Peter Yang
Voice will become computing's primary interface, but building viable tools requires dedicating the bulk of development time to manual prompt and audio iteration rather than automated code generation.
AI-assisted summary of Build an AI Language Tutor You Can Talk To (6 Steps) — original source. Check the original for full context.
Source published:
Key ideas
- Peter Yang demonstrates building 'Tabi', an AI-powered conversational Japanese tutor built on Gemini 3.8 Live APIs, showcasing voice as the emerging default interface for computing. (0:00)
- The entire application was planned, designed, coded, and deployed to Vercel in approximately three hours, with two full hours dedicated entirely to iteration and curriculum refinement. (16:30)
- During development, the AI autonomous deployment workflow preemptively introduced a passcode gate to protect live Gemini API consumption from unauthorized public usage. (14:57)
- Yang utilized a custom open-source 'human-review' tool alongside visual spec mockups to review and annotate AI-generated specifications directly before generating code. (5:01)
Detailed notes
## Background This tutorial was published by Peter Yang on YouTube on October 5, 2026. Sponsored by Google, the video demonstrates how to build Tabi, an AI-powered Japanese language coach utilizing Gemini 3.8 Live, through a structured six-step workflow spanning conceptualization, prototyping, refinement, and web deployment.
## TL;DR Peter Yang walks through building Tabi, a personal web application that uses Google's real-time voice APIs to teach conversational travel phrases through direct dialogue and roleplay scenarios. The development process follows a six-stage methodology: brainstorming requirements with an AI assistant, generating an interactive HTML specification, assembling a functional baseline in Google Antigravity, iterating on latency and audio issues using Claude Code, shaping a 10-lesson curriculum in Markdown, and deploying the application to Vercel with automated passcode protection. Completing the project in approximately three hours, Yang emphasizes that deliberate human testing and curriculum refinement account for most of the development time and distinguish a quality tool from low-effort AI output.
## Atmosphere & style The presentation is pragmatic, energetic, and candidly builder-focused, pairing ambitious assertions about the future of voice interfaces with unvarnished, hands-on development moments. Yang maintains a lighthearted, relatable demeanor—laughing off his own Japanese pronunciation drills and self-deprecatingly revoking an exposed API key on screen—while methodically debugging microphone routing discrepancies and refining avatar art. The tutorial moves briskly from structured product planning to deep technical iterations, giving viewers the tangible impression of looking over the shoulder of a seasoned product creator who values craft over raw generation speed.
## Bulletin - [00:00](https://www.youtube.com/watch?v=GiaDdNvsadA&t=0s) Peter Yang demonstrates building 'Tabi', an AI-powered conversational Japanese tutor built on Gemini 3.8 Live APIs, showcasing voice as the emerging default interface for computing. - [16:30](https://www.youtube.com/watch?v=GiaDdNvsadA&t=990s) The entire application was planned, designed, coded, and deployed to Vercel in approximately three hours, with two full hours dedicated entirely to iteration and curriculum refinement. - [14:57](https://www.youtube.com/watch?v=GiaDdNvsadA&t=897s) During development, the AI autonomous deployment workflow preemptively introduced a passcode gate to protect live Gemini API consumption from unauthorized public usage. - [05:01](https://www.youtube.com/watch?v=GiaDdNvsadA&t=301s) Yang utilized a custom open-source 'human-review' tool alongside visual spec mockups to review and annotate AI-generated specifications directly before generating code.
## Key takeaways - [00:00](https://www.youtube.com/watch?v=GiaDdNvsadA&t=0s) Voice interactions are positioned to become the default paradigm for human-computer interaction, supported by low-latency models like Gemini 3.8 Live. - [01:18](https://www.youtube.com/watch?v=GiaDdNvsadA&t=78s) Tabi structures each language lesson into two phases: explicit phrase instruction followed by interactive scenario roleplaying. - [02:45](https://www.youtube.com/watch?v=GiaDdNvsadA&t=165s) Exploratory AI prompting before writing code helps clarify user goals, pedagogical format, and model requirements via AI-generated questions. - [02:45](https://www.youtube.com/watch?v=GiaDdNvsadA&t=165s) Personal utility apps tailored to private needs without monetization are becoming practical software projects using modern AI stacks. - [05:01](https://www.youtube.com/watch?v=GiaDdNvsadA&t=301s) Combining technical PRD specifications with interactive visual UI mockups in an HTML spec dramatically accelerates alignment prior to implementation. - [05:01](https://www.youtube.com/watch?v=GiaDdNvsadA&t=301s) The open-source 'human-review' skill lets creators edit spec copy directly and pin visual feedback for automated agent iteration. - [08:24](https://www.youtube.com/watch?v=GiaDdNvsadA&t=504s) Google Antigravity generated the functional first version of the application from the spec document in a single pass. - [08:24](https://www.youtube.com/watch?v=GiaDdNvsadA&t=504s) API secrets must be added directly into local environment files rather than pasted into AI chat windows to avoid leaks or data ingestion. - [10:09](https://www.youtube.com/watch?v=GiaDdNvsadA&t=609s) Browser automation tools in Claude Code diagnosed physical audio routing bugs and interface race conditions during live speech testing. - [10:09](https://www.youtube.com/watch?v=GiaDdNvsadA&t=609s) Custom 3D miniature diorama visuals generated through Nano Banana/Imagen provided bespoke thematic consistency across all lesson cards. - [12:28](https://www.youtube.com/watch?v=GiaDdNvsadA&t=748s) Focusing language curriculum on phonetic conversational fluency rather than reading or writing Japanese scripts streamlines practical travel learning. - [12:28](https://www.youtube.com/watch?v=GiaDdNvsadA&t=748s) High craft in AI software development is defined by hands-on iteration, manual playtesting, and curriculum tuning rather than one-shot generation. - [14:57](https://www.youtube.com/watch?v=GiaDdNvsadA&t=897s) Deploying conversational voice apps to production requires safeguards like passcode gating to prevent unbounded live API token expenses.
## Detailed walkthrough ### [00:00](https://www.youtube.com/watch?v=GiaDdNvsadA&t=0s) Introduction: Voice Interfaces and the Six-Step Roadmap
Peter Yang opens with a bold thesis: "I think voice is going to become the default way that we all interact with computers soon." To demonstrate what this looks like in practice, he introduces **Tabi**, an AI language coach designed to teach Japanese through live conversation. After a brief, upbeat musical preview of the app in action, he lays out the exact six-step roadmap he will use to build the app from scratch:
```mermaid flowchart LR accTitle: Six-Step AI App Building Roadmap subgraph Phase1["Planning & Design"] S1["1. Explore idea with AI"] --> S2["2. Draft spec & design"] end subgraph Phase2["Development & Iteration"] S3["3. Build first version"] --> S4["4. Improve the app"] S4 --> S5["5. Improve the lessons"] end subgraph Phase3["Deployment"] S6["6. Launch"] end Phase1 --> Phase2 --> Phase3 ```
The video is sponsored by Google, and the project leans heavily on Google's ecosystem. Peter notes that Gemini's Live APIs are "essentially best-in-class for live speech and conversation," pointing to a benchmark chart to back up the claim.
- **Conversation engine:** Gemini Live APIs (Gemini 3.8 Live) - **Scene artwork:** Nano Banana - **Development tools:** Google Antigravity and Claude Code
[01:18](https://www.youtube.com/watch?v=GiaDdNvsadA&t=78s) Quick Tour: A Live Japanese Lesson with Yuki
Before diving into the code, Peter gives a quick tour of the finished application. The home screen features a path of 10 lessons, and expanding any lesson reveals custom diorama artwork representing that scenario. To show how the voice interaction feels, he initiates a live call for Lesson 1 with **Yuki**, the AI language coach.
Yuki immediately greets him and breaks down how to say "good morning" in Japanese, explaining that it is a set greeting where you add *gozaimasu* to make it polite (*Ohayou gozaimasu*). After Peter repeats the phrase, Yuki praises him ("Perfect") and offers a helpful pronunciation tip: "every vowel in Japanese always sounds the same." She then walks him through saying "yes" ("just one syllable: *Hai*"). Once the vocabulary drill wraps up, Yuki pivots into roleplay mode: "Nice work. Now, let's live one day in Tokyo. I'll play everyone you meet." She immediately acts as hotel staff saying *Ohayou gozaimasu*, prompting Peter to greet her back, and then sets up a second scenario where someone is blocking the sidewalk so Peter has to politely say "excuse me."
Laughing a bit at his own pronunciation—"Okay, I'm not sure about my Japanese pronunciation, but hopefully that gives you an idea of the app that we're going to build"—Peter explains the pedagogical structure behind the app. Every lesson is intentionally split into two distinct phases, and the entire framework can easily be repurposed for any other language a traveler wants to learn: - **Phase 1 (Instruction):** The AI coach explicitly teaches all 10 phrases in the lesson one by one. - **Phase 2 (Roleplay):** The coach runs through a realistic, back-and-forth conversation scenario where the user practices those exact 10 phrases in context.
[02:45](https://www.youtube.com/watch?v=GiaDdNvsadA&t=165s) Step 1: Explore the Idea with AI Before Building Anything
When starting a new project, Peter emphasizes that it is always best to brainstorm with AI first to nail down both the user problem and the shape of the solution. He shares the exact initial prompt he used: he is traveling to Japan and wants a phone-friendly web app that teaches 100 phrases a traveler actually uses, broken down into 10 lessons of 10 phrases each. Because he previously built an app called **Tastemaker** (which tracks movie and TV tastes) and loved its styling and aesthetics, he instructs the AI to inspect Tastemaker and copy its look and feel. He also specifies the core screens—a journey/path screen tracking progress across the 10 lessons, and a lesson screen featuring text bubbles and a call button for live voice—along with the required Google tech stack (Gemini's best voice/audio models and Nano Banana for scene images). Crucially, he ends his prompt with a strict guardrail: "don't build anything yet. Do some research first and ask me three questions to clarify things."
The AI follows instructions, researching the Tastemaker aesthetic and looking up the latest Gemini models—identifying Google's new live voice model for real-time calls, a separate text-to-speech model for tapping individual speech bubbles to hear them read aloud, and Nano Banana for image generation. It then returns three clarifying questions, which Peter answers to lock in the product direction:
| AI's Clarifying Question | Peter's Product Decision | |:--- |:--- | | **1. What should a live call feel like?** | First have a coach teach the 10 phrases, then roleplay back and forth to practice. | | **2. How should each phrase bubble be written?** | Include all three formats: Japanese script, Romaji, and English. | | **3. Who will use the app?** | Just Peter and a few friends (a personal app, no monetization planned since Gemini API calls cost money). |
Peter highlights this last point as a major trend in modern software creation: "You can build personal apps like this. They're just very useful for solving your own problems."
[05:01](https://www.youtube.com/watch?v=GiaDdNvsadA&t=301s) Step 2: Draft a Spec with Key Screen Designs
Moving to Step 2, Peter uses his custom **spec skill** to generate both a written product specification and two or three key visual screen mockups. He explains that while his spec skill originally only produced a traditional, text-heavy Product Requirements Document (PRD) like a typical product manager would write, he recently updated it to generate visual mockups alongside the text. Because he works without a dedicated designer, having immediate visual blocks to react to makes it dramatically easier to understand what the app will actually feel like.
Opening the generated `spec.html` file in the browser, Peter shows how the layout pairs interactive phone screen mockups on the left with detailed product requirements, tech stack choices, and API specifications in the right-hand rail. After prompting the AI to also include desktop layouts and an onboarding flow, he toggles the view to show clean desktop designs for Onboarding, the Path view, and the Lesson view.
To refine the document further without tedious re-prompting, he runs his open-source **human-review skill** (`human-review spec.html`). This tool wraps the HTML spec in a Google Docs-style interface complete with a feedback panel, allowing two types of interaction: - **Direct text and UI editing:** Peter clicks directly into the spec's text and mockup headers to rewrite copy on the fly—for instance, typing "Peter needs 100 travel phrases practiced out loud for a trip. Package it into 10 lessons with 10 phrases each," and changing a mockup title directly to "Phrases for Japan." - **Contextual AI comments:** He highlights a specific UI box on the mockup, leaves a comment saying, "Hey, update this lesson to talk about food instead," and clicks a button to send all compiled edits and comments straight back to the AI agent to execute.
Peter also shares how viewers can get these workflow tools for themselves: - **Human-Review Skill (Free / Open Source):** Available on his GitHub (`github.com/petergyang/human-review`). Users simply copy the repository link, paste it into their favorite AI harness, and ask the AI to install the skill. - **Spec Skill (Paid):** Available on his portal at `behindthecraft.com`, bundled alongside 16 other custom skills, AI tool discounts, and a full personal AI course designed to set up a personal AI system in an afternoon. - **DIY Spec Skill Alternative:** For those who want to build their own version for free, Peter advises simply prompting an AI to generate an HTML page with two or three key screen mockups on the left and the product requirements and tech stack in a right-hand rail—"It might not be as nuanced as what I have here, but it's a really good start."
[08:24](https://www.youtube.com/watch?v=GiaDdNvsadA&t=504s) Step 3: Build the First Version in Google Antigravity
With a complete spec containing both visual mocks and technical requirements in hand, Step 3 is to build the initial working version of the app. For this phase, Peter switches over to **Google Antigravity**, noting that "it knows about Google's APIs the best." His prompt is dead simple: he tells Antigravity to look at the spec, see if it can build out the full app, and go ahead and do it.
Because the app relies on Google's voice APIs, it requires a Gemini API key to function. Peter walks through the exact setup and security best practices for handling the key: 1. Navigate to **Google AI Studio** (`aistudio.google.com`), click into **API keys**, and generate a new key. 2. Copy the key to a local notepad—**never** paste a secret API key directly into an AI chat window, because "who knows, maybe it'll be used for training or like it'll leak somewhere." 3. Ask Antigravity to open the project's `.env` file (the local environment file that stores secret keys) and paste the key directly into that file.
Realizing that he just showed his real key on screen while recording the tutorial, Peter laughs and snorts—"Now, since I pasted the API key in this video, let me go ahead and actually delete this API key because I don't want it to leak"—and immediately revokes it in the dashboard. With the valid key safely in the `.env` file, Antigravity successfully builds the entire first version of the app in a single shot, setting the stage for Step 4: iterating with AI to improve the app.
[10:09](https://www.youtube.com/watch?v=GiaDdNvsadA&t=609s) Step 4 Continued: Bug Fixing, Audio Calibration, and Diorama Art
Returning to Claude Code allows the use of automated browser and computer control features to test the running application directly. During initial testing, the app fails to register spoken input because it defaults to the MacBook’s built-in microphone rather than an external dedicated microphone. Once prompted, the tool identifies the audio routing discrepancy, switches the input device, and exercises the live interface directly to confirm voice capture.
Addressing microphone capture is only the beginning of an extensive feedback loop: "This is the longest phase if you care about craft and quality." Reviewing the lesson flow exposes several UX flaws. During the teaching phase, the UI displays all lesson dialogue bubbles at once instead of revealing them phrase-by-phrase as the student advances. Additionally, conversational response times are sluggish. Claude Code works through this list, patching UI race conditions and latency issues.
Attention then shifts to visual polish. Rather than relying on generic placeholder assets, the development environment (switching back to Google Antigravity) is instructed to generate custom illustrations using Gemini's Imagen/Nano Banana image model. Yang requests a miniature "diorama style" aesthetic—scenes crafted to resemble small, detailed tabletop figurines. After validating a prototype render, the model generates custom diorama backdrops for all 10 curriculum modules.
```mermaid flowchart TD accTitle: App Refinement Loop accDescr: Iterative testing and visual enhancement using Claude Code and Google Antigravity. subgraph BugFixes["Claude Code Automation"] A["Browser & Computer Use Testing"] --> B["Fix Audio Input Routing"] B --> C["Stagger Chat Bubble Reveals"] C --> D["Optimize Gemini Response Latency"] end subgraph AssetGeneration["Antigravity Visual Polish"] E["Prompt Gemini Image Model"] --> F["Generate Diorama Scene Art (10 Lessons)"] F --> G["Design Yuki Coach Avatar"] end BugFixes --> AssetGeneration ```
The AI coach avatar requires similar design adjustments. When prompted to illustrate the character Yuki, the model initially returns an onigiri (rice ball) illustration. Because Yuki uses a warm, female synthetic voice, Yang corrects the prompt to depict a friendly young woman. The resulting diorama portrait is set as Yuki’s persistent call screen profile picture. Resolving these audio, latency, and aesthetic defects requires roughly 30 minutes of targeted iteration.
- Audio fix: Redirected WebRTC/audio streams from default MacBook mic to external USB microphone. - Visual theme: 3D miniature diorama art across every lesson card. - Character design: Transitioned Yuki from an onigiri visual to an illustrated girl character.
---
[12:28](https://www.youtube.com/watch?v=GiaDdNvsadA&t=748s) Step 5: Curriculum Design and Pedagogical Content
Once the UI and voice channels are stable, focus shifts to instructional content quality. Yang notes in retrospect that curriculum planning should ideally precede UI refinement, but handles it directly inside an isolated AI chat thread dedicated strictly to content development. The prompt asks the model to structure an optimal 10-lesson conversational track tailored specifically for an upcoming trip to Japan.
The assistant initially proposes a sequence running from basic pleasantries to medical and pharmacy emergencies. Yang steps in to modify the outline: he merges lessons six and seven to streamline pacing, and objects to concluding the curriculum with hospital visits. Ending a vacation crash course on emergencies feels like a negative note, so the lessons are rearranged to conclude on an upbeat, practical interaction.
Yang questions foundational assumptions about language acquisition: "Is learning to read Japanese important to speak and be conversational?" The AI confirms that phonetic conversational fluency does not require mastering written kanji, hiragana, or katakana, allowing the curriculum to focus entirely on listening comprehension and spoken romaji. The finalized lessons are exported to a central Markdown document containing instructional flows, target vocabulary, and coach system prompts.
Yang notes that distinguishing a serious tool from "a vibe coded slop app" comes down to running through the lessons personally, learning the phrases firsthand, identifying confusing conversational branches, and bringing in friends for beta testing.
- Curriculum structure: 10 situational travel scenarios prioritized for real-world utility over grammar rules. - Pedagogical philosophy: Prioritizes conversational speaking and listening speed over reading/writing scripts. - Source of truth: A structured Markdown curriculum containing dialogue scripts, situational vocabulary, and Yuki's tutor guidelines.
---
[14:57](https://www.youtube.com/watch?v=GiaDdNvsadA&t=897s) Step 6: Launching Tabi on Vercel
With the lessons finalized and the local prototype fully functional, the build moves to Step 6: public deployment. While alternatives like Google AI Studio's hosting features are available, Yang chooses Vercel to consolidate hosting across existing projects. Because the environment is connected to the deployment CLI, launching requires only the natural language instruction: `deploy the app to Vercel`.
The automated deployment takes roughly five minutes. During the build process, the AI detects and resolves an incompatible, outdated dependency before pushing the production bundle live. On the resulting public web build, the app boots directly to the coach screen: "Hey everyone, I'm Yuki. Let's get you ready for Japan."
```mermaid flowchart LR accTitle: Vercel Deployment Flow accDescr: The automated push from local development to production hosting on Vercel. A["Natural Language Deploy Prompt"] --> B["Dependency Audit & Package Fixes"] B --> C["Vercel Production Build"] C --> D["Production Deployment with Auto Passcode Gate"] ```
Because every spoken turn incurs a live Gemini API consumption cost, the agent autonomously inserts a passcode gate on the landing page without being explicitly asked. This security measure keeps the public URL protected from unauthorized API traffic. With the baseline architecture live, the web app can be extended to include persistent user logins, alternative teacher personas, or adaptations for other foreign languages like Italian or Spanish.
- Hosting provider: Vercel (free tier for hobby builds). - Deployment duration: Approximately 5 minutes. - Unprompted security implementation: Automatic passcode authentication to shield Gemini API credits.
---
[16:30](https://www.youtube.com/watch?v=GiaDdNvsadA&t=990s) Recap and Final Thoughts
Yang reviews the end-to-end framework used to create Tabi across six distinct stages:
```mermaid flowchart LR accTitle: Six Step AI App Development Workflow accDescr: The complete 6-stage lifecycle from initial exploration to production launch. S1["1. Explore Idea"] --> S2["2. Spec & Design"] S2 --> S3["3. Build MVP"] S3 --> S4["4. Iterate App UI/Voice"] S4 --> S5["5. Refine Curriculum"] S5 --> S6["6. Launch & Host"] ```
The entire build took approximately three hours from initial prompt to live production link. Notably, two of those three hours were spent strictly on Steps 4 and 5—iterating, testing audio flows, and refining lesson quality. Iteration is the determining factor that separates low-effort generation from a polished product.
Looking ahead, Yang underscores that voice will soon become the primary interface between humans and computers. Developers can explore these voice patterns using Google's Gemini 3.8 Live documentation, configure access keys via Google AI Studio, and adopt open tools like the `human-review` repository to build specialized foreign language coaches for any destination.
- Total development time: ~3 hours (~2 hours dedicated entirely to prompt/code iteration). - Core technologies: Gemini 3.8 Live API, Google AI Studio, Claude Code, Google Antigravity, Vercel. - Open resources: GitHub human-review skill and behindthecraft.com product templates.
## Notable quotes > [00:00](https://www.youtube.com/watch?v=GiaDdNvsadA&t=0s) I think voice is going to become the default way that we all interact with computers soon. — Peter Yang
> [01:18](https://www.youtube.com/watch?v=GiaDdNvsadA&t=78s) Nice work. Now, let's live one day in Tokyo. I'll play everyone you meet. — Yuki
> [01:18](https://www.youtube.com/watch?v=GiaDdNvsadA&t=78s) Okay, I'm not sure about my Japanese pronunciation, but hopefully that gives you an idea of the app that we're going to build — Peter Yang
> [02:45](https://www.youtube.com/watch?v=GiaDdNvsadA&t=165s) don't build anything yet. Do some research first and ask me three questions to clarify things. — Peter Yang
> [02:45](https://www.youtube.com/watch?v=GiaDdNvsadA&t=165s) You can build personal apps like this. They're just very useful for solving your own problems. — Peter Yang
> [05:01](https://www.youtube.com/watch?v=GiaDdNvsadA&t=301s) It might not be as nuanced as what I have here, but it's a really good start. — Peter Yang
> [08:24](https://www.youtube.com/watch?v=GiaDdNvsadA&t=504s) Now, since I pasted the API key in this video, let me go ahead and actually delete this API key because I don't want it to leak — Peter Yang
> [10:09](https://www.youtube.com/watch?v=GiaDdNvsadA&t=609s) This is the longest phase if you care about craft and quality. — Peter Yang
> [12:28](https://www.youtube.com/watch?v=GiaDdNvsadA&t=748s) Is learning to read Japanese important to speak and be conversational? — Peter Yang
> [14:57](https://www.youtube.com/watch?v=GiaDdNvsadA&t=897s) Hey everyone, I'm Yuki. Let's get you ready for Japan. — Yuki
## Mentioned Peter Yang, Tabi, Google, Gemini 3.8 Live, Gemini Live APIs, Nano Banana, Imagen, Google Antigravity, Claude Code, Yuki, Tastemaker, Google Docs, GitHub, human-review, Behind the Craft, Google AI Studio, MacBook, Vercel, Creator Economy
## Video description Learn more about Gemini 3.8 Live: https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-8-live-gemini-3-8-live-extended-thinking/ Get a Gemini API key in Google AI Studio: https://aistudio.google.com Get my free human-review skill: https://github.com/petergyang/human-review
I think voice is going to become the default way we talk to computers. So I built Tabi, an AI language coach that teaches you Japanese through live conversation with Gemini 3.8 Live, and in this tutorial I show you exactly how I built it in 6 steps, from exploring the idea with AI to launching it on the web. You can follow along to build a live voice language app for whatever country you're visiting next.
What I cover: (00:00) Why voice is the next way we'll use computers (00:14) What we're building: Tabi, a live AI language coach (00:40) The 6 steps to build it (01:18) Quick tour: a live Japanese lesson with Yuki (02:45) Step 1: Explore the idea with AI before building anything (05:01) Step 2: Draft a spec with key screen designs (08:24) Step 3: Build the first version in Google Antigravity (10:03) Step 4: Iterate with AI to improve the app (12:28) Step 5: Improve the lessons so you actually learn (14:57) Step 6: Launch the app on Vercel (16:30) Recap and final thoughts
This video is sponsored by Google but opinions are my own.
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[Source](https://www.youtube.com/watch?v=GiaDdNvsadA)