diff --git a/browse/test/data-platform.test.ts b/browse/test/data-platform.test.ts
new file mode 100644
index 00000000..7dc0f584
--- /dev/null
+++ b/browse/test/data-platform.test.ts
@@ -0,0 +1,176 @@
+/**
+ * Tests for the browser data platform: media extraction, network capture,
+ * path security, and structured data extraction.
+ */
+
+import { describe, it, expect } from 'bun:test';
+import { SizeCappedBuffer, type CapturedResponse } from '../src/network-capture';
+import { validateTempPath, validateOutputPath, validateReadPath } from '../src/path-security';
+import { TEMP_DIR } from '../src/platform';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+
+// ─── SizeCappedBuffer ─────────────────────────────────────────
+
+describe('SizeCappedBuffer', () => {
+ function makeEntry(size: number, url = 'https://example.com'): CapturedResponse {
+ return {
+ url,
+ status: 200,
+ headers: {},
+ body: 'x'.repeat(size),
+ contentType: 'text/plain',
+ timestamp: Date.now(),
+ size,
+ bodyTruncated: false,
+ };
+ }
+
+ it('stores entries within capacity', () => {
+ const buf = new SizeCappedBuffer(1000);
+ buf.push(makeEntry(100));
+ buf.push(makeEntry(200));
+ expect(buf.length).toBe(2);
+ expect(buf.byteSize).toBe(300);
+ });
+
+ it('evicts oldest entries when over capacity', () => {
+ const buf = new SizeCappedBuffer(500);
+ buf.push(makeEntry(200, 'https://a.com'));
+ buf.push(makeEntry(200, 'https://b.com'));
+ buf.push(makeEntry(200, 'https://c.com')); // should evict first entry
+ expect(buf.length).toBe(2);
+ const urls = buf.toArray().map(e => e.url);
+ expect(urls).toContain('https://b.com');
+ expect(urls).toContain('https://c.com');
+ expect(urls).not.toContain('https://a.com');
+ });
+
+ it('evicts multiple entries for one large push', () => {
+ const buf = new SizeCappedBuffer(500);
+ buf.push(makeEntry(100));
+ buf.push(makeEntry(100));
+ buf.push(makeEntry(100));
+ buf.push(makeEntry(400)); // evicts first two (need totalSize + 400 <= 500, so totalSize <= 100)
+ expect(buf.length).toBe(2); // one 100-byte entry + one 400-byte entry
+ expect(buf.byteSize).toBe(500);
+ });
+
+ it('clear resets buffer', () => {
+ const buf = new SizeCappedBuffer(1000);
+ buf.push(makeEntry(100));
+ buf.push(makeEntry(200));
+ buf.clear();
+ expect(buf.length).toBe(0);
+ expect(buf.byteSize).toBe(0);
+ });
+
+ it('exports to JSONL file', () => {
+ const buf = new SizeCappedBuffer(1000);
+ buf.push(makeEntry(10, 'https://a.com'));
+ buf.push(makeEntry(20, 'https://b.com'));
+
+ const tmpFile = path.join(os.tmpdir(), `test-export-${Date.now()}.jsonl`);
+ try {
+ const count = buf.exportToFile(tmpFile);
+ expect(count).toBe(2);
+ const lines = fs.readFileSync(tmpFile, 'utf-8').trim().split('\n');
+ expect(lines.length).toBe(2);
+ const parsed = JSON.parse(lines[0]);
+ expect(parsed.url).toBe('https://a.com');
+ } finally {
+ fs.unlinkSync(tmpFile);
+ }
+ });
+
+ it('summary shows entries', () => {
+ const buf = new SizeCappedBuffer(1000);
+ buf.push(makeEntry(1024, 'https://api.example.com/graphql'));
+ const summary = buf.summary();
+ expect(summary).toContain('1 responses');
+ expect(summary).toContain('graphql');
+ expect(summary).toContain('1KB');
+ });
+
+ it('summary shows empty message when no entries', () => {
+ const buf = new SizeCappedBuffer(1000);
+ expect(buf.summary()).toBe('No captured responses.');
+ });
+});
+
+// ─── validateTempPath ─────────────────────────────────────────
+
+describe('validateTempPath', () => {
+ let tmpFile: string;
+
+ it('allows paths within /tmp that exist', () => {
+ tmpFile = path.join(TEMP_DIR, `test-temp-path-${Date.now()}.jpg`);
+ fs.writeFileSync(tmpFile, 'test');
+ try {
+ expect(() => validateTempPath(tmpFile)).not.toThrow();
+ } finally {
+ fs.unlinkSync(tmpFile);
+ }
+ });
+
+ it('rejects non-existent files', () => {
+ expect(() => validateTempPath('/tmp/nonexistent-file-12345.jpg')).toThrow(/not found/i);
+ });
+
+ it('rejects paths in cwd', () => {
+ // Create a real file in cwd to test the path check (not the existence check)
+ const cwdFile = path.join(process.cwd(), 'package.json');
+ expect(() => validateTempPath(cwdFile)).toThrow(/temp directory/i);
+ });
+
+ it('rejects absolute paths outside safe dirs', () => {
+ expect(() => validateTempPath('/etc/passwd')).toThrow();
+ });
+});
+
+// ─── Command registration ─────────────────────────────────────
+
+describe('command registration', () => {
+ it('all new commands have descriptions', () => {
+ // The load-time validation in commands.ts throws if any command
+ // is missing from COMMAND_DESCRIPTIONS. If this import succeeds,
+ // all commands are properly registered.
+ const { COMMAND_DESCRIPTIONS, ALL_COMMANDS } = require('../src/commands');
+ const newCommands = ['media', 'data', 'download', 'scrape', 'archive'];
+ for (const cmd of newCommands) {
+ expect(ALL_COMMANDS.has(cmd)).toBe(true);
+ expect(COMMAND_DESCRIPTIONS[cmd]).toBeTruthy();
+ }
+ });
+
+ it('new commands are in correct scope sets', () => {
+ const { SCOPE_READ, SCOPE_WRITE } = require('../src/token-registry');
+ expect(SCOPE_READ.has('media')).toBe(true);
+ expect(SCOPE_READ.has('data')).toBe(true);
+ expect(SCOPE_WRITE.has('download')).toBe(true);
+ expect(SCOPE_WRITE.has('scrape')).toBe(true);
+ expect(SCOPE_WRITE.has('archive')).toBe(true);
+ });
+
+ it('media and data are in PAGE_CONTENT_COMMANDS', () => {
+ const { PAGE_CONTENT_COMMANDS } = require('../src/commands');
+ expect(PAGE_CONTENT_COMMANDS.has('media')).toBe(true);
+ expect(PAGE_CONTENT_COMMANDS.has('data')).toBe(true);
+ });
+});
+
+// ─── MIME type mapping ─────────────────────────────────────────
+
+describe('mimeToExt', () => {
+ // mimeToExt is a private function in write-commands.ts,
+ // so we test it indirectly through command behavior.
+ // This test verifies the source contains the expected mappings.
+ it('write-commands.ts contains MIME mappings', () => {
+ const src = fs.readFileSync(path.join(import.meta.dir, '../src/write-commands.ts'), 'utf-8');
+ expect(src).toContain("'image/png': '.png'");
+ expect(src).toContain("'image/jpeg': '.jpg'");
+ expect(src).toContain("'video/mp4': '.mp4'");
+ expect(src).toContain("'audio/mpeg': '.mp3'");
+ });
+});
diff --git a/browse/test/fixtures/media-page.html b/browse/test/fixtures/media-page.html
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+++ b/browse/test/fixtures/media-page.html
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