diff --git a/src/app/components/ActionGroup.tsx b/src/app/components/ActionGroup.tsx
index f3113b4..9af1a4e 100644
--- a/src/app/components/ActionGroup.tsx
+++ b/src/app/components/ActionGroup.tsx
@@ -29,8 +29,10 @@ import {
   summarizeActionGroup,
 } from "@/lib/actionGrouping";
 import { mergeApprovalDecision } from "@/lib/approvalDecision";
-import { formatToolLabel, toolArgumentPreview } from "@/lib/toolLabel";
+import { formatToolLabelWith, toolArgumentPreview } from "@/lib/toolLabel";
 import { autoApprovesTools, type ReviewMode } from "@/lib/reviewMode";
+import { useTranslations } from "next-intl";
+import { useToolLabels } from "@/app/hooks/useToolLabels";
 import {
   extractStringFromMessageContent,
   extractSubAgentContent,
@@ -114,6 +116,8 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
   compactionAnchorId,
   summarizationEvent,
 }) {
+  const t = useTranslations("chat");
+  const toolLabels = useToolLabels();
   const [open, setOpen] = useState(() => !defaultCollapsed);
   const [expandedSubAgents, setExpandedSubAgents] = useState<
     Record<string, boolean>
@@ -234,7 +238,7 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
               <div className="ml-2 mt-1 space-y-3 border-l border-border pl-3">
                 <div>
                   <div className="mb-1 text-[11px] font-semibold uppercase text-muted-foreground">
-                    Input
+                    {t("subAgent.input")}
                   </div>
                   <MarkdownContent
                     content={extractSubAgentContent(subAgent.input)}
@@ -244,7 +248,7 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
                 {steps.length > 0 && (
                   <div>
                     <div className="mb-1 text-[11px] font-semibold uppercase text-muted-foreground">
-                      Steps
+                      {t("subAgent.steps")}
                     </div>
                     <SubAgentSteps
                       steps={steps}
@@ -256,7 +260,7 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
                 {subAgent.output && (
                   <div>
                     <div className="mb-1 text-[11px] font-semibold uppercase text-muted-foreground">
-                      Output
+                      {t("subAgent.output")}
                     </div>
                     <MarkdownContent
                       content={extractSubAgentContent(subAgent.output)}
@@ -318,6 +322,7 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
       stream,
       subAgentSteps,
       submittedActionRequestKeys,
+      t,
       toggleSubAgent,
       ui,
     ]
@@ -325,19 +330,21 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
 
   const lastToolCall = summary.lastToolCall;
   const lastToolLabel = lastToolCall
-    ? formatToolLabel(lastToolCall.name, lastToolCall.args)
-    : "Working";
+    ? formatToolLabelWith(toolLabels, lastToolCall.name, lastToolCall.args)
+    : t("actionGroup.working");
   const lastToolPreview = lastToolCall
     ? toolArgumentPreview(lastToolCall.name, lastToolCall.args)
     : "";
-  const actionNoun = summary.total === 1 ? "action" : "actions";
   const primaryText = hasPendingApproval
-    ? "Approval required"
+    ? t("actionGroup.approvalRequired")
     : summary.failed > 0
-    ? `${summary.failed} of ${summary.total} ${actionNoun} failed`
+    ? t("actionGroup.failed", {
+        failed: summary.failed,
+        total: summary.total,
+      })
     : isStreaming || summary.pending > 0 || summary.interrupted > 0
-    ? `Working · ${summary.total} ${actionNoun}`
-    : `${summary.total} ${actionNoun} completed`;
+    ? t("actionGroup.workingWithCount", { total: summary.total })
+    : t("actionGroup.completed", { total: summary.total });
   const headerText = `${primaryText} · ${lastToolLabel}${
     lastToolPreview ? ` · ${lastToolPreview}` : ""
   }`;
@@ -345,12 +352,16 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
   return (
     <section
       className="my-2 overflow-hidden rounded-md border border-border bg-[var(--color-surface)]"
-      aria-label="Assistant work process"
+      aria-label={t("actionGroup.ariaLabel")}
     >
       <button
         type="button"
         aria-expanded={open}
-        aria-label={`${open ? "Collapse" : "Expand"} ${headerText}`}
+        aria-label={
+          open
+            ? t("actionGroup.collapseGroup", { summary: headerText })
+            : t("actionGroup.expandGroup", { summary: headerText })
+        }
         title={headerText}
         onClick={() => setOpen((current) => !current)}
         className="flex min-h-10 w-full items-center gap-2 px-3 py-2 text-left text-xs text-muted-foreground transition-colors hover:bg-accent focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring"
@@ -446,13 +457,15 @@ export const ActionGroup = React.memo<ActionGroupProps>(function ActionGroup({
             type="button"
             onClick={() => setOpen(false)}
             className="mt-1 flex min-h-8 w-full items-center justify-center gap-1.5 rounded-sm text-xs text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
-            aria-label={`Collapse ${summary.total} ${actionNoun}`}
+            aria-label={t("actionGroup.collapseCount", {
+              total: summary.total,
+            })}
           >
             <ChevronUp
               aria-hidden="true"
               className="size-3.5"
             />
-            Collapse
+            {t("actionGroup.collapse")}
           </button>
         </div>
       )}
diff --git a/src/app/components/AskUserInterrupt.tsx b/src/app/components/AskUserInterrupt.tsx
index b236607..dfdd174 100644
--- a/src/app/components/AskUserInterrupt.tsx
+++ b/src/app/components/AskUserInterrupt.tsx
@@ -5,6 +5,7 @@ import { Button } from "@/components/ui/button";
 import { Textarea } from "@/components/ui/textarea";
 import { MessageCircleQuestion } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { useTranslations } from "next-intl";
 
 interface Choice {
   value: string;
@@ -32,6 +33,8 @@ export function AskUserInterrupt({
   onCancel,
   isLoading,
 }: AskUserInterruptProps) {
+  const t = useTranslations("chat");
+  const tCommon = useTranslations("common");
   // answers[i] = final answer string; picked[i] = selected choice value or
   // OTHER for multiple_choice (null for free-text questions).
   const [answers, setAnswers] = useState<string[]>(() =>
@@ -62,7 +65,7 @@ export function AskUserInterrupt({
           aria-hidden="true"
         />
         <span className="text-xs font-semibold uppercase tracking-wider">
-          EvoScientist Needs Your Input
+          {t("askUser.title")}
         </span>
       </div>
 
@@ -114,13 +117,13 @@ export function AskUserInterrupt({
                       : "border-border bg-background hover:bg-accent"
                   )}
                 >
-                  Other…
+                  {t("askUser.other")}
                 </button>
                 {picked[i] === OTHER && (
                   <Textarea
                     value={answers[i]}
                     onChange={(e) => setAnswer(i, e.target.value)}
-                    placeholder="Type your answer…"
+                    placeholder={t("askUser.answerPlaceholder")}
                     className="text-sm"
                     rows={2}
                     disabled={isLoading}
@@ -133,8 +136,8 @@ export function AskUserInterrupt({
                 onChange={(e) => setAnswer(i, e.target.value)}
                 placeholder={
                   isOptional(q)
-                    ? "Type your answer… (optional)"
-                    : "Type your answer…"
+                    ? t("askUser.answerPlaceholderOptional")
+                    : t("askUser.answerPlaceholder")
                 }
                 className="text-sm"
                 rows={2}
@@ -152,7 +155,7 @@ export function AskUserInterrupt({
           onClick={onCancel}
           disabled={isLoading}
         >
-          Cancel
+          {tCommon("cancel")}
         </Button>
         <Button
           size="sm"
@@ -160,7 +163,7 @@ export function AskUserInterrupt({
           disabled={!canSubmit || isLoading}
           className="bg-[var(--brand-solid)] text-[var(--brand-foreground)] hover:opacity-90"
         >
-          {isLoading ? "Submitting…" : "Submit"}
+          {isLoading ? t("askUser.submitting") : t("askUser.submit")}
         </Button>
       </div>
     </div>
diff --git a/src/app/components/ChatInterface.tsx b/src/app/components/ChatInterface.tsx
index 6d3f6a9..2b4031f 100644
--- a/src/app/components/ChatInterface.tsx
+++ b/src/app/components/ChatInterface.tsx
@@ -115,6 +115,7 @@ import {
 } from "@/app/hooks/useAvailableModels";
 import { formatTokenCount, useUsage } from "@/app/hooks/useUsage";
 import { UsageDetailsDialog } from "@/app/components/UsageDetailsDialog";
+import { useTranslations } from "next-intl";
 
 type DashboardNavTarget =
   | {
@@ -142,44 +143,6 @@ interface ChatInterfaceProps {
   onNotifyReady?: (notify: MainChatReporter | null) => void;
 }
 
-const SUGGESTED_PROMPTS = [
-  "Survey recent papers on a topic",
-  "Design an experiment plan",
-  "Analyze workspace files",
-];
-
-const REVIEW_MODE_OPTIONS: Array<{
-  mode: ReviewMode;
-  label: string;
-  description: string;
-  icon: typeof Hand;
-  activeClassName: string;
-}> = [
-  {
-    mode: "manual",
-    label: "Manual review",
-    description: "Approve each tool action before it runs.",
-    icon: Hand,
-    activeClassName: "bg-[var(--brand-solid)] text-[var(--brand-foreground)]",
-  },
-  {
-    mode: "auto",
-    label: "Auto-approve",
-    description:
-      "Approve tool actions automatically; questions can still pause.",
-    icon: Zap,
-    activeClassName: "bg-amber-600 text-white hover:bg-amber-700",
-  },
-  {
-    mode: "full",
-    label: "Full approve",
-    description:
-      "Approve tool actions automatically and continue without questions.",
-    icon: ChevronsRight,
-    activeClassName: "bg-rose-700 text-white hover:bg-rose-800",
-  },
-];
-
 interface UploadedWorkspaceFile {
   name: string;
   path: string;
@@ -380,6 +343,43 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
     onOpenThread,
     workspaceOpen,
   }) => {
+    const t = useTranslations("chat");
+    const tCommon = useTranslations("common");
+    const suggestedPrompts = [
+      t("suggestedSurvey"),
+      t("suggestedExperiment"),
+      t("suggestedFiles"),
+    ];
+    const reviewModeOptions: Array<{
+      mode: ReviewMode;
+      label: string;
+      description: string;
+      icon: typeof Hand;
+      activeClassName: string;
+    }> = [
+      {
+        mode: "manual",
+        label: t("reviewMode.manual.label"),
+        description: t("reviewMode.manual.description"),
+        icon: Hand,
+        activeClassName:
+          "bg-[var(--brand-solid)] text-[var(--brand-foreground)]",
+      },
+      {
+        mode: "auto",
+        label: t("reviewMode.auto.label"),
+        description: t("reviewMode.auto.description"),
+        icon: Zap,
+        activeClassName: "bg-amber-600 text-white hover:bg-amber-700",
+      },
+      {
+        mode: "full",
+        label: t("reviewMode.full.label"),
+        description: t("reviewMode.full.description"),
+        icon: ChevronsRight,
+        activeClassName: "bg-rose-700 text-white hover:bg-rose-800",
+      },
+    ];
     const [metaOpen, setMetaOpen] = useState<"tasks" | "files" | null>(null);
     const tasksContainerRef = useRef<HTMLDivElement | null>(null);
     const textareaRef = useRef<HTMLTextAreaElement | null>(null);
@@ -522,10 +522,12 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
       usage.status.availability === "offline" ||
       usage.status.availability === "unavailable";
     const usageLabel = usage.loading
-      ? "Tokens loading"
+      ? t("usage.tokensLoading")
       : usageUnavailable || !usage.summary
-      ? "Tokens unavailable"
-      : `${formatTokenCount(usage.summary.total_tokens)} tokens`;
+      ? t("usage.tokensUnavailable")
+      : t("usage.tokensLabel", {
+          count: formatTokenCount(usage.summary.total_tokens),
+        });
 
     // Count of background async sub-agents (writing / data-analysis) still
     // running — drives the composer's "agents running" pulse. We poll each task's
@@ -617,9 +619,9 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
       // the user's own queue has drained.
       if (queuedMessages.length > 0) return;
       const reportedKeys = getThreadAutoNotifyReportedKeys(threadId);
-      for (const t of liveAgentTasks) {
-        if (!isTerminalStatus(t.liveStatus)) continue;
-        const key = asyncTaskReportKey(t);
+      for (const task of liveAgentTasks) {
+        if (!isTerminalStatus(task.liveStatus)) continue;
+        const key = asyncTaskReportKey(task);
         if (reportedKeys.has(key)) continue;
         if (
           messages.some(
@@ -627,7 +629,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
               message.type === "human" &&
               asyncUpdateMatchesTask(
                 extractStringFromMessageContent(message),
-                t
+                task
               )
           )
         ) {
@@ -636,9 +638,9 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
         }
         autoFireInFlightRef.current = true;
         markThreadAutoNotifyReported(threadId, key);
-        sendMessage(formatAsyncUpdateMessage(t), reviewMode);
+        sendMessage(formatAsyncUpdateMessage(task), reviewMode);
         toast.success(
-          `Auto-reported ${agentLabel(t.agent_name)} to the main chat.`
+          t("agents.autoReported", { agent: agentLabel(task.agent_name) })
         );
         break; // one per idle window; the rest fire once this turn settles
       }
@@ -649,6 +651,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
       input,
       messages,
       sendMessage,
+      t,
       threadId,
       queuedMessages,
       reviewMode,
@@ -953,17 +956,17 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
         applyReviewMode(mode);
         toast.info(
           mode === "auto"
-            ? "Auto-approve enabled for this chat."
-            : "Manual review enabled for this chat."
+            ? t("reviewMode.autoEnabled")
+            : t("reviewMode.manualEnabled")
         );
       },
-      [applyReviewMode, reviewMode, reviewModeLocked]
+      [applyReviewMode, reviewMode, reviewModeLocked, t]
     );
 
     const confirmFullApprove = useCallback(() => {
       applyReviewMode("full");
-      toast.info("Full approve enabled for this chat.");
-    }, [applyReviewMode]);
+      toast.info(t("reviewMode.fullEnabled"));
+    }, [applyReviewMode, t]);
 
     // Follow the thread and migrate the pending New Chat mode only when the first
     // submitted message created this thread.
@@ -1033,21 +1036,17 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
           }
           setPendingFiles((currentFiles) => [...currentFiles, ...data.files!]);
           notifyWorkspaceChanged(uploadThreadId);
-          toast.success(
-            `${data.files.length} file${
-              data.files.length === 1 ? "" : "s"
-            } uploaded to the workspace.`
-          );
+          toast.success(t("upload.uploaded", { count: data.files.length }));
         } catch (error) {
           errorToast(
             "chat.attachment",
-            error instanceof Error ? error.message : "Failed to upload files."
+            error instanceof Error ? error.message : t("upload.failed")
           );
         } finally {
           setIsUploadingFiles(false);
         }
       },
-      [ensureThread, threadId]
+      [ensureThread, t, threadId]
     );
 
     const removePendingFile = useCallback((filePath: string) => {
@@ -1139,10 +1138,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
         if (!target || messages[0]?.id === id) return messages;
         return [target, ...messages.filter((message) => message.id !== id)];
       });
-      toast.info(
-        "This message will run next without interrupting the current turn."
-      );
-    }, []);
+      toast.info(t("queue.steerToast"));
+    }, [t]);
 
     const moveQueuedMessage = useCallback((id: number, direction: -1 | 1) => {
       setQueuedMessages((messages) => {
@@ -1536,10 +1533,9 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
         >
           <DialogContent className="sm:max-w-md">
             <DialogHeader>
-              <DialogTitle>Enable Full approve?</DialogTitle>
+              <DialogTitle>{t("reviewMode.fullApprove.title")}</DialogTitle>
               <DialogDescription>
-                EvoScientist will approve reviewed tool actions automatically
-                and will not pause to ask you for clarification.
+                {t("reviewMode.fullApprove.description")}
               </DialogDescription>
             </DialogHeader>
             <div className="flex items-start gap-3 rounded-lg border border-amber-300 bg-amber-50 p-3 text-sm text-amber-950 dark:border-amber-800 dark:bg-amber-950/40 dark:text-amber-100">
@@ -1547,24 +1543,20 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                 className="mt-0.5 size-4 shrink-0"
                 aria-hidden="true"
               />
-              <p>
-                When details are missing, the model will make reasonable,
-                conservative assumptions and continue. This setting applies only
-                to the current research.
-              </p>
+              <p>{t("reviewMode.fullApprove.warning")}</p>
             </div>
             <DialogFooter>
               <Button
                 variant="outline"
                 onClick={() => setFullApproveDialogOpen(false)}
               >
-                Cancel
+                {tCommon("cancel")}
               </Button>
               <Button
                 onClick={confirmFullApprove}
                 className="bg-amber-600 text-white hover:bg-amber-700"
               >
-                Enable Full approve
+                {t("reviewMode.fullApprove.confirm")}
               </Button>
             </DialogFooter>
           </DialogContent>
@@ -1593,28 +1585,31 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
         >
           <DialogContent className="sm:max-w-md">
             <DialogHeader>
-              <DialogTitle>Choose model</DialogTitle>
+              <DialogTitle>{t("modelPicker.title")}</DialogTitle>
               <DialogDescription>
-                Saved for this chat; the next message freezes it into the
-                run&rsquo;s snapshot.
+                {t("modelPicker.description")}
               </DialogDescription>
             </DialogHeader>
             <div className="mt-2 space-y-2">
               <div className="text-xs text-muted-foreground">
-                Current:{" "}
+                {t("modelPicker.current")}{" "}
                 <span className="font-mono">
                   {modelSelection !== "inherit"
                     ? modelRefLabel(modelSelection.primary)
                     : currentModel
-                    ? `${currentModel.name}${
-                        currentModel.provider
-                          ? ` (${currentModel.provider})`
-                          : ""
-                      } · default`
-                    : "registry default"}
+                    ? t("modelPicker.currentDefault", {
+                        model: `${currentModel.name}${
+                          currentModel.provider
+                            ? ` (${currentModel.provider})`
+                            : ""
+                        }`,
+                      })
+                    : t("modelPicker.registryDefault")}
                 </span>
                 {modelRegistryLoading && (
-                  <span className="ml-2 italic">loading models…</span>
+                  <span className="ml-2 italic">
+                    {t("modelPicker.loadingModels")}
+                  </span>
                 )}
               </div>
               {modelRegistryUnavailable && (
@@ -1626,8 +1621,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                     {"\u26A0"}
                   </span>
                   <span>
-                    The deployment&rsquo;s selectable model list didn&rsquo;t
-                    load
+                    {t("modelPicker.unavailable")}
                     {modelRegistryError ? ` (${modelRegistryError})` : ""}.
                   </span>
                 </div>
@@ -1636,7 +1630,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                 type="text"
                 value={modelSearch}
                 onChange={(e) => setModelSearch(e.target.value)}
-                placeholder="Filter by name or provider…"
+                placeholder={t("modelPicker.filterPlaceholder")}
                 autoFocus
                 className="w-full rounded-md border border-border bg-background px-3 py-1.5 font-mono text-sm placeholder:font-sans placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
               />
@@ -1644,8 +1638,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                 {filteredPickerModels.length === 0 && (
                   <li className="px-3 py-2 text-xs text-muted-foreground">
                     {modelSearch
-                      ? `No models match "${modelSearch}".`
-                      : "No models are enabled."}
+                      ? t("modelPicker.noMatch", { query: modelSearch })
+                      : t("modelPicker.noneEnabled")}
                   </li>
                 )}
                 {filteredPickerModels.map((m) => {
@@ -1674,14 +1668,18 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                             await setModelSelection({
                               primary: ref,
                             });
-                            toast.success(`Model set to ${modelKey}.`);
+                            toast.success(
+                              t("modelPicker.setSuccess", { model: modelKey })
+                            );
                             setModelPickerOpen(false);
                           } catch (err) {
                             errorToast(
                               "chat.message",
                               err instanceof Error
-                                ? `Couldn't update model: ${err.message}`
-                                : "Couldn't update model — try again."
+                                ? t("modelPicker.updateFailed", {
+                                    message: err.message,
+                                  })
+                                : t("modelPicker.updateFailedGeneric")
                             );
                           }
                         }}
@@ -1707,22 +1705,26 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                 onClick={async () => {
                   try {
                     await setModelSelection("inherit");
-                    toast.success("Model reset to the registry default.");
+                    toast.success(t("modelPicker.resetSuccess"));
                     setModelPickerOpen(false);
                   } catch (err) {
                     errorToast(
                       "chat.message",
                       err instanceof Error
-                        ? `Couldn't reset model: ${err.message}`
-                        : "Couldn't reset model — try again."
+                        ? t("modelPicker.resetFailed", {
+                            message: err.message,
+                          })
+                        : t("modelPicker.resetFailedGeneric")
                     );
                   }
                 }}
                 disabled={modelSelection === "inherit"}
               >
-                Reset to default
+                {t("modelPicker.resetToDefault")}
+              </Button>
+              <Button onClick={() => setModelPickerOpen(false)}>
+                {tCommon("close")}
               </Button>
-              <Button onClick={() => setModelPickerOpen(false)}>Close</Button>
             </DialogFooter>
           </DialogContent>
         </Dialog>
@@ -1736,7 +1738,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
           >
             {isThreadLoading ? (
               <div className="flex items-center justify-center p-8">
-                <p className="text-muted-foreground">Loading…</p>
+                <p className="text-muted-foreground">{tCommon("loading")}</p>
               </div>
             ) : (
               <>
@@ -1749,14 +1751,13 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                       />
                     </div>
                     <h2 className="text-pretty text-2xl font-semibold tracking-tight sm:text-3xl">
-                      Where research evolves
+                      {t("emptyStateTitle")}
                     </h2>
                     <p className="mt-2 max-w-lg text-sm text-muted-foreground">
-                      Your self-evolving lab partner — reads the literature,
-                      runs experiments, and remembers what matters.
+                      {t("emptyStateSubtitle")}
                     </p>
                     <div className="mt-4 flex max-w-2xl flex-wrap justify-center gap-2">
-                      {SUGGESTED_PROMPTS.map((prompt) => (
+                      {suggestedPrompts.map((prompt) => (
                         <button
                           key={prompt}
                           type="button"
@@ -1891,7 +1892,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
         <div className="flex-shrink-0 bg-background">
           {queuedMessages.length > 0 && (
             <div
-              aria-label="Queued messages"
+              aria-label={t("queue.label")}
               className="relative mx-auto -mb-4 w-[calc(100%-16px)] max-w-[960px] px-2 sm:w-[calc(100%-24px)]"
             >
               <div className="rounded-b-lg rounded-t-2xl border border-border bg-background pb-5 pt-1 shadow-sm">
@@ -1932,10 +1933,11 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                             moveQueuedMessage(q.id, 1);
                           }
                         }}
-                        aria-label={`Reorder queued message ${index + 1} of ${
-                          queuedMessages.length
-                        }`}
-                        title="Drag to reorder, or use the arrow keys"
+                        aria-label={t("queue.reorderAria", {
+                          index: index + 1,
+                          total: queuedMessages.length,
+                        })}
+                        title={t("queue.reorderTitle")}
                         className="mt-0.5 inline-flex size-5 shrink-0 cursor-grab items-center justify-center rounded text-muted-foreground/60 focus-visible:ring-2 focus-visible:ring-ring active:cursor-grabbing"
                       >
                         <GripVertical
@@ -1957,8 +1959,9 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                               className="size-3 shrink-0"
                               aria-hidden="true"
                             />
-                            {q.files.length} file
-                            {q.files.length === 1 ? "" : "s"}
+                            {t("queue.filesAttached", {
+                              count: q.files.length,
+                            })}
                           </span>
                         )}
                       </div>
@@ -1966,21 +1969,23 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                         <button
                           type="button"
                           onClick={() => steerQueuedMessage(q.id)}
-                          aria-label="Steer with this message next"
-                          title="Submit next without interrupting the current turn"
+                          aria-label={t("queue.steerAria")}
+                          title={t("queue.steerTitle")}
                           className="inline-flex h-7 items-center gap-1 rounded-full px-2 text-xs font-medium text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
                         >
                           <CornerDownRight
                             className="size-3.5"
                             aria-hidden="true"
                           />
-                          <span className="hidden sm:inline">Steer</span>
+                          <span className="hidden sm:inline">
+                            {t("queue.steer")}
+                          </span>
                         </button>
                         <button
                           type="button"
                           onClick={() => removeQueuedMessage(q.id)}
-                          aria-label="Remove queued message"
-                          title="Remove from queue"
+                          aria-label={t("queue.removeAria")}
+                          title={t("queue.removeTitle")}
                           className="inline-flex size-7 items-center justify-center rounded-md text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
                         >
                           <Trash2
@@ -2007,8 +2012,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                           }}
                         >
                           <summary
-                            aria-label="More queued message actions"
-                            title="More actions"
+                            aria-label={t("queue.moreAria")}
+                            title={t("queue.moreTitle")}
                             className="inline-flex size-7 cursor-pointer list-none items-center justify-center rounded-full text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring [&::-webkit-details-marker]:hidden"
                           >
                             <Ellipsis
@@ -2027,7 +2032,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                                 className="size-4"
                                 aria-hidden="true"
                               />
-                              Edit message
+                              {t("editMessage")}
                             </button>
                             <button
                               type="button"
@@ -2038,7 +2043,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                                 className="size-4"
                                 aria-hidden="true"
                               />
-                              Close queue
+                              {t("queue.closeQueue")}
                             </button>
                           </div>
                         </details>
@@ -2093,7 +2098,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                                     key="label"
                                     className="ml-[1px] min-w-0 truncate text-sm"
                                   >
-                                    All tasks completed
+                                    {t("tasks.allCompleted")}
                                   </span>,
                                 ];
                               }
@@ -2107,9 +2112,12 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                                     key="label"
                                     className="ml-[1px] min-w-0 truncate text-sm"
                                   >
-                                    Task{" "}
-                                    {totalTasks - groupedTodos.pending.length}{" "}
-                                    of {totalTasks}
+                                    {t("tasks.progress", {
+                                      current:
+                                        totalTasks -
+                                        groupedTodos.pending.length,
+                                      total: totalTasks,
+                                    })}
                                   </span>,
                                   <span
                                     key="content"
@@ -2130,9 +2138,11 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                                   key="label"
                                   className="ml-[1px] min-w-0 truncate text-sm"
                                 >
-                                  Task{" "}
-                                  {totalTasks - groupedTodos.pending.length} of{" "}
-                                  {totalTasks}
+                                  {t("tasks.progress", {
+                                    current:
+                                      totalTasks - groupedTodos.pending.length,
+                                    total: totalTasks,
+                                  })}
                                 </span>,
                               ];
                             })()}
@@ -2154,7 +2164,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                             aria-expanded={metaOpen === "files"}
                           >
                             <FileIcon size={16} />
-                            Files (State)
+                            {t("tasks.filesState")}
                             <span className="h-4 min-w-4 rounded-full bg-[var(--brand-solid)] px-0.5 text-center text-[10px] leading-[16px] text-[var(--brand-foreground)]">
                               {Object.keys(files).length}
                             </span>
@@ -2188,7 +2198,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                           }
                           aria-expanded={metaOpen === "tasks"}
                         >
-                          Tasks
+                          {t("tasks.tasks")}
                         </button>
                       )}
                       {hasFiles && (
@@ -2202,14 +2212,14 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                           }
                           aria-expanded={metaOpen === "files"}
                         >
-                          Files (State)
+                          {t("tasks.filesState")}
                           <span className="h-4 min-w-4 rounded-full bg-[var(--brand-solid)] px-0.5 text-center text-[10px] leading-[16px] text-[var(--brand-foreground)]">
                             {Object.keys(files).length}
                           </span>
                         </button>
                       )}
                       <button
-                        aria-label="Close"
+                        aria-label={tCommon("close")}
                         className="flex-1"
                         onClick={() => setMetaOpen(null)}
                       />
@@ -2229,9 +2239,9 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                               <h3 className="mb-1 text-[10px] font-semibold uppercase tracking-wider text-tertiary">
                                 {
                                   {
-                                    pending: "Pending",
-                                    in_progress: "In Progress",
-                                    completed: "Completed",
+                                    pending: t("tasks.pending"),
+                                    in_progress: t("tasks.inProgress"),
+                                    completed: t("tasks.completed"),
                                   }[status]
                                 }
                               </h3>
@@ -2272,8 +2282,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                   <button
                     type="button"
                     onClick={() => setModelPickerOpen(true)}
-                    title="Click to change model for this chat"
-                    aria-label="Change model for this chat"
+                    title={t("modelPicker.changeTitle")}
+                    aria-label={t("modelPicker.changeAria")}
                     className="-mx-1 flex items-center gap-1.5 rounded px-1 py-0.5 transition-colors hover:bg-accent hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
                   >
                     <Sparkles
@@ -2305,15 +2315,15 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                         });
                         toast.success(
                           effort === null
-                            ? "Reasoning effort back to the registry default."
-                            : `Reasoning effort set to ${effort}.`
+                            ? t("reasoning.reset")
+                            : t("reasoning.set", { effort })
                         );
                       } catch (err) {
                         errorToast(
                           "chat.model",
                           err instanceof Error
-                            ? `Couldn't update reasoning effort: ${err.message}`
-                            : "Couldn't update reasoning effort — try again."
+                            ? t("reasoning.failed", { message: err.message })
+                            : t("reasoning.failedGeneric")
                         );
                       }
                     }}
@@ -2340,17 +2350,21 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                         });
                         toast.success(
                           value === null
-                            ? "Sampling back to the registry default."
+                            ? t("sampling.reset")
                             : value.kind === "temperature"
-                              ? `Temperature set to ${value.value.toFixed(2)} (top_p omitted).`
-                              : `Top P set to ${value.value.toFixed(2)} (temperature omitted).`
+                              ? t("sampling.temperatureSet", {
+                                  value: value.value.toFixed(2),
+                                })
+                              : t("sampling.topPSet", {
+                                  value: value.value.toFixed(2),
+                                })
                         );
                       } catch (err) {
                         errorToast(
                           "chat.model",
                           err instanceof Error
-                            ? `Couldn't update sampling: ${err.message}`
-                            : "Couldn't update sampling — try again."
+                            ? t("sampling.failed", { message: err.message })
+                            : t("sampling.failedGeneric")
                         );
                       }
                     }}
@@ -2367,7 +2381,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                     type="button"
                     onClick={() => setUsageDialogOpen(true)}
                     title={usageLabel}
-                    aria-label={`View token usage: ${usageLabel}`}
+                    aria-label={t("usage.viewAria", { label: usageLabel })}
                     className={cn(
                       "flex shrink-0 items-center gap-1.5 rounded px-1.5 py-0.5 transition-colors hover:bg-accent focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring",
                       currentModel && "ml-auto",
@@ -2387,19 +2401,19 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                   <button
                     type="button"
                     onClick={onShowAgents}
-                    title={`${runningAgents} background agent${
-                      runningAgents === 1 ? "" : "s"
-                    } running — click to view`}
-                    aria-label={`${runningAgents} background agent${
-                      runningAgents === 1 ? "" : "s"
-                    } running — view`}
+                    title={t("agents.runningTitle", {
+                      count: runningAgents,
+                    })}
+                    aria-label={t("agents.runningAria", {
+                      count: runningAgents,
+                    })}
                     className="flex shrink-0 items-center gap-1.5 rounded px-1.5 py-0.5 font-medium text-[var(--brand)] transition-colors hover:bg-accent focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
                   >
                     <span
                       className="size-2 animate-pulse rounded-full bg-[var(--color-warning)]"
                       aria-hidden="true"
                     />
-                    {runningAgents} agent{runningAgents === 1 ? "" : "s"}
+                    {t("agents.runningLabel", { count: runningAgents })}
                   </button>
                 )}
               </div>
@@ -2410,7 +2424,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
             >
               {pendingFiles.length > 0 && (
                 <div
-                  aria-label="Attached files"
+                  aria-label={t("upload.attachedFiles")}
                   className="flex flex-wrap gap-2 border-b border-border px-3 py-2"
                 >
                   {pendingFiles.map((file) => (
@@ -2431,8 +2445,12 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                       <button
                         type="button"
                         onClick={() => removePendingFile(file.path)}
-                        aria-label={`Remove ${file.name} from this message`}
-                        title={`Remove ${file.name} from this message`}
+                        aria-label={t("upload.removeAttachment", {
+                          name: file.name,
+                        })}
+                        title={t("upload.removeAttachment", {
+                          name: file.name,
+                        })}
                         className="rounded-sm text-muted-foreground transition-colors hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
                       >
                         <X
@@ -2449,16 +2467,16 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                 value={input}
                 onChange={(e) => setInput(e.target.value)}
                 onKeyDown={handleKeyDown}
-                aria-label="Message"
+                aria-label={t("messageInputLabel")}
                 disabled={hasPendingInterrupt}
                 placeholder={
                   hasPendingInterrupt
-                    ? "Respond to the request above to continue…"
+                    ? t("placeholderRespondToInterrupt")
                     : isReconnecting
-                    ? "Reconnecting to the running task…"
+                    ? t("placeholderReconnecting")
                     : isLoading
-                    ? "Queue a follow-up — sends when this turn finishes…"
-                    : "Ask EvoScientist anything…"
+                    ? t("placeholderQueueFollowUp")
+                    : t("placeholderDefault")
                 }
                 className="font-inherit field-sizing-content flex-1 resize-none border-0 bg-transparent px-3.5 pb-2.5 pt-3 text-sm leading-6 text-primary outline-none placeholder:text-tertiary disabled:cursor-not-allowed sm:px-4"
                 rows={1}
@@ -2481,8 +2499,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                     disabled={
                       !assistant || hasPendingInterrupt || isUploadingFiles
                     }
-                    aria-label="Upload files to workspace"
-                    title="Upload files to workspace (max 50 MB each)"
+                    aria-label={t("upload.aria")}
+                    title={t("upload.title")}
                     className="inline-flex size-8 items-center justify-center rounded-full text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50"
                   >
                     <Paperclip
@@ -2492,10 +2510,10 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                   </button>
                   <div
                     role="radiogroup"
-                    aria-label="Review mode"
+                    aria-label={t("reviewMode.label")}
                     className="inline-flex h-8 items-center rounded-md border border-border bg-muted/40 p-0.5"
                   >
-                    {REVIEW_MODE_OPTIONS.map((option) => {
+                    {reviewModeOptions.map((option) => {
                       const Icon = option.icon;
                       const active = reviewMode === option.mode;
                       return (
@@ -2527,12 +2545,16 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                     <button
                       type="button"
                       onClick={() => onNavigate({ view: "workspace" })}
-                      title={`${
-                        workspaceOpen ? "Close" : "Open"
-                      } conversation files`}
-                      aria-label={`${
-                        workspaceOpen ? "Close" : "Open"
-                      } conversation files`}
+                      title={
+                        workspaceOpen
+                          ? t("workspace.closeFiles")
+                          : t("workspace.openFiles")
+                      }
+                      aria-label={
+                        workspaceOpen
+                          ? t("workspace.closeFiles")
+                          : t("workspace.openFiles")
+                      }
                       aria-pressed={Boolean(workspaceOpen)}
                       className="inline-flex min-w-0 items-center gap-1.5 rounded-md px-2 py-1 text-xs font-medium text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
                     >
@@ -2541,7 +2563,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                         aria-hidden="true"
                       />
                       <span className="hidden max-w-[140px] truncate font-mono sm:inline lg:max-w-[220px]">
-                        Files
+                        {t("workspace.files")}
                       </span>
                     </button>
                   )}
@@ -2555,17 +2577,19 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(
                       !isLoading &&
                       (submitDisabled || isUploadingFiles || !input.trim())
                     }
-                    aria-label={isLoading ? "Stop generating" : "Send message"}
+                    aria-label={
+                      isLoading ? t("stopGenerating") : t("sendMessage")
+                    }
                   >
                     {isLoading ? (
                       <>
                         <Square size={14} />
-                        <span className="hidden sm:inline">Stop</span>
+                        <span className="hidden sm:inline">{t("stop")}</span>
                       </>
                     ) : (
                       <>
                         <ArrowUp size={18} />
-                        <span className="hidden sm:inline">Send</span>
+                        <span className="hidden sm:inline">{t("send")}</span>
                       </>
                     )}
                   </Button>
@@ -2597,6 +2621,13 @@ function ReasoningEffortSlider({
   value: ReasoningEffort | null;
   onCommit: (effort: ReasoningEffort | null) => void | Promise<void>;
 }) {
+  const t = useTranslations("chat");
+  const effortLabels: Record<ReasoningEffort, string> = {
+    auto: t("reasoning.auto"),
+    low: t("reasoning.low"),
+    medium: t("reasoning.medium"),
+    high: t("reasoning.high"),
+  };
   const committedIndex =
     value && value !== "auto" ? EFFORT_LEVELS.indexOf(value) : 0;
   const [draft, setDraft] = useState<number | null>(null);
@@ -2614,15 +2645,13 @@ function ReasoningEffortSlider({
     <span
       className={cn("flex items-center gap-1.5", disabled && "opacity-50")}
       title={
-        disabled
-          ? "Pick a model to override the registry-configured effort"
-          : "Reasoning effort for the primary model"
+        disabled ? t("reasoning.titleDisabled") : t("reasoning.title")
       }
     >
       <input
         type="range"
-        aria-label="Reasoning effort"
-        aria-valuetext={shown}
+        aria-label={t("reasoning.aria")}
+        aria-valuetext={effortLabels[shown]}
         disabled={disabled}
         min={0}
         max={EFFORT_LEVELS.length - 1}
@@ -2652,7 +2681,7 @@ function ReasoningEffortSlider({
             : "font-medium text-foreground"
         )}
       >
-        {shown}
+        {effortLabels[shown]}
       </span>
     </span>
   );
@@ -2679,6 +2708,7 @@ function GenerationParamSlider({
   step: number;
   onCommit: (value: number | null) => void | Promise<void>;
 }) {
+  const t = useTranslations("chat");
   const anchor = override ?? fallback ?? min;
   const [draft, setDraft] = useState<number | null>(null);
   const [editing, setEditing] = useState(false);
@@ -2725,10 +2755,13 @@ function GenerationParamSlider({
       )}
       title={
         disabled
-          ? `Pick a model to override the registry-configured ${ariaLabel}`
+          ? t("sampling.sliderTitleDisabled", { label: ariaLabel })
           : override === null
-            ? `${ariaLabel}: registry default ${fallback ?? "unset"} — drag to override or click the value to type one`
-            : `${ariaLabel} override — click the value to type an exact one; empty + Enter resets`
+            ? t("sampling.sliderTitleDefault", {
+                label: ariaLabel,
+                value: fallback ?? t("sampling.unset"),
+              })
+            : t("sampling.sliderTitleOverride", { label: ariaLabel })
       }
     >
       <input
@@ -2760,7 +2793,7 @@ function GenerationParamSlider({
         <input
           type="text"
           inputMode="decimal"
-          aria-label={`${ariaLabel} exact value`}
+          aria-label={t("sampling.exactValue", { label: ariaLabel })}
           autoFocus
           value={editText}
           onChange={(event) => setEditText(event.target.value)}
@@ -2782,7 +2815,7 @@ function GenerationParamSlider({
           type="button"
           disabled={disabled}
           onClick={startEdit}
-          title={`Click to type an exact ${ariaLabel} value`}
+          title={t("sampling.clickToType", { label: ariaLabel })}
           className={cn(
             "w-12 text-left text-xs tabular-nums",
             isOverride
@@ -2812,6 +2845,7 @@ function SamplingOverridePicker({
   fallbackTopP: number | null;
   onCommit: (value: SamplingOverride | null) => void | Promise<void>;
 }) {
+  const t = useTranslations("chat");
   const mode: "default" | "temperature" | "top_p" = override?.kind ?? "default";
 
   const select = (next: "default" | "temperature" | "top_p") => {
@@ -2832,7 +2866,7 @@ function SamplingOverridePicker({
   };
 
   const modes = [
-    { key: "default", label: "默认" },
+    { key: "default", label: t("sampling.modeDefault") },
     { key: "temperature", label: "T" },
     { key: "top_p", label: "P" },
   ] as const;
@@ -2841,9 +2875,7 @@ function SamplingOverridePicker({
     <span
       className={cn("flex items-center gap-1.5", disabled && "opacity-50")}
       title={
-        disabled
-          ? "Pick a model to override the registry-configured sampling"
-          : "Sampling override: temperature and top_p are mutually exclusive"
+        disabled ? t("sampling.titleDisabled") : t("sampling.title")
       }
     >
       {/* ≥sm: segmented control */}
@@ -2868,7 +2900,7 @@ function SamplingOverridePicker({
       </span>
       {/* <sm: dropdown */}
       <select
-        aria-label="Sampling override"
+        aria-label={t("sampling.aria")}
         disabled={disabled}
         value={mode}
         onChange={(event) =>
@@ -2884,7 +2916,7 @@ function SamplingOverridePicker({
       </select>
       {mode === "temperature" && (
         <GenerationParamSlider
-          ariaLabel="Temperature"
+          ariaLabel={t("sampling.temperature")}
           disabled={disabled}
           override={override?.kind === "temperature" ? override.value : null}
           fallback={fallbackTemperature}
@@ -2898,7 +2930,7 @@ function SamplingOverridePicker({
       )}
       {mode === "top_p" && (
         <GenerationParamSlider
-          ariaLabel="Top P"
+          ariaLabel={t("sampling.topP")}
           disabled={disabled}
           override={override?.kind === "top_p" ? override.value : null}
           fallback={fallbackTopP}
@@ -2915,6 +2947,7 @@ function SamplingOverridePicker({
 }
 
 function ThinkingTimer() {
+  const t = useTranslations("chat");
   const [seconds, setSeconds] = useState(0);
   useEffect(() => {
     const startedAt = Date.now();
@@ -2935,7 +2968,7 @@ function ThinkingTimer() {
         aria-hidden="true"
         className="size-2 animate-pulse rounded-full bg-[var(--brand)]"
       />
-      <span>思考中…</span>
+      <span>{t("thinkingTimer")}</span>
       <span className="tabular-nums">
         {mm}:{ss}
       </span>
diff --git a/src/app/components/ChatMessage.tsx b/src/app/components/ChatMessage.tsx
index 9de8b6f..de64d4b 100644
--- a/src/app/components/ChatMessage.tsx
+++ b/src/app/components/ChatMessage.tsx
@@ -32,6 +32,7 @@ import { mapActionRequestsToToolCalls } from "@/lib/actionGrouping";
 import { mergeApprovalDecision } from "@/lib/approvalDecision";
 import { autoApprovesTools, type ReviewMode } from "@/lib/reviewMode";
 import { errorToast } from "@/lib/errorReporter";
+import { useTranslations } from "next-intl";
 
 interface ChatMessageProps {
   message: Message;
@@ -75,6 +76,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
     subAgentSteps,
     threadId,
   }) => {
+    const t = useTranslations("chat");
     const isUser = message.type === "human";
     const messageContent = extractStringFromMessageContent(message);
     const hasContent = messageContent && messageContent.trim() !== "";
@@ -185,9 +187,9 @@ export const ChatMessage = React.memo<ChatMessageProps>(
         if (copyResetTimer.current) clearTimeout(copyResetTimer.current);
         copyResetTimer.current = setTimeout(() => setCopied(false), 2000);
       } else {
-        errorToast("clipboard", "Couldn't copy to clipboard.");
+        errorToast("clipboard", t("message.copyFailed"));
       }
-    }, [messageContent]);
+    }, [messageContent, t]);
     const [expandedSubAgents, setExpandedSubAgents] = useState<
       Record<string, boolean>
     >({});
@@ -218,7 +220,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
               className="size-3 text-[var(--brand)]"
               aria-hidden="true"
             />
-            Background agent reported back
+            {t("message.backgroundAgentReported")}
           </span>
         </div>
       );
@@ -256,7 +258,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
                   className="h-3.5 w-3.5"
                   aria-hidden="true"
                 />
-                Thinking
+                {t("message.thinking")}
               </button>
               {thinkingOpen && (
                 <div className="mt-2 whitespace-pre-wrap break-words border-l-2 border-border pl-3 text-sm leading-relaxed text-muted-foreground">
@@ -299,7 +301,9 @@ export const ChatMessage = React.memo<ChatMessageProps>(
               <button
                 type="button"
                 onClick={handleCopy}
-                aria-label={copied ? "Copied" : "Copy message"}
+                aria-label={
+                  copied ? t("message.copied") : t("message.copy")
+                }
                 className="inline-flex items-center rounded p-1.5 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
               >
                 {copied ? (
@@ -321,7 +325,9 @@ export const ChatMessage = React.memo<ChatMessageProps>(
               <button
                 type="button"
                 onClick={handleCopy}
-                aria-label={copied ? "Copied" : "Copy message"}
+                aria-label={
+                  copied ? t("message.copied") : t("message.copy")
+                }
                 className="inline-flex items-center rounded p-1.5 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
               >
                 {copied ? (
@@ -339,7 +345,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
               <button
                 type="button"
                 onClick={() => onEditMessage?.(messageContent)}
-                aria-label="Edit message"
+                aria-label={t("editMessage")}
                 className="inline-flex items-center rounded p-1.5 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
               >
                 <Pencil
@@ -421,7 +427,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
                     <div className="w-full max-w-full">
                       <div className="border-border-light rounded-md border bg-[var(--color-surface)] p-4">
                         <h4 className="mb-2 text-xs font-semibold uppercase tracking-wider text-[var(--color-text-secondary)]">
-                          Input
+                          {t("subAgent.input")}
                         </h4>
                         <div className="mb-4">
                           <MarkdownContent
@@ -432,7 +438,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
                         {(subAgentSteps?.[subAgent.id]?.length ?? 0) > 0 && (
                           <>
                             <h4 className="mb-2 text-xs font-semibold uppercase tracking-wider text-[var(--color-text-secondary)]">
-                              Steps
+                              {t("subAgent.steps")}
                             </h4>
                             <div className="mb-4">
                               <SubAgentSteps
@@ -445,7 +451,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
                         {subAgent.output && (
                           <>
                             <h4 className="mb-2 text-xs font-semibold uppercase tracking-wider text-[var(--color-text-secondary)]">
-                              Output
+                              {t("subAgent.output")}
                             </h4>
                             <MarkdownContent
                               content={extractSubAgentContent(subAgent.output)}
diff --git a/src/app/components/CompactionSummary.tsx b/src/app/components/CompactionSummary.tsx
index 328a151..fa4a936 100644
--- a/src/app/components/CompactionSummary.tsx
+++ b/src/app/components/CompactionSummary.tsx
@@ -5,6 +5,7 @@ import { ChevronRight, Layers } from "lucide-react";
 import { MarkdownContent } from "@/app/components/MarkdownContent";
 import { extractSummaryBody } from "@/lib/summarization";
 import { cn } from "@/lib/utils";
+import { useTranslations, useFormatter } from "next-intl";
 
 interface CompactionSummaryProps {
   /** Raw summary message content (wrapper + body). */
@@ -19,8 +20,11 @@ interface CompactionSummaryProps {
   budgetHardTokens?: number | null;
 }
 
-function formatTokens(value: number): string {
-  return value.toLocaleString("en-US");
+function formatTokens(
+  format: ReturnType<typeof useFormatter>,
+  value: number
+): string {
+  return format.number(value);
 }
 
 /**
@@ -37,6 +41,8 @@ export const CompactionSummary = React.memo<CompactionSummaryProps>(
     estimatedTokensAfter,
     budgetHardTokens,
   }) => {
+    const t = useTranslations("chat");
+    const format = useFormatter();
     const [open, setOpen] = useState(false);
     const body = extractSummaryBody(content);
     const hasTokenStats =
@@ -57,17 +63,19 @@ export const CompactionSummary = React.memo<CompactionSummaryProps>(
               className="size-3.5 text-[var(--brand)]"
               aria-hidden="true"
             />
-            Conversation compacted
+            {t("compaction.title")}
             {typeof summarizedCount === "number" && summarizedCount > 0 && (
               <span className="text-muted-foreground/70">
-                · {summarizedCount} earlier{" "}
-                {summarizedCount === 1 ? "message" : "messages"} summarized
+                · {t("compaction.summarized", { count: summarizedCount })}
               </span>
             )}
             {hasTokenStats && (
               <span className="text-muted-foreground/70">
-                · ≈{formatTokens(estimatedTokensBefore)} → ≈
-                {formatTokens(estimatedTokensAfter)} tokens
+                ·{" "}
+                {t("compaction.tokenStats", {
+                  before: formatTokens(format, estimatedTokensBefore),
+                  after: formatTokens(format, estimatedTokensAfter),
+                })}
               </span>
             )}
             <ChevronRight
@@ -85,13 +93,16 @@ export const CompactionSummary = React.memo<CompactionSummaryProps>(
             <MarkdownContent content={body} />
             {hasTokenStats && (
               <p className="mt-3 border-t border-border/60 pt-2 text-[11px] text-muted-foreground/80">
-                Prompt size (estimate): ≈{formatTokens(estimatedTokensBefore)}{" "}
-                tokens before compaction, ≈{formatTokens(estimatedTokensAfter)}{" "}
-                after
-                {typeof budgetHardTokens === "number" &&
-                  ` · hard message budget ≈${formatTokens(budgetHardTokens)} tokens`}
-                . Exact usage appears in token consumption once the next model
-                call completes.
+                {typeof budgetHardTokens === "number"
+                  ? t("compaction.detailsWithBudget", {
+                      before: formatTokens(format, estimatedTokensBefore),
+                      after: formatTokens(format, estimatedTokensAfter),
+                      budget: formatTokens(format, budgetHardTokens),
+                    })
+                  : t("compaction.detailsWithoutBudget", {
+                      before: formatTokens(format, estimatedTokensBefore),
+                      after: formatTokens(format, estimatedTokensAfter),
+                    })}
               </p>
             )}
           </div>
diff --git a/src/app/components/ContextUsageIndicator.tsx b/src/app/components/ContextUsageIndicator.tsx
index 82f9e69..2b6cef4 100644
--- a/src/app/components/ContextUsageIndicator.tsx
+++ b/src/app/components/ContextUsageIndicator.tsx
@@ -7,6 +7,7 @@ import {
   type ContextUsageEvent,
 } from "@/lib/contextUsage";
 import { cn } from "@/lib/utils";
+import { useTranslations } from "next-intl";
 
 /**
  * Live context-occupancy pill.
@@ -22,6 +23,7 @@ export const ContextUsageIndicator = React.memo<{
   usage: ContextUsageEvent | null;
   measuredTokens: number | null;
 }>(function ContextUsageIndicator({ usage, measuredTokens }) {
+  const t = useTranslations("chat");
   if (!usage) return null;
   const estimated = usage.usedTokens + usage.reservedTokens;
   const occupied = measuredTokens ?? estimated;
@@ -29,16 +31,20 @@ export const ContextUsageIndicator = React.memo<{
 
   const percent = Math.max(0, Math.round((occupied / limit) * 100));
   const nearlyFull = occupied >= limit * 0.85;
-  const label = `ctx ${percent}% · ${formatCompactTokens(
-    occupied
-  )}/${formatCompactTokens(limit)}`;
+  const label = t("contextUsage.label", {
+    percent,
+    used: formatCompactTokens(occupied),
+    limit: formatCompactTokens(limit),
+  });
+  const tooltipParams = {
+    used: occupied.toLocaleString(),
+    limit: limit.toLocaleString(),
+    soft: usage.softTokens.toLocaleString(),
+  };
   const tooltip =
-    (measuredTokens !== null
-      ? `Last model call used ${occupied.toLocaleString()} of ` +
-        `${limit.toLocaleString()} tokens (measured)`
-      : `Context used (estimate): ${occupied.toLocaleString()} of ` +
-        `${limit.toLocaleString()} tokens`) +
-    ` · auto-compact messages at ≈${usage.softTokens.toLocaleString()}.`;
+    measuredTokens !== null
+      ? t("contextUsage.tooltipMeasured", tooltipParams)
+      : t("contextUsage.tooltipEstimate", tooltipParams);
 
   return (
     <span
diff --git a/src/app/components/SubAgentIndicator.tsx b/src/app/components/SubAgentIndicator.tsx
index e4744c0..f570a0f 100644
--- a/src/app/components/SubAgentIndicator.tsx
+++ b/src/app/components/SubAgentIndicator.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import React from "react";
+import { useTranslations } from "next-intl";
 import { Button } from "@/components/ui/button";
 import { Bot, ChevronDown, ChevronUp, Loader2 } from "lucide-react";
 import type { SubAgent } from "@/app/types/types";
@@ -13,6 +14,7 @@ interface SubAgentIndicatorProps {
 
 export const SubAgentIndicator = React.memo<SubAgentIndicatorProps>(
   ({ subAgent, onClick, isExpanded = true }) => {
+    const t = useTranslations("chat");
     const running = subAgent.status === "pending";
     return (
       <div className="w-fit max-w-[70vw] overflow-hidden rounded-lg bg-card">
@@ -39,7 +41,7 @@ export const SubAgentIndicator = React.memo<SubAgentIndicatorProps>(
             {subAgent.subAgentName}
           </span>
           <span className="text-xs font-normal text-muted-foreground">
-            subagent
+            {t("subAgent.badge")}
           </span>
           {isExpanded ? (
             <ChevronUp
diff --git a/src/app/components/ThreadList.tsx b/src/app/components/ThreadList.tsx
index 1ed44b1..3baeb98 100644
--- a/src/app/components/ThreadList.tsx
+++ b/src/app/components/ThreadList.tsx
@@ -31,7 +31,6 @@ import {
   SelectValue,
 } from "@/components/ui/select";
 import { cn } from "@/lib/utils";
-import { formatTime, formatFullTime } from "@/lib/time";
 import type { ThreadItem } from "@/app/hooks/useThreads";
 import {
   useThreads,
@@ -52,16 +51,18 @@ import {
 } from "@/components/ui/dialog";
 import { Input } from "@/components/ui/input";
 import { errorToast } from "@/lib/errorReporter";
+import { useTranslations, useFormatter } from "next-intl";
 
 type StatusFilter = "all" | "idle" | "busy" | "interrupted" | "error";
 
-const GROUP_LABELS = {
-  interrupted: "Requiring Attention",
-  today: "Today",
-  yesterday: "Yesterday",
-  week: "This Week",
-  older: "Older",
-} as const;
+const GROUP_KEYS = [
+  "interrupted",
+  "today",
+  "yesterday",
+  "week",
+  "older",
+] as const;
+type GroupKey = (typeof GROUP_KEYS)[number];
 
 const STATUS_COLORS: Record<ThreadItem["status"], string> = {
   idle: "bg-transparent ring-1 ring-inset ring-green-500",
@@ -102,9 +103,10 @@ function StatusFilterItem({
 }
 
 function ErrorState({ message }: { message: string }) {
+  const t = useTranslations("threadList");
   return (
     <div className="flex flex-col items-center justify-center p-8 text-center">
-      <p className="text-sm text-red-600">Failed to load research</p>
+      <p className="text-sm text-red-600">{t("loadFailed")}</p>
       <p className="mt-1 text-xs text-muted-foreground">{message}</p>
     </div>
   );
@@ -124,10 +126,11 @@ function LoadingState() {
 }
 
 function EmptyState() {
+  const t = useTranslations("threadList");
   return (
     <div className="flex flex-col items-center justify-center p-8 text-center">
       <MessageSquare className="mb-2 h-12 w-12 text-gray-300" />
-      <p className="text-sm text-muted-foreground">No research yet</p>
+      <p className="text-sm text-muted-foreground">{t("empty")}</p>
     </div>
   );
 }
@@ -147,6 +150,9 @@ export function ThreadList({
   onMutateReady,
   onInterruptCountChange,
 }: ThreadListProps) {
+  const t = useTranslations("threadList");
+  const tCommon = useTranslations("common");
+  const format = useFormatter();
   const [currentThreadId, setThreadId] = useQueryState("threadId");
   const [view, setView] = useQueryState("view");
   // Badge the Memory nav when long-term memory changed since last viewed.
@@ -245,7 +251,7 @@ export function ThreadList({
 
   // Group threads by time and status
   const grouped = useMemo(() => {
-    const groups: Record<keyof typeof GROUP_LABELS, ThreadItem[]> = {
+    const groups: Record<GroupKey, ThreadItem[]> = {
       interrupted: [],
       today: [],
       yesterday: [],
@@ -279,6 +285,40 @@ export function ThreadList({
     return groups;
   }, [filtered, now, needsAttention]);
 
+  const groupLabels: Record<GroupKey, string> = {
+    interrupted: t("groups.requiringAttention"),
+    today: t("groups.today"),
+    yesterday: t("groups.yesterday"),
+    week: t("groups.thisWeek"),
+    older: t("groups.older"),
+  };
+
+  // Locale-aware replacements for lib/time.ts (which hardcodes "Yesterday" and
+  // uses the browser locale; we want the app locale).
+  const formatThreadTime = (date: Date): string => {
+    if (!Number.isFinite(date.getTime())) return "—";
+    const diff = now.getTime() - date.getTime();
+    const days = Math.floor(diff / (1000 * 60 * 60 * 24));
+    if (days <= 0) {
+      return format.dateTime(date, {
+        hour: "2-digit",
+        minute: "2-digit",
+        hourCycle: "h23",
+      });
+    }
+    if (days === 1) return t("groups.yesterday");
+    if (days < 7) return format.dateTime(date, { weekday: "long" });
+    return format.dateTime(date, { month: "2-digit", day: "2-digit" });
+  };
+  const formatThreadFullTime = (date: Date): string => {
+    if (!Number.isFinite(date.getTime())) return t("unknownTime");
+    return format.dateTime(date, {
+      dateStyle: "medium",
+      timeStyle: "short",
+      hourCycle: "h23",
+    });
+  };
+
   const interruptedCount = useMemo(() => {
     // Same predicate as the `grouped` bucket so the badge matches the visible
     // group exactly.
@@ -338,7 +378,7 @@ export function ThreadList({
       setRenameTarget(null);
       mutateFn();
     } catch {
-      errorToast("threads.rename", "Couldn't rename — try again.");
+      errorToast("threads.rename", t("renameFailed"));
     } finally {
       actionBusyRef.current = false;
       setActionBusy(false);
@@ -366,7 +406,7 @@ export function ThreadList({
       setDeleteTarget(null);
       mutateFn();
     } catch {
-      errorToast("threads.delete", "Couldn't delete — try again.");
+      errorToast("threads.delete", t("deleteFailed"));
     } finally {
       actionBusyRef.current = false;
       setActionBusy(false);
@@ -387,9 +427,7 @@ export function ThreadList({
     } catch {
       errorToast(
         "threads.pin",
-        thread.pinned
-          ? "Couldn't unpin — try again."
-          : "Couldn't pin — try again."
+        thread.pinned ? t("unpinFailed") : t("pinFailed")
       );
     } finally {
       pinBusyIdsRef.current.delete(thread.id);
@@ -412,7 +450,7 @@ export function ThreadList({
     try {
       await exportThread(thread.id, thread.title);
     } catch {
-      errorToast("threads.export", "Couldn't export — try again.");
+      errorToast("threads.export", t("exportFailed"));
     } finally {
       exportBusyIdsRef.current.delete(thread.id);
       setExportBusyIds((current) => {
@@ -464,9 +502,9 @@ export function ThreadList({
               <span className="ml-2 flex-shrink-0 text-xs tabular-nums text-muted-foreground">
                 <time
                   dateTime={thread.updatedAt.toISOString()}
-                  title={formatFullTime(thread.updatedAt)}
+                  title={formatThreadFullTime(thread.updatedAt)}
                 >
-                  {formatTime(thread.updatedAt, now)}
+                  {formatThreadTime(thread.updatedAt)}
                 </time>
               </span>
             </div>
@@ -479,10 +517,10 @@ export function ThreadList({
             type="button"
             aria-label={
               thread.pinned
-                ? `Unpin "${thread.title}"`
-                : `Pin "${thread.title}"`
+                ? t("unpinAria", { title: thread.title })
+                : t("pinAria", { title: thread.title })
             }
-            title={thread.pinned ? "Unpin" : "Pin"}
+            title={thread.pinned ? t("unpin") : t("pin")}
             onClick={() => togglePin(thread)}
             disabled={pinBusy}
             className={cn(
@@ -506,8 +544,8 @@ export function ThreadList({
           </button>
           <button
             type="button"
-            aria-label={`Rename "${thread.title}"`}
-            title="Rename"
+            aria-label={t("renameAria", { title: thread.title })}
+            title={t("rename")}
             onClick={() => {
               setRenameTarget(thread);
               setRenameValue(thread.title);
@@ -521,8 +559,8 @@ export function ThreadList({
           </button>
           <button
             type="button"
-            aria-label={`Export "${thread.title}" as JSON`}
-            title="Export JSON"
+            aria-label={t("exportAria", { title: thread.title })}
+            title={t("exportJson")}
             onClick={() => runExport(thread)}
             disabled={exportBusy}
             className="rounded p-1 text-muted-foreground transition-colors hover:bg-background hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50"
@@ -541,8 +579,8 @@ export function ThreadList({
           </button>
           <button
             type="button"
-            aria-label={`Delete "${thread.title}"`}
-            title="Delete"
+            aria-label={t("deleteAria", { title: thread.title })}
+            title={tCommon("delete")}
             onClick={() => setDeleteTarget(thread)}
             className="rounded p-1 text-muted-foreground transition-colors hover:bg-destructive/10 hover:text-destructive focus-visible:ring-2 focus-visible:ring-ring"
           >
@@ -576,7 +614,7 @@ export function ThreadList({
           className="size-4"
           aria-hidden="true"
         />
-        New Chat
+        {t("newChat")}
       </button>
       <button
         type="button"
@@ -599,7 +637,7 @@ export function ThreadList({
           className="size-4"
           aria-hidden="true"
         />
-        Research Skills
+        {t("researchSkills")}
       </button>
       <button
         type="button"
@@ -623,14 +661,12 @@ export function ThreadList({
           className="size-4"
           aria-hidden="true"
         />
-        EvoMemory
+        {t("evoMemory")}
         {view !== "memory" && memoryUnseen > 0 && (
           <span
             className="ml-auto inline-flex min-w-4 items-center justify-center rounded-full bg-[var(--brand-solid)] px-1 text-[10px] font-bold leading-none text-[var(--brand-foreground)]"
-            title={`${memoryUnseen} memory file${
-              memoryUnseen === 1 ? "" : "s"
-            } updated since you last looked`}
-            aria-label={`${memoryUnseen} memory updates`}
+            title={t("memoryUpdatesTitle", { count: memoryUnseen })}
+            aria-label={t("memoryUpdatesAria", { count: memoryUnseen })}
           >
             {memoryUnseen}
           </span>
@@ -657,7 +693,7 @@ export function ThreadList({
           className="size-4"
           aria-hidden="true"
         />
-        Scheduled
+        {t("scheduled")}
       </button>
       <div className="flex-shrink-0 border-b border-border p-2.5">
         <div className="relative">
@@ -670,8 +706,8 @@ export function ThreadList({
             name="research-search"
             value={search}
             onChange={(e) => setSearch(e.target.value)}
-            placeholder="Search research…"
-            aria-label="Search research"
+            placeholder={t("searchPlaceholder")}
+            aria-label={t("searchAria")}
             autoComplete="off"
             spellCheck={false}
             className="w-full rounded-md border border-border bg-background py-1.5 pl-8 pr-8 text-sm outline-none placeholder:text-muted-foreground focus-visible:ring-2 focus-visible:ring-ring"
@@ -679,7 +715,7 @@ export function ThreadList({
           {search && (
             <button
               type="button"
-              aria-label="Clear research search"
+              aria-label={t("clearSearch")}
               onClick={() => setSearch("")}
               className="absolute right-1 top-1/2 -translate-y-1/2 rounded p-1 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
             >
@@ -692,7 +728,9 @@ export function ThreadList({
         </div>
       </div>
       <div className="grid flex-shrink-0 grid-cols-[1fr_auto] items-center gap-2 border-b border-border px-3 py-2.5">
-        <h2 className="text-base font-semibold tracking-tight">Recents</h2>
+        <h2 className="text-base font-semibold tracking-tight">
+          {t("recents")}
+        </h2>
         <div className="flex items-center gap-2">
           <Select
             value={statusFilter}
@@ -702,37 +740,37 @@ export function ThreadList({
               <SelectValue />
             </SelectTrigger>
             <SelectContent align="end">
-              <SelectItem value="all">All</SelectItem>
+              <SelectItem value="all">{t("filterAll")}</SelectItem>
               <SelectSeparator />
               <SelectGroup>
-                <SelectLabel>Active</SelectLabel>
+                <SelectLabel>{t("filterActive")}</SelectLabel>
                 <SelectItem value="idle">
                   <StatusFilterItem
                     status="idle"
-                    label="Idle"
+                    label={t("filterIdle")}
                   />
                 </SelectItem>
                 <SelectItem value="busy">
                   <StatusFilterItem
                     status="busy"
-                    label="Busy"
+                    label={t("filterBusy")}
                   />
                 </SelectItem>
               </SelectGroup>
               <SelectSeparator />
               <SelectGroup>
-                <SelectLabel>Attention</SelectLabel>
+                <SelectLabel>{t("filterAttention")}</SelectLabel>
                 <SelectItem value="interrupted">
                   <StatusFilterItem
                     status="interrupted"
-                    label="Interrupted"
+                    label={t("filterInterrupted")}
                     badge={interruptedCount}
                   />
                 </SelectItem>
                 <SelectItem value="error">
                   <StatusFilterItem
                     status="error"
-                    label="Error"
+                    label={t("filterError")}
                   />
                 </SelectItem>
               </SelectGroup>
@@ -741,7 +779,7 @@ export function ThreadList({
           {onClose && (
             <button
               type="button"
-              aria-label={view ? "Close navigation" : "Close research"}
+              aria-label={view ? t("closeNavigation") : t("closeResearch")}
               onClick={onClose}
               className="rounded-md p-2 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-ring"
             >
@@ -771,7 +809,7 @@ export function ThreadList({
           filtered.length === 0 && (
             <div className="flex flex-col items-center justify-center p-8 text-center">
               <p className="text-sm text-muted-foreground">
-                No research matches your search.
+                {t("noMatch")}
               </p>
             </div>
           )}
@@ -782,7 +820,7 @@ export function ThreadList({
             {pinned.length > 0 && (
               <div className="mb-3">
                 <h4 className="m-0 px-2.5 py-1.5 text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
-                  Research
+                  {t("pinnedSection")}
                 </h4>
                 <div className="flex flex-col gap-1">
                   {pinned.map((thread) => renderThreadCard(thread))}
@@ -790,9 +828,7 @@ export function ThreadList({
               </div>
             )}
 
-            {(
-              Object.keys(GROUP_LABELS) as Array<keyof typeof GROUP_LABELS>
-            ).map((group) => {
+            {GROUP_KEYS.map((group) => {
               const groupThreads = grouped[group];
               if (groupThreads.length === 0) return null;
 
@@ -802,7 +838,7 @@ export function ThreadList({
                   className="mb-3"
                 >
                   <h4 className="m-0 px-2.5 py-1.5 text-[11px] font-semibold uppercase tracking-wide text-muted-foreground">
-                    {GROUP_LABELS[group]}
+                    {groupLabels[group]}
                   </h4>
                   <div className="flex flex-col gap-1">
                     {groupThreads.map((thread) => renderThreadCard(thread))}
@@ -822,10 +858,10 @@ export function ThreadList({
                   {isLoadingMore ? (
                     <>
                       <Loader2 className="mr-2 h-4 w-4 animate-spin" />
-                      Loading…
+                      {tCommon("loading")}
                     </>
                   ) : (
-                    "Load More"
+                    t("loadMore")
                   )}
                 </Button>
               </div>
@@ -844,9 +880,9 @@ export function ThreadList({
       >
         <DialogContent className="sm:max-w-md">
           <DialogHeader>
-            <DialogTitle>Rename research</DialogTitle>
+            <DialogTitle>{t("renameDialog.title")}</DialogTitle>
             <DialogDescription>
-              Give this conversation a custom title.
+              {t("renameDialog.description")}
             </DialogDescription>
           </DialogHeader>
           <Input
@@ -859,7 +895,7 @@ export function ThreadList({
                 submitRename();
               }
             }}
-            placeholder="Enter a title…"
+            placeholder={t("renameDialog.placeholder")}
             maxLength={100}
             disabled={actionBusy}
           />
@@ -869,13 +905,13 @@ export function ThreadList({
               onClick={() => setRenameTarget(null)}
               disabled={actionBusy}
             >
-              Cancel
+              {tCommon("cancel")}
             </Button>
             <Button
               onClick={submitRename}
               disabled={actionBusy || !renameValue.trim()}
             >
-              {actionBusy ? "Saving…" : "Save"}
+              {actionBusy ? t("renameDialog.saving") : tCommon("save")}
             </Button>
           </DialogFooter>
         </DialogContent>
@@ -902,10 +938,11 @@ export function ThreadList({
           }}
         >
           <DialogHeader>
-            <DialogTitle>Delete this research?</DialogTitle>
+            <DialogTitle>{t("deleteDialog.title")}</DialogTitle>
             <DialogDescription>
-              “{deleteTarget?.title}” will be permanently deleted. This can’t be
-              undone.
+              {t("deleteDialog.description", {
+                title: deleteTarget?.title ?? "",
+              })}
             </DialogDescription>
           </DialogHeader>
           <DialogFooter>
@@ -914,14 +951,14 @@ export function ThreadList({
               onClick={() => setDeleteTarget(null)}
               disabled={actionBusy}
             >
-              Cancel
+              {tCommon("cancel")}
             </Button>
             <Button
               onClick={confirmDelete}
               disabled={actionBusy}
               className="bg-destructive text-destructive-foreground hover:bg-destructive/90"
             >
-              {actionBusy ? "Deleting…" : "Delete"}
+              {actionBusy ? t("deleteDialog.deleting") : tCommon("delete")}
             </Button>
           </DialogFooter>
         </DialogContent>
diff --git a/src/app/components/ToolApprovalInterrupt.tsx b/src/app/components/ToolApprovalInterrupt.tsx
index 489368a..40ede3e 100644
--- a/src/app/components/ToolApprovalInterrupt.tsx
+++ b/src/app/components/ToolApprovalInterrupt.tsx
@@ -8,6 +8,7 @@ import { AlertCircle, Check, X, Pencil, ShieldCheck } from "lucide-react";
 import type { ActionRequest, ReviewConfig } from "@/app/types/types";
 import { cn } from "@/lib/utils";
 import type { ReviewMode } from "@/lib/reviewMode";
+import { useTranslations } from "next-intl";
 
 interface ToolApprovalInterruptProps {
   actionRequest: ActionRequest;
@@ -48,6 +49,8 @@ export function ToolApprovalInterrupt({
   isLoading,
   onSubmitted,
 }: ToolApprovalInterruptProps) {
+  const t = useTranslations("chat");
+  const tCommon = useTranslations("common");
   const [rejectionMessage, setRejectionMessage] = useState("");
   const [isEditing, setIsEditing] = useState(false);
   const [editedArgs, setEditedArgs] = useState<Record<string, unknown>>({});
@@ -167,7 +170,7 @@ export function ToolApprovalInterrupt({
           aria-hidden="true"
         />
         <span className="text-xs font-semibold uppercase tracking-wider">
-          Approval Required
+          {t("toolApproval.title")}
         </span>
       </div>
 
@@ -182,7 +185,7 @@ export function ToolApprovalInterrupt({
       <div className="mb-4 rounded-sm border border-border bg-background p-3">
         <div className="mb-2">
           <span className="text-xs font-medium uppercase tracking-wider text-muted-foreground">
-            Tool
+            {t("toolApproval.tool")}
           </span>
           <p className="mt-1 font-mono text-sm font-medium text-foreground">
             {actionRequest.name}
@@ -192,7 +195,7 @@ export function ToolApprovalInterrupt({
         {isEditing ? (
           <div>
             <span className="text-xs font-medium uppercase tracking-wider text-muted-foreground">
-              Edit Arguments
+              {t("toolApproval.editArguments")}
             </span>
             <div className="mt-2 space-y-3">
               {Object.entries(actionArgs).map(([key, value]) => (
@@ -224,7 +227,7 @@ export function ToolApprovalInterrupt({
         ) : (
           <div>
             <span className="text-xs font-medium uppercase tracking-wider text-muted-foreground">
-              Arguments
+              {t("toolApproval.arguments")}
             </span>
             <pre className="mt-2 overflow-x-auto whitespace-pre-wrap break-all rounded-sm border border-border bg-muted/40 p-2 font-mono text-xs text-foreground">
               {formatValue(actionArgs)}
@@ -237,12 +240,12 @@ export function ToolApprovalInterrupt({
       {showRejectionInput && !isEditing && (
         <div className="mb-4">
           <label className="mb-2 block text-xs font-medium text-foreground">
-            Rejection Message (optional)
+            {t("toolApproval.rejectionMessage")}
           </label>
           <Textarea
             value={rejectionMessage}
             onChange={(e) => setRejectionMessage(e.target.value)}
-            placeholder="Explain why you're rejecting this action…"
+            placeholder={t("toolApproval.rejectionPlaceholder")}
             className="text-sm"
             rows={2}
             disabled={isLoading}
@@ -261,7 +264,7 @@ export function ToolApprovalInterrupt({
               onClick={cancelEditing}
               disabled={isLoading}
             >
-              Cancel
+              {tCommon("cancel")}
             </Button>
             <Button
               type="button"
@@ -274,7 +277,9 @@ export function ToolApprovalInterrupt({
                 size={14}
                 aria-hidden="true"
               />
-              {isLoading ? "Saving…" : "Save & Approve"}
+              {isLoading
+                ? t("toolApproval.saving")
+                : t("toolApproval.saveApprove")}
             </Button>
           </>
         ) : showRejectionInput ? (
@@ -289,7 +294,7 @@ export function ToolApprovalInterrupt({
               }}
               disabled={isLoading}
             >
-              Cancel
+              {tCommon("cancel")}
             </Button>
             <Button
               type="button"
@@ -298,7 +303,9 @@ export function ToolApprovalInterrupt({
               onClick={handleRejectConfirm}
               disabled={isLoading}
             >
-              {isLoading ? "Rejecting…" : "Confirm Reject"}
+              {isLoading
+                ? t("toolApproval.rejecting")
+                : t("toolApproval.confirmReject")}
             </Button>
           </>
         ) : (
@@ -316,7 +323,7 @@ export function ToolApprovalInterrupt({
                   size={14}
                   aria-hidden="true"
                 />
-                Reject
+                {t("toolApproval.reject")}
               </Button>
             )}
             {allowedDecisions.includes("edit") && (
@@ -331,7 +338,7 @@ export function ToolApprovalInterrupt({
                   size={14}
                   aria-hidden="true"
                 />
-                Edit
+                {t("toolApproval.edit")}
               </Button>
             )}
             {allowedDecisions.includes("approve") && (
@@ -350,7 +357,9 @@ export function ToolApprovalInterrupt({
                     size={14}
                     aria-hidden="true"
                   />
-                  {isLoading ? "Approving…" : "Approve once"}
+                  {isLoading
+                    ? t("toolApproval.approving")
+                    : t("toolApproval.approveOnce")}
                 </Button>
                 <Button
                   type="button"
@@ -364,7 +373,7 @@ export function ToolApprovalInterrupt({
                     size={14}
                     aria-hidden="true"
                   />
-                  Auto-approve this chat
+                  {t("toolApproval.approveAuto")}
                 </Button>
               </>
             )}
diff --git a/src/app/components/ToolCallBox.tsx b/src/app/components/ToolCallBox.tsx
index 9636c13..f09f4bb 100644
--- a/src/app/components/ToolCallBox.tsx
+++ b/src/app/components/ToolCallBox.tsx
@@ -21,7 +21,9 @@ import { ToolCall, ActionRequest, ReviewConfig } from "@/app/types/types";
 import { cn } from "@/lib/utils";
 import { LoadExternalComponent } from "@langchain/langgraph-sdk/react-ui";
 import { ToolApprovalInterrupt } from "@/app/components/ToolApprovalInterrupt";
-import { formatToolLabel, toolArgumentPreview } from "@/lib/toolLabel";
+import { formatToolLabelWith, toolArgumentPreview } from "@/lib/toolLabel";
+import { useToolLabels } from "@/app/hooks/useToolLabels";
+import { useTranslations } from "next-intl";
 import type { ReviewMode } from "@/lib/reviewMode";
 
 // One-line preview of a tool-call argument value, shown next to the key in
@@ -75,6 +77,8 @@ export const ToolCallBox = React.memo<ToolCallBoxProps>(
     autoApprove,
     compact = false,
   }) => {
+    const t = useTranslations("chat");
+    const toolLabels = useToolLabels();
     const [isExpanded, setIsExpanded] = useState(
       () => !!uiComponent || (!!actionRequest && !autoApprove)
     );
@@ -126,7 +130,7 @@ export const ToolCallBox = React.memo<ToolCallBoxProps>(
       // args view, so Object.keys/entries never run on a string.
       const rawArgs: unknown = toolCall.args;
       return {
-        name: formatToolLabel(toolCall.name, rawArgs),
+        name: formatToolLabelWith(toolLabels, toolCall.name, rawArgs),
         argumentPreview: toolArgumentPreview(toolCall.name, rawArgs),
         args:
           rawArgs && typeof rawArgs === "object"
@@ -135,7 +139,7 @@ export const ToolCallBox = React.memo<ToolCallBoxProps>(
         result: toolCall.result,
         status: toolCall.status || "completed",
       };
-    }, [toolCall]);
+    }, [toolCall, toolLabels]);
 
     const statusIcon = useMemo(() => {
       switch (status) {
@@ -256,7 +260,7 @@ export const ToolCallBox = React.memo<ToolCallBoxProps>(
                   stream={stream}
                   message={uiComponent}
                   namespace={graphId}
-                  meta={{ status, args, result: result ?? "No Result Yet" }}
+                  meta={{ status, args, result: result ?? t("toolCall.noResultYet") }}
                 />
               </div>
             ) : showApproval ? (
@@ -281,7 +285,7 @@ export const ToolCallBox = React.memo<ToolCallBoxProps>(
                 {Object.keys(args).length > 0 && (
                   <div className={cn("mt-4", compact && "mt-2")}>
                     <h4 className="mb-1 text-xs font-semibold uppercase tracking-wider text-muted-foreground">
-                      Arguments
+                      {t("toolCall.arguments")}
                     </h4>
                     <div className="space-y-2">
                       {Object.entries(args).map(([key, value]) => {
@@ -354,7 +358,7 @@ export const ToolCallBox = React.memo<ToolCallBoxProps>(
                 {hasResult && (
                   <div className={cn("mt-4", compact && "mt-2")}>
                     <h4 className="mb-1 text-xs font-semibold uppercase tracking-wider text-muted-foreground">
-                      Result
+                      {t("toolCall.result")}
                     </h4>
                     <pre
                       className={cn(
diff --git a/src/app/hooks/useChat.ts b/src/app/hooks/useChat.ts
index ec7ce23..a031ffa 100644
--- a/src/app/hooks/useChat.ts
+++ b/src/app/hooks/useChat.ts
@@ -12,6 +12,7 @@ import {
 } from "@/lib/contextUsage";
 import { findActiveTurnId } from "@/lib/usageTurn";
 import { errorToast } from "@/lib/errorReporter";
+import { useTranslations } from "next-intl";
 import type { ModelRef, ThreadModelSelection } from "@/lib/modelRegistry";
 import { setThreadModelSelection, setThreadRunning } from "@/app/hooks/useThreads";
 import {
@@ -228,7 +229,7 @@ function latestTaskInterrupt(
 // `message`, JSON-of-`.error`, the raw string, finally a generic fallback.
 // Capped at 300 chars so a giant stack trace doesn't blow up the toast; the
 // full text is still available in the thread JSON via the export affordance.
-function formatStreamError(error: unknown): string {
+function formatStreamError(error: unknown): string | null {
   const cap = (s: string) => (s.length > 300 ? s.slice(0, 297) + "..." : s);
   if (typeof error === "string" && error.trim()) return cap(error.trim());
   if (error && typeof error === "object") {
@@ -249,7 +250,8 @@ function formatStreamError(error: unknown): string {
     const combined = name && body ? `${name}: ${body}` : name ?? body ?? "";
     if (combined) return cap(combined);
   }
-  return "Run failed.";
+  // Caller supplies the localized generic fallback.
+  return null;
 }
 
 // Stable empty fallbacks. Returning `?? []` / `?? {}` inline produces a NEW
@@ -281,6 +283,7 @@ export function useChat({
   onHistoryRevalidate?: () => void;
 }) {
   const [threadId, setThreadId] = useQueryState("threadId");
+  const t = useTranslations("chat");
   void activeAssistant;
   const [runConnection, setRunConnection] = useState<RunConnection | null>(
     null
@@ -297,17 +300,20 @@ export function useChat({
   const stoppedRunIdsRef = useRef(new Set<string>());
   const submittingRef = useRef(false);
 
-  const showError = useCallback((error: unknown, key: string) => {
-    const message = formatStreamError(error);
-    const now = Date.now();
-    if (
-      lastErrorToastRef.current?.key !== `${key}:${message}` ||
-      now - lastErrorToastRef.current.at > 10_000
-    ) {
-      lastErrorToastRef.current = { key: `${key}:${message}`, at: now };
-      errorToast("chat", message);
-    }
-  }, []);
+  const showError = useCallback(
+    (error: unknown, key: string) => {
+      const message = formatStreamError(error) ?? t("runFailed");
+      const now = Date.now();
+      if (
+        lastErrorToastRef.current?.key !== `${key}:${message}` ||
+        now - lastErrorToastRef.current.at > 10_000
+      ) {
+        lastErrorToastRef.current = { key: `${key}:${message}`, at: now };
+        errorToast("chat", message);
+      }
+    },
+    [t]
+  );
 
   const isRunLoading = isSubmitting || runConnection !== null;
   const isReconnecting = runConnection?.phase === "reconnecting";
@@ -422,10 +428,10 @@ export function useChat({
     let cancelled = false;
     void (async () => {
       try {
-        const { thread: t } = await getConversation(threadId);
+        const { thread } = await getConversation(threadId);
         if (cancelled) return;
         const stored = readSelectionFromMetadata(
-          (t.metadata ?? {}) as Record<string, unknown>
+          (thread.metadata ?? {}) as Record<string, unknown>
         );
         setModelSelectionState(stored.selection);
         setSelectionRevision(stored.revision);
@@ -437,17 +443,14 @@ export function useChat({
           activeRunRef.current = null;
           setRunConnection(null);
           void setThreadId(null);
-          errorToast(
-            "chat.conversation",
-            "Conversation is no longer available. Started a new chat."
-          );
+          errorToast("chat.conversation", t("conversationUnavailable"));
         }
       }
     })();
     return () => {
       cancelled = true;
     };
-  }, [setThreadId, threadId]);
+  }, [setThreadId, t, threadId]);
 
   // Persist + apply locally. Pre-thread (new chat with no threadId yet),
   // stashes the pick in a ref so the thread-id effect can persist it as soon
diff --git a/src/app/hooks/useToolLabels.ts b/src/app/hooks/useToolLabels.ts
new file mode 100644
index 0000000..96180ae
--- /dev/null
+++ b/src/app/hooks/useToolLabels.ts
@@ -0,0 +1,27 @@
+"use client";
+
+import { useTranslations } from "next-intl";
+import type { ToolLabelStrings } from "@/lib/toolLabel";
+
+/**
+ * Locale-aware tool labels for `formatToolLabelWith`. Tool labels are rendered
+ * inside ToolCallBox / ActionGroup headers, so they follow the chat domain.
+ */
+export function useToolLabels(): ToolLabelStrings {
+  const t = useTranslations("chat.toolLabels");
+  return {
+    unknownTool: t("unknownTool"),
+    adaptiveToolSelection: t("adaptiveToolSelection"),
+    reflection: t("reflection"),
+    readingMemory: t("readingMemory"),
+    updatingMemory: t("updatingMemory"),
+    skill: (name) => t("skill", { name }),
+    execute: t("execute"),
+    grep: t("grep"),
+    readFile: t("readFile"),
+    writeFile: t("writeFile"),
+    editFile: t("editFile"),
+    listFiles: t("listFiles"),
+    task: t("task"),
+  };
+}
diff --git a/src/i18n/messages/en/chat.ts b/src/i18n/messages/en/chat.ts
index 5c34883..dbe6d3f 100644
--- a/src/i18n/messages/en/chat.ts
+++ b/src/i18n/messages/en/chat.ts
@@ -1,3 +1,253 @@
 export default {
-  chat: {},
+  chat: {
+    send: "Send",
+    sendMessage: "Send message",
+    stop: "Stop",
+    stopGenerating: "Stop generating",
+    messageInputLabel: "Message",
+    placeholderDefault: "Ask EvoScientist anything…",
+    placeholderQueueFollowUp: "Queue a follow-up — sends when this turn finishes…",
+    placeholderReconnecting: "Reconnecting to the running task…",
+    placeholderRespondToInterrupt: "Respond to the request above to continue…",
+    emptyStateTitle: "Where research evolves",
+    emptyStateSubtitle:
+      "Your self-evolving lab partner — reads the literature, runs experiments, and remembers what matters.",
+    suggestedSurvey: "Survey recent papers on a topic",
+    suggestedExperiment: "Design an experiment plan",
+    suggestedFiles: "Analyze workspace files",
+    editMessage: "Edit message",
+    thinkingTimer: "Thinking…",
+    runFailed: "Run failed.",
+    conversationUnavailable:
+      "Conversation is no longer available. Started a new chat.",
+    upload: {
+      aria: "Upload files to workspace",
+      title: "Upload files to workspace (max 50 MB each)",
+      failed: "Failed to upload files.",
+      uploaded:
+        "{count, plural, one {# file uploaded to the workspace.} other {# files uploaded to the workspace.}}",
+      attachedFiles: "Attached files",
+      removeAttachment: "Remove {name} from this message",
+    },
+    reviewMode: {
+      label: "Review mode",
+      manual: {
+        label: "Manual review",
+        description: "Approve each tool action before it runs.",
+      },
+      auto: {
+        label: "Auto-approve",
+        description:
+          "Approve tool actions automatically; questions can still pause.",
+      },
+      full: {
+        label: "Full approve",
+        description:
+          "Approve tool actions automatically and continue without questions.",
+      },
+      autoEnabled: "Auto-approve enabled for this chat.",
+      manualEnabled: "Manual review enabled for this chat.",
+      fullEnabled: "Full approve enabled for this chat.",
+      fullApprove: {
+        title: "Enable Full approve?",
+        description:
+          "EvoScientist will approve reviewed tool actions automatically and will not pause to ask you for clarification.",
+        warning:
+          "When details are missing, the model will make reasonable, conservative assumptions and continue. This setting applies only to the current research.",
+        confirm: "Enable Full approve",
+      },
+    },
+    modelPicker: {
+      title: "Choose model",
+      description:
+        "Saved for this chat; the next message freezes it into the run’s snapshot.",
+      current: "Current:",
+      currentDefault: "{model} · default",
+      registryDefault: "registry default",
+      loadingModels: "loading models…",
+      unavailable: "The deployment’s selectable model list didn’t load",
+      filterPlaceholder: "Filter by name or provider…",
+      noMatch: "No models match “{query}”.",
+      noneEnabled: "No models are enabled.",
+      setSuccess: "Model set to {model}.",
+      resetSuccess: "Model reset to the registry default.",
+      updateFailed: "Couldn’t update model: {message}",
+      updateFailedGeneric: "Couldn’t update model — try again.",
+      resetFailed: "Couldn’t reset model: {message}",
+      resetFailedGeneric: "Couldn’t reset model — try again.",
+      resetToDefault: "Reset to default",
+      changeTitle: "Click to change model for this chat",
+      changeAria: "Change model for this chat",
+    },
+    reasoning: {
+      aria: "Reasoning effort",
+      title: "Reasoning effort for the primary model",
+      titleDisabled: "Pick a model to override the registry-configured effort",
+      auto: "auto",
+      low: "low",
+      medium: "medium",
+      high: "high",
+      reset: "Reasoning effort back to the registry default.",
+      set: "Reasoning effort set to {effort}.",
+      failed: "Couldn’t update reasoning effort: {message}",
+      failedGeneric: "Couldn’t update reasoning effort — try again.",
+    },
+    sampling: {
+      aria: "Sampling override",
+      title: "Sampling override: temperature and top_p are mutually exclusive",
+      titleDisabled:
+        "Pick a model to override the registry-configured sampling",
+      modeDefault: "Default",
+      temperature: "Temperature",
+      topP: "Top P",
+      unset: "unset",
+      exactValue: "{label} exact value",
+      clickToType: "Click to type an exact {label} value",
+      sliderTitleDisabled:
+        "Pick a model to override the registry-configured {label}",
+      sliderTitleDefault:
+        "{label}: registry default {value} — drag to override or click the value to type one",
+      sliderTitleOverride:
+        "{label} override — click the value to type an exact one; empty + Enter resets",
+      reset: "Sampling back to the registry default.",
+      temperatureSet: "Temperature set to {value} (top_p omitted).",
+      topPSet: "Top P set to {value} (temperature omitted).",
+      failed: "Couldn’t update sampling: {message}",
+      failedGeneric: "Couldn’t update sampling — try again.",
+    },
+    usage: {
+      tokensLoading: "Tokens loading",
+      tokensUnavailable: "Tokens unavailable",
+      tokensLabel: "{count} tokens",
+      viewAria: "View token usage: {label}",
+    },
+    agents: {
+      runningTitle:
+        "{count, plural, one {# background agent running — click to view} other {# background agents running — click to view}}",
+      runningAria:
+        "{count, plural, one {# background agent running — view} other {# background agents running — view}}",
+      runningLabel: "{count, plural, one {# agent} other {# agents}}",
+      autoReported: "Auto-reported {agent} to the main chat.",
+    },
+    queue: {
+      label: "Queued messages",
+      filesAttached: "{count, plural, one {# file} other {# files}}",
+      reorderAria: "Reorder queued message {index} of {total}",
+      reorderTitle: "Drag to reorder, or use the arrow keys",
+      steerAria: "Steer with this message next",
+      steerTitle: "Submit next without interrupting the current turn",
+      steer: "Steer",
+      steerToast: "This message will run next without interrupting the current turn.",
+      removeAria: "Remove queued message",
+      removeTitle: "Remove from queue",
+      moreAria: "More queued message actions",
+      moreTitle: "More actions",
+      closeQueue: "Close queue",
+    },
+    tasks: {
+      allCompleted: "All tasks completed",
+      progress: "Task {current} of {total}",
+      filesState: "Files (State)",
+      tasks: "Tasks",
+      pending: "Pending",
+      inProgress: "In Progress",
+      completed: "Completed",
+    },
+    workspace: {
+      files: "Files",
+      openFiles: "Open conversation files",
+      closeFiles: "Close conversation files",
+    },
+    message: {
+      copy: "Copy message",
+      copied: "Copied",
+      copyFailed: "Couldn’t copy to clipboard.",
+      thinking: "Thinking",
+      backgroundAgentReported: "Background agent reported back",
+    },
+    subAgent: {
+      badge: "subagent",
+      input: "Input",
+      steps: "Steps",
+      output: "Output",
+    },
+    toolCall: {
+      arguments: "Arguments",
+      result: "Result",
+      noResultYet: "No Result Yet",
+    },
+    toolApproval: {
+      title: "Approval Required",
+      tool: "Tool",
+      editArguments: "Edit Arguments",
+      arguments: "Arguments",
+      rejectionMessage: "Rejection Message (optional)",
+      rejectionPlaceholder: "Explain why you’re rejecting this action…",
+      saveApprove: "Save & Approve",
+      saving: "Saving…",
+      confirmReject: "Confirm Reject",
+      rejecting: "Rejecting…",
+      reject: "Reject",
+      edit: "Edit",
+      approveOnce: "Approve once",
+      approving: "Approving…",
+      approveAuto: "Auto-approve this chat",
+    },
+    askUser: {
+      title: "EvoScientist Needs Your Input",
+      other: "Other…",
+      answerPlaceholder: "Type your answer…",
+      answerPlaceholderOptional: "Type your answer… (optional)",
+      submit: "Submit",
+      submitting: "Submitting…",
+    },
+    compaction: {
+      title: "Conversation compacted",
+      summarized:
+        "{count, plural, one {# earlier message summarized} other {# earlier messages summarized}}",
+      tokenStats: "≈{before} → ≈{after} tokens",
+      detailsWithoutBudget:
+        "Prompt size (estimate): ≈{before} tokens before compaction, ≈{after} after. Exact usage appears in token consumption once the next model call completes.",
+      detailsWithBudget:
+        "Prompt size (estimate): ≈{before} tokens before compaction, ≈{after} after · hard message budget ≈{budget} tokens. Exact usage appears in token consumption once the next model call completes.",
+    },
+    actionGroup: {
+      ariaLabel: "Assistant work process",
+      working: "Working",
+      approvalRequired: "Approval required",
+      failed:
+        "{failed} of {total, plural, one {# action} other {# actions}} failed",
+      workingWithCount:
+        "Working · {total, plural, one {# action} other {# actions}}",
+      completed:
+        "{total, plural, one {# action} other {# actions}} completed",
+      collapse: "Collapse",
+      collapseCount:
+        "Collapse {total, plural, one {# action} other {# actions}}",
+      collapseGroup: "Collapse {summary}",
+      expandGroup: "Expand {summary}",
+    },
+    contextUsage: {
+      label: "ctx {percent}% · {used}/{limit}",
+      tooltipMeasured:
+        "Last model call used {used} of {limit} tokens (measured) · auto-compact messages at ≈{soft}.",
+      tooltipEstimate:
+        "Context used (estimate): {used} of {limit} tokens · auto-compact messages at ≈{soft}.",
+    },
+    toolLabels: {
+      unknownTool: "Unknown Tool",
+      adaptiveToolSelection: "Adaptive tool selection",
+      reflection: "Reflection",
+      readingMemory: "Reading memory",
+      updatingMemory: "Updating memory",
+      skill: "Skill: {name}",
+      execute: "Running command",
+      grep: "Searching files",
+      readFile: "Reading file",
+      writeFile: "Writing file",
+      editFile: "Editing file",
+      listFiles: "Listing files",
+      task: "Running subagent",
+    },
+  },
 };
diff --git a/src/i18n/messages/en/threadList.ts b/src/i18n/messages/en/threadList.ts
index b4e882c..f906017 100644
--- a/src/i18n/messages/en/threadList.ts
+++ b/src/i18n/messages/en/threadList.ts
@@ -1,3 +1,64 @@
 export default {
-  threadList: {},
+  threadList: {
+    newChat: "New Chat",
+    researchSkills: "Research Skills",
+    evoMemory: "EvoMemory",
+    memoryUpdatesTitle:
+      "{count, plural, one {# memory file updated since you last looked} other {# memory files updated since you last looked}}",
+    memoryUpdatesAria:
+      "{count, plural, one {# memory update} other {# memory updates}}",
+    scheduled: "Scheduled",
+    searchPlaceholder: "Search research…",
+    searchAria: "Search research",
+    clearSearch: "Clear research search",
+    recents: "Recents",
+    filterAll: "All",
+    filterActive: "Active",
+    filterIdle: "Idle",
+    filterBusy: "Busy",
+    filterAttention: "Attention",
+    filterInterrupted: "Interrupted",
+    filterError: "Error",
+    closeNavigation: "Close navigation",
+    closeResearch: "Close research",
+    loadFailed: "Failed to load research",
+    empty: "No research yet",
+    noMatch: "No research matches your search.",
+    pinnedSection: "Research",
+    groups: {
+      requiringAttention: "Requiring Attention",
+      today: "Today",
+      yesterday: "Yesterday",
+      thisWeek: "This Week",
+      older: "Older",
+    },
+    loadMore: "Load More",
+    unknownTime: "Unknown time",
+    pin: "Pin",
+    unpin: "Unpin",
+    pinAria: "Pin “{title}”",
+    unpinAria: "Unpin “{title}”",
+    rename: "Rename",
+    renameAria: "Rename “{title}”",
+    exportJson: "Export JSON",
+    exportAria: "Export “{title}” as JSON",
+    deleteAria: "Delete “{title}”",
+    renameDialog: {
+      title: "Rename research",
+      description: "Give this conversation a custom title.",
+      placeholder: "Enter a title…",
+      saving: "Saving…",
+    },
+    deleteDialog: {
+      title: "Delete this research?",
+      description:
+        "“{title}” will be permanently deleted. This can’t be undone.",
+      deleting: "Deleting…",
+    },
+    renameFailed: "Couldn’t rename — try again.",
+    deleteFailed: "Couldn’t delete — try again.",
+    pinFailed: "Couldn’t pin — try again.",
+    unpinFailed: "Couldn’t unpin — try again.",
+    exportFailed: "Couldn’t export — try again.",
+  },
 };
diff --git a/src/i18n/messages/zh/chat.ts b/src/i18n/messages/zh/chat.ts
index 5c34883..50ff808 100644
--- a/src/i18n/messages/zh/chat.ts
+++ b/src/i18n/messages/zh/chat.ts
@@ -1,3 +1,240 @@
 export default {
-  chat: {},
+  chat: {
+    send: "发送",
+    sendMessage: "发送消息",
+    stop: "停止",
+    stopGenerating: "停止生成",
+    messageInputLabel: "消息",
+    placeholderDefault: "向 EvoScientist 提问…",
+    placeholderQueueFollowUp: "排队一条追问 —— 本轮结束后自动发送…",
+    placeholderReconnecting: "正在重新连接运行中的任务…",
+    placeholderRespondToInterrupt: "请先回应上方的请求以继续…",
+    emptyStateTitle: "让研究持续进化",
+    emptyStateSubtitle:
+      "你的自我进化实验室伙伴 —— 阅读文献、运行实验，并记住关键内容。",
+    suggestedSurvey: "调研某主题的最新论文",
+    suggestedExperiment: "设计实验方案",
+    suggestedFiles: "分析工作区文件",
+    editMessage: "编辑消息",
+    thinkingTimer: "思考中…",
+    runFailed: "运行失败。",
+    conversationUnavailable: "对话已不可用，已开启新对话。",
+    upload: {
+      aria: "上传文件到工作区",
+      title: "上传文件到工作区（单个文件最大 50 MB）",
+      failed: "文件上传失败。",
+      uploaded: "{count, plural, other {已将 # 个文件上传到工作区。}}",
+      attachedFiles: "已附加的文件",
+      removeAttachment: "将 {name} 从这条消息中移除",
+    },
+    reviewMode: {
+      label: "审核模式",
+      manual: {
+        label: "手动审核",
+        description: "每个工具操作运行前都需要你批准。",
+      },
+      auto: {
+        label: "自动批准",
+        description: "自动批准工具操作；提问仍会暂停。",
+      },
+      full: {
+        label: "完全批准",
+        description: "自动批准工具操作，且不再因提问而暂停。",
+      },
+      autoEnabled: "已为此对话启用自动批准。",
+      manualEnabled: "已为此对话启用手动审核。",
+      fullEnabled: "已为此对话启用完全批准。",
+      fullApprove: {
+        title: "启用完全批准？",
+        description:
+          "EvoScientist 将自动批准需要审核的工具操作，并且不会暂停来向你求证。",
+        warning:
+          "当细节缺失时，模型将做出合理、保守的假设并继续执行。此设置仅应用于当前研究。",
+        confirm: "启用完全批准",
+      },
+    },
+    modelPicker: {
+      title: "选择模型",
+      description: "为此对话保存；下一条消息会将其冻结到运行的快照中。",
+      current: "当前：",
+      currentDefault: "{model} · 默认",
+      registryDefault: "注册表默认",
+      loadingModels: "正在加载模型…",
+      unavailable: "此部署的可用模型列表未能加载",
+      filterPlaceholder: "按名称或服务商筛选…",
+      noMatch: "没有匹配“{query}”的模型。",
+      noneEnabled: "没有已启用的模型。",
+      setSuccess: "模型已设置为 {model}。",
+      resetSuccess: "模型已重置为注册表默认。",
+      updateFailed: "无法更新模型：{message}",
+      updateFailedGeneric: "无法更新模型 —— 请重试。",
+      resetFailed: "无法重置模型：{message}",
+      resetFailedGeneric: "无法重置模型 —— 请重试。",
+      resetToDefault: "重置为默认",
+      changeTitle: "点击更换此对话的模型",
+      changeAria: "更换此对话的模型",
+    },
+    reasoning: {
+      aria: "推理强度",
+      title: "主模型的推理强度",
+      titleDisabled: "先选择模型，才能覆盖注册表配置的推理强度",
+      auto: "自动",
+      low: "低",
+      medium: "中",
+      high: "高",
+      reset: "推理强度已恢复为注册表默认。",
+      set: "推理强度已设置为 {effort}。",
+      failed: "无法更新推理强度：{message}",
+      failedGeneric: "无法更新推理强度 —— 请重试。",
+    },
+    sampling: {
+      aria: "采样覆盖",
+      title: "采样覆盖：temperature 和 top_p 互斥",
+      titleDisabled: "先选择模型，才能覆盖注册表配置的采样",
+      modeDefault: "默认",
+      temperature: "温度",
+      topP: "Top P",
+      unset: "未设置",
+      exactValue: "{label} 精确值",
+      clickToType: "点击数值以输入精确的 {label}",
+      sliderTitleDisabled: "先选择模型，才能覆盖注册表配置的 {label}",
+      sliderTitleDefault:
+        "{label}：注册表默认 {value} —— 拖动以覆盖，或点击数值直接输入",
+      sliderTitleOverride:
+        "{label} 覆盖 —— 点击数值可输入精确值；清空后回车重置",
+      reset: "采样已恢复为注册表默认。",
+      temperatureSet: "温度已设置为 {value}（top_p 已省略）。",
+      topPSet: "Top P 已设置为 {value}（temperature 已省略）。",
+      failed: "无法更新采样：{message}",
+      failedGeneric: "无法更新采样 —— 请重试。",
+    },
+    usage: {
+      tokensLoading: "Token 加载中",
+      tokensUnavailable: "Token 不可用",
+      tokensLabel: "{count} tokens",
+      viewAria: "查看 token 用量：{label}",
+    },
+    agents: {
+      runningTitle:
+        "{count, plural, other {# 个后台代理正在运行 —— 点击查看}}",
+      runningAria: "{count, plural, other {# 个后台代理正在运行 —— 查看}}",
+      runningLabel: "{count, plural, other {# 个代理}}",
+      autoReported: "已将 {agent} 自动回报给主对话。",
+    },
+    queue: {
+      label: "排队消息",
+      filesAttached: "{count, plural, other {# 个文件}}",
+      reorderAria: "调整第 {index} 条（共 {total} 条）排队消息的顺序",
+      reorderTitle: "拖拽排序，或使用方向键",
+      steerAria: "用这条消息优先引导",
+      steerTitle: "下一条优先发送，不打断当前回合",
+      steer: "引导",
+      steerToast: "这条消息将在当前回合结束后优先执行。",
+      removeAria: "移除排队消息",
+      removeTitle: "从队列中移除",
+      moreAria: "更多排队消息操作",
+      moreTitle: "更多操作",
+      closeQueue: "关闭队列",
+    },
+    tasks: {
+      allCompleted: "所有任务已完成",
+      progress: "任务 {current} / {total}",
+      filesState: "文件（状态）",
+      tasks: "任务",
+      pending: "待处理",
+      inProgress: "进行中",
+      completed: "已完成",
+    },
+    workspace: {
+      files: "文件",
+      openFiles: "打开对话文件",
+      closeFiles: "关闭对话文件",
+    },
+    message: {
+      copy: "复制消息",
+      copied: "已复制",
+      copyFailed: "无法复制到剪贴板。",
+      thinking: "思考",
+      backgroundAgentReported: "后台代理已回报",
+    },
+    subAgent: {
+      badge: "子代理",
+      input: "输入",
+      steps: "步骤",
+      output: "输出",
+    },
+    toolCall: {
+      arguments: "参数",
+      result: "结果",
+      noResultYet: "暂无结果",
+    },
+    toolApproval: {
+      title: "需要批准",
+      tool: "工具",
+      editArguments: "编辑参数",
+      arguments: "参数",
+      rejectionMessage: "拒绝理由（可选）",
+      rejectionPlaceholder: "说明拒绝此操作的原因…",
+      saveApprove: "保存并批准",
+      saving: "保存中…",
+      confirmReject: "确认拒绝",
+      rejecting: "拒绝中…",
+      reject: "拒绝",
+      edit: "编辑",
+      approveOnce: "仅批准此次",
+      approving: "批准中…",
+      approveAuto: "自动批准此对话",
+    },
+    askUser: {
+      title: "EvoScientist 需要你的输入",
+      other: "其他…",
+      answerPlaceholder: "输入你的回答…",
+      answerPlaceholderOptional: "输入你的回答…（可选）",
+      submit: "提交",
+      submitting: "提交中…",
+    },
+    compaction: {
+      title: "对话已压缩",
+      summarized: "{count, plural, other {已总结 # 条较早消息}}",
+      tokenStats: "≈{before} → ≈{after} tokens",
+      detailsWithoutBudget:
+        "提示词大小（估算）：压缩前 ≈{before} tokens，压缩后 ≈{after} tokens。下一次模型调用完成后，确切用量会显示在 token 消耗中。",
+      detailsWithBudget:
+        "提示词大小（估算）：压缩前 ≈{before} tokens，压缩后 ≈{after} tokens · 硬消息预算 ≈{budget} tokens。下一次模型调用完成后，确切用量会显示在 token 消耗中。",
+    },
+    actionGroup: {
+      ariaLabel: "助手工作过程",
+      working: "执行中",
+      approvalRequired: "需要批准",
+      failed: "{total} 项操作中有 {failed} 项失败",
+      workingWithCount: "执行中 · {total} 项操作",
+      completed: "{total} 项操作已完成",
+      collapse: "收起",
+      collapseCount: "收起 {total} 项操作",
+      collapseGroup: "收起 {summary}",
+      expandGroup: "展开 {summary}",
+    },
+    contextUsage: {
+      label: "ctx {percent}% · {used}/{limit}",
+      tooltipMeasured:
+        "上次模型调用使用了 {limit} 中的 {used} tokens（实测）· 约 {soft} 时自动压缩消息。",
+      tooltipEstimate:
+        "上下文占用（估算）：{limit} 中的 {used} tokens · 约 {soft} 时自动压缩消息。",
+    },
+    toolLabels: {
+      unknownTool: "未知工具",
+      adaptiveToolSelection: "自适应工具选择",
+      reflection: "反思",
+      readingMemory: "读取记忆",
+      updatingMemory: "更新记忆",
+      skill: "技能：{name}",
+      execute: "运行命令",
+      grep: "搜索文件",
+      readFile: "读取文件",
+      writeFile: "写入文件",
+      editFile: "编辑文件",
+      listFiles: "列出文件",
+      task: "运行子代理",
+    },
+  },
 };
diff --git a/src/i18n/messages/zh/threadList.ts b/src/i18n/messages/zh/threadList.ts
index b4e882c..0cdfcb9 100644
--- a/src/i18n/messages/zh/threadList.ts
+++ b/src/i18n/messages/zh/threadList.ts
@@ -1,3 +1,62 @@
 export default {
-  threadList: {},
+  threadList: {
+    newChat: "新对话",
+    researchSkills: "研究技能",
+    evoMemory: "EvoMemory",
+    memoryUpdatesTitle:
+      "{count, plural, other {自上次查看以来有 # 个记忆文件更新}}",
+    memoryUpdatesAria: "{count, plural, other {# 条记忆更新}}",
+    scheduled: "定时任务",
+    searchPlaceholder: "搜索研究…",
+    searchAria: "搜索研究",
+    clearSearch: "清除研究搜索",
+    recents: "最近",
+    filterAll: "全部",
+    filterActive: "活跃",
+    filterIdle: "空闲",
+    filterBusy: "忙碌",
+    filterAttention: "需要注意",
+    filterInterrupted: "已中断",
+    filterError: "错误",
+    closeNavigation: "关闭导航",
+    closeResearch: "关闭研究",
+    loadFailed: "加载研究失败",
+    empty: "暂无研究",
+    noMatch: "没有匹配搜索的研究。",
+    pinnedSection: "研究",
+    groups: {
+      requiringAttention: "需要注意",
+      today: "今天",
+      yesterday: "昨天",
+      thisWeek: "本周",
+      older: "更早",
+    },
+    loadMore: "加载更多",
+    unknownTime: "未知时间",
+    pin: "置顶",
+    unpin: "取消置顶",
+    pinAria: "置顶“{title}”",
+    unpinAria: "取消置顶“{title}”",
+    rename: "重命名",
+    renameAria: "重命名“{title}”",
+    exportJson: "导出 JSON",
+    exportAria: "将“{title}”导出为 JSON",
+    deleteAria: "删除“{title}”",
+    renameDialog: {
+      title: "重命名研究",
+      description: "为这个对话设置自定义标题。",
+      placeholder: "输入标题…",
+      saving: "保存中…",
+    },
+    deleteDialog: {
+      title: "删除这项研究？",
+      description: "“{title}” 将被永久删除，此操作无法撤销。",
+      deleting: "删除中…",
+    },
+    renameFailed: "无法重命名 —— 请重试。",
+    deleteFailed: "无法删除 —— 请重试。",
+    pinFailed: "无法置顶 —— 请重试。",
+    unpinFailed: "无法取消置顶 —— 请重试。",
+    exportFailed: "无法导出 —— 请重试。",
+  },
 };
diff --git a/src/lib/toolLabel.ts b/src/lib/toolLabel.ts
index 4dcc299..dc43b0d 100644
--- a/src/lib/toolLabel.ts
+++ b/src/lib/toolLabel.ts
@@ -41,15 +41,54 @@ function asArgsObject(args: unknown): Record<string, unknown> {
   return {};
 }
 
-export function formatToolLabel(name: string, args?: unknown): string {
-  if (!name) return "Unknown Tool";
+/** Translated strings for {@link formatToolLabelWith}; matches the
+ *  `chat.toolLabels.*` catalog keys. */
+export interface ToolLabelStrings {
+  unknownTool: string;
+  adaptiveToolSelection: string;
+  reflection: string;
+  readingMemory: string;
+  updatingMemory: string;
+  /** Skill label; `{name}` is the skill directory name. */
+  skill: (name: string) => string;
+  execute: string;
+  grep: string;
+  readFile: string;
+  writeFile: string;
+  editFile: string;
+  listFiles: string;
+  task: string;
+}
+
+const EN_TOOL_LABELS: ToolLabelStrings = {
+  unknownTool: "Unknown Tool",
+  adaptiveToolSelection: "Adaptive tool selection",
+  reflection: "Reflection",
+  readingMemory: "Reading memory",
+  updatingMemory: "Updating memory",
+  skill: (name) => `Skill: ${name}`,
+  execute: "Running command",
+  grep: "Searching files",
+  readFile: "Reading file",
+  writeFile: "Writing file",
+  editFile: "Editing file",
+  listFiles: "Listing files",
+  task: "Running subagent",
+};
+
+export function formatToolLabelWith(
+  labels: ToolLabelStrings,
+  name: string,
+  args?: unknown
+): string {
+  if (!name) return labels.unknownTool;
 
   // The tool-selector middleware's internal structured-output call.
-  if (name === "ToolSelectionResponse") return "Adaptive tool selection";
+  if (name === "ToolSelectionResponse") return labels.adaptiveToolSelection;
 
   const nameLower = name.toLowerCase();
 
-  if (nameLower === "think_tool") return "Reflection";
+  if (nameLower === "think_tool") return labels.reflection;
 
   if (
     nameLower === "read_file" ||
@@ -59,30 +98,42 @@ export function formatToolLabel(name: string, args?: unknown): string {
     const a = asArgsObject(args);
     const path = String(a.path ?? a.file_path ?? "");
     if (isMemoryPath(path)) {
-      return nameLower === "read_file" ? "Reading memory" : "Updating memory";
+      return nameLower === "read_file"
+        ? labels.readingMemory
+        : labels.updatingMemory;
     }
     if (nameLower === "read_file") {
       const skill = skillNameFromPath(path);
-      if (skill) return `Skill: ${skill}`;
+      if (skill) return labels.skill(skill);
     }
   }
 
-  const commonLabels: Record<string, string> = {
-    execute: "Running command",
-    grep: "Searching files",
-    read_file: "Reading file",
-    write_file: "Writing file",
-    edit_file: "Editing file",
-    ls: "Listing files",
-    list_files: "Listing files",
-    task: "Running subagent",
-  };
-  if (commonLabels[nameLower]) return commonLabels[nameLower];
+  switch (nameLower) {
+    case "execute":
+      return labels.execute;
+    case "grep":
+      return labels.grep;
+    case "read_file":
+      return labels.readFile;
+    case "write_file":
+      return labels.writeFile;
+    case "edit_file":
+      return labels.editFile;
+    case "ls":
+    case "list_files":
+      return labels.listFiles;
+    case "task":
+      return labels.task;
+  }
 
   // Everything else keeps its raw tool name.
   return name;
 }
 
+export function formatToolLabel(name: string, args?: unknown): string {
+  return formatToolLabelWith(EN_TOOL_LABELS, name, args);
+}
+
 function compactValue(value: unknown): string {
   if (typeof value === "string") return value.replace(/\s+/g, " ").trim();
   if (value === null || value === undefined) return "";