diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 00000000..afc51382
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,7 @@
+{
+  "name": "OpenCode Development",
+  "image": "mcr.microsoft.com/devcontainers/javascript-node:1-22-bookworm",
+  "features": {
+    "ghcr.io/devcontainers-extra/features/bun:1": {}
+  }
+}
\ No newline at end of file
diff --git a/packages/web/src/i18n/locales.test.ts b/packages/web/src/i18n/locales.test.ts
new file mode 100644
index 00000000..2cde1010
--- /dev/null
+++ b/packages/web/src/i18n/locales.test.ts
@@ -0,0 +1,44 @@
+import { describe, expect, test } from "bun:test"
+import { matchLocale } from "./locales"
+
+describe("matchLocale", () => {
+  test("returns null for blank or malformed input", () => {
+    expect(matchLocale("")).toBeNull()
+    expect(matchLocale("%E0%A4%A")).toBeNull()
+  })
+
+  test("matches exact locale aliases", () => {
+    expect(matchLocale("en")).toBe("root")
+    expect(matchLocale("br")).toBe("pt-br")
+    expect(matchLocale("pt-br")).toBe("pt-br")
+  })
+
+  test("matches simplified Chinese locales", () => {
+    expect(matchLocale("zh")).toBe("zh-cn")
+    expect(matchLocale("zh-CN")).toBe("zh-cn")
+  })
+
+  test("matches traditional Chinese locales", () => {
+    expect(matchLocale("zh-Hant")).toBe("zh-tw")
+    expect(matchLocale("zh-TW")).toBe("zh-tw")
+    expect(matchLocale("zh-HK")).toBe("zh-tw")
+  })
+
+  test("matches Portuguese regional locales", () => {
+    expect(matchLocale("pt-PT")).toBe("pt-br")
+  })
+
+  test("matches Norwegian locales", () => {
+    expect(matchLocale("no-NO")).toBe("nb")
+    expect(matchLocale("nb-NO")).toBe("nb")
+    expect(matchLocale("nn-NO")).toBe("nb")
+  })
+
+  test("matches supported regional locales", () => {
+    expect(matchLocale("fr-CA")).toBe("fr")
+  })
+
+  test("returns null for unsupported locales", () => {
+    expect(matchLocale("xx-YY")).toBeNull()
+  })
+})
\ No newline at end of file
diff --git a/packages/web/src/i18n/locales.ts b/packages/web/src/i18n/locales.ts
index d1b3e74d..0fade756 100644
--- a/packages/web/src/i18n/locales.ts
+++ b/packages/web/src/i18n/locales.ts
@@ -97,21 +97,24 @@ export function exactLocale(input: string) {
 
 export function matchLocale(input: string) {
   const value = parse(input)
-  if (!value) return null
+  let result: Locale | null = null
 
-  if (value.startsWith("zh")) {
-    if (value.includes("hant") || value.includes("-tw") || value.includes("-hk") || value.includes("-mo")) {
-      return "zh-tw"
+  if (value) {
+    if (value.startsWith("zh")) {
+      result =
+        value.includes("hant") || value.includes("-tw") || value.includes("-hk") || value.includes("-mo")
+          ? "zh-tw"
+          : "zh-cn"
+    } else if (value in localeAlias) {
+      result = localeAlias[value as keyof typeof localeAlias]
+    } else if (value.startsWith("pt")) {
+      result = "pt-br"
+    } else if (value.startsWith("no") || value.startsWith("nb") || value.startsWith("nn")) {
+      result = "nb"
+    } else {
+      result = starts.find((item) => value.startsWith(item[0]))?.[1] ?? null
     }
-    return "zh-cn"
-  }
-
-  if (value in localeAlias) {
-    return localeAlias[value as keyof typeof localeAlias]
   }
 
-  if (value.startsWith("pt")) return "pt-br"
-  if (value.startsWith("no") || value.startsWith("nb") || value.startsWith("nn")) return "nb"
-
-  return starts.find((item) => value.startsWith(item[0]))?.[1] ?? null
+  return result
 }