4ea2e32366
## 1. The `twenty-client-sdk` Package (Source of Truth)
The monorepo package at `packages/twenty-client-sdk` ships with:
- A **pre-built metadata client** (static, generated from a fixed
schema)
- A **stub core client** that throws at runtime (`CoreApiClient was not
generated...`)
- Both ESM (`.mjs`) and CJS (`.cjs`) bundles in `dist/`
- A `package.json` with proper `exports` map for
`twenty-client-sdk/core`, `twenty-client-sdk/metadata`, and
`twenty-client-sdk/generate`
## 2. Generation & Upload (Server-Side, at Migration Time)
**When**: `WorkspaceMigrationRunnerService.run()` executes after a
metadata schema change.
**What happens in `SdkClientGenerationService.generateAndStore()`**:
1. Copies the stub `twenty-client-sdk` package from the server's assets
(resolved via `SDK_CLIENT_PACKAGE_DIRNAME` — from
`dist/assets/twenty-client-sdk/` in production, or from `node_modules`
in dev)
2. Filters out `node_modules/` and `src/` during copy — only
`package.json` + `dist/` are kept (like an npm publish)
3. Calls `replaceCoreClient()` which uses `@genql/cli` to introspect the
**application-scoped** GraphQL schema and generates a real
`CoreApiClient`, then compiles it to ESM+CJS and overwrites
`dist/core.mjs` and `dist/core.cjs`
4. Archives the **entire package** (with `package.json` + `dist/`) into
`twenty-client-sdk.zip`
5. Uploads the single archive to S3 under
`FileFolder.GeneratedSdkClient`
6. Sets `isSdkLayerStale = true` on the `ApplicationEntity` in the
database
## 3. Invalidation Signal
The `isSdkLayerStale` boolean column on `ApplicationEntity` is the
invalidation mechanism:
- **Set to `true`** by `generateAndStore()` after uploading a new client
archive
- **Checked** by both logic function drivers before execution — if
`true`, they rebuild their local layer
- **Set back to `false`** by `markSdkLayerFresh()` after the driver has
successfully consumed the new archive
Default is `false` so existing applications without a generated client
aren't affected.
## 4a. Logic Functions — Local Driver
**`ensureSdkLayer()`** is called before every execution:
1. Checks if the local SDK layer directory exists AND `isSdkLayerStale`
is `false` → early return
2. Otherwise, cleans the local layer directory
3. Calls `downloadAndExtractToPackage()` which streams the zip from S3
directly to disk and extracts the full package into
`<tmpdir>/sdk/<workspaceId>-<appId>/node_modules/twenty-client-sdk/`
4. Calls `markSdkLayerFresh()` to set `isSdkLayerStale = false`
**At execution time**, `assembleNodeModules()` symlinks everything from
the deps layer's `node_modules/` **except** `twenty-client-sdk`, which
is symlinked from the SDK layer instead. This ensures the logic
function's `import ... from 'twenty-client-sdk/core'` resolves to the
generated client.
## 4b. Logic Functions — Lambda Driver
**`ensureSdkLayer()`** is called during `build()`:
1. Checks if `isSdkLayerStale` is `false` and an existing Lambda layer
ARN exists → early return
2. Otherwise, deletes all existing layer versions for this SDK layer
name
3. Calls `downloadArchiveBuffer()` to get the raw zip from S3 (no disk
extraction)
4. Calls `reprefixZipEntries()` which streams the zip entries into a
**new zip** with the path prefix
`nodejs/node_modules/twenty-client-sdk/` — this is the Lambda layer
convention path. All done in memory, no disk round-trip
5. Publishes the re-prefixed zip as a new Lambda layer via
`publishLayer()`
6. Calls `markSdkLayerFresh()`
**At function creation**, the Lambda is created with **two layers**:
`[depsLayerArn, sdkLayerArn]`. The SDK layer is listed last so it
overwrites the stub `twenty-client-sdk` from the deps layer (later
layers take precedence in Lambda's `/opt` merge).
## 5. Front Components
Front components are built by `app:build` with `twenty-client-sdk/core`
and `twenty-client-sdk/metadata` as **esbuild externals**. The stored
`.mjs` in S3 has unresolved bare import specifiers like `import {
CoreApiClient } from 'twenty-client-sdk/core'`.
SDK import resolution is split between the **frontend host** (fetching &
caching SDK modules) and the **Web Worker** (rewriting imports):
**Server endpoints**:
- `GET /rest/front-components/:id` —
`FrontComponentService.getBuiltComponentStream()` returns the **raw
`.mjs`** directly from file storage. No bundling, no SDK injection.
- `GET /rest/sdk-client/:applicationId/:moduleName` —
`SdkClientController` reads a single file (e.g. `dist/core.mjs`) from
the generated SDK archive via
`SdkClientGenerationService.readFileFromArchive()` and serves it as
JavaScript.
**Frontend host** (`FrontComponentRenderer` in `twenty-front`):
1. Queries `FindOneFrontComponent` which returns `applicationId`,
`builtComponentChecksum`, `usesSdkClient`, and `applicationTokenPair`
2. If `usesSdkClient` is `true`, renders
`FrontComponentRendererWithSdkClient` which calls the
`useApplicationSdkClient` hook
3. `useApplicationSdkClient({ applicationId, accessToken })` checks the
Jotai atom family cache for existing blob URLs. On cache miss, fetches
both SDK modules from `GET /rest/sdk-client/:applicationId/core` and
`/metadata`, creates **blob URLs** for each, and stores them in the atom
family
4. Once the blob URLs are cached, passes them as `sdkClientUrls`
(already blob URLs, not server URLs) to `SharedFrontComponentRenderer` →
`FrontComponentWorkerEffect` → worker's `render()` call via
`HostToWorkerRenderContext`
**Worker** (`remote-worker.ts` in `twenty-sdk`):
1. Fetches the raw component `.mjs` source as text
2. If `sdkClientUrls` are provided and the source contains SDK import
specifiers (`twenty-client-sdk/core`, `twenty-client-sdk/metadata`),
**rewrites** the bare specifiers to the blob URLs received from the host
(e.g. `'twenty-client-sdk/core'` → `'blob:...'`)
3. Creates a blob URL for the rewritten source and `import()`s it
4. Revokes only the component blob URL after the module is loaded — the
SDK blob URLs are owned and managed by the host's Jotai cache
This approach eliminates server-side esbuild bundling on every request,
caches SDK modules per application in the frontend, and keeps the
worker's job to a simple string rewrite.
## Summary Diagram
```
app:build (SDK)
└─ twenty-client-sdk stub (metadata=real, core=stub)
│
▼
WorkspaceMigrationRunnerService.run()
└─ SdkClientGenerationService.generateAndStore()
├─ Copy stub package (package.json + dist/)
├─ replaceCoreClient() → regenerate core.mjs/core.cjs
├─ Zip entire package → upload to S3
└─ Set isSdkLayerStale = true
│
┌────────┴────────────────────┐
▼ ▼
Logic Functions Front Components
│ │
├─ Local Driver ├─ GET /rest/sdk-client/:appId/core
│ └─ downloadAndExtract │ → core.mjs from archive
│ → symlink into │
│ node_modules ├─ Host (useApplicationSdkClient)
│ │ ├─ Fetch SDK modules
└─ Lambda Driver │ ├─ Create blob URLs
└─ downloadArchiveBuffer │ └─ Cache in Jotai atom family
→ reprefixZipEntries │
→ publish as Lambda ├─ GET /rest/front-components/:id
layer │ → raw .mjs (no bundling)
│
└─ Worker (browser)
├─ Fetch component .mjs
├─ Rewrite imports → blob URLs
└─ import() rewritten source
```
## Next PR
- Estimate perf improvement by implementing a redis caching for front
component client storage ( we don't even cache front comp initially )
- Implem frontent blob invalidation sse event from server
---------
Co-authored-by: Charles Bochet <charlesBochet@users.noreply.github.com>
This is a Twenty application project bootstrapped with create-twenty-app.
Getting Started
First, authenticate to your workspace:
yarn twenty remote add --local
Then, start development mode to sync your app and watch for changes:
yarn twenty dev
Open your Twenty instance and go to /settings/applications section to see the result.
Available Commands
Run yarn twenty help to list all available commands. Common commands:
# Remotes & Authentication
yarn twenty remote add --local # Authenticate with Twenty
yarn twenty remote status # Check auth status
yarn twenty remote switch # Switch default remote
yarn twenty remote list # List all configured remotes
yarn twenty remote remove <name> # Remove a remote
# Application
yarn twenty dev # Start dev mode (watch, build, sync, and auto-generate typed client)
yarn twenty add # Add a new entity (object, field, function, front-component, role, view, navigation-menu-item)
yarn twenty logs # Stream function logs
yarn twenty exec # Execute a function with JSON payload
yarn twenty uninstall # Uninstall app from workspace
Integration Tests
If your project includes the example integration test (src/__tests__/app-install.integration-test.ts), you can run it with:
# Make sure a Twenty server is running at http://localhost:3000
yarn test
The test builds and installs the app, then verifies it appears in the applications list. Test configuration (API URL and API key) is defined in vitest.config.ts.
LLMs instructions
Main docs and pitfalls are available in LLMS.md file.
Learn More
To learn more about Twenty applications, take a look at the following resources:
- twenty-sdk - learn about
twenty-sdktool. - Twenty doc - Twenty's documentation.
- Join our Discord
You can check out the Twenty GitHub repository - your feedback and contributions are welcome!