diff --git a/src/app/components/ChatInterface.tsx b/src/app/components/ChatInterface.tsx
index c3691a9..3d5fa1f 100644
--- a/src/app/components/ChatInterface.tsx
+++ b/src/app/components/ChatInterface.tsx
@@ -110,6 +110,19 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
     [handleSubmit, submitDisabled]
   );
 
+  // Pull a previous user message back into the composer to edit/resend it,
+  // placing the cursor at the end so the user can keep typing.
+  const handleEditMessage = useCallback((content: string) => {
+    setInput(content);
+    requestAnimationFrame(() => {
+      const el = textareaRef.current;
+      if (el) {
+        el.focus();
+        el.setSelectionRange(content.length, content.length);
+      }
+    });
+  }, []);
+
   // TODO: can we make this part of the hook?
   const processedMessages = useMemo(() => {
     /*
@@ -253,7 +266,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
         >
           {isThreadLoading ? (
             <div className="flex items-center justify-center p-8">
-              <p className="text-muted-foreground">Loading...</p>
+              <p className="text-muted-foreground">Loading…</p>
             </div>
           ) : (
             <>
@@ -278,6 +291,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
                     stream={stream}
                     onResumeInterrupt={resumeInterrupt}
                     graphId={assistant?.graph_id}
+                    onEditMessage={handleEditMessage}
                   />
                 );
               })}
@@ -290,7 +304,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
         <div
           className={cn(
             "mx-4 mb-6 flex flex-shrink-0 flex-col overflow-hidden rounded-xl border border-border bg-background",
-            "mx-auto w-[calc(100%-32px)] max-w-[1024px] transition-colors duration-200 ease-in-out"
+            "mx-auto w-[calc(100%-32px)] max-w-[1024px] transition-colors duration-200 ease-in-out",
+            "focus-within:ring-2 focus-within:ring-ring"
           )}
         >
           {(hasTasks || hasFiles) && (
@@ -393,7 +408,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
                         >
                           <FileIcon size={16} />
                           Files (State)
-                          <span className="h-4 min-w-4 rounded-full bg-[#2F6868] px-0.5 text-center text-[10px] leading-[16px] text-white">
+                          <span className="h-4 min-w-4 rounded-full bg-[var(--brand)] px-0.5 text-center text-[10px] leading-[16px] text-white">
                             {Object.keys(files).length}
                           </span>
                         </button>
@@ -439,7 +454,7 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
                         aria-expanded={metaOpen === "files"}
                       >
                         Files (State)
-                        <span className="h-4 min-w-4 rounded-full bg-[#2F6868] px-0.5 text-center text-[10px] leading-[16px] text-white">
+                        <span className="h-4 min-w-4 rounded-full bg-[var(--brand)] px-0.5 text-center text-[10px] leading-[16px] text-white">
                           {Object.keys(files).length}
                         </span>
                       </button>
@@ -509,7 +524,8 @@ export const ChatInterface = React.memo<ChatInterfaceProps>(({ assistant }) => {
               value={input}
               onChange={(e) => setInput(e.target.value)}
               onKeyDown={handleKeyDown}
-              placeholder={isLoading ? "Running..." : "Write your message..."}
+              aria-label="Message"
+              placeholder={isLoading ? "Running…" : "Write your message…"}
               className="font-inherit field-sizing-content flex-1 resize-none border-0 bg-transparent px-[18px] pb-[13px] pt-[14px] text-sm leading-7 text-primary outline-none placeholder:text-tertiary"
               rows={1}
             />
diff --git a/src/app/components/ChatMessage.tsx b/src/app/components/ChatMessage.tsx
index 48eadde..a9a8c5b 100644
--- a/src/app/components/ChatMessage.tsx
+++ b/src/app/components/ChatMessage.tsx
@@ -11,6 +11,7 @@ import type {
   ReviewConfig,
 } from "@/app/types/types";
 import { Message } from "@langchain/langgraph-sdk";
+import { Brain, Check, ChevronRight, Copy, Pencil } from "lucide-react";
 import {
   extractSubAgentContent,
   extractStringFromMessageContent,
@@ -27,6 +28,7 @@ interface ChatMessageProps {
   stream?: any;
   onResumeInterrupt?: (value: any) => void;
   graphId?: string;
+  onEditMessage?: (content: string) => void;
 }
 
 export const ChatMessage = React.memo<ChatMessageProps>(
@@ -40,11 +42,19 @@ export const ChatMessage = React.memo<ChatMessageProps>(
     stream,
     onResumeInterrupt,
     graphId,
+    onEditMessage,
   }) => {
     const isUser = message.type === "human";
     const messageContent = extractStringFromMessageContent(message);
     const hasContent = messageContent && messageContent.trim() !== "";
     const hasToolCalls = toolCalls.length > 0;
+    // Extended-thinking / reasoning text (Anthropic & friends store it here).
+    const reasoning = useMemo(() => {
+      const r = (
+        message.additional_kwargs as Record<string, unknown> | undefined
+      )?.reasoning_content;
+      return typeof r === "string" && r.trim() ? r.trim() : null;
+    }, [message.additional_kwargs]);
     const subAgents = useMemo(() => {
       return toolCalls
         .filter((toolCall: ToolCall) => {
@@ -70,6 +80,15 @@ export const ChatMessage = React.memo<ChatMessageProps>(
         });
     }, [toolCalls]);
 
+    const [thinkingOpen, setThinkingOpen] = useState(false);
+    const [copied, setCopied] = useState(false);
+    const handleCopy = useCallback(() => {
+      if (!messageContent) return;
+      navigator.clipboard?.writeText(messageContent).then(() => {
+        setCopied(true);
+        setTimeout(() => setCopied(false), 2000);
+      });
+    }, [messageContent]);
     const [expandedSubAgents, setExpandedSubAgents] = useState<
       Record<string, boolean>
     >({});
@@ -87,7 +106,7 @@ export const ChatMessage = React.memo<ChatMessageProps>(
     return (
       <div
         className={cn(
-          "flex w-full max-w-full overflow-x-hidden",
+          "group flex w-full max-w-full overflow-x-hidden",
           isUser && "flex-row-reverse"
         )}
       >
@@ -97,6 +116,34 @@ export const ChatMessage = React.memo<ChatMessageProps>(
             isUser ? "max-w-[70%]" : "w-full"
           )}
         >
+          {!isUser && reasoning && (
+            <div className="mt-4">
+              <button
+                type="button"
+                onClick={() => setThinkingOpen((v) => !v)}
+                aria-expanded={thinkingOpen}
+                className="flex items-center gap-1.5 text-xs font-medium text-muted-foreground hover:text-foreground"
+              >
+                <ChevronRight
+                  className={cn(
+                    "h-3.5 w-3.5 transition-transform",
+                    thinkingOpen && "rotate-90"
+                  )}
+                  aria-hidden="true"
+                />
+                <Brain
+                  className="h-3.5 w-3.5"
+                  aria-hidden="true"
+                />
+                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">
+                  {reasoning}
+                </div>
+              )}
+            </div>
+          )}
           {hasContent && (
             <div className={cn("relative flex items-end gap-0")}>
               <div
@@ -122,6 +169,61 @@ export const ChatMessage = React.memo<ChatMessageProps>(
               </div>
             </div>
           )}
+          {!isUser && hasContent && (
+            <div className="mt-1">
+              <button
+                type="button"
+                onClick={handleCopy}
+                aria-label={copied ? "Copied" : "Copy message"}
+                className="inline-flex items-center rounded p-1.5 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+              >
+                {copied ? (
+                  <Check
+                    className="h-4 w-4"
+                    aria-hidden="true"
+                  />
+                ) : (
+                  <Copy
+                    className="h-4 w-4"
+                    aria-hidden="true"
+                  />
+                )}
+              </button>
+            </div>
+          )}
+          {isUser && hasContent && (
+            <div className="mt-1 flex justify-end gap-1 opacity-0 transition-opacity focus-within:opacity-100 group-hover:opacity-100">
+              <button
+                type="button"
+                onClick={handleCopy}
+                aria-label={copied ? "Copied" : "Copy message"}
+                className="inline-flex items-center rounded p-1.5 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+              >
+                {copied ? (
+                  <Check
+                    className="h-4 w-4"
+                    aria-hidden="true"
+                  />
+                ) : (
+                  <Copy
+                    className="h-4 w-4"
+                    aria-hidden="true"
+                  />
+                )}
+              </button>
+              <button
+                type="button"
+                onClick={() => onEditMessage?.(messageContent)}
+                aria-label="Edit message"
+                className="inline-flex items-center rounded p-1.5 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+              >
+                <Pencil
+                  className="h-4 w-4"
+                  aria-hidden="true"
+                />
+              </button>
+            </div>
+          )}
           {hasToolCalls && (
             <div className="mt-4 flex w-full flex-col">
               {toolCalls.map((toolCall: ToolCall) => {
diff --git a/src/app/components/ConfigDialog.tsx b/src/app/components/ConfigDialog.tsx
index 04b85f4..41880cc 100644
--- a/src/app/components/ConfigDialog.tsx
+++ b/src/app/components/ConfigDialog.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useState, useEffect } from "react";
+import { useState, useEffect, useRef } from "react";
 import {
   Dialog,
   DialogContent,
@@ -30,21 +30,33 @@ export function ConfigDialog({
   const [deploymentUrl, setDeploymentUrl] = useState(
     initialConfig?.deploymentUrl || "http://127.0.0.1:6174"
   );
+  const [error, setError] = useState<string | null>(null);
+  const inputRef = useRef<HTMLInputElement | null>(null);
 
   useEffect(() => {
-    if (open && initialConfig) {
-      setDeploymentUrl(initialConfig.deploymentUrl);
+    if (open) {
+      setError(null);
+      if (initialConfig) setDeploymentUrl(initialConfig.deploymentUrl);
     }
   }, [open, initialConfig]);
 
   const handleSave = () => {
-    if (!deploymentUrl) {
-      alert("Please enter the deployment URL");
+    const url = deploymentUrl.trim();
+    if (!url) {
+      setError("Enter your deployment URL to continue.");
+      inputRef.current?.focus();
+      return;
+    }
+    try {
+      new URL(url);
+    } catch {
+      setError("Enter a valid URL, e.g. http://127.0.0.1:6174");
+      inputRef.current?.focus();
       return;
     }
 
     onSave({
-      deploymentUrl,
+      deploymentUrl: url,
       // Fixed to the EvoScientist main agent (see DEFAULT_ASSISTANT_ID).
       assistantId: DEFAULT_ASSISTANT_ID,
     });
@@ -69,11 +81,36 @@ export function ConfigDialog({
           <div className="grid gap-2">
             <Label htmlFor="deploymentUrl">Deployment URL</Label>
             <Input
+              ref={inputRef}
               id="deploymentUrl"
+              name="deploymentUrl"
+              type="url"
+              inputMode="url"
+              autoComplete="off"
+              spellCheck={false}
+              autoFocus
               placeholder="http://127.0.0.1:6174"
               value={deploymentUrl}
-              onChange={(e) => setDeploymentUrl(e.target.value)}
+              onChange={(e) => {
+                setDeploymentUrl(e.target.value);
+                if (error) setError(null);
+              }}
+              onKeyDown={(e) => {
+                if (e.key === "Enter") handleSave();
+              }}
+              aria-invalid={error ? true : undefined}
+              aria-describedby={error ? "deploymentUrl-error" : undefined}
             />
+            {error && (
+              <p
+                id="deploymentUrl-error"
+                role="alert"
+                aria-live="polite"
+                className="text-sm text-destructive"
+              >
+                {error}
+              </p>
+            )}
           </div>
         </div>
         <DialogFooter>
diff --git a/src/app/globals.css b/src/app/globals.css
index 5a3f4bb..409a78e 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -36,6 +36,12 @@
     --color-file-button: #ffffff;
     --color-file-button-hover: #e5e7eb;
 
+    /* Brand accent — single source of truth. Change this to re-theme
+       (e.g. EvoScientist blue) in one place. */
+    --brand: #2f6868;
+    --brand-hover: #275757;
+    --brand-foreground: #ffffff;
+
     /* Dark theme colors */
     --color-primary-dark: #2dd4bf;
     --color-user-message-dark: #076699;
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index e8de5e3..e2ccd98 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -1,4 +1,4 @@
-import type { Metadata } from "next";
+import type { Metadata, Viewport } from "next";
 import { Inter } from "next/font/google";
 import { NuqsAdapter } from "nuqs/adapters/next/app";
 import { Toaster } from "sonner";
@@ -12,6 +12,11 @@ export const metadata: Metadata = {
     "Web UI for EvoScientist — a self-evolving AI scientist built on DeepAgents/LangGraph.",
 };
 
+export const viewport: Viewport = {
+  themeColor: "#f9f9f9",
+  colorScheme: "light",
+};
+
 export default function RootLayout({
   children,
 }: {
diff --git a/src/app/page.tsx b/src/app/page.tsx
index 792f127..64582d4 100644
--- a/src/app/page.tsx
+++ b/src/app/page.tsx
@@ -131,7 +131,10 @@ function HomePageInner({
                 onClick={() => setSidebar("1")}
                 className="rounded-md border border-border bg-card p-3 text-foreground hover:bg-accent"
               >
-                <MessagesSquare className="mr-2 h-4 w-4" />
+                <MessagesSquare
+                  className="mr-2 h-4 w-4"
+                  aria-hidden="true"
+                />
                 Threads
                 {interruptCount > 0 && (
                   <span className="ml-2 inline-flex min-h-4 min-w-4 items-center justify-center rounded-full bg-destructive px-1 text-[10px] text-destructive-foreground">
@@ -151,7 +154,10 @@ function HomePageInner({
               size="sm"
               onClick={() => setConfigDialogOpen(true)}
             >
-              <Settings className="mr-2 h-4 w-4" />
+              <Settings
+                className="mr-2 h-4 w-4"
+                aria-hidden="true"
+              />
               Settings
             </Button>
             <Button
@@ -159,9 +165,12 @@ function HomePageInner({
               size="sm"
               onClick={() => setThreadId(null)}
               disabled={!threadId}
-              className="border-[#2F6868] bg-[#2F6868] text-white hover:bg-[#2F6868]/80"
+              className="border-[var(--brand)] bg-[var(--brand)] text-[var(--brand-foreground)] hover:bg-[var(--brand-hover)]"
             >
-              <SquarePen className="mr-2 h-4 w-4" />
+              <SquarePen
+                className="mr-2 h-4 w-4"
+                aria-hidden="true"
+              />
               New Thread
             </Button>
           </div>
diff --git a/src/lib/config.ts b/src/lib/config.ts
index ea859af..9a5b4e9 100644
--- a/src/lib/config.ts
+++ b/src/lib/config.ts
@@ -19,6 +19,10 @@ export function getConfig(): DeploymentConfig | null {
 
   try {
     const parsed = JSON.parse(stored) as DeploymentConfig;
+    // A stored config with no usable deployment URL would make the SDK send
+    // requests to the app's own origin (404s). Treat it as unconfigured so
+    // the config dialog reappears instead.
+    if (!parsed.deploymentUrl?.trim()) return null;
     // Always pin the assistant to the EvoScientist main agent.
     return { ...parsed, assistantId: DEFAULT_ASSISTANT_ID };
   } catch {