examples: text keys - lang/i18n (k"" and kn"" keys, == on them, a @Text Key field's derived key, @TextKey, a component's t('key', ...) and its one line of English left, en.po with a plural and descriptions, tr.po missing, fuzzy and extra) and rejected/i18n_keys (a key en.po lacks, a plural key without msgid_plural, a Key / string mix-up, a derived key en.po lacks, a template's missing t() key, hole counts and an undescribed split); their cases in ludic-dev test (added, not run)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/lang/i18n/data/i18n_items.lres

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+# i18n.ludic's items: a @Text name is a Key, derived when the row gives none (items.rope.name)
+rope { weight: 0.4 }
+lamp { name: k"items.lamp.name", weight: 1.2 }

examples/lang/i18n/i18n.ludic

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+# i18n.ludic — keys, not English (LANGUAGE.md, "Text keys"). A text the player reads is named by a
+# key, k"pause.resume", of the builtin type Key: not a string, and no string is one. Its English is
+# lang/en.po (package.ludic says `lang "lang" en`), and the compiler checks every key against it. A
+# registry's @Text Key field a row leaves out is filled with its derived key - <registry>.<row>.<field>,
+# or the registry's @TextKey prefix. At run time a Key is its text after a marker byte (1, or 2 for a
+# plural kn"..."), so ludic.i18n's tr() is a cast; here tr, trf and trn are stand-ins that show the key.
+#
+# Running it prints:  pause.resume yes no 13 12 hud.day(3) catch.count[2](trout) items.rope.name items.lamp.name steps.gather_wood.hint
+program I18n {
+  property Item {
+    key: string = ""
+    @Text name: Key = null
+    weight: float = 0.0
+  }
+  registry Items of Item as IT from "data/i18n_items.lres"
+  property StepKind {
+    key: string = ""
+    @Text hint: Key = null
+  }
+  @TextKey("steps") registry StepKinds of StepKind as SK
+  def StepKinds gather_wood { }
+  # ludic.i18n's three, stood in for: the key's text without its marker
+  function tr(key: Key) -> string {
+    let s = string(key)
+    return s[1..len(s)]
+  }
+  function trf(key: Key, a: string) -> string { return `{tr(key)}({a})` }
+  function trn(key: Key, n: int, a: string) -> string { return `{tr(key)}[{n}]({a})` }
+  function yn(b: bool) -> string {
+    if b { return "yes" }
+    return "no"
+  }
+  entry {
+    let resume = k"pause.resume"
+    let same = resume == k"pause.resume"
+    let other = resume == k"pause.close"
+    var out = `{tr(resume)} {yn(same)} {yn(other)} {len(string(resume))} {len(string(kn"catch.count"))} {trf(k"hud.day", "3")}`
+    out = out + ` {trn(kn"catch.count", 2, "trout")} {tr(Items[IT_ROPE].name)} {tr(Items[IT_LAMP].name)} {tr(StepKinds[SK_GATHER_WOOD].hint)}`
+    print(out)
+  }
+}

examples/lang/i18n/i18n_ui.ludic

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+# i18n_ui.ludic — a component's template against lang/en.po: every t('key', ...) in a {hole} names
+# a key en.po has, and gives as many values as its English has holes. Words a player would read that
+# are not a key are "English left" (a warning, counted by ludic deps as english_left) - here the
+# "Paused" line; an element with translate="no" is left alone. `ludicc --check` reports both.
+import "ludic.ui"
+program I18nUi {
+  import "parts/Pause.ludic"
+  entry { print(1) }
+}

examples/lang/i18n/lang/en.po

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+# The example's source language: the English of every key i18n.ludic and i18n_ui.ludic use.
+msgid ""
+msgstr ""
+"Content-Type: text/plain; charset=UTF-8\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#. On the pause menu: returns to play.
+msgid "pause.resume"
+msgstr "Resume"
+
+#. On the pause menu: closes the menu and returns to play.
+msgid "pause.close"
+msgstr "Close"
+
+#. On the map screen: closes the map.
+msgid "map.close"
+msgstr "Close"
+
+#. The day on the HUD. {1} = the day number
+msgid "hud.day"
+msgstr "Day {1}"
+
+#. A catch, counted. {1} = how many, {2} = the species
+msgid "catch.count"
+msgid_plural "catch.count"
+msgstr[0] "{1} {2} caught"
+msgstr[1] "{1} {2} "
+"caught"
+
+#. An item's name: a coil of rope.
+msgid "items.rope.name"
+msgstr "Rope"
+
+#. An item's name: a brass lamp.
+msgid "items.lamp.name"
+msgstr "Lamp"
+
+#. What a chapter step says to do: gather firewood.
+msgid "steps.gather_wood.hint"
+msgstr "Gather wood"

examples/lang/i18n/lang/tr.po

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+# Turkish: one key missing (hud.day), one fuzzy (pause.close) and one en.po does not have (old.title)
+msgid ""
+msgstr ""
+"Content-Type: text/plain; charset=UTF-8\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+msgid "pause.resume"
+msgstr "Devam et"
+
+#, fuzzy
+msgid "pause.close"
+msgstr "Kapat"
+
+msgid "map.close"
+msgstr "Kapat"
+
+msgid "catch.count"
+msgid_plural "catch.count"
+msgstr[0] "{1} {2} tutuldu"
+msgstr[1] "{1} {2} tutuldu"
+
+msgid "items.rope.name"
+msgstr "Halat"
+
+msgid "items.lamp.name"
+msgstr "Fener"
+
+msgid "steps.gather_wood.hint"
+msgstr "Odun topla"
+
+msgid "old.title"
+msgstr "Eski"

examples/lang/i18n/package.ludic

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+# the key-based text example (i18n.ludic, i18n_ui.ludic): its languages are lang/<code>.po, and
+# lang/en.po is the source every key is checked against
+lang "lang" en

examples/lang/i18n/parts/Pause.ludic

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+# Pause.ludic - i18n_ui.ludic's component: its text is keys (Pause.xml), one of them a field the
+# template reads - a Key reaches a template as its marked text, for t(expr)
+component Pause {
+  prop day: int = 1
+  prop caught: int = 0
+  back: Key = k"pause.close"
+}

examples/lang/i18n/parts/Pause.xml

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+<div class="pause">
+  <p>{t('pause.resume')}</p>
+  <button title="{t('pause.close')}">{t('hud.day', day)}</button>
+  <button>{t(back)}</button>
+  <p>{t('catch.count', caught, 'trout')}</p>
+  <p translate="no">Maroon Lake 0.5 <b>beta</b></p>
+  <p>Paused</p>
+</div>