diff --git a/docs/research/pre_work_error_ledger.md b/docs/research/pre_work_error_ledger.md
index 9f0235e3..a82ea0b6 100644
--- a/docs/research/pre_work_error_ledger.md
+++ b/docs/research/pre_work_error_ledger.md
@@ -76,7 +76,7 @@ For large architecture or release work, also read:
 | ERR-043 | Localhost POST requests trusted CORS response headers as an execution guard; report Chromium could load external/local resources; async job IDs were predictable and persisted without capability authentication or TTL. | mitigated 2026-07-11 | Keep `tests/test_runtime_security_p0.py`; enforce Origin/Host/JSON, sandbox report resources, use random capability tokens, `0600` atomic records, TTL deletion and a bounded worker queue. Run an isolated Chromium network PoC before declaring the renderer fully hardened. |
 | ERR-044 | Focused selections that include legacy full chart API tests can still exceed the 120-second desktop command budget even after pure calculation tests pass. | observed 2026-07-11 | Keep P0 calculation/security tests pure and fast; profile the legacy chart fixture separately before using the full API file as a blocking CI gate. |
 | ERR-045 | Three-engine readiness was mistaken for completed same-chart parity. Public replay on 2026-07-11 captured PyJHora and jyotishganit raw, but VedAstro returned `official_snapshot_budget_exhausted` with no raw response. | active external blocker | Keep `three_engine_parity_runner.py`; status remains `blocked`/`partial` until all required raw artifacts are normalized into comparison rows. |
-| ERR-046 | Report-renderer SSRF/file PoC could not run because the Playwright Chromium binary was absent and installation exceeded the desktop outer timeout. | blocked environment | Keep route/JS-denial tests; rerun isolated HTTP/file PoC only after a verified Chromium installation, then update this ledger with the measured request count. |
+| ERR-046 | Report-renderer SSRF/file PoC cannot complete because the Playwright Chromium binary is unavailable. | blocked environment | Keep route/JS-denial tests and run `scripts/report_renderer_isolation_poc.py`; only `status=pass` with zero HTTP probe requests and blocked file/http resources proves isolated rendering. Latest run 2026-07-13: `blocked: chromium_unavailable:Error`. |
 | ERR-047 | Initial `slow` marker partition for `test_api_server_security.py` still exceeded the 120-second desktop budget; heavy paths extend beyond VedAstro/high-rigor prefix groups. | active profiling blocker | Profile test node IDs in bounded subprocess batches, mark only measured heavy tests, and keep fast-security acceptance separate from long CI integration coverage. |
 | ERR-048 | Candidate-time scanner assumed all documented D4/D24/D30 divisions were exposed by `jyotish_engine.py varga`; actual `--d4` failed at runtime. | mitigated 2026-07-12 | Candidate scans must record unsupported Varga flags as `unavailable_vargas`; only successfully computed D1/D9/D10 fields may drive local sensitivity output until a unified Varga contract exists. |
 | ERR-049 | PyJHora benchmark runner executed on `--help`, used a wrong repository-root path in `run_skill_baseline.py`, and failed when reused without pre-created output directories. | mitigated 2026-07-12 | Keep `tests/test_pyjhora_compare_cli.py`; require explicit `--build-local`, safe argparse help, correct repo root, and directory creation inside `run_sample()`. |
diff --git a/scripts/report_renderer_isolation_poc.py b/scripts/report_renderer_isolation_poc.py
new file mode 100644
index 00000000..e2c13e3e
--- /dev/null
+++ b/scripts/report_renderer_isolation_poc.py
@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+"""Run an isolated Chromium proof that report rendering cannot fetch external resources."""
+from __future__ import annotations
+
+import json
+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__":
+    print(json.dumps(run_poc(), ensure_ascii=False, sort_keys=True))
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