# Building EventMocha: An Autonomous Multi-Agent Assistant with Google ADK, Gemini Live Voice, and Workspace Automation > Source: > Published: 2026-08-31 22:05:31+00:00 🚀 **This app was built for entering the #AllThingsAgentic Hackathon** ## ⚡ TL;DR - **What it is**: **EventMocha** ☕ is an autonomous, full-stack multi-agent assistant that transforms high-level event concepts into complete, production-ready promotional campaigns and scheduled calendar workflows in real time. - **Key Capabilities**: - 🎨 **Multimodal Generation**: Interleaved HTML copy, Imagen visual posters, and cinematic Veo video teasers. - 🔄 **Targeted Revisions**: Visual reference conditioning, copy preservation, and full version history tracking (`v1` → `v2` ). - 📅 **Workspace Automation**: Automated creation of Google Calendar events, Google Tasks, and Gmail drafts via Model Context Protocol (MCP). - 🎙️ **Live Voice**: Real-time bidirectional voice conversation via Gemini Live API + Web AudioWorklets. - **Core Tech**: Google ADK (Python), Gemini 3.7 Flash, Gemini 2.5 Flash, Imagen, Veo, React 19, FastAPI, Cloud Firestore, GCS. ## 💡 The Problem: The Fragmented Chaos of Event Planning Planning any event — whether a 500-person developer conference, a community workshop, or a product launch — usually requires juggling multiple disconnected tools: - Brainstorming themes and agendas in note apps. - Generating copy in text-only chatbots. - Designing graphics and posters in separate design software. - Rendering video teasers. - Manually entering calendar blocks, task checklists, and email invite drafts. When feedback arrives (*"Can we make the poster darker and update the date?"*), the entire manual cycle repeats. I built **EventMocha** to bridge this gap. It acts as an autonomous creative agency and coordinator in a single continuous session. ## 🏗️ Multi-Agent Architecture EventMocha is built on a modular multi-agent system powered by the **Google Agent Development Kit (ADK)** and the **Gemini 2.5 / 3.7 Flash** model family. ## 🔍 Under the Hood: Key Engineering Highlights ### 1. 🎨 Symmetrical Multimodal Pipeline (Imagen & Veo) To keep persistent session state lightweight and prevent token bloat, I designed a symmetrical `after_model_callback` architecture: - **Copy & Placeholder Generation**: Specialist agents (`MultimodalContentCreator` and `VideoGenerator` ) output rich HTML copy alongside placeholders. - **Callback Media Generation**: An asynchronous callback intercepts these placeholders, triggers Google GenAI / Imagen for visuals and Google Veo for 720p HD video teasers, uploads assets directly to Cloud Storage (GCS), and injects live media URLs into the rendered card. ### 2. 🔄 Targeted Revisions with Version Lineage Tracking One of the toughest challenges in creative AI is the **revision loop**. If a user asks to tweak one specific asset, you shouldn't regenerate unrelated assets or discard approved copy. - **Deterministic Staging**: The `stage_revision_targets` tool matches natural language critique to specific assets by title, category, or ID. - **Visual Reference Conditioning**: When revising an image, previous version image bytes are passed to Imagen as conditioning context to preserve composition and character consistency. - **Copy Preservation & Reuse**: If only copy changes, existing media URLs are preserved without triggering expensive re-rendering. - **Version History (**`v1` → `v2` → `v3` ): Every asset maintains complete lineage in Firestore and session state, allowing users to toggle between historical versions in the UI. ### 3. 📅 Real-World Action via Google Workspace MCP Content creation is paired with immediate execution. EventMocha integrates with a dedicated FastMCP server over HTTP: - Automatically schedules **Google Calendar** events with proper timezone offsets. - Populates actionable items in **Google Tasks**. - Composes ready-to-send email drafts in **Gmail** with embedded HTML bodies. - Uses stateless OAuth 2.1 with AES-GCM token encryption. ### 4. 🎙️ Low-Latency Live Voice Interaction (Gemini Live API) Instead of relying on standard turn-based text chat, EventMocha supports bidirectional, real-time voice streaming: - **AudioWorklet Resampling**: The frontend captures microphone audio at 16kHz mono via custom `AudioWorkletProcessor` nodes and streams back 24kHz agent speech over WebSockets. - **Dynamic Live Transcripts**: Real-time speech-to-text bubbles accumulate fluidly on the screen with real-time waveform visualizers. - **Multimodal Voice Controls**: Users can speak instructions while simultaneously typing, attaching images, or inspecting generated visual cards. ## 🛠️ Tech Stack Overview - **Frontend**: React 19, Vite, TanStack Query, TailwindCSS, Web Audio API (AudioWorklet). - **Backend & Multi-Agent**: FastAPI, Python ADK (Agent Development Kit), Gemini 3.7 Flash, Gemini 2.5 Flash (Live Voice API), Google GenAI SDK. - **Storage & State**: Cloud Firestore (Native Mode), Google Cloud Storage (GCS), Vertex AI Agent Engine (`VertexAiSessionService` ). - **Integrations**: FastMCP (Google Workspace), Google Search Grounding. - **Monorepo**: pnpm Workspaces + Turborepo. ## 🚀 Key Takeaways & What I Learned - **State Cleanliness is Paramount**: Keeping heavy binary data and verbose copy out of the persistent ADK session state while relying on flat asset registries (`root_asset_id -> entry` ) dramatically improved routing reliability and reduced token latency. - **AudioWorklets Unlock Real Voice UX**: Moving audio resampling off the main browser thread to Web Audio Worklets made bidirectional streaming feel instantaneous and conversational. - **Agent Specialization Makes Debugging Predictable**: Isolating responsibilities across dedicated agents (`ResearchAndPlanner` , `MultimodalContentCreator` , `VideoGenerator` , and `WorkspaceMCP` ) made prompt iterations and tool trajectories modular and easier to trace. ## 💬 What are your thoughts? I'd love to hear from the community: - How are you approaching multi-agent orchestration and revision workflows in your AI apps? - What features or integrations would you find most valuable in an automated event assistant? *Drop your thoughts, questions, or feedback in the comments!*