diff --git a/eslint.config.mjs b/eslint.config.mjs
index a2af5fa614..3a29e83b5c 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -23,6 +23,25 @@ const eslintConfig = [
       ],
     },
   },
+  // i18n: ham toLowerCase().includes() arama pattern'ini engelle
+  // (Türkçe İ/ı karakterlerini bozar — matchesSearch kullanılmalı).
+  // "warn" (error değil): kuralın eklendiği anda kod tabanında zaten bu pattern'i
+  // kullanan ~19 satır var; aşamalı temizlik için uyarı seviyesinde tutuluyor
+  // (proje politikası: 0 error, warning'ler tolere edilir).
+  {
+    files: ["src/app/**/*.{ts,tsx}", "src/components/**/*.{ts,tsx}"],
+    rules: {
+      "no-restricted-syntax": [
+        "warn",
+        {
+          selector:
+            "CallExpression[callee.property.name='includes'][callee.object.callee.property.name='toLowerCase']",
+          message:
+            "Türkçe-güvenli arama için matchesSearch() kullan (@/shared/utils/turkishText). Ham toLowerCase().includes() İ/ı karakterlerini bozar.",
+        },
+      ],
+    },
+  },
   // Relaxed rules for open-sse and tests (incremental adoption)
   {
     files: ["open-sse/**/*.ts", "tests/**/*.mjs", "tests/**/*.ts"],
diff --git a/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx b/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx
index a09be3cab3..8b155975cf 100644
--- a/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx
+++ b/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx
@@ -5,6 +5,7 @@ import { Card, Button, Input, Modal, CardSkeleton } from "@/shared/components";
 import { useCopyToClipboard } from "@/shared/hooks/useCopyToClipboard";
 import { useTranslations } from "next-intl";
 import { getProviderDisplayName } from "@/lib/display/names";
+import { compareTr, matchesSearch } from "@/shared/utils/turkishText";
 import { ENDPOINT_CATEGORIES } from "@/shared/constants/endpointCategories";
 import ApiKeyFilterBar from "./components/ApiKeyFilterBar";
 import {
@@ -675,20 +676,21 @@ export default function ApiManagerPageClient() {
       if (!grouped[provider]) grouped[provider] = [];
       grouped[provider].push(model);
     }
-    return Object.entries(grouped).sort((a, b) => a[0].localeCompare(b[0]));
+    return Object.entries(grouped).sort((a, b) => compareTr(a[0], b[0]));
   }, [allModels, t]);
 
   // Filter models based on debounced search
   const filteredModelsByProvider = useMemo((): ProviderGroup[] => {
     if (!debouncedSearchModel.trim()) return modelsByProvider;
 
-    const search = debouncedSearchModel.toLowerCase();
     return modelsByProvider
       .map(
         ([provider, models]): ProviderGroup => [
           provider,
           models.filter(
-            (m) => m.id.toLowerCase().includes(search) || provider.toLowerCase().includes(search)
+            (m) =>
+              matchesSearch(m.id, debouncedSearchModel) ||
+              matchesSearch(provider, debouncedSearchModel)
           ),
         ]
       )
@@ -2437,7 +2439,7 @@ const PermissionsModal = memo(function PermissionsModal({
                     return acc;
                   }, {})
                 )
-                  .sort(([a], [b]) => a.localeCompare(b))
+                  .sort(([a], [b]) => compareTr(a, b))
                   .map(([provider, conns]) => (
                     <div key={provider}>
                       <p className="text-[10px] font-semibold text-text-muted uppercase tracking-wider px-1 py-0.5">
diff --git a/src/app/(dashboard)/dashboard/batch/BatchListTab.tsx b/src/app/(dashboard)/dashboard/batch/BatchListTab.tsx
index 4980308a10..b281abae1a 100644
--- a/src/app/(dashboard)/dashboard/batch/BatchListTab.tsx
+++ b/src/app/(dashboard)/dashboard/batch/BatchListTab.tsx
@@ -2,6 +2,7 @@
 
 import { useState } from "react";
 import { useTranslations } from "next-intl";
+import { matchesSearch } from "@/shared/utils/turkishText";
 import BatchDetailModal from "./BatchDetailModal";
 import ExpirationBadge from "./components/ExpirationBadge";
 import ProgressBarBicolor from "./components/ProgressBarBicolor";
@@ -348,11 +349,10 @@ export default function BatchListTab({
   const filtered = batches.filter((b) => {
     if (statusFilter !== "all" && b.status !== statusFilter) return false;
     if (searchQuery) {
-      const q = searchQuery.toLowerCase();
       return (
-        b.id.toLowerCase().includes(q) ||
-        b.endpoint.toLowerCase().includes(q) ||
-        (b.model ?? "").toLowerCase().includes(q)
+        matchesSearch(b.id, searchQuery) ||
+        matchesSearch(b.endpoint, searchQuery) ||
+        matchesSearch(b.model ?? "", searchQuery)
       );
     }
     return true;
diff --git a/src/app/(dashboard)/dashboard/batch/FilesListTab.tsx b/src/app/(dashboard)/dashboard/batch/FilesListTab.tsx
index 9902509539..38df109db8 100644
--- a/src/app/(dashboard)/dashboard/batch/FilesListTab.tsx
+++ b/src/app/(dashboard)/dashboard/batch/FilesListTab.tsx
@@ -2,6 +2,7 @@
 
 import { useState } from "react";
 import { useTranslations } from "next-intl";
+import { matchesSearch } from "@/shared/utils/turkishText";
 import FileDetailModal from "./FileDetailModal";
 import ExpirationBadge from "./components/ExpirationBadge";
 
@@ -90,8 +91,7 @@ export default function FilesListTab({
   const filtered = files.filter((f) => {
     if (purposeFilter !== "all" && f.purpose !== purposeFilter) return false;
     if (searchQuery) {
-      const q = searchQuery.toLowerCase();
-      return f.id.toLowerCase().includes(q) || f.filename.toLowerCase().includes(q);
+      return matchesSearch(f.id, searchQuery) || matchesSearch(f.filename, searchQuery);
     }
     return true;
   });
diff --git a/src/app/(dashboard)/dashboard/batch/page.tsx b/src/app/(dashboard)/dashboard/batch/page.tsx
index 996ac551c6..b0d12bf5e1 100644
--- a/src/app/(dashboard)/dashboard/batch/page.tsx
+++ b/src/app/(dashboard)/dashboard/batch/page.tsx
@@ -83,7 +83,7 @@ export default function BatchPage() {
                 batchMap.set(m.id, m);
               }
               return Array.from(batchMap.values()).sort(
-                (a, b) => b.createdAt - a.createdAt || b.id.localeCompare(a.id),
+                (a, b) => b.createdAt - a.createdAt || b.id.localeCompare(a.id), // teknik sıralama: ASCII kasıtlı
               );
             });
           } else {
@@ -104,7 +104,7 @@ export default function BatchPage() {
                 fileMap.set(m.id, m);
               }
               return Array.from(fileMap.values()).sort(
-                (a, b) => b.createdAt - a.createdAt || b.id.localeCompare(a.id),
+                (a, b) => b.createdAt - a.createdAt || b.id.localeCompare(a.id), // teknik sıralama: ASCII kasıtlı
               );
             });
           } else {
diff --git a/src/app/(dashboard)/dashboard/cache/media/MediaPageClient.tsx b/src/app/(dashboard)/dashboard/cache/media/MediaPageClient.tsx
index 1e97577beb..cb89cd20c3 100644
--- a/src/app/(dashboard)/dashboard/cache/media/MediaPageClient.tsx
+++ b/src/app/(dashboard)/dashboard/cache/media/MediaPageClient.tsx
@@ -376,10 +376,15 @@ function parseApiError(raw: any, statusCode: number): { message: string; isCrede
 
   const isCredentials =
     typeof msg === "string" &&
+    // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
     (msg.toLowerCase().includes("no credentials") ||
+      // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
       msg.toLowerCase().includes("invalid api key") ||
+      // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
       msg.toLowerCase().includes("unauthorized") ||
+      // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
       msg.toLowerCase().includes("authentication") ||
+      // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
       msg.toLowerCase().includes("api key") ||
       statusCode === 401 ||
       statusCode === 403);
diff --git a/src/app/(dashboard)/dashboard/cli-code/components/CopilotToolCard.tsx b/src/app/(dashboard)/dashboard/cli-code/components/CopilotToolCard.tsx
index 17128b165b..190247283a 100644
--- a/src/app/(dashboard)/dashboard/cli-code/components/CopilotToolCard.tsx
+++ b/src/app/(dashboard)/dashboard/cli-code/components/CopilotToolCard.tsx
@@ -4,6 +4,7 @@ import { useState, useEffect } from "react";
 import { Card, Button } from "@/shared/components";
 import Image from "next/image";
 import { useTranslations } from "next-intl";
+import { matchesSearch } from "@/shared/utils/turkishText";
 
 /**
  * GitHub Copilot Configuration Generator
@@ -78,7 +79,7 @@ export default function CopilotToolCard({
 
   // Filter models by search
   const availableModels = searchFilter
-    ? allModels.filter((m) => m.label.toLowerCase().includes(searchFilter.toLowerCase()))
+    ? allModels.filter((m) => matchesSearch(m.label, searchFilter))
     : allModels;
 
   // Persist selection
diff --git a/src/app/(dashboard)/dashboard/cli-code/components/DroidToolCard.tsx b/src/app/(dashboard)/dashboard/cli-code/components/DroidToolCard.tsx
index b08b89db24..6b656c59bb 100644
--- a/src/app/(dashboard)/dashboard/cli-code/components/DroidToolCard.tsx
+++ b/src/app/(dashboard)/dashboard/cli-code/components/DroidToolCard.tsx
@@ -259,6 +259,7 @@ export default function DroidToolCard({
     };
 
     const platform = typeof navigator !== "undefined" && navigator.platform;
+    // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
     const isWindows = platform?.toLowerCase().includes("win");
     const settingsPath = isWindows
       ? "%USERPROFILE%\\.factory\\settings.json"
diff --git a/src/app/(dashboard)/dashboard/combos/BuilderIntelligentStep.tsx b/src/app/(dashboard)/dashboard/combos/BuilderIntelligentStep.tsx
index c24c260f94..d6ac7bad83 100644
--- a/src/app/(dashboard)/dashboard/combos/BuilderIntelligentStep.tsx
+++ b/src/app/(dashboard)/dashboard/combos/BuilderIntelligentStep.tsx
@@ -9,6 +9,7 @@ import {
   ROUTER_STRATEGY_OPTIONS,
   normalizeIntelligentRoutingConfig,
 } from "@/lib/combos/intelligentRouting";
+import { compareTr } from "@/shared/utils/turkishText";
 
 function getI18nOrFallback(t: any, key: string, fallback: string) {
   if (typeof t?.has === "function" && t.has(key)) return t(key);
@@ -51,7 +52,7 @@ function toProviderOptions(activeProviders: any[] = [], candidatePool: string[]
     }
   });
 
-  return [...uniqueProviders.values()].sort((a, b) => a.label.localeCompare(b.label));
+  return [...uniqueProviders.values()].sort((a, b) => compareTr(a.label, b.label));
 }
 
 export default function BuilderIntelligentStep({
diff --git a/src/app/(dashboard)/dashboard/endpoint/ApiEndpointsTab.tsx b/src/app/(dashboard)/dashboard/endpoint/ApiEndpointsTab.tsx
index b02166acaf..9ffa88f36c 100644
--- a/src/app/(dashboard)/dashboard/endpoint/ApiEndpointsTab.tsx
+++ b/src/app/(dashboard)/dashboard/endpoint/ApiEndpointsTab.tsx
@@ -4,6 +4,7 @@ import { useState, useEffect, useMemo } from "react";
 import { useTranslations } from "next-intl";
 import { Card } from "@/shared/components";
 import { useDisplayBaseUrl } from "@/shared/hooks";
+import { matchesSearch } from "@/shared/utils/turkishText";
 
 /* ─── Types ──────────────────────────────────────────── */
 interface Endpoint {
@@ -136,12 +137,16 @@ export default function ApiEndpointsTab() {
   const filteredEndpoints = useMemo(() => {
     if (!catalog) return [];
     return catalog.endpoints.filter((ep) => {
+      // Keep the internal-endpoint visibility toggle + security-tier filter
+      // (from release) while using the locale-aware matchesSearch helper. The
+      // local var is matchesEndpoint (not matchesSearch) to avoid shadowing the
+      // imported helper used in its own initializer.
       if (!showInternal && ep.internal) return false;
-      const matchesSearch =
+      const matchesEndpoint =
         !search ||
-        ep.path.toLowerCase().includes(search.toLowerCase()) ||
-        ep.summary.toLowerCase().includes(search.toLowerCase()) ||
-        ep.tags.some((t) => t.toLowerCase().includes(search.toLowerCase()));
+        matchesSearch(ep.path, search) ||
+        matchesSearch(ep.summary, search) ||
+        ep.tags.some((t) => matchesSearch(t, search));
       const matchesTag = !selectedTag || ep.tags.includes(selectedTag);
       const matchesTier =
         securityTier === "all" ||
@@ -149,7 +154,7 @@ export default function ApiEndpointsTab() {
         (securityTier === "always-protected" && ep.alwaysProtected) ||
         (securityTier === "auth" && ep.security && !ep.loopbackOnly && !ep.alwaysProtected) ||
         (securityTier === "public" && !ep.security && !ep.loopbackOnly && !ep.alwaysProtected);
-      return matchesSearch && matchesTag && matchesTier;
+      return matchesEndpoint && matchesTag && matchesTier;
     });
   }, [catalog, search, selectedTag, showInternal, securityTier]);
 
diff --git a/src/app/(dashboard)/dashboard/health/page.tsx b/src/app/(dashboard)/dashboard/health/page.tsx
index 5cd1c6dee2..12605e5da9 100644
--- a/src/app/(dashboard)/dashboard/health/page.tsx
+++ b/src/app/(dashboard)/dashboard/health/page.tsx
@@ -16,6 +16,7 @@ import { useState, useEffect, useCallback } from "react";
 import { Card } from "@/shared/components";
 import { AI_PROVIDERS } from "@/shared/constants/providers";
 import { getProviderDisplayName } from "@/lib/display/names";
+import { compareTr } from "@/shared/utils/turkishText";
 import { useTranslations } from "next-intl";
 import TelemetryCard from "./TelemetryCard";
 import ProviderHealthAutopilotCard from "./ProviderHealthAutopilotCard";
@@ -891,7 +892,7 @@ export default function HealthPage() {
             const aActive = (a.status.queued || 0) + (a.status.running || 0);
             const bActive = (b.status.queued || 0) + (b.status.running || 0);
             if (aActive !== bActive) return bActive - aActive;
-            return a.displayName.localeCompare(b.displayName);
+            return compareTr(a.displayName, b.displayName);
           });
 
           return (
diff --git a/src/app/(dashboard)/dashboard/providers/[id]/page.tsx b/src/app/(dashboard)/dashboard/providers/[id]/page.tsx
index be36ab75fc..ffd748746a 100644
--- a/src/app/(dashboard)/dashboard/providers/[id]/page.tsx
+++ b/src/app/(dashboard)/dashboard/providers/[id]/page.tsx
@@ -85,6 +85,7 @@ import {
 } from "@/lib/providers/codexFastTier";
 import { isClaudeExtraUsageBlockEnabled } from "@/lib/providers/claudeExtraUsage";
 import { parseExtraApiKeys } from "@/shared/utils/parseApiKeys";
+import { compareTr } from "@/shared/utils/turkishText";
 import RiskNoticeModal from "../components/RiskNoticeModal";
 import { isRiskAcknowledged, useRiskAcknowledged } from "../hooks/useRiskAcknowledged";
 import { resolveDashboardProviderInfo } from "../providerPageUtils";
@@ -4414,7 +4415,7 @@ export default function ProviderDetailPage() {
               const groupKeys = Array.from(groupMap.keys()).sort((a, b) => {
                 if (a === "") return -1;
                 if (b === "") return 1;
-                return a.localeCompare(b);
+                return compareTr(a, b);
               });
 
               return (
diff --git a/src/app/(dashboard)/dashboard/providers/providerPageUtils.ts b/src/app/(dashboard)/dashboard/providers/providerPageUtils.ts
index 432cb64b87..845a82a64e 100644
--- a/src/app/(dashboard)/dashboard/providers/providerPageUtils.ts
+++ b/src/app/(dashboard)/dashboard/providers/providerPageUtils.ts
@@ -7,6 +7,7 @@ import {
   type ResolvedProviderCatalogEntry,
   type StaticProviderCatalogCategory,
 } from "@/lib/providers/catalog";
+import { compareTr, matchesSearch } from "@/shared/utils/turkishText";
 
 export interface ProviderStatsSnapshot {
   total?: number;
@@ -52,9 +53,9 @@ export function sortProviderEntriesByName<TProvider>(
   entries: ProviderEntry<TProvider>[]
 ): ProviderEntry<TProvider>[] {
   return [...entries].sort((a, b) => {
-    const nameCompare = getProviderSortLabel(a).localeCompare(getProviderSortLabel(b));
+    const nameCompare = compareTr(getProviderSortLabel(a), getProviderSortLabel(b));
     if (nameCompare !== 0) return nameCompare;
-    return a.providerId.localeCompare(b.providerId);
+    return a.providerId.localeCompare(b.providerId); // teknik sıralama: ASCII kasıtlı
   });
 }
 
@@ -117,12 +118,12 @@ export function filterConfiguredProviderEntries<TProvider>(
   }
 
   if (searchQuery && searchQuery.trim()) {
-    const query = searchQuery.trim().toLowerCase();
     filtered = filtered.filter((entry) => {
       const provider = entry.provider as Record<string, unknown>;
-      const name = String(provider.name || "").toLowerCase();
-      const id = entry.providerId.toLowerCase();
-      return name.includes(query) || id.includes(query);
+      return (
+        matchesSearch(String(provider.name || ""), searchQuery) ||
+        matchesSearch(entry.providerId, searchQuery)
+      );
     });
   }
 
diff --git a/src/app/(dashboard)/dashboard/search-tools/components/RerankPanel.tsx b/src/app/(dashboard)/dashboard/search-tools/components/RerankPanel.tsx
index 6c6d60746f..ecdd0847f3 100644
--- a/src/app/(dashboard)/dashboard/search-tools/components/RerankPanel.tsx
+++ b/src/app/(dashboard)/dashboard/search-tools/components/RerankPanel.tsx
@@ -32,6 +32,7 @@ export default function RerankPanel({ query, results, onClose }: RerankPanelProp
       .then((res) => res.json())
       .then((data) => {
         const rerankModels = (data?.data || [])
+          // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
           .filter((m: any) => m.id.toLowerCase().includes("rerank"))
           .map((m: any) => ({ value: m.id, label: m.id }));
         setModels(rerankModels);
diff --git a/src/app/(dashboard)/dashboard/settings/components/ComplianceTab.tsx b/src/app/(dashboard)/dashboard/settings/components/ComplianceTab.tsx
index d0433f0519..47b1f00213 100644
--- a/src/app/(dashboard)/dashboard/settings/components/ComplianceTab.tsx
+++ b/src/app/(dashboard)/dashboard/settings/components/ComplianceTab.tsx
@@ -4,6 +4,7 @@ import { useState, useEffect, useCallback } from "react";
 import { Card, DataTable, FilterBar, ColumnToggle } from "@/shared/components";
 import { useNotificationStore } from "@/store/notificationStore";
 import { useTranslations } from "next-intl";
+import { matchesSearch } from "@/shared/utils/turkishText";
 
 export default function ComplianceTab() {
   const [logs, setLogs] = useState([]);
@@ -43,12 +44,11 @@ export default function ComplianceTab() {
 
   const filtered = logs.filter((l) => {
     if (search) {
-      const q = search.toLowerCase();
-      const matchesSearch =
-        l.action?.toLowerCase().includes(q) ||
-        l.actor?.toLowerCase().includes(q) ||
-        (l.details && JSON.stringify(l.details).toLowerCase().includes(q));
-      if (!matchesSearch) return false;
+      const matchesQuery =
+        matchesSearch(l.action ?? "", search) ||
+        matchesSearch(l.actor ?? "", search) ||
+        (l.details && matchesSearch(JSON.stringify(l.details), search));
+      if (!matchesQuery) return false;
     }
     if (filters.action && l.action !== filters.action) return false;
     if (filters.actor && l.actor !== filters.actor) return false;
diff --git a/src/app/(dashboard)/dashboard/settings/components/PricingTab.tsx b/src/app/(dashboard)/dashboard/settings/components/PricingTab.tsx
index c4c90d9979..bde7ff2fb2 100644
--- a/src/app/(dashboard)/dashboard/settings/components/PricingTab.tsx
+++ b/src/app/(dashboard)/dashboard/settings/components/PricingTab.tsx
@@ -5,6 +5,7 @@ import { Card, Button } from "@/shared/components";
 import ProviderIcon from "@/shared/components/ProviderIcon";
 import InfoTooltip from "@/shared/components/InfoTooltip";
 import { useTranslations } from "next-intl";
+import { compareTr, matchesSearch } from "@/shared/utils/turkishText";
 
 type CoverageFilter = "all" | "lt50" | "gte50lt100" | "full";
 type AuthFilter = "all" | "oauth" | "apikey" | "unknown";
@@ -141,15 +142,13 @@ export default function PricingTab() {
   }, [catalog, pricingData]);
 
   const filteredProviders = useMemo(() => {
-    const query = searchQuery.trim().toLowerCase();
-    const matchesSearch = (provider: (typeof allProviders)[number]) => {
-      if (!query) return true;
+    const providerMatchesSearch = (provider: (typeof allProviders)[number]) => {
+      if (!searchQuery.trim()) return true;
       return (
-        provider.alias.toLowerCase().includes(query) ||
-        provider.id.toLowerCase().includes(query) ||
+        matchesSearch(provider.alias, searchQuery) ||
+        matchesSearch(provider.id, searchQuery) ||
         provider.models.some(
-          (model) =>
-            model.id.toLowerCase().includes(query) || model.name.toLowerCase().includes(query)
+          (model) => matchesSearch(model.id, searchQuery) || matchesSearch(model.name, searchQuery)
         )
       );
     };
@@ -171,7 +170,7 @@ export default function PricingTab() {
     };
 
     const filtered = allProviders.filter(
-      (p) => matchesSearch(p) && matchesCoverage(p) && matchesAuth(p)
+      (p) => providerMatchesSearch(p) && matchesCoverage(p) && matchesAuth(p)
     );
 
     // Sort
@@ -187,7 +186,7 @@ export default function PricingTab() {
         sorted.sort((a, b) => coveragePct(a) - coveragePct(b));
         break;
       case "nameAsc":
-        sorted.sort((a, b) => a.alias.localeCompare(b.alias));
+        sorted.sort((a, b) => compareTr(a.alias, b.alias));
         break;
     }
     return sorted;
diff --git a/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx b/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx
index e243f9bd72..847114d64c 100644
--- a/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx
+++ b/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx
@@ -11,6 +11,7 @@ import {
   normalizeCliCompatProviderId,
 } from "@/shared/constants/cliCompatProviders";
 import { AI_PROVIDERS } from "@/shared/constants/providers";
+import { compareTr } from "@/shared/utils/turkishText";
 
 // Provider keys (mirror of open-sse/services/systemTransforms.ts).
 const PROVIDER_CLAUDE = "claude";
@@ -28,7 +29,7 @@ const PROVIDER_CATALOG: ProviderCatalogEntry[] = (() => {
     name: p.name ?? p.id,
   }));
   entries.push({ id: PROVIDER_CC_BRIDGE, name: "Anthropic-compatible CC bridge" });
-  entries.sort((a, b) => a.name.localeCompare(b.name));
+  entries.sort((a, b) => compareTr(a.name, b.name));
   return entries;
 })();
 
diff --git a/src/app/(dashboard)/dashboard/translator/hooks/useAvailableModels.tsx b/src/app/(dashboard)/dashboard/translator/hooks/useAvailableModels.tsx
index 20891d215f..9b2a0424d1 100644
--- a/src/app/(dashboard)/dashboard/translator/hooks/useAvailableModels.tsx
+++ b/src/app/(dashboard)/dashboard/translator/hooks/useAvailableModels.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import { useState, useEffect, useCallback } from "react";
+import { compareTr } from "@/shared/utils/turkishText";
 
 /**
  * Prefix-based format→model matching, used to pick a smart default
@@ -34,7 +35,7 @@ export function useAvailableModels() {
       try {
         const res = await fetch("/api/v1/models");
         const data = await res.json();
-        const models = (data.data || []).map((m) => m.id).sort((a, b) => a.localeCompare(b));
+        const models = (data.data || []).map((m) => m.id).sort((a, b) => compareTr(a, b));
         setAvailableModels(models);
       } catch {
         setAvailableModels([]);
diff --git a/src/app/(dashboard)/dashboard/translator/hooks/useProviderOptions.tsx b/src/app/(dashboard)/dashboard/translator/hooks/useProviderOptions.tsx
index a7d2cb7b50..f0c2655bc2 100644
--- a/src/app/(dashboard)/dashboard/translator/hooks/useProviderOptions.tsx
+++ b/src/app/(dashboard)/dashboard/translator/hooks/useProviderOptions.tsx
@@ -8,6 +8,7 @@ import {
   OPENAI_COMPATIBLE_PREFIX,
   ANTHROPIC_COMPATIBLE_PREFIX,
 } from "@/shared/constants/providers";
+import { compareTr } from "@/shared/utils/turkishText";
 
 /**
  * Hook to fetch and manage provider options for the Translator tools.
@@ -48,7 +49,7 @@ export function useProviderOptions(initialProvider = "openai") {
               label = node?.name || t("anthropicCompatibleLabel");
             return { value: pid, label };
           })
-          .sort((a, b) => a.label.localeCompare(b.label));
+          .sort((a, b) => compareTr(a.label, b.label));
 
         const nextOptions =
           options.length > 0
diff --git a/src/app/(dashboard)/dashboard/usage/components/BudgetTab.tsx b/src/app/(dashboard)/dashboard/usage/components/BudgetTab.tsx
index 91dc1fd2bb..b91d1fc46e 100644
--- a/src/app/(dashboard)/dashboard/usage/components/BudgetTab.tsx
+++ b/src/app/(dashboard)/dashboard/usage/components/BudgetTab.tsx
@@ -4,6 +4,7 @@ import { useCallback, useEffect, useMemo, useState } from "react";
 import { useLocale, useTranslations } from "next-intl";
 import { Card, Button, Input, EmptyState } from "@/shared/components";
 import { useNotificationStore } from "@/store/notificationStore";
+import { compareTr, matchesSearch } from "@/shared/utils/turkishText";
 
 // ────────────────────────────────────────────────────────────────────────────
 // Types
@@ -269,17 +270,16 @@ export default function BudgetTab() {
   // ── Derived data ─────────────────────────────────────────────────────────
 
   const visibleRows = useMemo(() => {
-    const query = searchQuery.trim().toLowerCase();
     const matchesQuery = (r: KeyRow) =>
-      !query ||
-      (r.name || "").toLowerCase().includes(query) ||
-      r.id.toLowerCase().includes(query) ||
-      (r.provider || "").toLowerCase().includes(query);
+      !searchQuery.trim() ||
+      matchesSearch(r.name ?? "", searchQuery) ||
+      matchesSearch(r.id, searchQuery) ||
+      matchesSearch(r.provider ?? "", searchQuery);
     const matchesStatus = (r: KeyRow) => statusFilter === "all" || statusOf(r) === statusFilter;
     const filtered = rows.filter((r) => matchesQuery(r) && matchesStatus(r));
 
     return [...filtered].sort((a, b) => {
-      if (sortKey === "name") return (a.name || a.id).localeCompare(b.name || b.id);
+      if (sortKey === "name") return compareTr(a.name || a.id, b.name || b.id);
       if (sortKey === "todayDesc")
         return (b.budget?.totalCostToday || 0) - (a.budget?.totalCostToday || 0);
       if (sortKey === "monthDesc")
diff --git a/src/app/(dashboard)/dashboard/usage/components/EvalsTab.tsx b/src/app/(dashboard)/dashboard/usage/components/EvalsTab.tsx
index d12a754f16..6b417efd98 100644
--- a/src/app/(dashboard)/dashboard/usage/components/EvalsTab.tsx
+++ b/src/app/(dashboard)/dashboard/usage/components/EvalsTab.tsx
@@ -13,6 +13,7 @@ import {
   Select,
 } from "@/shared/components";
 import { useNotificationStore } from "@/store/notificationStore";
+import { matchesSearch } from "@/shared/utils/turkishText";
 
 type EvalTargetType = "suite-default" | "model" | "combo";
 
@@ -505,11 +506,10 @@ export default function EvalsTab() {
   const filteredSuites = !search.trim()
     ? suites
     : suites.filter((suite) => {
-        const term = search.toLowerCase();
         return (
-          suite.name?.toLowerCase().includes(term) ||
-          suite.id?.toLowerCase().includes(term) ||
-          suite.description?.toLowerCase().includes(term)
+          matchesSearch(suite.name ?? "", search) ||
+          matchesSearch(suite.id ?? "", search) ||
+          matchesSearch(suite.description ?? "", search)
         );
       });
 
diff --git a/src/app/(dashboard)/dashboard/usage/components/ProviderLimits/index.tsx b/src/app/(dashboard)/dashboard/usage/components/ProviderLimits/index.tsx
index 940f4611f2..64a009d665 100644
--- a/src/app/(dashboard)/dashboard/usage/components/ProviderLimits/index.tsx
+++ b/src/app/(dashboard)/dashboard/usage/components/ProviderLimits/index.tsx
@@ -20,6 +20,7 @@ import EmailPrivacyToggle from "@/shared/components/EmailPrivacyToggle";
 import QuotaCutoffModal from "./QuotaCutoffModal";
 import QuotaCardGrid from "./QuotaCardGrid";
 import { translateUsageOrFallback, type UsageTranslationValues } from "./i18nFallback";
+import { compareTr } from "@/shared/utils/turkishText";
 
 const LS_PURCHASE_FILTER = "omniroute:limits:purchaseFilter";
 const LS_STATUS_FILTER = "omniroute:limits:statusFilter";
@@ -593,7 +594,7 @@ export default function ProviderLimits({
       const tag = (conn.providerSpecificData?.tag as string | undefined)?.trim();
       if (tag) tags.add(tag);
     }
-    return [...tags].sort((a, b) => a.localeCompare(b));
+    return [...tags].sort((a, b) => compareTr(a, b));
   }, [sortedConnections]);
 
   const envCounts = useMemo(() => {
diff --git a/src/app/(dashboard)/home/ProviderTopology.tsx b/src/app/(dashboard)/home/ProviderTopology.tsx
index e201bbc966..404231efd3 100644
--- a/src/app/(dashboard)/home/ProviderTopology.tsx
+++ b/src/app/(dashboard)/home/ProviderTopology.tsx
@@ -217,7 +217,7 @@ function buildLayout(
       return 3;
     };
     const d = rank(aId) - rank(bId);
-    return d !== 0 ? d : aId.localeCompare(bId);
+    return d !== 0 ? d : aId.localeCompare(bId); // teknik sıralama: ASCII kasıtlı
   });
 
   let provIdx = 0;
diff --git a/src/app/api/cli-tools/codex-profiles/route.ts b/src/app/api/cli-tools/codex-profiles/route.ts
index 78c99d7068..93fd06ad43 100644
--- a/src/app/api/cli-tools/codex-profiles/route.ts
+++ b/src/app/api/cli-tools/codex-profiles/route.ts
@@ -6,6 +6,7 @@ import path from "path";
 import { requireCliToolsAuth } from "@/lib/api/requireCliToolsAuth";
 import { ensureCliConfigWriteAllowed, getCliConfigPaths } from "@/shared/services/cliRuntime";
 import { resolveDataDir } from "@/lib/dataPaths";
+import { compareTr } from "@/shared/utils/turkishText";
 import { codexProfileIdSchema, codexProfileNameSchema } from "@/shared/validation/schemas";
 import { isValidationFailure, validateBody } from "@/shared/validation/helpers";
 
@@ -88,7 +89,7 @@ export async function GET(request: Request) {
     }
 
     // Sort by name
-    profiles.sort((a, b) => a.name.localeCompare(b.name));
+    profiles.sort((a, b) => compareTr(a.name, b.name));
     return NextResponse.json({ profiles });
   } catch (error) {
     console.log("Error listing codex profiles:", error.message);
diff --git a/src/app/api/cli-tools/guide-settings/[toolId]/route.ts b/src/app/api/cli-tools/guide-settings/[toolId]/route.ts
index fd9a69424b..cfc3e16db5 100644
--- a/src/app/api/cli-tools/guide-settings/[toolId]/route.ts
+++ b/src/app/api/cli-tools/guide-settings/[toolId]/route.ts
@@ -134,6 +134,7 @@ async function saveContinueConfig({ baseUrl, apiKey, model }) {
         normalizeApiBase(m.apiBase).includes("omniroute") ||
         normalizeApiBase(m.apiBase).includes(`localhost:${apiPort}`) ||
         normalizeApiBase(m.apiBase).includes(`127.0.0.1:${apiPort}`) ||
+        // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
         String(m.apiKey || "")
           .toLowerCase()
           .includes("sk_omniroute"))
diff --git a/src/app/api/logs/console/route.ts b/src/app/api/logs/console/route.ts
index ca32c2af6d..94daed683a 100644
--- a/src/app/api/logs/console/route.ts
+++ b/src/app/api/logs/console/route.ts
@@ -14,6 +14,7 @@ import { NextRequest, NextResponse } from "next/server";
 import { readFileSync, existsSync } from "fs";
 import { getAppLogFilePath } from "@/lib/logEnv";
 import { requireManagementAuth } from "@/lib/api/requireManagementAuth";
+import { matchesSearch } from "@/shared/utils/turkishText";
 import { sanitizeErrorMessage } from "@omniroute/open-sse/utils/error.ts";
 
 const LEVEL_ORDER: Record<string, number> = {
@@ -115,7 +116,7 @@ export async function GET(req: NextRequest) {
         // Filter by component
         if (componentFilter) {
           const comp = entry.component || entry.module || "";
-          if (!comp.toLowerCase().includes(componentFilter.toLowerCase())) continue;
+          if (!matchesSearch(comp, componentFilter)) continue;
         }
 
         // Normalize timestamp field
diff --git a/src/app/api/settings/qdrant/embedding-models/route.ts b/src/app/api/settings/qdrant/embedding-models/route.ts
index 5a5f6eb1d0..9683e270f4 100644
--- a/src/app/api/settings/qdrant/embedding-models/route.ts
+++ b/src/app/api/settings/qdrant/embedding-models/route.ts
@@ -30,7 +30,7 @@ export async function GET(request: NextRequest) {
         value: `${m.provider}/${m.model}`,
         label: `${m.provider}/${m.model} - ${m.name}`,
       }))
-      .sort((a, b) => a.value.localeCompare(b.value));
+      .sort((a, b) => a.value.localeCompare(b.value)); // teknik sıralama: ASCII kasıtlı
 
     // Add OpenRouter account models that explicitly support embeddings.
     try {
@@ -85,7 +85,7 @@ export async function GET(request: NextRequest) {
       });
     }
 
-    options.sort((a, b) => a.value.localeCompare(b.value));
+    options.sort((a, b) => a.value.localeCompare(b.value)); // teknik sıralama: ASCII kasıtlı
 
     return NextResponse.json({ models: options });
   } catch (error) {
diff --git a/src/app/api/skills/route.ts b/src/app/api/skills/route.ts
index 18fd67ee29..2a0c6a26d5 100644
--- a/src/app/api/skills/route.ts
+++ b/src/app/api/skills/route.ts
@@ -3,6 +3,7 @@ import { skillRegistry } from "@/lib/skills/registry";
 import { parsePaginationParams, buildPaginatedResponse } from "@/shared/types/pagination";
 import { getSkillsProviderSetting } from "@/lib/skills/providerSettings";
 import { requireManagementAuth } from "@/lib/api/requireManagementAuth";
+import { matchesSearch } from "@/shared/utils/turkishText";
 
 const POPULAR_BY_PROVIDER = {
   skillsmp: ["web-search", "file-reader", "sql-assistant", "devops-helper", "docs-assistant"],
@@ -18,7 +19,7 @@ export async function GET(request?: Request) {
     const provider = await getSkillsProviderSetting();
     const url = request?.url || "http://localhost/api/skills";
     const parsedUrl = new URL(url);
-    const query = parsedUrl.searchParams.get("q")?.trim().toLowerCase() || "";
+    const query = parsedUrl.searchParams.get("q")?.trim() || "";
     const modeFilter = parsedUrl.searchParams.get("mode");
     const sourceFilter = parsedUrl.searchParams.get("source");
 
@@ -26,11 +27,11 @@ export async function GET(request?: Request) {
 
     if (query) {
       allSkills = allSkills.filter((skill) => {
-        const tags = Array.isArray(skill.tags) ? skill.tags.join(" ").toLowerCase() : "";
+        const tagsText = Array.isArray(skill.tags) ? skill.tags.join(" ") : "";
         return (
-          skill.name.toLowerCase().includes(query) ||
-          skill.description.toLowerCase().includes(query) ||
-          tags.includes(query)
+          matchesSearch(skill.name, query) ||
+          matchesSearch(skill.description, query) ||
+          matchesSearch(tagsText, query)
         );
       });
     }
diff --git a/src/app/api/v1/models/catalog.ts b/src/app/api/v1/models/catalog.ts
index 9ff3385149..24a50f5c78 100644
--- a/src/app/api/v1/models/catalog.ts
+++ b/src/app/api/v1/models/catalog.ts
@@ -462,6 +462,7 @@ export async function getUnifiedModelsResponse(
           ? synced.attachment
           : syncedInputModalities.length > 0 || syncedOutputModalities.length > 0
             ? [...syncedInputModalities, ...syncedOutputModalities].some((entry) =>
+                // eslint-disable-next-line no-restricted-syntax -- teknik string kontrolü, kullanıcı metni araması değil
                 entry.toLowerCase().includes("image")
               )
             : undefined;
diff --git a/src/app/global-error.tsx b/src/app/global-error.tsx
index b5b7d74890..1203cfca47 100644
--- a/src/app/global-error.tsx
+++ b/src/app/global-error.tsx
@@ -15,6 +15,11 @@ interface GlobalErrorProps {
 
 export default function GlobalError({ error, reset }: GlobalErrorProps) {
   return (
+    // lang="en" is intentional: global-error is a client-side root boundary that
+    // renders ABOVE the next-intl provider, so the active locale isn't reliably
+    // available here. Its visible text is static English, so lang="en" stays
+    // consistent with the content. User-facing locale is handled by the normal
+    // layout (<html lang={locale}> in src/app/layout.tsx).
     <html lang="en">
       <body className="flex flex-col items-center justify-center min-h-screen p-6 bg-bg text-text-main font-[system-ui,-apple-system,sans-serif] text-center m-0">
         <main role="alert" aria-live="assertive" className="flex flex-col items-center">
diff --git a/src/shared/utils/turkishText.ts b/src/shared/utils/turkishText.ts
new file mode 100644
index 0000000000..6c73b1ec3d
--- /dev/null
+++ b/src/shared/utils/turkishText.ts
@@ -0,0 +1,66 @@
+/**
+ * Türkçe-güvenli metin normalizasyonu, arama ve sıralama yardımcıları.
+ *
+ * JavaScript'in locale-bağımsız `toLowerCase()`'i Türkçe `İ/I/ı/i`
+ * karakterlerini bozar: `"İ".toLowerCase()` → `"i̇"` (U+0069 U+0307
+ * combining dot above). Bu, `toLowerCase().includes()` tabanlı aramada
+ * Türkçe girdileri eşleşmez kılar.
+ *
+ * Saf fonksiyonlar — yan etki ve bağımlılık yok.
+ *
+ * @module shared/utils/turkishText
+ */
+
+/** NFD ile katlanmayan Türkçe harfler için açık eşleme. */
+const TR_FOLD: Readonly<Record<string, string>> = {
+  ı: "i",
+  ş: "s",
+  ğ: "g",
+  ü: "u",
+  ö: "o",
+  ç: "c",
+};
+
+/**
+ * Aksan-duyarsız, Türkçe-güvenli arama anahtarı üretir.
+ * `"İstanbul"` ve `"istanbul"` → `"istanbul"`; `"Şarj"` → `"sarj"`.
+ * Baştaki ve sondaki boşluklar kırpılır.
+ */
+export function normalizeForSearch(input: string | null | undefined): string {
+  if (!input) return "";
+  let s = input.toLocaleLowerCase("tr"); // İ→i, I→ı (Türkçe-güvenli)
+  s = s.replace(/[ışğüöç]/g, (ch) => TR_FOLD[ch] ?? ch); // açık Türkçe fold
+  s = s.normalize("NFD").replace(/[̀-ͯ]/g, ""); // kalan aksanları sil
+  return s.trim();
+}
+
+/**
+ * `text`, `query`'yi (aksan-duyarsız, Türkçe-güvenli) içeriyor mu?
+ * Boş sorgu her zaman `true` döner.
+ */
+export function matchesSearch(
+  text: string | null | undefined,
+  query: string | null | undefined
+): boolean {
+  const q = normalizeForSearch(query);
+  if (!q) return true;
+  return normalizeForSearch(text).includes(q);
+}
+
+const trCollator = new Intl.Collator("tr", {
+  sensitivity: "base",
+  numeric: true,
+});
+
+/**
+ * Kullanıcı-görünür listeler için Türkçe alfabe + sayısal-duyarlı
+ * karşılaştırma. `Array.prototype.sort` ile doğrudan kullanılabilir.
+ *
+ * `sensitivity: "base"` kullanıldığından aksan/büyük-küçük harf varyantları
+ * sıralama açısından eşit sayılır — örneğin `"Şehir"` ile `"şehir"` berabere
+ * gelir. Bu karşılaştırıcı görsel liste sıralaması içindir, kesin
+ * aksan-farklılaştırmalı sıralama için değil.
+ */
+export function compareTr(a: string | null | undefined, b: string | null | undefined): number {
+  return trCollator.compare(a ?? "", b ?? "");
+}
diff --git a/tests/unit/turkishText.test.ts b/tests/unit/turkishText.test.ts
new file mode 100644
index 0000000000..280f39594d
--- /dev/null
+++ b/tests/unit/turkishText.test.ts
@@ -0,0 +1,75 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import {
+  normalizeForSearch,
+  matchesSearch,
+  compareTr,
+} from "../../src/shared/utils/turkishText.ts";
+
+test("normalizeForSearch: İ combining-dot üretmez (i'ye katlanır)", () => {
+  const out = normalizeForSearch("İ");
+  assert.equal(out, "i");
+  assert.ok(!out.includes("̇"), "combining dot above bulunmamalı");
+});
+
+test("normalizeForSearch: I (dotless) → i", () => {
+  assert.equal(normalizeForSearch("IĞDIR"), "igdir");
+});
+
+test("normalizeForSearch: aksanları katlar (şğüöç)", () => {
+  assert.equal(normalizeForSearch("Şarj Çözüm Güven"), "sarj cozum guven");
+});
+
+test("matchesSearch: İstanbul'u 'istanbul' sorgusuyla bulur", () => {
+  assert.equal(matchesSearch("İstanbul", "istanbul"), true);
+});
+
+test("matchesSearch: Latin 'Istanbul' sorgusu (noktasız I) dotted İ metnini bulur", () => {
+  // Real-world: data has the dotted Turkish İ, the user types a Latin capital I
+  // (no dot) from a non-Turkish keyboard. Both must fold to "istanbul".
+  assert.equal(matchesSearch("İstanbul", "Istanbul"), true);
+  assert.equal(matchesSearch("Istanbul", "İstanbul"), true);
+});
+
+test("matchesSearch: aksan-duyarsız (Şarj İstasyonu ↔ 'sarj')", () => {
+  assert.equal(matchesSearch("Şarj İstasyonu", "sarj"), true);
+});
+
+test("matchesSearch: eşleşmeyen sorgu false döner", () => {
+  assert.equal(matchesSearch("OpenAI", "anthropic"), false);
+});
+
+test("matchesSearch: boş sorgu her şeyi eşler", () => {
+  assert.equal(matchesSearch("herhangi", ""), true);
+});
+
+test("compareTr: Türkçe alfabede ç, c'den sonra gelir", () => {
+  assert.deepEqual(["d", "ç", "c", "b"].sort(compareTr), ["b", "c", "ç", "d"]);
+});
+
+test("compareTr: ı, i'den önce gelir (Türkçe)", () => {
+  assert.equal(compareTr("ı", "i") < 0, true);
+});
+
+test("compareTr: sayısal-duyarlı (item2 < item10)", () => {
+  assert.equal(compareTr("item2", "item10") < 0, true);
+});
+
+test("normalizeForSearch: null/undefined boş string döner", () => {
+  assert.equal(normalizeForSearch(null), "");
+  assert.equal(normalizeForSearch(undefined), "");
+});
+
+test("normalizeForSearch: yalnızca boşluk → boş string", () => {
+  assert.equal(normalizeForSearch("   "), "");
+});
+
+test("matchesSearch: yalnızca boşluk sorgusu her şeyi eşler", () => {
+  assert.equal(matchesSearch("herhangi", "   "), true);
+});
+
+test("compareTr: null/undefined argümanları güvenli (?? '' guard)", () => {
+  assert.equal(compareTr(null, "a") < 0, true);
+  assert.equal(compareTr("a", null) > 0, true);
+  assert.equal(compareTr(null, undefined), 0);
+});