feat: add CLI update check with npm registry indicator

On app start, check the npm registry for the latest
@anthropic-ai/claude-code version and compare against the installed
version. If behind, the CLI badge turns amber with a pulsing up-arrow
and a tooltip advising how to update.

Also bumps SUPPORTED_CLI_VERSION to 2.1.72.

src/lib/components/CliVersion.svelte

@@ -2,9 +2,10 @@
   import { invoke } from "@tauri-apps/api/core";
   import { onMount } from "svelte";
 
-  const SUPPORTED_CLI_VERSION = "2.1.53";
+  const SUPPORTED_CLI_VERSION = "2.1.72";
 
   let installedVersion = $state("Loading...");
+  let latestNpmVersion = $state<string | null>(null);
 
   function compareVersions(a: string, b: string): number {
     const aParts = a.split(".").map(Number);
@@ -32,6 +33,15 @@
     return "current";
   });
 
+  let updateAvailable = $derived.by(() => {
+    if (!latestNpmVersion || installedVersion === "Loading..." || installedVersion === "Unknown") {
+      return false;
+    }
+    const semverMatch = /(\d+\.\d+\.\d+)/.exec(installedVersion);
+    if (!semverMatch) return false;
+    return compareVersions(semverMatch[1], latestNpmVersion) < 0;
+  });
+
   async function fetchVersion() {
     try {
       const result = await invoke<string>("get_claude_version");
@@ -42,13 +52,28 @@
     }
   }
 
+  async function fetchLatestNpmVersion() {
+    try {
+      const result = await invoke<string>("check_cli_latest_version");
+      latestNpmVersion = result;
+    } catch (error) {
+      console.error("Failed to check latest CLI version:", error);
+    }
+  }
+
   onMount(() => {
     fetchVersion();
+    fetchLatestNpmVersion();
   });
 </script>
 
 <div class="cli-versions">
-  <div class="cli-version">
+  <div
+    class="cli-version {updateAvailable ? 'update-available' : ''}"
+    title={updateAvailable
+      ? `Update available: ${latestNpmVersion} — run: npm install -g @anthropic-ai/claude-code`
+      : "Installed CLI version"}
+  >
     <svg
       class="terminal-icon"
       width="14"
@@ -64,6 +89,22 @@
       <line x1="12" y1="19" x2="20" y2="19" />
     </svg>
     <span class="version-text">CLI {displayVersion}</span>
+    {#if updateAvailable}
+      <svg
+        class="update-icon"
+        width="12"
+        height="12"
+        viewBox="0 0 24 24"
+        fill="none"
+        stroke="currentColor"
+        stroke-width="2.5"
+        stroke-linecap="round"
+        stroke-linejoin="round"
+      >
+        <polyline points="17 11 12 6 7 11" />
+        <line x1="12" y1="6" x2="12" y2="18" />
+      </svg>
+    {/if}
   </div>
 
   <div class="cli-version supported {supportedBadgeState}" title="Highest audited CLI version">
@@ -135,6 +176,27 @@
     color: var(--error-color, #f44336);
   }
 
+  .cli-version.update-available {
+    border-color: var(--warning-color, #ff9800);
+    color: var(--warning-color, #ff9800);
+    cursor: help;
+  }
+
+  .update-icon {
+    flex-shrink: 0;
+    animation: pulse 2s ease-in-out infinite;
+  }
+
+  @keyframes pulse {
+    0%,
+    100% {
+      opacity: 1;
+    }
+    50% {
+      opacity: 0.5;
+    }
+  }
+
   .terminal-icon {
     flex-shrink: 0;
     opacity: 0.7;

src/lib/components/CliVersion.test.ts

@@ -19,7 +19,7 @@
 
 import { describe, it, expect } from "vitest";
 
-const SUPPORTED_CLI_VERSION = "2.1.53";
+const SUPPORTED_CLI_VERSION = "2.1.72";
 
 function compareVersions(a: string, b: string): number {
   const aParts = a.split(".").map(Number);
@@ -41,7 +41,7 @@ describe("SUPPORTED_CLI_VERSION", () => {
   });
 
   it("matches the expected audited version", () => {
-    expect(SUPPORTED_CLI_VERSION).toBe("2.1.53");
+    expect(SUPPORTED_CLI_VERSION).toBe("2.1.72");
   });
 });
 
@@ -128,7 +128,55 @@ describe("compareVersions", () => {
     });
 
     it("returns 0 for exactly the supported version", () => {
-      expect(compareVersions("2.1.53", SUPPORTED_CLI_VERSION)).toBe(0);
+      expect(compareVersions("2.1.72", SUPPORTED_CLI_VERSION)).toBe(0);
     });
   });
 });
+
+// Mirrors the updateAvailable derived logic in CliVersion.svelte
+function isUpdateAvailable(installedVersion: string, latestNpmVersion: string | null): boolean {
+  if (!latestNpmVersion || installedVersion === "Loading..." || installedVersion === "Unknown") {
+    return false;
+  }
+  const semverMatch = /(\d+\.\d+\.\d+)/.exec(installedVersion);
+  if (!semverMatch) return false;
+  return compareVersions(semverMatch[1], latestNpmVersion) < 0;
+}
+
+describe("updateAvailable", () => {
+  it("returns false when latestNpmVersion is null", () => {
+    expect(isUpdateAvailable("2.1.70", null)).toBe(false);
+  });
+
+  it("returns false when installed is Loading...", () => {
+    expect(isUpdateAvailable("Loading...", "2.1.72")).toBe(false);
+  });
+
+  it("returns false when installed is Unknown", () => {
+    expect(isUpdateAvailable("Unknown", "2.1.72")).toBe(false);
+  });
+
+  it("returns false when installed equals latest", () => {
+    expect(isUpdateAvailable("2.1.72", "2.1.72")).toBe(false);
+  });
+
+  it("returns false when installed is ahead of latest", () => {
+    expect(isUpdateAvailable("2.1.73", "2.1.72")).toBe(false);
+  });
+
+  it("returns true when installed is behind latest", () => {
+    expect(isUpdateAvailable("2.1.70", "2.1.72")).toBe(true);
+  });
+
+  it("returns true when installed has a lower minor version", () => {
+    expect(isUpdateAvailable("2.0.99", "2.1.72")).toBe(true);
+  });
+
+  it("handles version strings with extra info like '2.1.70 (build 123)'", () => {
+    expect(isUpdateAvailable("2.1.70 (build 123)", "2.1.72")).toBe(true);
+  });
+
+  it("returns false for unparseable installed version", () => {
+    expect(isUpdateAvailable("not-a-version", "2.1.72")).toBe(false);
+  });
+});