diff --git a/graphify/__main__.py b/graphify/__main__.py
index 74ffb8b..87f3d7b 100644
--- a/graphify/__main__.py
+++ b/graphify/__main__.py
@@ -1002,6 +1002,7 @@ def main() -> None:
         print("  watch <path>            watch a folder and rebuild the graph on code changes")
         print("  update <path>           re-extract code files and update the graph (no LLM needed)")
         print("  cluster-only <path>     rerun clustering on an existing graph.json and regenerate report")
+        print("    --no-viz                skip graph.html generation (useful for >5000 node graphs / CI)")
         print("  query \"<question>\"       BFS traversal of graph.json for a question")
         print("    --dfs                   use depth-first instead of breadth-first")
         print("    --budget N              cap output at N tokens (default 2000)")
@@ -1379,6 +1380,7 @@ def main() -> None:
 
     elif cmd == "cluster-only":
         watch_path = Path(sys.argv[2]) if len(sys.argv) > 2 else Path(".")
+        no_viz = "--no-viz" in sys.argv
         graph_json = watch_path / "graphify-out" / "graph.json"
         if not graph_json.exists():
             print(f"error: no graph found at {graph_json} — run /graphify first", file=sys.stderr)
@@ -1407,8 +1409,25 @@ def main() -> None:
         out = watch_path / "graphify-out"
         (out / "GRAPH_REPORT.md").write_text(report, encoding="utf-8")
         to_json(G, communities, str(out / "graph.json"))
-        to_html(G, communities, str(out / "graph.html"), community_labels=labels or None)
-        print(f"Done — {len(communities)} communities. GRAPH_REPORT.md, graph.json and graph.html updated.")
+
+        # Mirror watch.py pattern: gate to_html so core outputs (graph.json +
+        # GRAPH_REPORT.md) always land. Honor --no-viz explicitly; otherwise
+        # fall back to ValueError handling so an oversized graph doesn't crash
+        # the CLI mid-write and leave a stale graph.html on disk.
+        html_target = out / "graph.html"
+        if no_viz:
+            if html_target.exists():
+                html_target.unlink()
+            print(f"Done — {len(communities)} communities. GRAPH_REPORT.md and graph.json updated (--no-viz; graph.html removed).")
+        else:
+            try:
+                to_html(G, communities, str(html_target), community_labels=labels or None)
+                print(f"Done — {len(communities)} communities. GRAPH_REPORT.md, graph.json and graph.html updated.")
+            except ValueError as viz_err:
+                if html_target.exists():
+                    html_target.unlink()
+                print(f"Skipped graph.html: {viz_err}")
+                print(f"Done — {len(communities)} communities. GRAPH_REPORT.md and graph.json updated.")
 
     elif cmd == "update":
         if len(sys.argv) > 2:
diff --git a/graphify/export.py b/graphify/export.py
index 220a940..2dce21d 100644
--- a/graphify/export.py
+++ b/graphify/export.py
@@ -25,6 +25,22 @@ COMMUNITY_COLORS = [
 MAX_NODES_FOR_VIZ = 5_000
 
 
+def _viz_node_limit() -> int:
+    """Return the effective viz node limit, honoring GRAPHIFY_VIZ_NODE_LIMIT env var.
+
+    Falls back to MAX_NODES_FOR_VIZ when the env var is unset, empty, or non-integer.
+    Set to 0 to disable HTML viz unconditionally (useful for CI runners).
+    """
+    import os
+    raw = os.environ.get("GRAPHIFY_VIZ_NODE_LIMIT")
+    if raw is None or not raw.strip():
+        return MAX_NODES_FOR_VIZ
+    try:
+        return int(raw)
+    except ValueError:
+        return MAX_NODES_FOR_VIZ
+
+
 def _html_styles() -> str:
     return """<style>
   * { box-sizing: border-box; margin: 0; padding: 0; }
@@ -395,15 +411,18 @@ def to_html(
 
     Features: node size by degree, click-to-inspect panel, search box,
     community filter, physics clustering by community, confidence-styled edges.
-    Raises ValueError if graph exceeds MAX_NODES_FOR_VIZ.
+    Raises ValueError if graph exceeds the effective viz node limit
+    (MAX_NODES_FOR_VIZ by default; overridable via GRAPHIFY_VIZ_NODE_LIMIT env var).
 
     If member_counts is provided (aggregated community view), node sizes are
     based on community member counts rather than graph degree.
     """
-    if G.number_of_nodes() > MAX_NODES_FOR_VIZ:
+    limit = _viz_node_limit()
+    if G.number_of_nodes() > limit:
         raise ValueError(
-            f"Graph has {G.number_of_nodes()} nodes - too large for HTML viz. "
-            f"Use --no-viz or reduce input size."
+            f"Graph has {G.number_of_nodes()} nodes - too large for HTML viz "
+            f"(limit: {limit}). Use --no-viz, raise GRAPHIFY_VIZ_NODE_LIMIT, "
+            f"or reduce input size."
         )
 
     node_community = _node_community_map(communities)
diff --git a/tests/test_export.py b/tests/test_export.py
index e93ba81..3f892b1 100644
--- a/tests/test_export.py
+++ b/tests/test_export.py
@@ -1,9 +1,19 @@
 import json
+import os
 import tempfile
+import pytest
 from pathlib import Path
 from graphify.build import build_from_json
 from graphify.cluster import cluster
-from graphify.export import to_json, to_cypher, to_graphml, to_html, to_canvas
+from graphify.export import (
+    to_json,
+    to_cypher,
+    to_graphml,
+    to_html,
+    to_canvas,
+    _viz_node_limit,
+    MAX_NODES_FOR_VIZ,
+)
 
 FIXTURES = Path(__file__).parent / "fixtures"
 
@@ -127,6 +137,62 @@ def test_to_html_contains_nodes_and_edges():
         assert "RAW_EDGES" in content
 
 
+# --- GRAPHIFY_VIZ_NODE_LIMIT env var --------------------------------------------
+
+@pytest.fixture
+def restore_viz_env(monkeypatch):
+    """Ensure each test runs without GRAPHIFY_VIZ_NODE_LIMIT bleeding across cases."""
+    monkeypatch.delenv("GRAPHIFY_VIZ_NODE_LIMIT", raising=False)
+    yield
+
+
+def test_viz_node_limit_default(restore_viz_env):
+    assert _viz_node_limit() == MAX_NODES_FOR_VIZ
+
+
+def test_viz_node_limit_env_override_higher(restore_viz_env, monkeypatch):
+    monkeypatch.setenv("GRAPHIFY_VIZ_NODE_LIMIT", "20000")
+    assert _viz_node_limit() == 20000
+
+
+def test_viz_node_limit_env_override_zero_disables(restore_viz_env, monkeypatch):
+    """Setting to 0 lets users disable HTML viz unconditionally (CI runners)."""
+    monkeypatch.setenv("GRAPHIFY_VIZ_NODE_LIMIT", "0")
+    assert _viz_node_limit() == 0
+
+
+def test_viz_node_limit_invalid_falls_back_to_default(restore_viz_env, monkeypatch):
+    monkeypatch.setenv("GRAPHIFY_VIZ_NODE_LIMIT", "not-an-int")
+    assert _viz_node_limit() == MAX_NODES_FOR_VIZ
+
+
+def test_viz_node_limit_empty_falls_back_to_default(restore_viz_env, monkeypatch):
+    monkeypatch.setenv("GRAPHIFY_VIZ_NODE_LIMIT", "  ")
+    assert _viz_node_limit() == MAX_NODES_FOR_VIZ
+
+
+def test_to_html_raises_with_lowered_limit(restore_viz_env, monkeypatch):
+    """Lowering the limit below the test graph's size triggers ValueError."""
+    G = make_graph()
+    communities = cluster(G)
+    monkeypatch.setenv("GRAPHIFY_VIZ_NODE_LIMIT", "1")
+    with tempfile.TemporaryDirectory() as tmp:
+        out = Path(tmp) / "graph.html"
+        with pytest.raises(ValueError, match="too large for HTML viz"):
+            to_html(G, communities, str(out))
+
+
+def test_to_html_writes_with_raised_limit(restore_viz_env, monkeypatch):
+    """Raising the limit above the graph's size lets to_html proceed normally."""
+    G = make_graph()
+    communities = cluster(G)
+    monkeypatch.setenv("GRAPHIFY_VIZ_NODE_LIMIT", "100000")
+    with tempfile.TemporaryDirectory() as tmp:
+        out = Path(tmp) / "graph.html"
+        to_html(G, communities, str(out))
+        assert out.exists()
+
+
 def test_to_html_member_counts_accepted():
     """to_html accepts member_counts without raising."""
     G = make_graph()