diff --git a/README.md b/README.md
index 0c576965..0a9484f5 100644
--- a/README.md
+++ b/README.md
@@ -256,6 +256,8 @@ code-review-graph visualize --format graphml   # Export as GraphML
 code-review-graph visualize --format svg       # Export as SVG
 code-review-graph visualize --format obsidian  # Export as Obsidian vault
 code-review-graph visualize --format cypher    # Export as Neo4j Cypher
+code-review-graph visualize --format json      # Export as understand-quickly-compatible JSON
+code-review-graph visualize --publish-to-uq    # Publish to looptech-ai/understand-quickly registry
 code-review-graph wiki             # Generate markdown wiki from communities
 code-review-graph detect-changes   # Risk-scored change impact analysis
 code-review-graph register <path>  # Register repo in multi-repo registry
diff --git a/code_review_graph/cli.py b/code_review_graph/cli.py
index 9573d168..3f10201f 100644
--- a/code_review_graph/cli.py
+++ b/code_review_graph/cli.py
@@ -528,10 +528,20 @@ def main() -> None:
     )
     vis_cmd.add_argument(
         "--format",
-        choices=["html", "graphml", "cypher", "obsidian", "svg"],
+        choices=["html", "graphml", "cypher", "obsidian", "svg", "json"],
         default="html",
         help="Export format (default: html)",
     )
+    vis_cmd.add_argument(
+        "--publish-to-uq",
+        action="store_true",
+        help=(
+            "After writing the graph, fire a repository_dispatch at "
+            "looptech-ai/understand-quickly so the registry resyncs this entry. "
+            "Implies --format json. Requires UNDERSTAND_QUICKLY_TOKEN; without "
+            "the token the JSON is still written and the dispatch is skipped."
+        ),
+    )
     vis_cmd.add_argument(
         "--data-dir",
         default=None,
@@ -996,8 +1006,26 @@ def main() -> None:
 
             data_dir = get_data_dir(repo_root)
             fmt = getattr(args, "format", "html") or "html"
+            publish_to_uq = getattr(args, "publish_to_uq", False)
+            # --publish-to-uq implies --format json, since the registry only
+            # consumes the JSON shape. Force the override for any non-json
+            # format and warn when the user explicitly asked for something
+            # else (html is the default, so don't warn for it).
+            if publish_to_uq and fmt != "json":
+                if fmt != "html":
+                    print(
+                        f"warning: --publish-to-uq requires --format json; "
+                        f"ignoring --format {fmt}",
+                        file=sys.stderr,
+                    )
+                fmt = "json"
+
+            if fmt == "json" or publish_to_uq:
+                from .publish import publish as _publish_to_uq
 
-            if fmt == "graphml":
+                out = data_dir / "graph.json"
+                _publish_to_uq(store, repo_root, out, publish_to_uq=publish_to_uq)
+            elif fmt == "graphml":
                 from .exports import export_graphml
 
                 out = data_dir / "graph.graphml"
diff --git a/code_review_graph/publish.py b/code_review_graph/publish.py
new file mode 100644
index 00000000..20ac9f22
--- /dev/null
+++ b/code_review_graph/publish.py
@@ -0,0 +1,167 @@
+"""Opt-in JSON export + understand-quickly registry publish.
+
+Wraps :func:`code_review_graph.visualization.export_graph_data` with the
+metadata block looptech-ai/understand-quickly expects, writes the result to
+``<data_dir>/graph.json``, and optionally fires a ``repository_dispatch`` so
+the registry resyncs the entry. Gated on ``UNDERSTAND_QUICKLY_TOKEN`` — without
+it, the JSON is still written and the dispatch is skipped (an informational
+message is printed to stdout pointing at the nightly sync fallback).
+
+Protocol: https://github.com/looptech-ai/understand-quickly/blob/main/docs/integrations/protocol.md
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+import os
+import re
+import subprocess  # nosec B404
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Optional, Tuple
+from urllib import error as urlerror
+from urllib import request as urlrequest
+
+from .graph import GraphStore
+from .visualization import export_graph_data
+
+logger = logging.getLogger(__name__)
+
+REGISTRY_REPO = "looptech-ai/understand-quickly"
+DISPATCH_URL = f"https://api.github.com/repos/{REGISTRY_REPO}/dispatches"
+TOOL_NAME = "code-review-graph"
+
+
+def _git_head_sha(repo_root: Path) -> Optional[str]:
+    try:
+        out = subprocess.check_output(  # nosec B603 B607
+            ["git", "rev-parse", "HEAD"], cwd=str(repo_root), stderr=subprocess.DEVNULL,
+        )
+        sha = out.decode().strip()
+        if re.fullmatch(r"[0-9a-f]{40}", sha):
+            return sha
+    except (OSError, subprocess.CalledProcessError) as exc:
+        logger.debug("git rev-parse HEAD failed: %s", exc)
+    return None
+
+
+def _git_origin_owner_repo(repo_root: Path) -> Optional[Tuple[str, str]]:
+    """Parse ``owner/repo`` from ``git remote get-url origin`` (https or ssh)."""
+    try:
+        out = subprocess.check_output(  # nosec B603 B607
+            ["git", "remote", "get-url", "origin"],
+            cwd=str(repo_root), stderr=subprocess.DEVNULL,
+        )
+        url = out.decode().strip()
+    except (OSError, subprocess.CalledProcessError) as exc:
+        logger.debug("git remote get-url failed: %s", exc)
+        return None
+    for pat in (
+        r"https?://[^/]+/([^/]+)/([^/]+?)(?:\.git)?/?$",
+        r"[^@]+@[^:]+:([^/]+)/([^/]+?)(?:\.git)?$",
+    ):
+        m = re.match(pat, url)
+        if m:
+            return m.group(1), m.group(2)
+    return None
+
+
+def _tool_version() -> str:
+    try:
+        from importlib.metadata import PackageNotFoundError
+        from importlib.metadata import version as pkg_version
+        return pkg_version("code-review-graph")
+    except PackageNotFoundError:
+        return "dev"
+    except Exception as exc:  # noqa: BLE001
+        logger.debug("tool_version lookup failed: %s", exc)
+        return "dev"
+
+
+def build_publish_payload(store: GraphStore, repo_root: Path) -> dict:
+    """Return ``export_graph_data(store)`` with a registry-shaped metadata block."""
+    data = export_graph_data(store)
+    metadata = {
+        "tool": TOOL_NAME,
+        "tool_version": _tool_version(),
+        "generated_at": datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ"),
+    }
+    sha = _git_head_sha(repo_root)
+    if sha:
+        metadata["commit"] = sha
+    data["metadata"] = metadata
+    return data
+
+
+def write_publish_json(store: GraphStore, repo_root: Path, output_path: Path) -> Path:
+    payload = build_publish_payload(store, repo_root)
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+    output_path.write_text(json.dumps(payload, indent=2, default=str), encoding="utf-8")
+    return output_path
+
+
+def fire_dispatch(owner: str, repo: str, token: str) -> Tuple[bool, str]:
+    """POST a ``sync-entry`` repository_dispatch. Returns ``(ok, message)``."""
+    body = json.dumps(
+        {"event_type": "sync-entry", "client_payload": {"id": f"{owner}/{repo}"}}
+    ).encode()
+    req = urlrequest.Request(  # nosec B310 - fixed https URL
+        DISPATCH_URL, data=body, method="POST",
+        headers={
+            "Accept": "application/vnd.github+json",
+            "Authorization": f"Bearer {token}",
+            "X-GitHub-Api-Version": "2022-11-28",
+            "Content-Type": "application/json",
+            "User-Agent": f"{TOOL_NAME}-publish",
+        },
+    )
+    try:
+        with urlrequest.urlopen(req, timeout=15) as resp:  # nosec B310
+            status = getattr(resp, "status", 0) or resp.getcode()
+            if 200 <= status < 300:
+                return True, f"dispatch sent (HTTP {status})"
+            return False, f"unexpected HTTP {status}"
+    except urlerror.HTTPError as exc:
+        return False, f"HTTP {exc.code}"
+    except urlerror.URLError as exc:
+        return False, f"network error: {exc.reason}"
+
+
+def publish(
+    store: GraphStore, repo_root: Path, output_path: Path, publish_to_uq: bool = False,
+) -> Path:
+    """Write JSON and optionally ping the registry. Always writes the JSON."""
+    written = write_publish_json(store, repo_root, output_path)
+    print(f"JSON exported: {written}")
+
+    if not publish_to_uq:
+        return written
+
+    token = os.environ.get("UNDERSTAND_QUICKLY_TOKEN")
+    if not token:
+        print(
+            "[understand-quickly] UNDERSTAND_QUICKLY_TOKEN not set; "
+            "skipping repository_dispatch (nightly sync will pick this up)."
+        )
+        return written
+
+    owner_repo = _git_origin_owner_repo(repo_root)
+    if owner_repo is None:
+        print(
+            "[understand-quickly] could not derive owner/repo from "
+            "`git remote get-url origin`; skipping dispatch."
+        )
+        return written
+
+    owner, repo = owner_repo
+    ok, message = fire_dispatch(owner, repo, token)
+    if ok:
+        print(f"[understand-quickly] {message} for {owner}/{repo}")
+    else:
+        print(
+            f"[understand-quickly] dispatch failed for {owner}/{repo}: {message}. "
+            "If this repo is not yet registered, register it once with: "
+            "npx @understand-quickly/cli add"
+        )
+    return written
diff --git a/tests/test_publish.py b/tests/test_publish.py
new file mode 100644
index 00000000..4f07d440
--- /dev/null
+++ b/tests/test_publish.py
@@ -0,0 +1,135 @@
+"""Tests for the opt-in understand-quickly publish flow."""
+
+from __future__ import annotations
+
+import io
+import json
+import re
+from pathlib import Path
+from unittest import mock
+
+import pytest
+
+from code_review_graph import publish as publish_mod
+from code_review_graph.graph import GraphStore
+from code_review_graph.parser import NodeInfo
+
+
+@pytest.fixture
+def store(tmp_path: Path) -> GraphStore:
+    db_path = tmp_path / "test.db"
+    s = GraphStore(db_path)
+    s.upsert_node(
+        NodeInfo(
+            kind="File",
+            name="auth.py",
+            file_path="src/auth.py",
+            line_start=1,
+            line_end=10,
+            language="python",
+            parent_name=None,
+            params=None,
+            return_type=None,
+            modifiers=None,
+            is_test=False,
+            extra={},
+        )
+    )
+    return s
+
+
+def test_build_publish_payload_embeds_metadata(store: GraphStore, tmp_path: Path):
+    payload = publish_mod.build_publish_payload(store, tmp_path)
+    assert "nodes" in payload and "edges" in payload
+    md = payload["metadata"]
+    assert md["tool"] == "code-review-graph"
+    assert md["tool_version"]  # non-empty
+    assert re.fullmatch(r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z", md["generated_at"])
+    # commit is omitted when not in a git repo (tmp_path has no .git)
+    assert "commit" not in md or re.fullmatch(r"[0-9a-f]{40}", md["commit"])
+
+
+def test_write_publish_json_writes_to_disk(store: GraphStore, tmp_path: Path):
+    out = tmp_path / ".code-review-graph" / "graph.json"
+    publish_mod.write_publish_json(store, tmp_path, out)
+    assert out.exists()
+    data = json.loads(out.read_text())
+    assert data["metadata"]["tool"] == "code-review-graph"
+
+
+def test_publish_without_token_skips_dispatch(
+    store: GraphStore, tmp_path: Path, monkeypatch, capsys
+):
+    monkeypatch.delenv("UNDERSTAND_QUICKLY_TOKEN", raising=False)
+    out = tmp_path / "graph.json"
+    with mock.patch.object(publish_mod.urlrequest, "urlopen") as m_open:
+        publish_mod.publish(store, tmp_path, out, publish_to_uq=True)
+    m_open.assert_not_called()
+    captured = capsys.readouterr().out
+    assert "UNDERSTAND_QUICKLY_TOKEN not set" in captured
+
+
+def test_publish_with_token_fires_dispatch(
+    store: GraphStore, tmp_path: Path, monkeypatch, capsys
+):
+    monkeypatch.setenv("UNDERSTAND_QUICKLY_TOKEN", "ghp_fake")
+
+    fake_resp = mock.MagicMock()
+    fake_resp.__enter__.return_value = fake_resp
+    fake_resp.status = 204
+    fake_resp.getcode.return_value = 204
+
+    with mock.patch.object(
+        publish_mod, "_git_origin_owner_repo", return_value=("looptech-ai", "demo")
+    ), mock.patch.object(publish_mod.urlrequest, "urlopen", return_value=fake_resp) as m_open:
+        out = tmp_path / "graph.json"
+        publish_mod.publish(store, tmp_path, out, publish_to_uq=True)
+
+    m_open.assert_called_once()
+    sent = m_open.call_args[0][0]
+    assert sent.full_url == publish_mod.DISPATCH_URL
+    body = json.loads(sent.data.decode())
+    assert body == {
+        "event_type": "sync-entry",
+        "client_payload": {"id": "looptech-ai/demo"},
+    }
+    assert sent.headers["Authorization"] == "Bearer ghp_fake"
+    captured = capsys.readouterr().out
+    assert "dispatch sent" in captured
+
+
+def test_publish_dispatch_failure_is_soft(
+    store: GraphStore, tmp_path: Path, monkeypatch, capsys
+):
+    monkeypatch.setenv("UNDERSTAND_QUICKLY_TOKEN", "ghp_fake")
+    from urllib import error as urlerror
+
+    err = urlerror.HTTPError(
+        publish_mod.DISPATCH_URL, 422, "Unprocessable", {}, io.BytesIO(b"")
+    )
+    out = tmp_path / "graph.json"
+    with mock.patch.object(
+        publish_mod, "_git_origin_owner_repo", return_value=("looptech-ai", "demo")
+    ), mock.patch.object(publish_mod.urlrequest, "urlopen", side_effect=err):
+        # Must not raise — soft-fail and inform the user.
+        publish_mod.publish(store, tmp_path, out, publish_to_uq=True)
+    captured = capsys.readouterr().out
+    assert "dispatch failed" in captured
+    assert "npx @understand-quickly/cli add" in captured
+    assert out.exists()
+
+
+@pytest.mark.parametrize(
+    "url,expected",
+    [
+        ("https://github.com/looptech-ai/demo.git", ("looptech-ai", "demo")),
+        ("https://github.com/looptech-ai/demo", ("looptech-ai", "demo")),
+        ("git@github.com:looptech-ai/demo.git", ("looptech-ai", "demo")),
+        ("git@github.com:looptech-ai/demo", ("looptech-ai", "demo")),
+    ],
+)
+def test_origin_owner_repo_parsing(url: str, expected: tuple[str, str], tmp_path: Path):
+    with mock.patch.object(
+        publish_mod.subprocess, "check_output", return_value=(url + "\n").encode()
+    ):
+        assert publish_mod._git_origin_owner_repo(tmp_path) == expected