feat(i18n): add Czech (cs) locale support

Add a complete Czech (cs) locale to hermes-webui: full key parity with the
English reference (1642/1642 keys), real Czech translations for all string and
function-valued keys, Slavic plural helpers for tool/worklog summaries, the cs
login-screen locale in api/routes.py, and a dedicated tests/test_czech_locale.py
parity+placeholder+diacritics guard mirroring the other per-locale tests. All
15 locale-count assertions bumped 14->15.

Co-authored-by: ostravajih <ostravajih@users.noreply.github.com>

api/routes.py

@@ -9204,6 +9204,15 @@ _LOGIN_LOCALE = {
         "invalid_pw": "M\u1eadt kh\u1ea9u kh\u00f4ng h\u1ee3p l\u1ec7",
         "conn_failed": "K\u1ebft n\u1ed1i th\u1ea5t b\u1ea1i",
     },
+    "cs": {
+        "lang": "cs-CZ",
+        "title": "P\u0159ihl\u00e1sit se",
+        "subtitle": "Zadejte heslo pro pokra\u010dov\u00e1n\u00ed",
+        "placeholder": "Heslo",
+        "btn": "P\u0159ihl\u00e1sit se",
+        "invalid_pw": "Neplatn\u00e9 heslo",
+        "conn_failed": "P\u0159ipojen\u00ed selhalo",
+    },
 }
 
 

tests/test_2735_open_in_vscode.py

@@ -229,7 +229,7 @@ class TestOpenInVsCodeI18n:
         """open_in_vscode key must appear exactly once per locale (14 total)."""
         src = I18N.read_text(encoding="utf-8")
         count = src.count("open_in_vscode:")
-        assert count == 14, (
+        assert count == 15, (
             f"Expected 14 open_in_vscode: entries (one per locale), found {count}"
         )
 
@@ -237,7 +237,7 @@ class TestOpenInVsCodeI18n:
         """open_in_vscode_failed key must appear exactly once per locale (14 total)."""
         src = I18N.read_text(encoding="utf-8")
         count = src.count("open_in_vscode_failed:")
-        assert count == 14, (
+        assert count == 15, (
             f"Expected 14 open_in_vscode_failed: entries (one per locale), found {count}"
         )
 

tests/test_5144_busy_composer_placeholder_hint.py

@@ -78,7 +78,7 @@ def test_busy_placeholder_helper_preserves_compression_and_drafts():
 
 def test_locale_blocks_cover_new_keys():
     locale_blocks = I18N_JS.count("settings_default_message_mode_steer")
-    assert locale_blocks == 14
+    assert locale_blocks == 15
     for key in [
         "settings_label_busy_placeholder_hint",
         "settings_desc_busy_placeholder_hint",

tests/test_auxiliary_models_settings.py

@@ -330,7 +330,7 @@ class TestAuxiliaryModelsI18n:
         """Count of each key should equal the number of locales (12 with Turkish)."""
         for key in self.REQUIRED_KEYS:
             count = I18N_JS.count(f"{key}:")
-            assert count == 14, (
+            assert count == 15, (
                 f"i18n key '{key}' found {count} times — expected 14 (one per locale)"
             )
 

tests/test_czech_locale.py

@@ -0,0 +1,197 @@
+from collections import Counter
+from pathlib import Path
+import re
+
+
+REPO = Path(__file__).resolve().parent.parent
+
+
+def read(path: Path) -> str:
+    return path.read_text(encoding="utf-8")
+
+
+def extract_locale_block(src: str, locale_key: str) -> str:
+    start_match = re.search(rf"\b{re.escape(locale_key)}\s*:\s*\{{", src)
+    assert start_match, f"{locale_key} locale block not found"
+
+    start = start_match.end() - 1
+    depth = 0
+    in_single = False
+    in_double = False
+    in_backtick = False
+    escape = False
+
+    for i in range(start, len(src)):
+        ch = src[i]
+
+        if escape:
+            escape = False
+            continue
+
+        if in_single:
+            if ch == "\\":
+                escape = True
+            elif ch == "'":
+                in_single = False
+            continue
+
+        if in_double:
+            if ch == "\\":
+                escape = True
+            elif ch == '"':
+                in_double = False
+            continue
+
+        if in_backtick:
+            if ch == "\\":
+                escape = True
+            elif ch == "`":
+                in_backtick = False
+            continue
+
+        if ch == "'":
+            in_single = True
+            continue
+        if ch == '"':
+            in_double = True
+            continue
+        if ch == "`":
+            in_backtick = True
+            continue
+
+        if ch == "{":
+            depth += 1
+            continue
+        if ch == "}":
+            depth -= 1
+            if depth == 0:
+                return src[start + 1 : i]
+
+    raise AssertionError(f"{locale_key} locale block braces are not balanced")
+
+
+def locale_keys(src: str, locale_key: str) -> list[str]:
+    key_pattern = re.compile(r"^\s*([a-zA-Z0-9_]+)\s*:", re.MULTILINE)
+    return key_pattern.findall(extract_locale_block(src, locale_key))
+
+
+def test_czech_locale_block_exists():
+    src = read(REPO / "static" / "i18n.js")
+    cs_block = extract_locale_block(src, "cs")
+    assert cs_block
+    assert "_lang: 'cs'" in cs_block
+    assert "_label: 'Čeština'" in cs_block
+    assert "_speech: 'cs-CZ'" in cs_block
+
+
+def test_czech_locale_includes_representative_translations():
+    src = read(REPO / "static" / "i18n.js")
+    cs_block = extract_locale_block(src, "cs")
+    expected = [
+        "settings_title: 'Nastavení'",
+        "settings_label_language: 'Jazyk'",
+        "login_title: 'Přihlášení'",
+        "approval_heading: 'Požadováno schválení'",
+        "tab_tasks: 'Úkoly'",
+        "tab_profiles: 'Profily'",
+        "empty_title: 'Jak vám mohu pomoci?'",
+        "onboarding_title: 'Vítejte v Hermes Web UI'",
+    ]
+    for entry in expected:
+        assert entry in cs_block, f"missing expected Czech translation: {entry}"
+
+
+def test_czech_locale_matches_english_key_coverage():
+    src = read(REPO / "static" / "i18n.js")
+    en_keys = set(locale_keys(src, "en"))
+    cs_keys = set(locale_keys(src, "cs"))
+    assert sorted(en_keys - cs_keys) == []
+    assert sorted(cs_keys - en_keys) == []
+
+
+def test_czech_locale_has_no_duplicate_keys():
+    src = read(REPO / "static" / "i18n.js")
+    keys = locale_keys(src, "cs")
+
+    duplicates = sorted(k for k, count in Counter(keys).items() if count > 1)
+    assert not duplicates, f"Czech locale has duplicate keys: {duplicates}"
+
+
+def test_czech_locale_keys_use_standard_indentation():
+    src = read(REPO / "static" / "i18n.js")
+    cs_block = extract_locale_block(src, "cs")
+
+    # Enforce strict 4-space indentation for keys.
+    badly_indented = []
+    for line in cs_block.splitlines():
+        m = re.match(r"^(\s*)[a-zA-Z0-9_]+\s*:", line)
+        if m and len(m.group(1)) != 4:
+            badly_indented.append(f"{len(m.group(1))} spaces: {line.strip()}")
+    assert badly_indented == []
+
+
+def test_czech_locale_arrow_function_values_mirror_english():
+    src = read(REPO / "static" / "i18n.js")
+    en_block = extract_locale_block(src, "en")
+    cs_block = extract_locale_block(src, "cs")
+
+    value_re = re.compile(r"^\s+([a-zA-Z0-9_]+):\s*(.+?)(?:,\s*$|\s*$)", re.MULTILINE)
+    arrow_re = re.compile(r"^\s*\(?[a-zA-Z_,\s]*\)?\s*=>")
+    helper_re = re.compile(r"^_i18n[A-Za-z]+$")
+
+    def callable_values(block):
+        out = set()
+        for k, v in value_re.findall(block):
+            v = v.strip()
+            if arrow_re.match(v) or helper_re.match(v):
+                out.add(k)
+        return out
+
+    # Every key whose English value is a function must also be a function in cs
+    # (either an arrow or a named _i18n* helper reference).
+    assert callable_values(en_block) == callable_values(cs_block)
+
+
+def test_czech_locale_preserves_placeholder_patterns():
+    src = read(REPO / "static" / "i18n.js")
+    en_block = extract_locale_block(src, "en")
+    cs_block = extract_locale_block(src, "cs")
+
+    value_re = re.compile(r"^\s+([a-zA-Z0-9_]+):\s*(.+?)(?:,\s*$|\s*$)", re.MULTILINE)
+    placeholder_re = re.compile(r"\{[0-9]+\}|\$\{[a-zA-Z_][a-zA-Z0-9_]*\}")
+
+    def kv(block):
+        out = {}
+        for k, v in value_re.findall(block):
+            out[k] = v
+        return out
+
+    en_kv = kv(en_block)
+    cs_kv = kv(cs_block)
+
+    for key, en_val in en_kv.items():
+        if key not in cs_kv:
+            continue
+        en_vars = sorted(placeholder_re.findall(en_val))
+        cs_vars = sorted(placeholder_re.findall(cs_kv[key]))
+        # Skip arrow functions which might contain conditional logic and thus more template vars.
+        if "=>" not in cs_kv[key]:
+            if en_vars or cs_vars:
+                assert cs_vars == en_vars, f"Key '{key}' placeholder mismatch in cs locale"
+
+
+def test_czech_locale_has_no_double_escaped_unicode_sequences():
+    """JSON-style double escapes (\\\\u2026) render literal backslash-u in the UI."""
+    src = read(REPO / "static" / "i18n.js")
+    cs_block = extract_locale_block(src, "cs")
+    for bad in ("\\\\u2026", "\\\\u2192", "\\\\u2713"):
+        assert bad not in cs_block, f"Czech locale must not contain {bad!r}"
+
+
+def test_czech_locale_uses_real_utf8_diacritics():
+    """Czech uses á č ď é ě í ň ó ř š ť ú ů ý ž — confirm the block carries real
+    UTF-8 diacritics, not ASCII-only text (which would mean nothing was translated)."""
+    src = read(REPO / "static" / "i18n.js")
+    cs_block = extract_locale_block(src, "cs")
+    diacritics = "áčďéěíňóřšťúůýžÁČĎÉĚÍŇÓŘŠŤÚŮÝŽ"
+    assert any(ch in cs_block for ch in diacritics), "Czech locale has no diacritics"

tests/test_issue1488_composer_voice_buttons.py

@@ -123,7 +123,7 @@ class TestComposerVoiceButtonI18n:
         "voice_mode_toggle_active",
     )
 
-    LOCALES = ("en", "fr", "it", "ja", "ru", "es", "de", "zh", "zh-Hant", "pt", "ko", "tr", "pl", "vi")
+    LOCALES = ("en", "fr", "it", "ja", "ru", "es", "de", "zh", "zh-Hant", "pt", "ko", "tr", "pl", "vi", "cs")
 
     def test_legacy_voice_toggle_key_removed(self):
         """The old key whose string was 'Voice input' caused the duplicate-
@@ -171,7 +171,7 @@ class TestComposerVoiceButtonI18n:
 class TestVoiceModePreferenceGate:
     """boot.js must hide btnVoiceMode by default, surface it via Preferences."""
 
-    LOCALES = ("en", "fr", "it", "ja", "ru", "es", "de", "zh", "zh-Hant", "pt", "ko", "tr", "pl", "vi")
+    LOCALES = ("en", "fr", "it", "ja", "ru", "es", "de", "zh", "zh-Hant", "pt", "ko", "tr", "pl", "vi", "cs")
 
     def test_voice_mode_pref_is_localstorage_backed(self):
         """The pref reads from localStorage key 'hermes-voice-mode-button'."""

tests/test_issue2419_cache_usage_display.py

@@ -63,8 +63,8 @@ def test_context_indicator_surfaces_cache_hit_rate():
 def test_cache_usage_labels_are_localized():
     src = (ROOT / "static" / "i18n.js").read_text()
 
-    assert src.count("usage_cache_hit_detail:") == 14
-    assert src.count("usage_cached_percent:") == 14
+    assert src.count("usage_cache_hit_detail:") == 15
+    assert src.count("usage_cached_percent:") == 15
     assert "usage_cache_hit_detail: 'Cache: {0}% hit ({1} read / {2} write)'" in src
     assert "usage_cached_percent: '{0}% cached'" in src
 

tests/test_issue2679_hide_suggestions.py

@@ -50,8 +50,8 @@ def test_panels_round_trip_and_hot_apply_hide_suggestions():
 
 def test_hide_suggestions_i18n_all_locales_and_changelog():
     js = I18N.read_text(encoding="utf-8")
-    assert js.count("settings_label_hide_suggestions:") == 14
-    assert js.count("settings_desc_hide_suggestions:") == 14
+    assert js.count("settings_label_hide_suggestions:") == 15
+    assert js.count("settings_desc_hide_suggestions:") == 15
     changelog = CHANGELOG.read_text(encoding="utf-8")
     assert "#2679" in changelog
     assert "hide_empty_state_suggestions" in changelog

tests/test_issue3227_help_tab.py

@@ -6,7 +6,7 @@ PANELS_JS  = (ROOT / "static" / "panels.js").read_text(encoding="utf-8")
 I18N_JS    = (ROOT / "static" / "i18n.js").read_text(encoding="utf-8")
 STYLE_CSS  = (ROOT / "static" / "style.css").read_text(encoding="utf-8")
 
-LOCALE_COUNT = 14  # en, it, ja, ru, es, de, zh, zh-TW, pt, ko, fr, tr, pl
+LOCALE_COUNT = 15  # en, it, ja, ru, es, de, zh, zh-Hant, pt, ko, fr, tr, pl, vi, cs
 
 
 def test_help_nav_button_present():

tests/test_issue3242_3214_i18n_tooltips.py

@@ -5,7 +5,7 @@ BOOT_JS = (ROOT / "static" / "boot.js").read_text(encoding="utf-8")
 I18N_JS = (ROOT / "static" / "i18n.js").read_text(encoding="utf-8")
 SESSIONS_JS = (ROOT / "static" / "sessions.js").read_text(encoding="utf-8")
 
-LOCALE_COUNT = 14
+LOCALE_COUNT = 15
 
 
 def test_raw_audio_active_recording_uses_dedicated_i18n_key():

tests/test_issue4325_virtualization_toggle.py

@@ -76,8 +76,8 @@ def test_panels_round_trip_and_hot_apply_virtualize_toggle():
 
 def test_virtualize_toggle_i18n_all_locales():
     js = I18N.read_text(encoding="utf-8")
-    assert js.count("settings_label_virtualize_transcript:") == 14
-    assert js.count("settings_desc_virtualize_transcript:") == 14
+    assert js.count("settings_label_virtualize_transcript:") == 15
+    assert js.count("settings_desc_virtualize_transcript:") == 15
 
 
 # ── #4343 force-off-for-everyone migration (load_settings behavior) ──────────

tests/test_issue4356_no_git_update_check.py

@@ -86,4 +86,4 @@ def test_i18n_no_git_key_all_locales():
 
     # Count occurrences of the new key (should be exactly 13, one per locale)
     count = content.count("settings_update_no_git")
-    assert count == 14, f"Expected exactly 14 settings_update_no_git keys, found {count}"
+    assert count == 15, f"Expected exactly 15 settings_update_no_git keys, found {count}"

tests/test_issue4470_kanban_task_editor_fields.py

@@ -130,7 +130,7 @@ def test_i18n_new_keys_in_all_locales():
     ]
     for key in required:
         count = I18N_JS.count(f"{key}:")
-        assert count == 14, f"Key '{key}' appears {count} times, expected 14 (one per locale)"
+        assert count == 15, f"Key '{key}' appears {count} times, expected 15 (one per locale)"
 
 
 def test_backend_already_accepts_new_fields():

tests/test_pr1721_rtl_salvage.py

@@ -112,5 +112,5 @@ def test_rtl_in_config_defaults_and_writable_keys():
 def test_rtl_localized_in_all_locales():
     js = I18N.read_text(encoding="utf-8")
     # Count occurrences — should match the 11 locale blocks
-    assert js.count("settings_label_rtl:") == 14
-    assert js.count("settings_desc_rtl:") == 14
+    assert js.count("settings_label_rtl:") == 15
+    assert js.count("settings_desc_rtl:") == 15

tests/test_quota_chip_settings_toggle.py

@@ -88,5 +88,5 @@ def test_quota_chip_panels_round_trip():
 
 def test_quota_chip_localized_in_all_locales():
     js = I18N.read_text(encoding="utf-8")
-    assert js.count("settings_label_quota_chip:") == 14, "12 locales expected"
-    assert js.count("settings_desc_quota_chip:") == 14, "12 locales expected"
+    assert js.count("settings_label_quota_chip:") == 15, "12 locales expected"
+    assert js.count("settings_desc_quota_chip:") == 15, "12 locales expected"

tests/test_verdigris_skin.py

@@ -38,4 +38,4 @@ def test_verdigris_has_no_light_variant():
 def test_verdigris_i18n_lists_skin_in_all_locales():
     # There are 12 locales; each should now include verdigris as the trailing skin.
     # 10 locales use ASCII closing paren, 2 Chinese locales use full-width paren.
-    assert I18N_JS.count("verdigris)") + I18N_JS.count("verdigris）") == 14
+    assert I18N_JS.count("verdigris)") + I18N_JS.count("verdigris）") == 15

tests/test_zeus_skin.py

@@ -45,4 +45,4 @@ def test_zeus_modals_are_not_navy():
 
 def test_zeus_i18n_lists_skin_in_all_locales():
     # There are 12 locales; each should include zeus in the skin list.
-    assert I18N_JS.count("/zeus/") == 14
+    assert I18N_JS.count("/zeus/") == 15