PROJECT KNOWLEDGE BASE

This file provides guidance to AI agents when working with code in this repository.

KEY NOTES

If you run into any missing python dependency errors, try running your command with source .venv/bin/activate
to assume the python venv.
To make tests work, check the .env file at the root of the project to find an OpenAI key.
If using playwright to explore the frontend, you can usually log in with username a@example.com and password a. The app can be accessed at http://localhost:3000.
You should assume that all Onyx services are running. To verify, you can check the backend/log directory to make sure we see logs coming out from the relevant service.
To connect to the Postgres database, use: docker exec -it onyx-relational_db-1 psql -U postgres -c "<SQL>"
When making calls to the backend, always go through the frontend. E.g. make a call to http://localhost:3000/api/persona not http://localhost:8080/api/persona
Put ALL db operations under the backend/onyx/db / backend/ee/onyx/db directories. Don't run queries outside of those directories.

Project Overview

Onyx (formerly Danswer) is an open-source Gen-AI and Enterprise Search platform that connects to company documents, apps, and people. It features a modular architecture with both Community Edition (MIT licensed) and Enterprise Edition offerings.

Background Workers (Celery)

Onyx uses Celery for asynchronous task processing with multiple specialized workers:

Worker Types

Primary Worker (celery_app.py)
- Coordinates core background tasks and system-wide operations
- Handles connector management, document sync, pruning, and periodic checks
- Runs with 4 threads concurrency
- Tasks: connector deletion, vespa sync, pruning, LLM model updates, user file sync
Docfetching Worker (docfetching)
- Fetches documents from external data sources (connectors)
- Spawns docprocessing tasks for each document batch
- Implements watchdog monitoring for stuck connectors
- Configurable concurrency (default from env)
Docprocessing Worker (docprocessing)
- Processes fetched documents through the indexing pipeline:
  - Upserts documents to PostgreSQL
  - Chunks documents and adds contextual information
  - Embeds chunks via model server
  - Writes chunks to Vespa vector database
  - Updates document metadata
- Configurable concurrency (default from env)
Light Worker (light)
- Handles lightweight, fast operations
- Tasks: vespa operations, document permissions sync, external group sync
- Higher concurrency for quick tasks
Heavy Worker (heavy)
- Handles resource-intensive operations
- Primary task: document pruning operations
- Runs with 4 threads concurrency
KG Processing Worker (kg_processing)
- Handles Knowledge Graph processing and clustering
- Builds relationships between documents
- Runs clustering algorithms
- Configurable concurrency
Monitoring Worker (monitoring)
- System health monitoring and metrics collection
- Monitors Celery queues, process memory, and system status
- Single thread (monitoring doesn't need parallelism)
- Cloud-specific monitoring tasks
User File Processing Worker (user_file_processing)
- Processes user-uploaded files
- Handles user file indexing and project synchronization
- Configurable concurrency
Beat Worker (beat)
- Celery's scheduler for periodic tasks
- Uses DynamicTenantScheduler for multi-tenant support
- Schedules tasks like:
  - Indexing checks (every 15 seconds)
  - Connector deletion checks (every 20 seconds)
  - Vespa sync checks (every 20 seconds)
  - Pruning checks (every 20 seconds)
  - KG processing (every 60 seconds)
  - Monitoring tasks (every 5 minutes)
  - Cleanup tasks (hourly)

Key Features

Thread-based Workers: All workers use thread pools (not processes) for stability
Tenant Awareness: Multi-tenant support with per-tenant task isolation. There is a middleware layer that automatically finds the appropriate tenant ID when sending tasks via Celery Beat.
Task Prioritization: High, Medium, Low priority queues
Monitoring: Built-in heartbeat and liveness checking
Failure Handling: Automatic retry and failure recovery mechanisms
Redis Coordination: Inter-process communication via Redis
PostgreSQL State: Task state and metadata stored in PostgreSQL

Important Notes

Defining Tasks:

Always use @shared_task rather than @celery_app
Put tasks under background/celery/tasks/ or ee/background/celery/tasks
Never enqueue a task without an expiration. Always supply expires= when sending tasks, either from the beat schedule or directly from another task. It should never be acceptable to submit code which enqueues tasks without an expiration, as doing so can lead to unbounded task queue growth.

Defining APIs: When creating new FastAPI APIs, do NOT use the response_model field. Instead, just type the function.

Testing Updates: If you make any updates to a celery worker and you want to test these changes, you will need to ask me to restart the celery worker. There is no auto-restart on code-change mechanism.

Task Time Limits: Since all tasks are executed in thread pools, the time limit features of Celery are silently disabled and won't work. Timeout logic must be implemented within the task itself.

Code Quality

# Install and run pre-commit hooks
pre-commit install
pre-commit run --all-files

NOTE: Always make sure everything is strictly typed (both in Python and Typescript).

Architecture Overview

Technology Stack

Backend: Python 3.11, FastAPI, SQLAlchemy, Alembic, Celery
Frontend: Next.js 15+, React 18, TypeScript, Tailwind CSS
Database: PostgreSQL with Redis caching
Search: Vespa vector database
Auth: OAuth2, SAML, multi-provider support
AI/ML: LangChain, LiteLLM, multiple embedding models

Directory Structure

backend/
├── onyx/
│   ├── auth/                    # Authentication & authorization
│   ├── chat/                    # Chat functionality & LLM interactions
│   ├── connectors/              # Data source connectors
│   ├── db/                      # Database models & operations
│   ├── document_index/          # Vespa integration
│   ├── federated_connectors/    # External search connectors
│   ├── llm/                     # LLM provider integrations
│   └── server/                  # API endpoints & routers
├── ee/                          # Enterprise Edition features
├── alembic/                     # Database migrations
└── tests/                       # Test suites

web/
├── src/app/                     # Next.js app router pages
├── src/components/              # Reusable React components
└── src/lib/                     # Utilities & business logic

Frontend Standards

1. Import Standards

Always use absolute imports with the @ prefix.

Reason: Moving files around becomes easier since you don't also have to update those import statements. This makes modifications to the codebase much nicer.

// ✅ Good
import { Button } from "@/components/ui/button";
import { useAuth } from "@/hooks/useAuth";
import { Text } from "@/refresh-components/texts/Text";

// ❌ Bad
import { Button } from "../../../components/ui/button";
import { useAuth } from "./hooks/useAuth";

2. React Component Functions

Prefer regular functions over arrow functions for React components.

Reason: Functions just become easier to read.

// ✅ Good
function UserProfile({ userId }: UserProfileProps) {
  return <div>User Profile</div>
}

// ❌ Bad
const UserProfile = ({ userId }: UserProfileProps) => {
  return <div>User Profile</div>
}

3. Props Interface Extraction

Extract prop types into their own interface definitions.

Reason: Functions just become easier to read.

// ✅ Good
interface UserCardProps {
  user: User
  showActions?: boolean
  onEdit?: (userId: string) => void
}

function UserCard({ user, showActions = false, onEdit }: UserCardProps) {
  return <div>User Card</div>
}

// ❌ Bad
function UserCard({
  user,
  showActions = false,
  onEdit
}: {
  user: User
  showActions?: boolean
  onEdit?: (userId: string) => void
}) {
  return <div>User Card</div>
}

4. Spacing Guidelines

Prefer padding over margins for spacing.

Reason: We want to consolidate usage to paddings instead of margins.

// ✅ Good
<div className="p-4 space-y-2">
  <div className="p-2">Content</div>
</div>

// ❌ Bad
<div className="m-4 space-y-2">
  <div className="m-2">Content</div>
</div>

5. Tailwind Dark Mode

Strictly forbid using the dark: modifier in Tailwind classes, except for logo icon handling.

Reason: The colors.css file already, VERY CAREFULLY, defines what the exact opposite colour of each light-mode colour is. Overriding this behaviour is VERY bad and will lead to horrible UI breakages.

Exception: The createLogoIcon helper in web/src/components/icons/icons.tsx uses dark: modifiers (dark:invert, dark:hidden, dark:block) to handle third-party logo icons that cannot automatically adapt through colors.css. This is the ONLY acceptable use of dark mode modifiers.

// ✅ Good - Standard components use `tailwind-themes/tailwind.config.js` / `src/app/css/colors.css`
<div className="bg-background-neutral-03 text-text-02">
  Content
</div>

// ✅ Good - Logo icons with dark mode handling via createLogoIcon
export const GithubIcon = createLogoIcon(githubLightIcon, {
  monochromatic: true,  // Will apply dark:invert internally
});

export const GitbookIcon = createLogoIcon(gitbookLightIcon, {
  darkSrc: gitbookDarkIcon,  // Will use dark:hidden/dark:block internally
});

// ❌ Bad - Manual dark mode overrides
<div className="bg-white dark:bg-black text-black dark:text-white">
  Content
</div>

6. Class Name Utilities

Use the cn utility instead of raw string formatting for classNames.

Reason: cns are easier to read. They also allow for more complex types (i.e., string-arrays) to get formatted properly (it flattens each element in that string array down). As a result, it can allow things such as conditionals (i.e., myCondition && "some-tailwind-class", which evaluates to false when myCondition is false) to get filtered out.

import { cn } from '@/lib/utils'

// ✅ Good
<div className={cn(
  'base-class',
  isActive && 'active-class',
  className
)}>
  Content
</div>

// ❌ Bad
<div className={`base-class ${isActive ? 'active-class' : ''} ${className}`}>
  Content
</div>

7. Custom Hooks Organization

Follow a "hook-per-file" layout. Each hook should live in its own file within web/src/hooks.

Reason: This is just a layout preference. Keeps code clean.

// web/src/hooks/useUserData.ts
export function useUserData(userId: string) {
  // hook implementation
}

// web/src/hooks/useLocalStorage.ts
export function useLocalStorage<T>(key: string, initialValue: T) {
  // hook implementation
}

8. Icon Usage

ONLY use icons from the web/src/icons directory. Do NOT use icons from react-icons, lucide, or other external libraries.

Reason: We have a very carefully curated selection of icons that match our Onyx guidelines. We do NOT want to muddy those up with different aesthetic stylings.

// ✅ Good
import SvgX from "@/icons/x";
import SvgMoreHorizontal from "@/icons/more-horizontal";

// ❌ Bad
import { User } from "lucide-react";
import { FiSearch } from "react-icons/fi";

Missing Icons: If an icon is needed but doesn't exist in the web/src/icons directory, import it from Figma using the Figma MCP tool and add it to the icons directory. If you need help with this step, reach out to raunak@onyx.app.

9. Text Rendering

Prefer using the refresh-components/texts/Text component for all text rendering. Avoid "naked" text nodes.

Reason: The Text component is fully compliant with the stylings provided in Figma. It provides easy utilities to specify the text-colour and font-size in the form of flags. Super duper easy.

// ✅ Good
import { Text } from '@/refresh-components/texts/Text'

function UserCard({ name }: { name: string }) {
  return (
    <Text
      {/* The `text03` flag makes the text it renders to be coloured the 3rd-scale grey */}
      text03
      {/* The `mainAction` flag makes the text it renders to be "main-action" font + line-height + weightage, as described in the Figma */}
      mainAction
    >
      {name}
    </Text>
  )
}

// ❌ Bad
function UserCard({ name }: { name: string }) {
  return (
    <div>
      <h2>{name}</h2>
      <p>User details</p>
    </div>
  )
}

10. Component Usage

Heavily avoid raw HTML input components. Always use components from the web/src/refresh-components or web/lib/opal/src directory.

Reason: We've put in a lot of effort to unify the components that are rendered in the Onyx app. Using raw components breaks the entire UI of the application, and leaves it in a muddier state than before.

// ✅ Good
import Button from '@/refresh-components/buttons/Button'
import InputTypeIn from '@/refresh-components/inputs/InputTypeIn'
import SvgPlusCircle from '@/icons/plus-circle'

function ContactForm() {
  return (
    <form>
      <InputTypeIn placeholder="Search..." />
      <Button type="submit" leftIcon={SvgPlusCircle}>Submit</Button>
    </form>
  )
}

// ❌ Bad
function ContactForm() {
  return (
    <form>
      <input placeholder="Name" />
      <textarea placeholder="Message" />
      <button type="submit">Submit</button>
    </form>
  )
}

11. Colors

Always use custom overrides for colors and borders rather than built in Tailwind CSS colors. These overrides live in web/tailwind-themes/tailwind.config.js.

Reason: Our custom color system uses CSS variables that automatically handle dark mode and maintain design consistency across the app. Standard Tailwind colors bypass this system.

Available color categories:

Text: text-01 through text-05, text-inverted-XX
Backgrounds: background-neutral-XX, background-tint-XX (and inverted variants)
Borders: border-01 through border-05, border-inverted-XX
Actions: action-link-XX, action-danger-XX
Status: status-info-XX, status-success-XX, status-warning-XX, status-error-XX
Theme: theme-primary-XX, theme-red-XX, theme-blue-XX, etc.

// ✅ Good - Use custom Onyx color classes
<div className="bg-background-neutral-01 border border-border-02" />
<div className="bg-background-tint-02 border border-border-01" />
<div className="bg-status-success-01" />
<div className="bg-action-link-01" />
<div className="bg-theme-primary-05" />

// ❌ Bad - Do NOT use standard Tailwind colors
<div className="bg-gray-100 border border-gray-300 text-gray-600" />
<div className="bg-white border border-slate-200" />
<div className="bg-green-100 text-green-700" />
<div className="bg-blue-100 text-blue-600" />
<div className="bg-indigo-500" />

12. Data Fetching

Prefer using useSWR for data fetching. Data should generally be fetched on the client side. Components that need data should display a loader / placeholder while waiting for that data. Prefer loading data within the component that needs it rather than at the top level and passing it down.

Reason: Client side fetching allows us to load the skeleton of the page without waiting for data to load, leading to a snappier UX. Loading data where needed reduces dependencies between a component and its parent component(s).

Database & Migrations

Running Migrations

# Standard migrations
alembic upgrade head

# Multi-tenant (Enterprise)
alembic -n schema_private upgrade head

Creating Migrations

# Create migration
alembic revision -m "description"

# Multi-tenant migration
alembic -n schema_private revision -m "description"

Write the migration manually and place it in the file that alembic creates when running the above command.

Testing Strategy

First, you must activate the virtual environment with source .venv/bin/activate.

There are 4 main types of tests within Onyx:

Unit Tests

These should not assume any Onyx/external services are available to be called. Interactions with the outside world should be mocked using unittest.mock. Generally, only write these for complex, isolated modules e.g. citation_processing.py.

To run them:

pytest -xv backend/tests/unit

External Dependency Unit Tests

These tests assume that all external dependencies of Onyx are available and callable (e.g. Postgres, Redis, MinIO/S3, Vespa are running + OpenAI can be called + any request to the internet is fine + etc.).

However, the actual Onyx containers are not running and with these tests we call the function to test directly. We can also mock components/calls at will.

The goal with these tests are to minimize mocking while giving some flexibility to mock things that are flakey, need strictly controlled behavior, or need to have their internal behavior validated (e.g. verify a function is called with certain args, something that would be impossible with proper integration tests).

A great example of this type of test is backend/tests/external_dependency_unit/connectors/confluence/test_confluence_group_sync.py.

To run them:

python -m dotenv -f .vscode/.env run -- pytest backend/tests/external_dependency_unit

Integration Tests

Standard integration tests. Every test in backend/tests/integration runs against a real Onyx deployment. We cannot mock anything in these tests. Prefer writing integration tests (or External Dependency Unit Tests if mocking/internal verification is necessary) over any other type of test.

Tests are parallelized at a directory level.

When writing integration tests, make sure to check the root conftest.py for useful fixtures + the backend/tests/integration/common_utils directory for utilities. Prefer (if one exists), calling the appropriate Manager class in the utils over directly calling the APIs with a library like requests. Prefer using fixtures rather than calling the utilities directly (e.g. do NOT create admin users with admin_user = UserManager.create(name="admin_user"), instead use the admin_user fixture).

A great example of this type of test is backend/tests/integration/tests/streaming_endpoints/test_chat_stream.py.

To run them:

python -m dotenv -f .vscode/.env run -- pytest backend/tests/integration

Playwright (E2E) Tests

These tests are an even more complete version of the Integration Tests mentioned above. Has all services of Onyx running, including the Web Server.

Use these tests for anything that requires significant frontend <-> backend coordination.

Tests are located at web/tests/e2e. Tests are written in TypeScript.

To run them:

npx playwright test <TEST_NAME>

For shared fixtures, best practices, and detailed guidance, see backend/tests/README.md.

Logs

When (1) writing integration tests or (2) doing live tests (e.g. curl / playwright) you can get access to logs via the backend/log/<service_name>_debug.log file. All Onyx services (api_server, web_server, celery_X) will be tailing their logs to this file.

Security Considerations

Never commit API keys or secrets to repository
Use encrypted credential storage for connector credentials
Follow RBAC patterns for new features
Implement proper input validation with Pydantic models
Use parameterized queries to prevent SQL injection

AI/LLM Integration

Multiple LLM providers supported via LiteLLM
Configurable models per feature (chat, search, embeddings)
Streaming support for real-time responses
Token management and rate limiting
Custom prompts and agent actions

Creating a Plan

When creating a plan in the plans directory, make sure to include at least these elements:

Issues to Address What the change is meant to do.

Important Notes Things you come across in your research that are important to the implementation.

Implementation strategy How you are going to make the changes happen. High level approach.

Tests What unit (use rarely), external dependency unit, integration, and playwright tests you plan to write to verify the correct behavior. Don't overtest. Usually, a given change only needs one type of test.

Do NOT include these: Timeline, Rollback plan

This is a minimal list - feel free to include more. Do NOT write code as part of your plan. Keep it high level. You can reference certain files or functions though.

Before writing your plan, make sure to do research. Explore the relevant sections in the codebase.

Error Handling

Always raise OnyxError from onyx.error_handling.exceptions instead of HTTPException. Never hardcode status codes or use starlette.status / fastapi.status constants directly.

A global FastAPI exception handler converts OnyxError into a JSON response with the standard {"error_code": "...", "detail": "..."} shape. This eliminates boilerplate and keeps error handling consistent across the entire backend.

from onyx.error_handling.error_codes import OnyxErrorCode
from onyx.error_handling.exceptions import OnyxError

# ✅ Good
raise OnyxError(OnyxErrorCode.NOT_FOUND, "Session not found")

# ✅ Good — no extra message needed
raise OnyxError(OnyxErrorCode.UNAUTHENTICATED)

# ✅ Good — upstream service with dynamic status code
raise OnyxError(OnyxErrorCode.BAD_GATEWAY, detail, status_code_override=upstream_status)

# ❌ Bad — using HTTPException directly
raise HTTPException(status_code=404, detail="Session not found")

# ❌ Bad — starlette constant
raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Access denied")

Available error codes are defined in backend/onyx/error_handling/error_codes.py. If a new error category is needed, add it there first — do not invent ad-hoc codes.

Upstream service errors: When forwarding errors from an upstream service where the HTTP status code is dynamic (comes from the upstream response), use status_code_override:

raise OnyxError(OnyxErrorCode.BAD_GATEWAY, detail, status_code_override=e.response.status_code)

Best Practices

In addition to the other content in this file, best practices for contributing to the codebase can be found at contributing_guides/best_practices.md. Understand its contents and follow them.

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PROJECT KNOWLEDGE BASE

KEY NOTES

Project Overview

Background Workers (Celery)

Worker Types

Key Features

Important Notes

Code Quality

Architecture Overview

Technology Stack

Directory Structure

Frontend Standards

1. Import Standards

2. React Component Functions

3. Props Interface Extraction

4. Spacing Guidelines

5. Tailwind Dark Mode

6. Class Name Utilities

7. Custom Hooks Organization

8. Icon Usage

9. Text Rendering

10. Component Usage

11. Colors

12. Data Fetching

Database & Migrations

Running Migrations

Creating Migrations

Testing Strategy

Unit Tests

External Dependency Unit Tests

Integration Tests

Playwright (E2E) Tests

Logs

Security Considerations

AI/LLM Integration

Creating a Plan

Error Handling

Best Practices