diff --git a/core/cli.py b/core/cli.py
new file mode 100644
index 00000000..61dc7b9b
--- /dev/null
+++ b/core/cli.py
@@ -0,0 +1,180 @@
+"""core CLI — single entry point for the versor engine.
+
+Subcommands
+-----------
+core chat              Start interactive chat session (delegates to python -m chat)
+core test [args]       Run pytest suite with sane defaults
+core check             Run ruff on the whole project
+core trace <text>      Trace one turn: show field condition, dialogue role, proposition
+core oov <token>       Ground a single unknown token and show the constructed versor info
+core pack list         List mounted language packs
+core pack verify <id>  Verify a language pack checksum
+"""
+from __future__ import annotations
+
+import subprocess
+import sys
+from typing import NoReturn
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _run(*args: str, check: bool = True) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(args, check=check, text=True)
+
+
+def _die(msg: str) -> NoReturn:
+    print(f"error: {msg}", file=sys.stderr)
+    sys.exit(1)
+
+
+def _usage() -> NoReturn:
+    print(__doc__)
+    sys.exit(0)
+
+
+# ---------------------------------------------------------------------------
+# Subcommands
+# ---------------------------------------------------------------------------
+
+def cmd_chat(argv: list[str]) -> None:
+    """Launch the readline REPL backed by ChatRuntime."""
+    _run(sys.executable, "-m", "chat", *argv, check=False)
+
+
+def cmd_test(argv: list[str]) -> None:
+    """Run the pytest suite.  Extra args are forwarded to pytest."""
+    default_args = ["-q", "--tb=short"]
+    _run(sys.executable, "-m", "pytest", *(argv or default_args), check=False)
+
+
+def cmd_check(argv: list[str]) -> None:
+    """Run ruff over the project source."""
+    targets = argv or [
+        "algebra", "ingest", "field", "vocab", "vault", "persona",
+        "generate", "session", "chat", "core", "language_packs", "tests",
+    ]
+    _run(sys.executable, "-m", "ruff", "check", *targets, check=False)
+
+
+def cmd_trace(argv: list[str]) -> None:
+    """Trace one chat turn and print field telemetry."""
+    if not argv:
+        _die("usage: core trace <text>")
+    text = " ".join(argv)
+
+    from chat.runtime import ChatRuntime
+    rt = ChatRuntime()
+    resp = rt.chat(text)
+
+    print(f"input          : {text}")
+    print(f"surface        : {resp.surface}")
+    print(f"dialogue_role  : {resp.dialogue_role}")
+    print(f"versor_cond    : {resp.versor_condition:.2e}")
+    p = resp.proposition
+    print(f"proposition    : {p.surface!r}")
+    print(f"  frame_id     : {p.frame_id}")
+    print(f"  subject      : {p.subject_surface!r}")
+    print(f"  predicate    : {p.predicate_surface!r}")
+    if hasattr(p, "object_surface") and p.object_surface:
+        print(f"  object       : {p.object_surface!r}")
+    import numpy as np
+    print(f"  relation_norm: {float(np.linalg.norm(p.relation)):.4f}")
+
+    session = rt.session
+    print(f"vault_entries  : {len(session.vault)}")
+    oov = getattr(session.vocab, "unknown_token_log", [])
+    if oov:
+        print(f"oov_grounded   : {len(oov)} token(s)")
+        for entry in oov:
+            print(f"  {entry}")
+
+
+def cmd_oov(argv: list[str]) -> None:
+    """Ground a single unknown token and show the constructed versor info."""
+    if not argv:
+        _die("usage: core oov <token>")
+    token = argv[0]
+
+    from chat.runtime import ChatRuntime
+    from algebra.versor import versor_condition
+    rt = ChatRuntime()
+    vocab = rt.session.vocab
+
+    # Try known first
+    try:
+        v = vocab.get_versor(token)
+        print(f"{token!r} is already in the manifold")
+        import numpy as np
+        print(f"  versor_cond: {versor_condition(v):.2e}")
+        return
+    except KeyError:
+        pass
+
+    # Ground it
+    from ingest.gate import inject
+    state = inject([token], vocab)
+
+    import numpy as np
+    print(f"{token!r} — grounded as transient")
+    print(f"  versor_cond : {versor_condition(state.F):.2e}")
+    oov_log = getattr(vocab, "unknown_token_log", [])
+    if oov_log:
+        last = oov_log[-1]
+        print(f"  root_used   : {last.get('root_used', '?')}")
+        print(f"  ops_applied : {last.get('operators_applied', [])}")
+
+
+def cmd_pack(argv: list[str]) -> None:
+    """Manage language packs."""
+    if not argv:
+        _die("usage: core pack [list | verify <pack_id>]")
+
+    sub = argv[0]
+
+    if sub == "list":
+        from language_packs import list_packs
+        packs = list_packs()
+        if not packs:
+            print("no compiled packs found")
+        for pid in packs:
+            print(pid)
+
+    elif sub == "verify":
+        if len(argv) < 2:
+            _die("usage: core pack verify <pack_id>")
+        pack_id = argv[1]
+        _run(sys.executable, "-m", "language_packs", "verify", pack_id, check=False)
+
+    else:
+        _die(f"unknown pack subcommand: {sub!r}")
+
+
+# ---------------------------------------------------------------------------
+# Dispatch
+# ---------------------------------------------------------------------------
+
+_COMMANDS = {
+    "chat":  cmd_chat,
+    "test":  cmd_test,
+    "check": cmd_check,
+    "trace": cmd_trace,
+    "oov":   cmd_oov,
+    "pack":  cmd_pack,
+}
+
+
+def main() -> None:
+    args = sys.argv[1:]
+    if not args or args[0] in {"-h", "--help"}:
+        _usage()
+    sub = args[0]
+    if sub not in _COMMANDS:
+        _die(f"unknown subcommand {sub!r}. Try: {', '.join(_COMMANDS)}")
+    _COMMANDS[sub](args[1:])
+
+
+if __name__ == "__main__":
+    main()
diff --git a/pyproject.toml b/pyproject.toml
index cb1beec6..a4d2a665 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,9 @@ dev = [
     "hypothesis>=6.100",
 ]
 
+[project.scripts]
+core = "core.cli:main"
+
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
 testpaths = ["tests"]