Fcode I18N

Factorial Code — i18n

A workspace keeps one locale per language it speaks: a YAML file of translation keys under i18n/, synced by the CLI like any other resource. fcode.i18n("key") resolves a key against the locale the current execution is using — in process code, in module code, and (substituted server-side) in form schemas. Platform model in fcode-core-concepts; CLI flow in fcode-cli; form embedding in fcode-forms.

Gotchas

• Never alias fcode.i18n — translations are only shipped to an execution when fcode.i18n( is statically detected in the source, so const t = fcode.i18n; t("k") throws "i18n is disabled" at runtime. Always call it literally, with the key as a hardcoded string (same class of rule as fcode.import module names).
• The helper never fails. A key with no translation anywhere resolves to the key itself — a raw greetings.hello in output means a missing translation, never a broken run. A placeholder you pass no argument for is left exactly as written; a non-object args (including arrays) is ignored.
• Locale identifiers are case-sensitive (pt-BR ≠ pt-br) and this is permanent platform-wide. Valid: up to 20 letters, numbers, - or _, starting with a letter or number (^[A-Za-z0-9][A-Za-z0-9_-]{0,19}$) — no dots. On a case-folding filesystem (macOS/Windows defaults) the CLI refuses to pull two locales differing only in case, since their files would collapse into one.
• Never edit i18n/<locale>.inherited.yaml — read-only, gitignored, regenerated on pull. To override an inherited key, write it into your own i18n/<locale>.yaml: overrides layer key by key, never file by file, so keys you don't mention keep resolving to the parent's text.
• locale is a reserved name on form and webhook endpoints, like version_tag and async: it selects the language and is stripped before the parameters are built. A form field or webhook body field named locale never reaches the process — use another name for business data.
• Form-token arguments must be a flat object of scalars — { "max": "500" } works, { "max": { "chars": "500" } } does not; a token with nested braces is left untouched in the served schema.
• A mistyped version tag resolves against the current files silently — it never blanks output. When released text looks un-frozen, check the pinned tag before anything else. Same shape for a per-call { locale } naming a locale that doesn't exist: the lookup behaves as if no locale was named.
• A pinned version must be an inline literal string — the snapshot to ship is read from the source, so { version: chosenTag } resolves against the current files. The locale option has no such rule: its value may be any runtime expression, and options built elsewhere still work.
• A YAML key written without a value counts as untranslated — it falls through to the fallback locale rather than resolving to an empty string.

Locale files

One YAML mapping of keys to text per locale, at i18n/<locale>.yaml. Nesting is a convenience for whoever writes the file, not a data model: nested keys are addressed with dots, so these two files are the same locale —

# i18n/en.yaml
greetings:
  hello: "Hi %{name}"
  farewell: "See you"

# identical to the file above
"greetings.hello": "Hi %{name}"
"greetings.farewell": "See you"

— which is what lets a child workspace override a single key without repeating the parent's structure. %{name} placeholders are filled from the arguments passed to the helper. A locale file is capped at 256 KB (the whole merged set travels with each execution).

What the workspace inherits sits alongside what it owns, in i18n/<locale>.inherited.yaml — read-only, gitignored (the CLI adds the entry). When several parent workspaces define the same locale, the inherited file holds their merge in the platform's resolution order, rewritten as a flat mapping of dotted keys under a generated header; with a single parent the file is kept verbatim, comments included. A local run layers your own file over it exactly as the cloud does.

The fcode.i18n helper

fcode.i18n(key, args, options) — same name and semantics in JavaScript and Python, available in processes and modules (a process reaching it only through a module still gets its translations):

const greeting = fcode.i18n("greetings.hello", { name: "Ada" }); // "Hi Ada" in `en`
fcode.i18n("greetings.farewell");                    // no placeholders → no args
fcode.i18n("legal.terms", null, { version: "v1.0.0" }); // pinned to a published version
fcode.i18n("greetings.hello", { name: "Ada" }, { locale: "es" }); // another locale, this lookup only
const recipient = { name: "Ada", locale: "pt-BR" };               // ...and the value may be dynamic,
fcode.i18n("greetings.hello", { name: recipient.name }, { locale: recipient.locale }); // per recipient
fcode.i18n("legal.terms", null, { version: "v1.0.0", locale: "es" }); // both combine
const locale = fcode.i18n.locale;                    // the execution's locale

greeting = fcode.i18n("greetings.hello", {"name": "Ada"})
fcode.i18n("greetings.farewell")
fcode.i18n("legal.terms", None, {"version": "v1.0.0"})
fcode.i18n("greetings.hello", {"name": "Ada"}, {"locale": "es"})
recipient = {"name": "Ada", "locale": "pt-BR"}
fcode.i18n("greetings.hello", {"name": recipient["name"]}, {"locale": recipient["locale"]})
fcode.i18n("legal.terms", None, {"version": "v1.0.0", "locale": "es"})
locale = fcode.i18n.locale

• version — a locale version tag or alias, as an inline literal string (see Gotchas); versioning below.
• locale — reads that lookup in another locale, and the value may be dynamic (an employee's language), so one execution can speak several languages. A key the named locale hasn't translated falls back to the execution's locale, then the primary; a locale that doesn't exist behaves as if none was named — never worse than without the option. fcode.i18n.locale keeps reporting the execution's locale. Form-schema tokens do not take this option — a render is already in the language the request chose.
• Interpolation is a single pass over own properties: a substituted value containing %{...} is never rescanned (one argument can't reach another), and %{constructor} resolves nothing. Missing keys and arguments never throw (see Gotchas).

Translating form schemas

Form schemas are rendered by the browser, so there is no runtime to resolve keys in. Write the same call as a string in parametersSchema.json — in titles, descriptions, ui:placeholder, embedFormOptions.loadingOverlayContent, any visible text — and the platform substitutes it before serving the schema. The browser receives a schema already written in one language; translations never reach the client. Substitution runs after preRenderProcess, so text a pre-render injects is translated too.

{
  "type": "object",
  "properties": {
    "reason": {
      "type": "string",
      "title": "fcode.i18n(\"form.reason.label\")",
      "description": "fcode.i18n(\"form.reason.help\", { max: \"500\" })"
    }
  }
}

Arguments follow relaxed JavaScript syntax (single quotes, unquoted field names, trailing commas all accepted) but must stay a flat object of scalars — a nested value leaves the whole token unsubstituted (see Gotchas).

The reader's locale comes from the embed: locale in the embed options or the data-fcode-form-locale attribute, sent to the platform as the Fcode-Locale header. Changing it refetches the schema, and the submit carries the same header, so the execution runs in the language the form was rendered in. Embedding mechanics in fcode-forms. (fallbackLocale in the embed options plays no part here — it only selects the language of rjsf's built-in validation messages when locale isn't one it ships.)

How the execution locale is chosen

A malformed locale on the public endpoints is a 400; an unknown-but-valid one merely falls back. The chosen locale is stored on the execution, which is why a rerun reproduces the original run's language even if the workspace's default has moved since.

When nothing names a locale, the workspace's primary locale is used — primaryLocale in settings.json (set it under Settings → Details, or edit the file and fcode settings:push; field reference in fcode-cli) — and when none is chosen, the first locale alphabetically. The primary locale is also the key-level fallback: a key the chosen locale hasn't translated resolves from the primary, and only a key missing from both resolves to its own name. So a partially translated locale still resolves every key — but keep the primary complete.

CLI: syncing and testing locales

Locales are a CLI resource like any other:

fcode i18n:pull            # fetch every locale, inherited ones included
fcode i18n:status          # what changed locally vs the cloud
fcode i18n:add pt-BR       # track a new local file
fcode i18n:push            # create or update in the cloud
fcode i18n:remove pt-BR    # stop tracking it locally
fcode i18n:reset           # discard local changes

• Aggregate fcode pull / push / status include locales, so the usual whole-workspace commands already cover them.
• There is no extract command — moving hardcoded strings into locale files is the agent's job (next section); the CLI only syncs the files.
• Pushing an identifier a parent workspace owns creates an override here, layered key by key — it never edits the parent's file.
• primaryLocale lives in settings.json and syncs with fcode settings:push.

Local runs resolve fcode.i18n against the same i18n/ files, layered exactly as the cloud does, so fcode run my-process behaves like production. Pass --locale to run in a specific one:

fcode run my-process --locale pt-BR

--locale is not format-validated locally: a typo silently matches no file and every key resolves to itself. If a local run shows raw keys, check the flag's spelling (and case) first.

Internationalizing existing code

There is no automated extraction — internationalizing a workspace is a code transformation you perform, with the CLI as the sync vehicle:

1. Agree scope with the user: which locales, and which is primary. If unset, write primaryLocale in settings.json and fcode settings:push.
2. Inventory the user-facing strings. Translate: form-schema titles, descriptions, placeholders and loadingOverlayContent; result message strings a form displays (these are markdown — keep any formatting like **bold**, links or table syntax intact in every locale); email subjects and bodies; webhook response bodies end users see. Do not translate: log messages, developer-facing errors, datastore keys, variable names, slugs and identifiers.
3. Name the keys in dotted namespaces: <process-slug>.<area>.<name> (order-sync.form.title, order-sync.email.subject), with strings shared across processes under common.*. Extract dynamic parts as %{placeholders} — never concatenate translated fragments.
4. Replace each string: in code with a literal fcode.i18n("key", { args }) call (never aliased, key hardcoded); in schemas with the token string (flat scalar args only).
5. Populate i18n/<locale>.yaml for every locale (fcode i18n:add for new ones). The primary locale must cover every key — it is the fallback all the others lean on.
6. Test per locale: fcode run <slug> --locale <loc>. A raw dotted key in the output is a missing translation; a literal %{name} is a missing argument.
7. Push: fcode i18n:push (or aggregate fcode push), plus fcode settings:push if primaryLocale changed.

Versioning locales

Locales are versioned like processes and modules (model in fcode-core-concepts): publishing snapshots the YAML under an immutable tag, and aliases are movable pointers — but per locale: production on en and production on es are two different aliases.

A pinned call ({ version: "v1.0.0" }) resolves per file in the inheritance chain: each locale file answers with its snapshot at that tag, or with its current content when it has no snapshot at that tag, layered key by key as usual. So a locale created after the version was cut still contributes its keys, a parent that never published the tag still contributes its text, and a mistyped tag resolves everything against the current files rather than blanking output. { version: "v1.0.0", locale: "es" } combine: the snapshot is read in the requested locale, with the same fallbacks. Deleting a version sends the calls pinned to it back to the current files; deleting a locale deletes its versions with it.

One layer resolves differently: a parent workspace pinned to one of its versions answers with its snapshot at the pin, and falls back to that snapshot rather than to its current file when the call names a tag it never published. Its live translations never reach the child — see fcode-core-concepts.

A workspace version freezes translations with the release. Creating one (fcode settings:versions:create, see fcode-cli) publishes a version of every owned locale — locales first, so the pins below have a target — and rewrites the published snapshots so bare fcode.i18n calls pin the tag, in process code, module code, and form schemas:

// Working copy (never modified)
fcode.i18n("greetings.hello", { name: "Ada" });
fcode.i18n("welcome", { name: "Ada" }, { locale: "es" });

// Published v1.0.0 snapshot
fcode.i18n("greetings.hello", { name: "Ada" }, { version: "v1.0.0" });
fcode.i18n("welcome", { name: "Ada" }, { version: "v1.0.0", locale: "es" });

A call whose options already name a version — even a dynamic one — is considered intentional and left untouched; options naming none (only a locale, an empty object, an explicit null/None) get the tag spliced in, so a localized call freezes with the release while its locale stays as written — a dynamic value ({ locale: employee.locale }) is preserved verbatim too. (Note the asymmetry with module imports, which are pinned in the string form — fcode.import("m", "v1.0.0") — for compatibility with older executors; don't "fix" one to look like the other.) Fixing a released typo means publishing again — snapshots are immutable.

REST API, SDKs & MCP tools

Locales are addressed by identifier, and PUT upserts, so a sync never needs to know whether the workspace already had the locale:

GET    /{team}/rest/locales
GET    /{team}/rest/locales/{locale}
PUT    /{team}/rest/locales/{locale}     body: { "content": "<yaml>" }
DELETE /{team}/rest/locales/{locale}

Both SDKs expose the same surface as FcodeI18n:

import { FcodeI18n } from "@factorialco/fcode-sdk";
const i18n = new FcodeI18n();
await i18n.list();                                        // inherited included
await i18n.set("pt-BR", 'greetings:\n  hello: "Olá %{name}"\n');
await i18n.delete("pt-BR");

from fcode_sdk import FcodeI18n
i18n = FcodeI18n()
i18n.list()
i18n.set("pt-BR", 'greetings:\n  hello: "Olá %{name}"\n')
i18n.delete("pt-BR")

set() on an identifier a parent workspace owns creates an override here — the same key-by-key layering the CLI push does.

The MCP server exposes get_locales, get_locale, save_locale and delete_locale. save_locale replaces the locale's content entirely — to add keys, get_locale first and write back the merged YAML.