fix: scheme-validate crawler source_url before rendering as a link

Harvested source_url (external content) rendered as an admin <a href> without
scheme validation — a javascript:/data: link would execute on click (audit M2).
safeExternalHref() gates to http(s); CrawlerHistoryTable/DeadJobsTable fall back
to plain text otherwise. Tested in safeHref.test.ts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/Cargo.lock

@@ -1558,7 +1558,7 @@ checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
 
 [[package]]
 name = "mangalord"
-version = "0.128.10"
+version = "0.128.11"
 dependencies = [
  "anyhow",
  "argon2",

backend/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.128.10"
+version = "0.128.11"
 edition = "2021"
 default-run = "mangalord"
 

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.128.10",
+  "version": "0.128.11",
   "private": true,
   "type": "module",
   "scripts": {

frontend/src/lib/components/crawler/CrawlerHistoryTable.svelte

@@ -2,6 +2,7 @@
     import { onMount } from 'svelte';
     import Pager from '$lib/components/Pager.svelte';
     import { fmtDuration } from '$lib/format';
+    import { safeExternalHref } from '$lib/safeHref';
     import SearchBar from './SearchBar.svelte';
     import {
         listCrawlerJobHistory,
@@ -175,9 +176,14 @@
                         <td class="kind">{r.kind ?? '—'}</td>
                         <td>
                             {#if !r.manga_title && r.payload_title && r.source_url}
-                                <a href={r.source_url} target="_blank" rel="noreferrer noopener"
-                                    >{target(r)}</a
-                                >
+                                {@const href = safeExternalHref(r.source_url)}
+                                {#if href}
+                                    <a {href} target="_blank" rel="noreferrer noopener"
+                                        >{target(r)}</a
+                                    >
+                                {:else}
+                                    {target(r)}
+                                {/if}
                             {:else}
                                 {target(r)}
                             {/if}

frontend/src/lib/components/crawler/DeadJobsTable.svelte

@@ -2,6 +2,7 @@
     import Pager from '$lib/components/Pager.svelte';
     import type { DeadJob, RequeueScope } from '$lib/api/admin';
     import SearchBar from './SearchBar.svelte';
+    import { safeExternalHref } from '$lib/safeHref';
 
     let {
         jobs,
@@ -60,9 +61,14 @@
                                 {j.manga_title}
                             {:else if j.payload_title}
                                 {#if j.source_url}
-                                    <a href={j.source_url} target="_blank" rel="noreferrer noopener"
-                                        >{j.payload_title}</a
-                                    >
+                                    {@const href = safeExternalHref(j.source_url)}
+                                    {#if href}
+                                        <a {href} target="_blank" rel="noreferrer noopener"
+                                            >{j.payload_title}</a
+                                        >
+                                    {:else}
+                                        {j.payload_title}
+                                    {/if}
                                 {:else}
                                     {j.payload_title}
                                 {/if}

frontend/src/lib/safeHref.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect } from 'vitest';
+import { safeExternalHref } from './safeHref';
+
+describe('safeExternalHref', () => {
+    it('passes through http and https URLs', () => {
+        expect(safeExternalHref('http://example.com/manga/1')).toBe(
+            'http://example.com/manga/1'
+        );
+        expect(safeExternalHref('https://example.com/x?y=1#z')).toBe(
+            'https://example.com/x?y=1#z'
+        );
+    });
+
+    it('rejects dangerous schemes', () => {
+        expect(safeExternalHref('javascript:alert(document.cookie)')).toBeNull();
+        expect(safeExternalHref('JavaScript:alert(1)')).toBeNull();
+        expect(safeExternalHref('data:text/html,<script>alert(1)</script>')).toBeNull();
+        expect(safeExternalHref('vbscript:msgbox(1)')).toBeNull();
+        expect(safeExternalHref('file:///etc/passwd')).toBeNull();
+    });
+
+    it('rejects relative, malformed, empty, and nullish input', () => {
+        expect(safeExternalHref('/relative/path')).toBeNull();
+        expect(safeExternalHref('not a url')).toBeNull();
+        expect(safeExternalHref('')).toBeNull();
+        expect(safeExternalHref(null)).toBeNull();
+        expect(safeExternalHref(undefined)).toBeNull();
+    });
+});

frontend/src/lib/safeHref.ts

@@ -0,0 +1,21 @@
+/**
+ * Return `url` only if it is a well-formed `http(s)` URL that is safe to place
+ * in an `href`, otherwise `null`.
+ *
+ * Crawler `source_url` values are external/untrusted content harvested from
+ * scraped source sites. Svelte does NOT sanitize URL schemes in `href`
+ * bindings, so a harvested `javascript:`/`data:`/`vbscript:` link would execute
+ * (or phish) in the admin origin on click. Callers render the title as plain
+ * text when this returns `null`.
+ */
+export function safeExternalHref(url: string | null | undefined): string | null {
+    if (!url) return null;
+    let parsed: URL;
+    try {
+        parsed = new URL(url);
+    } catch {
+        // Relative or malformed — not a safe external link.
+        return null;
+    }
+    return parsed.protocol === 'http:' || parsed.protocol === 'https:' ? url : null;
+}