fix: prioritize system language over timezone for locale detection (#51), clean up session data on deletion (#47, #680)

packages/opencode/src/cli/cmd/tui/context/sync.tsx

@@ -361,7 +361,8 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
           break
 
         case "session.deleted": {
-          const result = Binary.search(store.session, event.properties.info.id, (s) => s.id)
+          const deletedID = event.properties.info.id
+          const result = Binary.search(store.session, deletedID, (s) => s.id)
           if (result.found) {
             setStore(
               "session",
@@ -370,6 +371,27 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
               }),
             )
           }
+          batch(() => {
+            setStore("message", deletedID, undefined as any)
+            setStore("todo", deletedID, undefined as any)
+            setStore("task", deletedID, undefined as any)
+            setStore("actor", deletedID, undefined as any)
+            setStore("permission", deletedID, undefined as any)
+            setStore("question", deletedID, undefined as any)
+            setStore("session_cwd", deletedID, undefined as any)
+            setStore("session_diff", deletedID, undefined as any)
+            setStore("session_goal", deletedID, undefined as any)
+            setStore("session_status", deletedID, undefined as any)
+            const msgs = store.message[deletedID]
+            if (msgs) {
+              const msgIDs = new Set(msgs.map((m: any) => m.id))
+              setStore("part", produce((draft: any) => {
+                for (const key of Object.keys(draft)) {
+                  if (msgIDs.has(key)) delete draft[key]
+                }
+              }))
+            }
+          })
           break
         }
         case "session.updated": {

packages/opencode/src/cli/cmd/tui/util/system-locale.ts

@@ -188,8 +188,12 @@ function detectTimezoneLocale(): Locale | undefined {
 }
 
 export function detectSystemLocale(): Locale {
-  const tz = detectTimezoneLocale()
-  if (tz) return tz
+  // Priority: 1) system language (most accurate), 2) env vars, 3) timezone (geographic hint)
+  try {
+    const intl = Intl.DateTimeFormat().resolvedOptions().locale.toLowerCase()
+    const match = matchers.find((m) => m.test(intl))
+    if (match) return match.locale
+  } catch {}
   for (const env of ["LC_ALL", "LC_MESSAGES", "LANG", "LANGUAGE"] as const) {
     const value = process.env[env]
     if (!value) continue
@@ -200,10 +204,7 @@ export function detectSystemLocale(): Locale {
       if (match) return match.locale
     }
   }
-  try {
-    const intl = Intl.DateTimeFormat().resolvedOptions().locale.toLowerCase()
-    const match = matchers.find((m) => m.test(intl))
-    if (match) return match.locale
-  } catch {}
+  const tz = detectTimezoneLocale()
+  if (tz) return tz
   return "en"
 }