• Heavy chart libraries — Chart.js, D3.js add bundle bloat. Use Canvas + CSS Grid.
• Multiple webviews for related views — Consolidate into one tabbed panel.
• Server-side rendering on every message — Embed data once, let client-side JS handle interactions.
• External CSS/JS files — Inline everything for portability (CSP compliance).
• Forgetting retainContextWhenHidden — Tabs lose state when user switches away.
• JavaScript tooltips — Use pure CSS tooltips. Lighter and theme-aware via CSS variables.
• Inline HTML attribute styling — Use CSS classes and VS Code theme variables for consistent theming.
• Rendering canvas charts on hidden tabs — Canvas elements inside display: none containers return offsetWidth === 0. Setting canvas.width = canvas.offsetWidth produces a zero-width bitmap. Always defer canvas rendering until the tab is visible. Add offsetWidth === 0 guards as safety nets.
• Re-attaching event listeners on re-render — When a render function is called multiple times (e.g., on tab switch), use a guard (Set, flag) to attach listeners only once. Otherwise each call stacks duplicate handlers.