---
title: "Installation"
description: "Install the package and its Payload peers, and the bundled Lexical admin patch."
requested_language: fr
language: en
translation_notice: "This page isn't translated yet"
url: https://docs.systhema.app/fr/next/payload/installation
version: unreleased (main)
docs_index: https://docs.systhema.app/fr/next/llms.txt
---
> This page isn't translated yet. Showing English.


Install `@systhemaui/payload` together with the Systhema packages it builds on and the Payload peers each project pins itself.

```bash
pnpm add @systhemaui/core @systhemaui/react @systhemaui/next @systhemaui/payload
pnpm add -D @payloadcms/next @payloadcms/plugin-import-export \
  @payloadcms/plugin-nested-docs @payloadcms/plugin-redirects \
  @payloadcms/plugin-seo @payloadcms/richtext-lexical @payloadcms/ui
```

The peer dependencies above can't be bundled into `@systhemaui/payload` because PayloadCMS is highly version-sensitive — they install separately so each project pins compatible versions.

For a complete, working setup including Next.js App Router files, see [Templates / PayloadCMS](https://docs.systhema.app/fr/next/getting-started/templates/payload.md).

## The Lexical admin patch

Systhema ships a `pnpm patch` against `@payloadcms/richtext-lexical` inside `@systhemaui/cli` (`node_modules/@systhemaui/cli/patches/`). The patch changes no API and no editing behaviour — it collapses redundant schema payloads and sharpens one error message. It lives inside the CLI rather than `@systhemaui/payload` so it is available before the new `@systhemaui/payload` is installed in the consumer's `node_modules`.

The CLI installs it on three paths, all keyed by the same supported `@payloadcms/richtext-lexical` range:

- `systhema create` adds it to every Payload scaffold.
- `systhema upgrade` reconciles it in the Dependencies phase, after the peer bumps and before the install: it removes any entry Systhema authored for an older version, copies the bundled `.patch` into your `patches/` directory and merges the matching `pnpm.patchedDependencies` entry into your `package.json`, when the resolved lexical range is one the patch supports. The `pnpm install` that `systhema upgrade` runs afterwards applies it.
- `systhema doctor` reports a missing, unapplied or stale entry as the fixable `lexical-patch` check (`systhema doctor --fix` installs it), and reports an out-of-range or non-applying installed version without a fix.

What the patch does:

1. **schemaPath dedup** — memoizes `initLexicalFeatures` by `(sanitizedEditorConfig, clientFieldSchemaMap, schemaPath)` so two nested editors at the same schema location share the _same_ JS object reference for their feature-schema map. React Flight collapses the duplicates to a single `$`-reference, so a 30-section page that used to ship the same ~1.85 MB schemaMap 29 times now ships it once.
2. **content dedup** — after `initLexicalFeatures` builds a feature-schema map, the patch walks the map and content-keys-dedupes its values into a per-request pool. A typical Payload schemaMap has ~30 K positions pointing to ~300 distinct field-config arrays — 99 % structural duplicates that React Flight serializes inline because the JS identities differ. The pool rewrites later same-content positions to share the first occurrence's array reference.
3. **actionable block validation errors** — upstream reports every failed block write as `block node failed to validate: The following fields are invalid: content`, whichever block at whatever depth actually failed. The patch names the block and carries each nested field's own error message up, so a misplaced block deep in a document reads like `Block "section": the following fields are invalid: content (Block "columns" not found)` and points at the real culprit.

On `templates/payload`, all blocks enabled, the combined effect on `/admin/collections/pages/<id>` (30-section synthetic page) is **~91 MB → ~21 MB (−77 %)**, with warm response time roughly halved.

The patch is one-way safe — it never changes the schemaMap shape or field semantics, only collapses byte-identical references and rewords the validation message. When upstream lands equivalent memoization, the codemod can be told to roll the patch back; until then it's the cheapest way to get the wins.

### Why the Admin needs it

Without the patch, Payload builds each Lexical editor's client field-schema map by prefix-scanning the global schema map, which pulls in every descendant nested editor's block schema. With Systhema's deep nesting (root, region, fragment, slot, and a fragment-stack cycle) that expands combinatorially: a content-heavy page's Admin edit view serialized a payload of about 243 MB, took 15 to 30 seconds to load, and failed with `ERR_HTTP2_PROTOCOL_ERROR` on deploy. With the patch the payload drops to about 3.6 MB (about 98% smaller), server-render TTFB falls from about 4.5 seconds to about 50ms, and no editing capability is lost.