diff --git a/plugins/llm-security/scanners/ide-extension-scanner.mjs b/plugins/llm-security/scanners/ide-extension-scanner.mjs
index af678ea..1ce93d1 100644
--- a/plugins/llm-security/scanners/ide-extension-scanner.mjs
+++ b/plugins/llm-security/scanners/ide-extension-scanner.mjs
@@ -33,9 +33,14 @@ import {
   loadJetBrainsBlocklist,
   normalizeId,
 } from './lib/ide-extension-data.mjs';
-import { fetchVsixFromUrl, detectUrlType } from './lib/vsix-fetch.mjs';
+import { fetchVsixFromUrl, fetchPluginFromUrl, detectUrlType } from './lib/vsix-fetch.mjs';
 import { extractToDir, ZipError } from './lib/zip-extract.mjs';
-import { runVsixWorker } from './lib/vsix-sandbox.mjs';
+import {
+  runVsixWorker,
+  runPluginWorker,
+  DEFAULT_VSIX_WORKER_PATH,
+  DEFAULT_JETBRAINS_WORKER_PATH,
+} from './lib/vsix-sandbox.mjs';
 
 import { scan as scanUnicode } from './unicode-scanner.mjs';
 import { scan as scanEntropy } from './entropy-scanner.mjs';
@@ -132,6 +137,111 @@ async function fetchAndExtractVsixUrl(url, opts = {}) {
   }
 }
 
+/**
+ * Generalized URL fetch + extract for JetBrains plugins (and callable for VSIX
+ * too via `workerKind: 'vsix'`). Uses the generalized `runPluginWorker` from
+ * `vsix-sandbox.mjs` so both worker kinds share the same sandbox pipeline.
+ *
+ * JetBrains-specific differences from the VSIX helper:
+ *   - Worker is `DEFAULT_JETBRAINS_WORKER_PATH` (emits the plugin root under
+ *     <tempDir>, not `<tempDir>/extension`).
+ *   - In-process fallback uses `fetchJetBrainsPlugin` + manual extRoot probe
+ *     mirroring the worker (first child of tempDir with `lib/*.jar`).
+ *
+ * Caller MUST `await rm(result.tempDir, { recursive: true, force: true })` in finally.
+ *
+ * @param {string} url
+ * @param {{ useSandbox?: boolean, workerKind?: 'jetbrains'|'vsix' }} [opts]
+ * @returns {Promise<{ extRoot: string, tempDir: string, source: object, sandbox: 'sandbox-exec'|'bwrap'|null|'in-process' }>}
+ */
+async function fetchAndExtractPluginUrl(url, opts = {}) {
+  const useSandbox = opts.useSandbox !== false;
+  const workerKind = opts.workerKind || 'jetbrains';
+  const workerPath = workerKind === 'vsix' ? DEFAULT_VSIX_WORKER_PATH : DEFAULT_JETBRAINS_WORKER_PATH;
+  const tempDir = await mkdtemp(join(tmpdir(), `llm-sec-${workerKind}-`));
+  try {
+    if (useSandbox) {
+      const { ok, sandbox, payload } = await runPluginWorker(
+        workerPath,
+        ['--url', url, '--tmpdir', tempDir],
+        tempDir,
+      );
+      if (!ok) {
+        const msg = payload && payload.error ? payload.error : 'worker failed';
+        throw new Error(msg);
+      }
+      const { type: kind, ...sourceMeta } = payload.source;
+      const source = {
+        type: 'url',
+        kind,
+        url,
+        finalUrl: payload.finalUrl,
+        sha256: payload.sha256,
+        size: payload.size,
+        sandbox: sandbox || 'none',
+        ...sourceMeta,
+      };
+      return { extRoot: payload.extRoot, tempDir, source, sandbox: sandbox || null };
+    }
+
+    // In-process path — used by tests that mock globalThis.fetch.
+    let fetched;
+    try {
+      fetched = await fetchPluginFromUrl(url);
+    } catch (err) {
+      throw new Error(`fetch failed: ${err.message}`);
+    }
+    try {
+      await extractToDir(fetched.buffer, tempDir);
+    } catch (err) {
+      if (err instanceof ZipError) {
+        throw new Error(`malformed plugin archive (${err.code}): ${err.message}`);
+      }
+      throw err;
+    }
+
+    // JetBrains archives: first child dir containing lib/*.jar is the plugin root.
+    let extRoot = tempDir;
+    if (workerKind === 'jetbrains') {
+      try {
+        const { readdirSync, statSync } = await import('node:fs');
+        for (const name of readdirSync(tempDir)) {
+          const candidate = join(tempDir, name);
+          try {
+            if (!statSync(candidate).isDirectory()) continue;
+            const libDir = join(candidate, 'lib');
+            if (!statSync(libDir).isDirectory()) continue;
+            const libEntries = readdirSync(libDir);
+            if (libEntries.some((n) => n.toLowerCase().endsWith('.jar'))) {
+              extRoot = candidate;
+              break;
+            }
+          } catch { /* skip */ }
+        }
+      } catch { /* fallback to tempDir */ }
+    } else {
+      const nested = join(tempDir, 'extension');
+      if (existsSync(nested)) extRoot = nested;
+    }
+
+    const { type: kind, ...sourceMeta } = fetched.source;
+    const source = {
+      type: 'url',
+      kind,
+      url,
+      finalUrl: fetched.finalUrl,
+      sha256: fetched.sha256,
+      size: fetched.size,
+      sandbox: 'in-process',
+      ...sourceMeta,
+    };
+    return { extRoot, tempDir, source, sandbox: 'in-process' };
+  } catch (err) {
+    await rm(tempDir, { recursive: true, force: true }).catch(() => {});
+    throw err;
+  }
+}
+
 // ---------------------------------------------------------------------------
 // IDE-specific checks (operate on parsed manifest)
 // ---------------------------------------------------------------------------
@@ -694,13 +804,28 @@ export async function scan(target, options = {}) {
   let urlSource = null;
   let urlTempDir = null;
 
-  // URL mode: fetch VSIX, extract to temp dir, then treat extracted dir as single target.
+  // URL mode: fetch plugin archive, extract to temp dir, then treat extracted dir as single target.
   if (isUrlTarget(target)) {
     const detected = detectUrlType(target);
     if (detected.type === 'unknown') {
-      warnings.push(`unsupported URL: ${target} (expected VS Code Marketplace, OpenVSX, or direct .vsix)`);
+      warnings.push(`unsupported URL: ${target} (expected VS Code Marketplace, OpenVSX, direct .vsix, or plugins.jetbrains.com)`);
     } else if (detected.type === 'github') {
       warnings.push('GitHub repo URLs are not supported in v6.4.0 — would require build step. Use the Marketplace, OpenVSX, or a direct .vsix link.');
+    } else if (detected.type === 'jetbrains') {
+      try {
+        const fetched = await fetchAndExtractPluginUrl(target, {
+          useSandbox: options.useSandbox,
+          workerKind: 'jetbrains',
+        });
+        urlSource = fetched.source;
+        urlTempDir = fetched.tempDir;
+        target = fetched.extRoot;
+        if (fetched.sandbox === null && options.useSandbox !== false) {
+          warnings.push('OS sandbox unavailable on this platform — JetBrains plugin extracted without sandbox-exec/bwrap. Defense-in-depth reduced to in-process zip-extract validation.');
+        }
+      } catch (err) {
+        warnings.push(`URL fetch/extract failed: ${err.message}`);
+      }
     } else {
       try {
         const fetched = await fetchAndExtractVsixUrl(target, { useSandbox: options.useSandbox });
@@ -726,28 +851,64 @@ export async function scan(target, options = {}) {
   if (urlFetchFailed) {
     // Don't fall through to discovery when the user asked for a specific URL.
   } else if (singleTargetPath) {
-    // Single-directory mode
-    const parsed = await parseVSCodeExtension(singleTargetPath);
-    if (!parsed) {
-      warnings.push(`cannot parse extension at ${singleTargetPath}`);
+    // Single-directory mode — detect plugin type from layout.
+    // - `lib/*.jar` subtree → JetBrains plugin (parsed via parseIntelliJPlugin)
+    // - `package.json` at root → VS Code extension (parsed via parseVSCodeExtension)
+    // - neither → warn + skip
+    const hasLibDir = existsSync(join(singleTargetPath, 'lib'));
+    const hasPackageJson = existsSync(join(singleTargetPath, 'package.json'));
+    const isJetBrainsLayout = hasLibDir && !hasPackageJson;
+
+    if (isJetBrainsLayout) {
+      const parsed = await parseIntelliJPlugin(singleTargetPath);
+      if (!parsed || !parsed.manifest) {
+        warnings.push(`cannot parse JetBrains plugin at ${singleTargetPath}`);
+        if (parsed && parsed.warnings) warnings.push(...parsed.warnings);
+      } else {
+        const m = parsed.manifest;
+        extensions.push({
+          id: m.id,
+          publisher: m.publisher || null,
+          name: m.name || null,
+          version: m.version || null,
+          location: singleTargetPath,
+          type: 'jetbrains',
+          source: null,
+          isBuiltin: false,
+          installedTimestamp: null,
+          targetPlatform: null,
+          publisherDisplayName: null,
+          signed: false,
+          rootDir: singleTargetPath,
+        });
+        rootsScanned.push(singleTargetPath);
+        warnings.push(...parsed.warnings);
+      }
+    } else if (hasPackageJson) {
+      const parsed = await parseVSCodeExtension(singleTargetPath);
+      if (!parsed) {
+        warnings.push(`cannot parse extension at ${singleTargetPath}`);
+      } else {
+        const m = parsed.manifest;
+        extensions.push({
+          id: m.id,
+          publisher: m.publisher,
+          name: m.name,
+          version: m.version,
+          location: singleTargetPath,
+          type: 'vscode',
+          source: null,
+          isBuiltin: false,
+          installedTimestamp: null,
+          targetPlatform: null,
+          publisherDisplayName: null,
+          signed: m.hasSignature,
+          rootDir: singleTargetPath,
+        });
+        rootsScanned.push(singleTargetPath);
+      }
     } else {
-      const m = parsed.manifest;
-      extensions.push({
-        id: m.id,
-        publisher: m.publisher,
-        name: m.name,
-        version: m.version,
-        location: singleTargetPath,
-        type: 'vscode',
-        source: null,
-        isBuiltin: false,
-        installedTimestamp: null,
-        targetPlatform: null,
-        publisherDisplayName: null,
-        signed: m.hasSignature,
-        rootDir: singleTargetPath,
-      });
-      rootsScanned.push(singleTargetPath);
+      warnings.push(`cannot determine plugin type at ${singleTargetPath} (no package.json, no lib/ dir)`);
     }
   } else {
     // Discovery mode
@@ -762,7 +923,9 @@ export async function scan(target, options = {}) {
       rootsScanned.push(...vs.rootsScanned);
     }
     if (!options.vscodeOnly) {
-      const jb = await discoverJetBrainsExtensions({});
+      const jb = await discoverJetBrainsExtensions({
+        rootsOverride: options.rootsOverride,
+      });
       extensions.push(...jb.extensions);
       warnings.push(...jb.warnings);
       rootsScanned.push(...jb.rootsScanned);
diff --git a/plugins/llm-security/scanners/lib/jetbrains-fetch-worker.mjs b/plugins/llm-security/scanners/lib/jetbrains-fetch-worker.mjs
new file mode 100644
index 0000000..a37350f
--- /dev/null
+++ b/plugins/llm-security/scanners/lib/jetbrains-fetch-worker.mjs
@@ -0,0 +1,114 @@
+#!/usr/bin/env node
+// jetbrains-fetch-worker.mjs — Sub-process worker that fetches a JetBrains
+// plugin URL and extracts the downloaded ZIP into a writable directory.
+// Mirrors `vsix-fetch-worker.mjs` IPC exactly.
+//
+// Contract:
+//   stdin:  none
+//   argv:   --url <url> --tmpdir <writable-dir>
+//   stdout: single JSON line {ok:true, sha256, size, finalUrl, source, extRoot}
+//           on success, or {ok:false, error:"<msg>", code?:"<ZIP_CODE>"} on failure
+//   stderr: never (silent — all errors via JSON on stdout)
+//   exit:   0 on success, 1 on any failure (caller still parses stdout)
+//
+// Key JetBrains-specific difference from the VSIX worker: plugin archives are
+// NOT nested under `extension/`. The top-level entry is usually the plugin
+// directory itself — identified by the presence of a `lib/` subdir containing
+// at least one `*.jar`. If no such directory is found, fall back to `<tmpdir>`
+// itself and let the parser surface a warning.
+
+import { existsSync, readdirSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import { fetchJetBrainsPlugin, detectUrlType } from './vsix-fetch.mjs';
+import { extractToDir, ZipError } from './zip-extract.mjs';
+
+function emit(obj) {
+  process.stdout.write(JSON.stringify(obj) + '\n');
+}
+
+function parseArgs(argv) {
+  const out = { url: null, tmpdir: null };
+  for (let i = 0; i < argv.length; i++) {
+    if (argv[i] === '--url' && i + 1 < argv.length) out.url = argv[++i];
+    else if (argv[i] === '--tmpdir' && i + 1 < argv.length) out.tmpdir = argv[++i];
+  }
+  return out;
+}
+
+// Find the top-level plugin dir inside an extracted JetBrains archive.
+// JetBrains plugin zips contain `<plugin-name>/lib/*.jar`. We walk immediate
+// children of <tmpdir>; the first child with a `lib/` subdir containing a
+// `.jar` file is the plugin root. Fallback: return <tmpdir>.
+function findPluginRoot(tmpdir) {
+  let entries;
+  try { entries = readdirSync(tmpdir); } catch { return tmpdir; }
+  for (const name of entries) {
+    const candidate = join(tmpdir, name);
+    let s;
+    try { s = statSync(candidate); } catch { continue; }
+    if (!s.isDirectory()) continue;
+    const libDir = join(candidate, 'lib');
+    let libStat;
+    try { libStat = statSync(libDir); } catch { continue; }
+    if (!libStat.isDirectory()) continue;
+    let libEntries;
+    try { libEntries = readdirSync(libDir); } catch { continue; }
+    if (libEntries.some((n) => n.toLowerCase().endsWith('.jar'))) {
+      return candidate;
+    }
+  }
+  return tmpdir;
+}
+
+async function main() {
+  const { url, tmpdir: dir } = parseArgs(process.argv.slice(2));
+  if (!url || !dir) {
+    emit({ ok: false, error: 'missing --url or --tmpdir' });
+    process.exit(1);
+  }
+  const detected = detectUrlType(url);
+  if (detected.type !== 'jetbrains') {
+    emit({ ok: false, error: `worker expected JetBrains URL, got type=${detected.type}` });
+    process.exit(1);
+  }
+
+  let fetched;
+  try {
+    fetched = await fetchJetBrainsPlugin({
+      numericId: detected.numericId,
+      xmlId: detected.xmlId,
+      version: detected.version,
+    });
+  } catch (err) {
+    emit({ ok: false, error: `fetch failed: ${err.message}` });
+    process.exit(1);
+  }
+
+  try {
+    await extractToDir(fetched.buffer, dir);
+  } catch (err) {
+    if (err instanceof ZipError) {
+      emit({ ok: false, error: `malformed JetBrains plugin (${err.code}): ${err.message}`, code: err.code });
+    } else {
+      emit({ ok: false, error: `extract failed: ${err.message}` });
+    }
+    process.exit(1);
+  }
+
+  const extRoot = existsSync(dir) ? findPluginRoot(dir) : dir;
+
+  emit({
+    ok: true,
+    sha256: fetched.sha256,
+    size: fetched.size,
+    finalUrl: fetched.finalUrl,
+    source: fetched.source,
+    extRoot,
+  });
+  process.exit(0);
+}
+
+main().catch((err) => {
+  emit({ ok: false, error: `worker crashed: ${err.message || String(err)}` });
+  process.exit(1);
+});
diff --git a/plugins/llm-security/tests/scanners/jetbrains-fetch.test.mjs b/plugins/llm-security/tests/scanners/jetbrains-fetch.test.mjs
new file mode 100644
index 0000000..da95420
--- /dev/null
+++ b/plugins/llm-security/tests/scanners/jetbrains-fetch.test.mjs
@@ -0,0 +1,266 @@
+// jetbrains-fetch.test.mjs — Integration tests for `/security ide-scan <url>`
+// with a JetBrains Marketplace URL. Mocks `globalThis.fetch` so we never hit
+// real plugins.jetbrains.com endpoints. `useSandbox: false` is required because
+// mocks do not cross process boundaries — this mirrors the VSIX test strategy.
+//
+// Covers:
+//   1. Spawned worker emits well-formed JSON when fed a bogus URL (sub-process
+//      path — no mock, we just assert the IPC contract holds).
+//   2. End-to-end `scan()` on a `/plugin/<numericId>-<slug>` URL resolves
+//      numericId → xmlId via metadata, then downloads + extracts.
+//   3. End-to-end `scan()` on a `/plugin/download?pluginId=<xmlId>` URL
+//      skips the metadata round-trip and downloads directly.
+//   4. Network failure / malformed archive bubble up as warnings.
+//   5. URL kind discriminator (`meta.source.kind === 'jetbrains'`) distinguishes
+//      JetBrains plugins from VS Code extensions in the envelope.
+//
+// See: plan step 12 (`ultraplan-2026-04-17-jetbrains-ide-scan.md`).
+
+import { describe, it, before, after } from 'node:test';
+import assert from 'node:assert/strict';
+import { spawn } from 'node:child_process';
+import { join, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { resetCounter } from '../../scanners/lib/output.mjs';
+import { scan } from '../../scanners/ide-extension-scanner.mjs';
+import { createZip } from '../helpers/zip-writer.mjs';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const JB_WORKER_PATH = join(
+  __dirname,
+  '..',
+  '..',
+  'scanners',
+  'lib',
+  'jetbrains-fetch-worker.mjs',
+);
+
+const realFetch = globalThis.fetch;
+
+function mockBufferResponse(buffer, { status = 200 } = {}) {
+  const stream = new ReadableStream({
+    start(controller) { controller.enqueue(buffer); controller.close(); },
+  });
+  return new Response(stream, {
+    status,
+    headers: { 'content-type': 'application/zip' },
+  });
+}
+
+function jsonResponse(obj, { status = 200 } = {}) {
+  return new Response(JSON.stringify(obj), {
+    status,
+    headers: { 'content-type': 'application/json' },
+  });
+}
+
+function installFetchRouter(routes) {
+  globalThis.fetch = async (url) => {
+    const handler = routes(String(url));
+    if (!handler) throw new Error(`unrouted fetch: ${url}`);
+    return handler;
+  };
+}
+
+// Build a synthetic JetBrains plugin archive with the layout
+// <plugin-name>/lib/<plugin>.jar → containing META-INF/plugin.xml.
+// The outer archive is what plugins.jetbrains.com ships; the inner jar is what
+// parseIntelliJPlugin walks for the manifest.
+function buildBenignJetBrainsArchive() {
+  const pluginXml = `<?xml version="1.0"?>
+<idea-plugin>
+  <id>com.example.benign</id>
+  <name>Benign</name>
+  <version>1.0.0</version>
+  <vendor>Example</vendor>
+</idea-plugin>`;
+  const innerJar = createZip([
+    { name: 'META-INF/plugin.xml', data: pluginXml },
+    { name: 'META-INF/MANIFEST.MF', data: 'Manifest-Version: 1.0\n' },
+  ]);
+  return createZip([
+    { name: 'com.example.benign/lib/main.jar', data: innerJar },
+  ]);
+}
+
+// ---------------------------------------------------------------------------
+// 1. Worker IPC contract
+// ---------------------------------------------------------------------------
+
+describe('jetbrains-fetch-worker — IPC contract', () => {
+  it('emits ok:false JSON on missing args and exits 1', async () => {
+    const child = spawn('node', [JB_WORKER_PATH], { stdio: ['ignore', 'pipe', 'pipe'] });
+    let out = '';
+    child.stdout.on('data', (c) => { out += c.toString('utf8'); });
+    const code = await new Promise((resolve) => child.on('close', resolve));
+    assert.equal(code, 1);
+    const parsed = JSON.parse(out.trim());
+    assert.equal(parsed.ok, false);
+    assert.match(parsed.error, /missing --url or --tmpdir/);
+  });
+
+  it('emits ok:false JSON when given a non-JetBrains URL', async () => {
+    // Reject non-JetBrains URLs at the worker level — defense-in-depth in case
+    // orchestrator routes a wrong URL to the JB worker.
+    const child = spawn(
+      'node',
+      [JB_WORKER_PATH, '--url', 'https://example.com/x.vsix', '--tmpdir', '/tmp'],
+      { stdio: ['ignore', 'pipe', 'pipe'] },
+    );
+    let out = '';
+    child.stdout.on('data', (c) => { out += c.toString('utf8'); });
+    const code = await new Promise((resolve) => child.on('close', resolve));
+    assert.equal(code, 1);
+    const parsed = JSON.parse(out.trim());
+    assert.equal(parsed.ok, false);
+    assert.match(parsed.error, /expected JetBrains URL/);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// 2. End-to-end scan() with mocked fetch
+// ---------------------------------------------------------------------------
+
+describe('ide-extension-scanner — JetBrains URL mode', () => {
+  before(() => resetCounter());
+  after(() => { globalThis.fetch = realFetch; });
+
+  it('resolves numericId → xmlId via metadata, then downloads + scans', async () => {
+    const archive = buildBenignJetBrainsArchive();
+    const calls = [];
+    installFetchRouter((url) => {
+      calls.push(url);
+      if (/\/api\/plugins\/7973$/.test(url)) {
+        return jsonResponse({ xmlId: 'com.example.benign' });
+      }
+      if (/\/plugin\/download\?pluginId=com\.example\.benign/.test(url)) {
+        return mockBufferResponse(archive);
+      }
+      return null;
+    });
+
+    const env = await scan(
+      'https://plugins.jetbrains.com/plugin/7973-benign',
+      { useSandbox: false },
+    );
+
+    // Two fetches: metadata + download.
+    assert.equal(calls.length, 2, `calls: ${calls.join(', ')}`);
+    assert.match(calls[0], /\/api\/plugins\/7973/);
+    assert.match(calls[1], /\/plugin\/download\?pluginId=com\.example\.benign/);
+
+    // Envelope shape.
+    assert.ok(env.meta.source, 'expected meta.source to be set');
+    assert.equal(env.meta.source.type, 'url');
+    assert.equal(env.meta.source.kind, 'jetbrains');
+    assert.equal(env.meta.source.xmlId, 'com.example.benign');
+    assert.equal(env.meta.source.numericId, '7973');
+    assert.match(env.meta.source.sha256, /^[a-f0-9]{64}$/);
+    assert.equal(env.meta.source.sandbox, 'in-process');
+    assert.equal(env.meta.target, 'https://plugins.jetbrains.com/plugin/7973-benign');
+
+    // Scanner parsed the inner plugin.xml and produced exactly one JB extension.
+    assert.equal(env.extensions.length, 1);
+    assert.equal(env.extensions[0].type, 'jetbrains');
+    assert.equal(env.extensions[0].id, 'com.example.benign');
+    assert.equal(env.extensions[0].version, '1.0.0');
+  });
+
+  it('downloads by xmlId directly (no metadata round-trip)', async () => {
+    const archive = buildBenignJetBrainsArchive();
+    let metaCalled = false;
+    let downloadCalled = false;
+    installFetchRouter((url) => {
+      if (/\/api\/plugins\//.test(url)) {
+        metaCalled = true;
+        return jsonResponse({ xmlId: 'should.not.be.used' });
+      }
+      if (/\/plugin\/download\?pluginId=com\.example\.benign/.test(url)) {
+        downloadCalled = true;
+        return mockBufferResponse(archive);
+      }
+      return null;
+    });
+
+    const env = await scan(
+      'https://plugins.jetbrains.com/plugin/download?pluginId=com.example.benign',
+      { useSandbox: false },
+    );
+
+    assert.equal(metaCalled, false, 'metadata should not be fetched when xmlId is explicit');
+    assert.equal(downloadCalled, true);
+    assert.equal(env.meta.source.kind, 'jetbrains');
+    assert.equal(env.meta.source.xmlId, 'com.example.benign');
+    assert.equal(env.extensions.length, 1);
+    assert.equal(env.extensions[0].type, 'jetbrains');
+  });
+
+  it('passes version query through unchanged', async () => {
+    const archive = buildBenignJetBrainsArchive();
+    const calls = [];
+    installFetchRouter((url) => {
+      calls.push(url);
+      if (/\/plugin\/download\?pluginId=com\.example\.benign/.test(url)) {
+        return mockBufferResponse(archive);
+      }
+      return null;
+    });
+
+    await scan(
+      'https://plugins.jetbrains.com/plugin/download?pluginId=com.example.benign&version=2.3.4',
+      { useSandbox: false },
+    );
+
+    assert.equal(calls.length, 1);
+    assert.match(calls[0], /version=2\.3\.4/);
+  });
+
+  it('reports fetch network failure as a warning, no extensions scanned', async () => {
+    installFetchRouter(() => { throw new Error('ECONNREFUSED'); });
+    const env = await scan(
+      'https://plugins.jetbrains.com/plugin/download?pluginId=com.example.benign',
+      { useSandbox: false },
+    );
+    assert.equal(env.extensions.length, 0);
+    assert.ok(
+      env.meta.warnings.some((w) => /URL fetch\/extract failed/.test(w)),
+      `warnings: ${env.meta.warnings.join(' | ')}`,
+    );
+  });
+
+  it('reports malformed archive as a warning, no extensions scanned', async () => {
+    installFetchRouter((url) => {
+      if (/\/plugin\/download/.test(url)) {
+        return mockBufferResponse(Buffer.from('not a zip at all'));
+      }
+      return null;
+    });
+    const env = await scan(
+      'https://plugins.jetbrains.com/plugin/download?pluginId=com.example.benign',
+      { useSandbox: false },
+    );
+    assert.equal(env.extensions.length, 0);
+    assert.ok(
+      env.meta.warnings.some((w) => /malformed plugin archive|URL fetch\/extract failed/.test(w)),
+      `warnings: ${env.meta.warnings.join(' | ')}`,
+    );
+  });
+
+  it('cannot reach JetBrains path via the VS Code-only toggle', async () => {
+    // Sanity: --vscode-only should not short-circuit URL fetches, but also
+    // shouldn't gate on extension type (URL scan fetches regardless of toggle).
+    const archive = buildBenignJetBrainsArchive();
+    installFetchRouter((url) => {
+      if (/\/plugin\/download/.test(url)) return mockBufferResponse(archive);
+      return null;
+    });
+    const env = await scan(
+      'https://plugins.jetbrains.com/plugin/download?pluginId=com.example.benign',
+      { useSandbox: false, vscodeOnly: true },
+    );
+    // The URL was explicitly JB; we still scan it.
+    assert.equal(env.meta.source.kind, 'jetbrains');
+    assert.equal(env.extensions.length, 1);
+    assert.equal(env.extensions[0].type, 'jetbrains');
+  });
+});