diff --git a/scripts/configure_vedastro_secret.py b/scripts/configure_vedastro_secret.py
new file mode 100644
index 00000000..9d510216
--- /dev/null
+++ b/scripts/configure_vedastro_secret.py
@@ -0,0 +1,64 @@
+"""Configure VedAstro local secret without echoing it.
+
+Run manually from a trusted terminal. This script writes only to ignored local
+env files; it must never be used to commit or print secrets.
+"""
+
+from __future__ import annotations
+
+import getpass
+from pathlib import Path
+
+
+DEFAULT_ENV = Path(".env.local")
+DEFAULT_ENDPOINT = "https://api.vedastro.org/api"
+
+
+def update_env_text(text: str, updates: dict[str, str]) -> str:
+    lines = text.splitlines()
+    seen: set[str] = set()
+    output: list[str] = []
+    for line in lines:
+        stripped = line.strip()
+        if not stripped or stripped.startswith("#") or "=" not in line:
+            output.append(line)
+            continue
+        key, _value = line.split("=", 1)
+        key = key.strip()
+        if key in updates:
+            output.append(f"{key}={updates[key]}")
+            seen.add(key)
+        else:
+            output.append(line)
+    for key, value in updates.items():
+        if key not in seen:
+            output.append(f"{key}={value}")
+    return "\n".join(output).rstrip() + "\n"
+
+
+def write_env(path: Path, updates: dict[str, str]) -> None:
+    existing = path.read_text(encoding="utf-8") if path.exists() else ""
+    path.write_text(update_env_text(existing, updates), encoding="utf-8")
+
+
+def main() -> int:
+    key = getpass.getpass("VedAstro API key (hidden): ").strip()
+    if not key:
+        print("No key entered; nothing changed.")
+        return 1
+    endpoint = input(f"VedAstro endpoint [{DEFAULT_ENDPOINT}]: ").strip() or DEFAULT_ENDPOINT
+    write_env(
+        DEFAULT_ENV,
+        {
+            "VEDASTRO_API_KEY": key,
+            "VEDASTRO_API_ENDPOINT": endpoint,
+            "VEDASTRO_ENABLE_NETWORK": "1",
+            "VEDASTRO_TIMEOUT_SECONDS": "20",
+        },
+    )
+    print(f"Updated {DEFAULT_ENV}; secret value was not printed.")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/scripts/report_renderer_isolation_poc.py b/scripts/report_renderer_isolation_poc.py
new file mode 100644
index 00000000..bbc10cfe
--- /dev/null
+++ b/scripts/report_renderer_isolation_poc.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+"""Run an isolated Chromium proof that report rendering cannot fetch external resources."""
+from __future__ import annotations
+
+import json
+import argparse
+import tempfile
+import threading
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from pathlib import Path
+from typing import Any
+
+try:
+    from report_builder import is_allowed_report_resource_url
+except ImportError:
+    from scripts.report_builder import is_allowed_report_resource_url
+
+
+class _ProbeHandler(BaseHTTPRequestHandler):
+    requests = 0
+
+    def do_GET(self) -> None:  # noqa: N802
+        type(self).requests += 1
+        self.send_response(200)
+        self.end_headers()
+
+    def log_message(self, _format: str, *_args: Any) -> None:
+        return
+
+
+def run_poc() -> dict[str, Any]:
+    try:
+        from playwright.sync_api import sync_playwright
+    except ImportError:
+        return {"scope": "report_renderer_isolation_poc", "status": "blocked", "reason": "playwright_python_missing"}
+
+    server = ThreadingHTTPServer(("127.0.0.1", 0), _ProbeHandler)
+    thread = threading.Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    try:
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            secret = root / "secret.txt"
+            secret.write_text("must-not-load", encoding="utf-8")
+            html = root / "report.html"
+            remote_url = f"http://127.0.0.1:{server.server_port}/probe"
+            html.write_text(
+                f'<img src="{remote_url}"><img src="{secret.as_uri()}"><p>report</p>',
+                encoding="utf-8",
+            )
+            report_url = html.as_uri()
+            blocked: list[str] = []
+            try:
+                with sync_playwright() as playwright:
+                    browser = playwright.chromium.launch(headless=True)
+                    context = browser.new_context(java_script_enabled=False)
+                    page = context.new_page()
+                    page.route(
+                        "**/*",
+                        lambda route: route.continue_()
+                        if is_allowed_report_resource_url(route.request.url, report_url=report_url)
+                        else (blocked.append(route.request.url), route.abort())[1],
+                    )
+                    page.goto(report_url, wait_until="networkidle")
+                    context.close()
+                    browser.close()
+            except Exception as exc:  # Browser binary/startup is an environment boundary.
+                return {"scope": "report_renderer_isolation_poc", "status": "blocked", "reason": f"chromium_unavailable:{type(exc).__name__}"}
+            return {
+                "scope": "report_renderer_isolation_poc",
+                "status": "pass" if _ProbeHandler.requests == 0 and len(blocked) >= 2 else "fail",
+                "http_probe_requests": _ProbeHandler.requests,
+                "blocked_resource_count": len(blocked),
+                "blocked_schemes": sorted({url.split(":", 1)[0] for url in blocked}),
+            }
+    finally:
+        server.shutdown()
+        server.server_close()
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--strict", action="store_true", help="Return nonzero unless the isolation probe passes.")
+    args = parser.parse_args()
+    result = run_poc()
+    print(json.dumps(result, ensure_ascii=False, sort_keys=True))
+    raise SystemExit(0 if not args.strict or result["status"] == "pass" else 1)
diff --git a/tests/test_configure_vedastro_secret.py b/tests/test_configure_vedastro_secret.py
new file mode 100644
index 00000000..c251dee7
--- /dev/null
+++ b/tests/test_configure_vedastro_secret.py
@@ -0,0 +1,18 @@
+from scripts.configure_vedastro_secret import update_env_text
+
+
+def test_update_env_text_adds_and_replaces_vedastro_settings():
+    text = "VEDASTRO_API_ENDPOINT=https://old.example/api\nOTHER=value\n"
+    updated = update_env_text(
+        text,
+        {
+            "VEDASTRO_API_KEY": "sample-secret",
+            "VEDASTRO_API_ENDPOINT": "https://api.vedastro.org/api",
+            "VEDASTRO_ENABLE_NETWORK": "1",
+        },
+    )
+    assert "VEDASTRO_API_ENDPOINT=https://api.vedastro.org/api" in updated
+    assert "VEDASTRO_API_KEY=sample-secret" in updated
+    assert "VEDASTRO_ENABLE_NETWORK=1" in updated
+    assert "OTHER=value" in updated
+    assert "https://old.example/api" not in updated
diff --git a/tests/test_report_renderer_isolation_poc.py b/tests/test_report_renderer_isolation_poc.py
new file mode 100644
index 00000000..108a6edd
--- /dev/null
+++ b/tests/test_report_renderer_isolation_poc.py
@@ -0,0 +1,9 @@
+from scripts.report_renderer_isolation_poc import run_poc
+
+
+def test_report_renderer_isolation_poc_never_claims_pass_without_browser() -> None:
+    result = run_poc()
+    assert result["status"] in {"pass", "fail", "blocked"}
+    if result["status"] == "pass":
+        assert result["http_probe_requests"] == 0
+        assert result["blocked_resource_count"] >= 2