Submission by AechaEopteryX

ECHO is an immersive 3D globe experience that lets you time-travel to any city in any historical era through AI-generated audio. Click London in 1666 and you're standing in the Great Fire. Click Tokyo in 1920 and the jazz age roars around you. Vendors shout in local languages, crowds react to the events unfolding, and a hyper-specific ambient soundscape pulls you into the moment. Or slow down and let a narrator guide you through a four-part documentary about the city and era you've landed in. Then, when you're ready, talk to a historian who was actually there — someone who lived through it, speaks from it, and knows only what the world knew then. ECHO was built using every major Kiro feature alongside deep ElevenLabs API integration. Spec-driven development formed the backbone - 21 specs (10 feature + 11 bugfix) written before any code, following a requirements → design → tasks workflow that kept the audio pipeline and agent integration reliable; bugfix specs were especially valuable because documenting the exact failure condition before touching code led to precise fixes. The ElevenLabs Kiro Power provided 25+ MCP tools - the historian agent was created via create_agent without opening a dashboard, voices discovered via search_voices, and TTS/SFX prompts live-tested during development. Three agent hooks automated the loop (lint on save, tests after each task, build verification before commits) and three steering docs kept Kiro aligned with project conventions across sessions. On the ElevenLabs side, textToSpeech.convert() powers 8 character voices and documentary narration, textToSoundEffects.convert() generates ambient soundscape loops and scene SFX clips, and Conversation.startSession() drives the real-time historian agent built with ElevenLabs' Conversational AI platform, configured with a custom knowledge base of historical context so the agent speaks authentically from within their era and knows only what the world knew then. Vibe coding handled UI iteration, globe layout, and prompt engineering — a deliberate hybrid: specs for complexity, vibe coding for speed.