diff --git a/README.md b/README.md
index 0459f57cf..91590aeb1 100644
--- a/README.md
+++ b/README.md
@@ -307,7 +307,7 @@ This writes a small config file that tells your assistant to consult the knowled
 
 **CodeBuddy** does the same two things as Claude Code: writes a `CODEBUDDY.md` section telling CodeBuddy to read `graphify-out/GRAPH_REPORT.md` before answering architecture questions, and installs `PreToolUse` hooks (`.codebuddy/settings.json`) that fire before Bash search commands and file reads, nudging toward `graphify query` instead.
 
-**Codex** writes to `AGENTS.md` and also installs a `PreToolUse` hook in `.codex/hooks.json` that fires before every Bash tool call, same always-on mechanism as Claude Code.
+**Codex** writes to `AGENTS.md`, which is what actually carries the always-on graph guidance on this platform. `graphify codex install` also registers a `PreToolUse` hook in `.codex/hooks.json` (`graphify hook-check`), but that entry is deliberately a **no-op**: Codex Desktop rejects `hookSpecificOutput.additionalContext` on `PreToolUse`, so emitting a nudge there would break Bash tool calls. Unlike Claude Code — where the hook (`graphify hook-guard`) does the nudging — on Codex the hook fires and intentionally does nothing, and `AGENTS.md` is the always-on mechanism.
 
 **Kilo Code** installs the Graphify skill to `~/.config/kilo/skills/graphify/SKILL.md` and a native `/graphify` command to `~/.config/kilo/command/graphify.md`. `graphify kilo install` also writes `AGENTS.md` plus a native `tool.execute.before` plugin (`.kilo/plugins/graphify.js` + `.kilo/kilo.json` or `.kilo/kilo.jsonc` registration) so Kilo gets the same always-on graph reminder behavior through native `.kilo` config.
 
diff --git a/graphify/install.py b/graphify/install.py
index 1a8d3e3d3..2df3b72c2 100644
--- a/graphify/install.py
+++ b/graphify/install.py
@@ -1388,7 +1388,11 @@ def _install_codex_hook(project_dir: Path) -> None:
     existing["hooks"]["PreToolUse"] = [h for h in pre_tool if "graphify" not in str(h)]
     existing["hooks"]["PreToolUse"].extend(hook_entry["hooks"]["PreToolUse"])
     hooks_path.write_text(json.dumps(existing, indent=2), encoding="utf-8")
-    print(f"  .codex/hooks.json  ->  PreToolUse hook registered ({graphify_exe} hook-check)")
+    print(
+        f"  .codex/hooks.json  ->  PreToolUse hook registered ({graphify_exe} hook-check"
+        " - intentional no-op; Codex Desktop rejects additionalContext on PreToolUse,"
+        " so graph guidance comes from AGENTS.md)"
+    )
 def _uninstall_codex_hook(project_dir: Path) -> None:
     """Remove graphify PreToolUse hook from .codex/hooks.json."""
     hooks_path = project_dir / ".codex" / "hooks.json"
diff --git a/tests/test_install.py b/tests/test_install.py
index ac4497cff..8cea17b4c 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -1116,3 +1116,59 @@ def test_hermes_skill_destination_posix_uses_home():
     with patch("graphify.__main__.platform.system", return_value="Linux"):
         dst = _platform_skill_destination("hermes", project=False)
     assert str(dst).endswith(".hermes/skills/graphify/SKILL.md"), dst
+
+
+def _cli_dispatched_commands() -> set[str]:
+    """Subcommand names the CLI actually dispatches.
+
+    `graphify`'s dispatcher is an `elif cmd == "..."` chain rather than a declarative
+    table, so the set is read back out of the source. Used to prove a hook command
+    written by an installer is not a stale/renamed subcommand (#2165).
+    """
+    import re
+    from graphify import cli
+
+    source = Path(cli.__file__).read_text(encoding="utf-8")
+    names = set(re.findall(r'cmd\s*==\s*"([a-z0-9][a-z0-9-]*)"', source))
+    names |= {
+        m
+        for group in re.findall(r'cmd\s+in\s+\(([^)]*)\)', source)
+        for m in re.findall(r'"([a-z0-9][a-z0-9-]*)"', group)
+    }
+    return names
+
+
+def test_codex_hook_command_is_a_real_cli_subcommand(tmp_path):
+    """#2165: the PreToolUse command in .codex/hooks.json must be a command the CLI
+    dispatches, so a renamed subcommand can never leave a permanently dead hook.
+
+    `hook-check` is intentionally a no-op on Codex (Codex Desktop rejects
+    additionalContext on PreToolUse), but it must still be a *recognized* command --
+    an unrecognized one exits non-zero and would break every Bash tool call.
+    """
+    import json
+
+    from graphify.install import _install_codex_hook
+
+    _install_codex_hook(tmp_path)
+    hooks = json.loads((tmp_path / ".codex" / "hooks.json").read_text(encoding="utf-8"))
+
+    entries = [
+        h
+        for group in hooks["hooks"]["PreToolUse"]
+        for h in group["hooks"]
+        if "graphify" in h.get("command", "")
+    ]
+    assert entries, "codex install must register a graphify PreToolUse hook"
+
+    dispatched = _cli_dispatched_commands()
+    assert "hook-check" in dispatched, "sanity: parser must find known commands"
+
+    for entry in entries:
+        # command is "<abs exe path> <subcommand> [args...]"
+        parts = entry["command"].split()
+        subcommand = parts[1] if len(parts) > 1 else ""
+        assert subcommand in dispatched, (
+            f"codex hook registers {subcommand!r}, which the CLI does not dispatch "
+            f"(#2165). Known commands: {sorted(dispatched)}"
+        )