Migration from Lingui to Palamedes

The main changes are typically framework wiring, runtime access, configuration, extraction, and imports—not a rewrite of every translated component.

Who This Migration Is For

Switch now if you want:

• faster transforms and extraction without a Babel-heavy path
• source-string-first catalogs with message + context identity
• one runtime model via getI18n()
• a calmer long-term foundation than Lingui's broader historical surface
• a repository-owned local workflow that remains useful without a managed service

Wait if you need:

• maximum compatibility with every older Lingui runtime or authoring path
• explicit author-facing id support to remain untouched
• a zero-opinion migration with no cleanup decisions

Migration Checklist

• Replace Lingui framework integration with @palamedes/vite-plugin or @palamedes/next-plugin
• Add @palamedes/runtime and register the active i18n instance
• Add palamedes.yaml
• Rewrite Lingui macro imports to Palamedes macro imports
• Switch extraction to pnpm exec pmds extract
• Remove explicit authoring id usage
• Verify .po loading and runtime translations
• Verify one source locale and one non-source locale end to end
• Remove older accessor-specific runtime paths

Breaking Changes At A Glance

What Usually Stays The Same

Most authoring patterns remain familiar, but the import sources must change. The Palamedes transform recognizes Palamedes macro packages; Lingui macro imports are left untouched.

import { t, plural, select, selectOrdinal } from "@palamedes/core/macro";

import { Trans, Plural, Select, SelectOrdinal } from "@palamedes/react/macro";

Palamedes requires eager translation macros to live inside a function, method, or callback. This applies to t, plural, select, selectOrdinal, <Plural>, <Select>, and <SelectOrdinal> and prevents translation from running while a module is loaded, before request- or render-local i18n activation. <Trans> can remain at module scope because it resolves when the component renders. Class field initializers do not satisfy the rule, even for instance fields; migrate those calls to a method or getter.

That continuity is the point. The migration is primarily a tooling, catalog, and runtime cleanup, not an authoring reset.

The result is Palamedes as the full local open-source toolchain. Palamedes+ is planned as an optional managed layer for translation automation and collaboration; it is not required for the migration or the local workflow.

Before / After

1. Runtime access

Before:

// older context-specific runtime access path

After:

import { getI18n } from "@palamedes/runtime";

function currentLocale() {
  return getI18n().locale;
}

Call getI18n() inside a function or component, not at module top level — at import time there is no active i18n instance yet.

2. Explicit IDs

Before (Lingui):

t({ id: "checkout.cta", message: "Buy now" });
defineMessage({ id: "checkout.cta", message: "Buy now" });

After:

function checkoutButtonLabel() {
  return t({ message: "Buy now", context: "checkout button" });
}

Palamedes does not expose deferred message descriptors. Move former msg or defineMessage declarations into a function or callback and translate with t when the value is actually needed.

3. Framework integration

Before:

// Lingui-specific Vite or Next wiring

After for Vite:

import { palamedes } from "@palamedes/vite-plugin";

export default defineConfig({
  plugins: [palamedes()],
});

After for Next.js:

const { withPalamedes } = require("@palamedes/next-plugin");

module.exports = withPalamedes({});

Recommended Migration Order

1. Get one app path working

Do not start by cleaning every edge case in the codebase.

Start by wiring:

• one framework adapter
• one runtime registration path
• one extraction run
• one translated route or component

The first working translation guide is the best way to establish that baseline.

2. Migrate runtime wiring

For the standard Vite, Next, Remix, Solid, Waku, and React Router paths, remove app-owned runtime and catalog wiring. The adapter initializes the parser-free runtime, derives compiled dependencies from translated module use, and awaits the active locale before the module runs. Do not import locale catalogs, maintain a locale loader map, or call load()/activate() from the application. Locale selection and ordinary host error UI remain host policy.

For an explicit custom integration outside a supported adapter, use the parser-free /compiled API and executable CompiledCatalogMessages contract; raw ICU maps are not a runtime compatibility path. See the @palamedes/core API reference.

Server-side:

import { setServerI18nGetter } from "@palamedes/runtime";

setServerI18nGetter(() => getRequestScopedI18n());

For Next.js App Router Server Components on the Node runtime, prefer the Next render-lifetime helper:

// src/lib/i18n.server.ts
import "server-only";

import { cache } from "react";
import { createNextServerI18nScope } from "@palamedes/next-plugin/server";
import type { PalamedesI18n } from "@palamedes/core";

export const serverI18n = createNextServerI18nScope<PalamedesI18n>();

const loadActiveServerI18n = cache(async () => {
  const locale = await resolveLocaleFromCookiesOrHeaders();
  const i18n = await loadI18n(locale);
  return { i18n, locale };
});

export async function createActiveServerI18n() {
  const active = await loadActiveServerI18n();
  serverI18n.activate(active.i18n);
  return active;
}

// app/page.tsx
import { t } from "@palamedes/core/macro";
import { createActiveServerI18n } from "@/lib/i18n.server";

function CheckoutTitle() {
  return <h1>{t`Checkout`}</h1>;
}

export default async function Page() {
  await createActiveServerI18n();
  return <CheckoutTitle />;
}

This follows the official RSC model: server-only modules prevent accidental client imports, React cache() memoizes setup work within the current request, and the Next adapter keeps the active instance bound through the RSC and Client Component server-render passes, including suspension and resumption. Create one scope at module level, activate a fresh instance per request, and do not register a global server getter from every Server Component render.

For backend servers outside React frameworks, use the same runtime getter with request-local storage. The Hono/Express pattern is documented here:

• Palamedes in backend servers

3. Remove explicit IDs

This is the most important semantic cleanup.

Palamedes treats:

• message as the source string
• context as the disambiguator
• message + context as the only public identity

If your existing codebase still has explicit authoring IDs, remove them deliberately instead of expecting compatibility shims.

4. Switch extraction and catalogs

Run extraction through Palamedes:

pnpm exec pmds extract

That moves catalogs onto the source-first path and aligns updates, audits, and ICU diagnostics with the current native core and ferrocat.

Existing translations carried over from Lingui or a TMS keep their ICU quoting. Doubled apostrophes (Ada''s) render as a single ', and '{' still emits a literal brace — this used to be a documented divergence in the Palamedes runtime and is no longer one. Plain apostrophes in prose (don't, client's, and l'été) stay unchanged in newly extracted PO identities. An apostrophe immediately before generated ICU syntax is still escaped, so t`L'${title}` is stored as L''{title} and the placeholder remains live at runtime.

When an existing PO catalog uses the other spelling solely because an older Palamedes extractor doubled its natural apostrophes, pmds extract reuses the unique matching (msgid, msgctxt) entry. Its translation, translator comments, flags, and machine metadata survive, including with --force-clean, and repeated extraction is stable. Exact identities always win; Palamedes does not merge ambiguous entries or entries with different contexts. See Quoting and literal text.

Common Migration Errors

"Catalog dependency failed before translated UI"

Cause:

• the adapter could not load the active locale's compiled fragment, or the document locale does not match the host's locale policy

Fix:

• keep the ordinary host error view independent of translated messages and offer a full document reload; verify that the adapter config covers the translated module and that <html lang> is set before the entry runs

Supported adapters initialize the client runtime and derive catalog dependencies automatically. Do not add setClientI18n, direct locale imports, or an application loader map to recover this failure.

"No active server i18n instance" in a custom integration

Supported host adapters create the request-local scope and load the active compiled catalog themselves. An explicit custom server integration must expose its request-local instance through @palamedes/runtime; this is outside the standard adapter path.

Extraction works, but translations do not render

Cause:

• the translated source module is outside the configured catalog include pattern, or its document locale was not selected before entry evaluation

Fix:

• fix the catalog configuration and host locale policy; supported adapters derive and await the active compiled fragment before rendering

Explicit id usage now fails

Cause:

• Palamedes no longer supports author-facing explicit IDs as a normal path

Fix:

• move to source-string-first descriptors and use context when disambiguation is needed

What Gets Better After The Move

• transforms, extraction, catalog updates, and audits move to a native core
• runtime assumptions get simpler
• catalog identity gets cleaner
• the work is easier to reason about when something breaks

That is why the migration is worth doing. The visible authoring surface stays familiar, but the stack under it gets easier to understand and easier to trust.

Next Steps

• First working translation in 5 minutes
• Palamedes vs. Lingui
• Proof, benchmarks, and current maturity