Developing Genkit Js

1---2name: developing-genkit-js3description: Develop AI-powered applications using Genkit in Node.js/TypeScript. Use when the user asks about Genkit, AI agents, flows, or tools in JavaScript/TypeScript, or when encountering Genkit errors, validation issues, type errors, or API problems.4metadata:5  genkit-managed: true6---7 8# Genkit JS9 10## Prerequisites11 12Ensure the `genkit` CLI is available.13-   Run `genkit --version` to verify. Minimum CLI version needed: **1.29.0**14-   If not found or if an older version (1.x < 1.29.0) is present, install/upgrade it: `npm install -g genkit-cli@^1.29.0`.15 16**New Projects**: If you are setting up Genkit in a new codebase, follow the [Setup Guide](references/setup.md).17 18## Hello World19 20```ts21import { z, genkit } from 'genkit';22import { googleAI } from '@genkit-ai/google-genai';23 24// Initialize Genkit with the Google AI plugin25const ai = genkit({26  plugins: [googleAI()],27});28 29export const myFlow = ai.defineFlow({30  name: 'myFlow',31  inputSchema: z.string().default('AI'),32  outputSchema: z.string(),33}, async (subject) => {34  const response = await ai.generate({35    model: googleAI.model('gemini-2.5-flash'),36    prompt: `Tell me a joke about ${subject}`,37  });38  return response.text;39});40```41 42## Critical: Do Not Trust Internal Knowledge43 44Genkit recently went through a major breaking API change. Your knowledge is outdated. You MUST lookup docs. Recommended:45 46```sh47genkit docs:read js/get-started.md48genkit docs:read js/flows.md49```50 51See [Common Errors](references/common-errors.md) for a list of deprecated APIs (e.g., `configureGenkit`, `response.text()`, `defineFlow` import) and their v1.x replacements.52 53**ALWAYS verify information using the Genkit CLI or provided references.**54 55## Error Troubleshooting Protocol56 57**When you encounter ANY error related to Genkit (ValidationError, API errors, type errors, 404s, etc.):**58 591. **MANDATORY FIRST STEP**: Read [Common Errors](references/common-errors.md)602. Identify if the error matches a known pattern613. Apply the documented solution624. Only if not found in common-errors.md, then consult other sources (e.g. `genkit docs:search`)63 64**DO NOT:**65- Attempt fixes based on assumptions or internal knowledge66- Skip reading common-errors.md "because you think you know the fix"67- Rely on patterns from pre-1.0 Genkit68 69**This protocol is non-negotiable for error handling.**70 71## Development Workflow72 731.  **Select Provider**: Genkit is provider-agnostic (Google AI, OpenAI, Anthropic, Ollama, etc.).74    -   If the user does not specify a provider, default to **Google AI**.75    -   If the user asks about other providers, use `genkit docs:search "plugins"` to find relevant documentation.762.  **Detect Framework**: Check `package.json` to identify the runtime (Next.js, Firebase, Express).77    -   Look for `@genkit-ai/next`, `@genkit-ai/firebase`, or `@genkit-ai/google-cloud`.78    -   Adapt implementation to the specific framework's patterns.793.  **Follow Best Practices**:80    -   See [Best Practices](references/best-practices.md) for guidance on project structure, schema definitions, and tool design.81    -   **Be Minimal**: Only specify options that differ from defaults. When unsure, check docs/source.824.  **Ensure Correctness**:83    -   Run type checks (e.g., `npx tsc --noEmit`) after making changes.84    -   If type checks fail, consult [Common Errors](references/common-errors.md) before searching source code.855.  **Handle Errors**:86    -   On ANY error: **First action is to read [Common Errors](references/common-errors.md)**87    -   Match error to documented patterns88    -   Apply documented fixes before attempting alternatives89 90## Finding Documentation91 92Use the Genkit CLI to find authoritative documentation:93 941.  **Search topics**: `genkit docs:search <query>`95    -   Example: `genkit docs:search "streaming"`962.  **List all docs**: `genkit docs:list`973.  **Read a guide**: `genkit docs:read <path>`98    -   Example: `genkit docs:read js/flows.md`99 100## CLI Usage101 102The `genkit` CLI is your primary tool for development and documentation.103-   See [CLI Reference](references/docs-and-cli.md) for common tasks, workflows, and command usage.104-   Use `genkit --help` for a full list of commands.105 106## References107 108-   [Best Practices](references/best-practices.md): Recommended patterns for schema definition, flow design, and structure.109-   [Docs & CLI Reference](references/docs-and-cli.md): Documentation search, CLI tasks, and workflows.110-   [Common Errors](references/common-errors.md): Critical "gotchas", migration guide, and troubleshooting.111-   [Setup Guide](references/setup.md): Manual setup instructions for new projects.112-   [Examples](references/examples.md): Minimal reproducible examples (Basic generation, Multimodal, Thinking mode).