docs: document offline export workflow (#79)

README.md

@@ -66,6 +66,22 @@ normally — pxpipe compresses the *request* only, never the model's output.
 Recent turns stay text; the system prompt, tool docs, and older bulk history
 are imaged.
 
+## Offline export (no proxy)
+
+You can render text, files, or diffs to PNG pages without running the proxy or
+connecting Claude Code:
+
+```bash
+pxpipe export src/
+cat prompt.txt | pxpipe export --stdin
+pxpipe export --git
+```
+
+The command writes an output folder containing `page-*.png`, `factsheet.txt`,
+`manifest.json`, and `prompt.txt`. Upload the PNG pages and paste the prompt
+into image-upload clients such as Cursor when you want dense visual context
+without running the proxy.
+
 ## The honest part
 
 - **It is lossy.** Exact 12-char hex strings in dense imaged content:

tests/readme-offline-export.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from 'vitest';
+import * as fs from 'node:fs';
+
+const README_PATH = 'README.md';
+const OFFLINE_EXPORT_HEADING = '## Offline export (no proxy)';
+const REQUIRED_OFFLINE_EXPORT_TEXT = [
+  'pxpipe export',
+  '--stdin',
+  '--git',
+  'page-*.png',
+  'factsheet.txt',
+  'prompt.txt',
+  'Cursor',
+  'without running the proxy',
+] as const;
+
+describe('README offline export documentation', () => {
+  it('documents the proxy-free image export workflow', () => {
+    const readme = fs.readFileSync(README_PATH, 'utf8');
+    const sectionStart = readme.indexOf(OFFLINE_EXPORT_HEADING);
+
+    expect(sectionStart).toBeGreaterThanOrEqual(0);
+
+    const nextSectionStart = readme.indexOf('\n## ', sectionStart + OFFLINE_EXPORT_HEADING.length);
+    const section =
+      nextSectionStart === -1 ? readme.slice(sectionStart) : readme.slice(sectionStart, nextSectionStart);
+
+    for (const requiredText of REQUIRED_OFFLINE_EXPORT_TEXT) {
+      expect(section).toContain(requiredText);
+    }
+  });
+});