fix: model cost/info matches first substring key (gpt-4o-mini billed as gpt-4o) (#1439)

* fix: match model name to the longest known key, not the first substring

* test: model key matching prefers the longest specific key

tests/test_match_model_key_js.py

@@ -0,0 +1,48 @@
+"""Pin matchModelKey (static/js/model/matchKey.js).
+
+Driven through `node --input-type=module` (same approach as test_compare_js.py);
+skips when `node` is not installed.
+
+Regression: model name -> info/pricing lookups returned the FIRST substring
+match, so "gpt-4o-mini" matched the shorter "gpt-4o" key and was billed at
+gpt-4o rates (~16x) with the wrong context window.
+"""
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+_REPO = Path(__file__).resolve().parent.parent
+_HELPER = _REPO / "static" / "js" / "model" / "matchKey.js"
+_HAS_NODE = shutil.which("node") is not None
+
+_KEYS = ["gpt-4o", "gpt-4o-mini", "gpt-4", "o1", "o1-mini", "o1-pro", "o3", "o3-mini"]
+
+
+def _match(name):
+    js = (
+        f"import {{ matchModelKey }} from '{_HELPER.as_posix()}';"
+        f"console.log(JSON.stringify(matchModelKey({json.dumps(name)}, {json.dumps(_KEYS)})));"
+    )
+    proc = subprocess.run(
+        ["node", "--input-type=module"],
+        input=js, capture_output=True, text=True, cwd=str(_REPO), timeout=30,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout.strip())
+
+
+@pytest.mark.skipif(not _HAS_NODE, reason="node binary not on PATH")
+def test_prefers_longest_specific_key():
+    assert _match("gpt-4o-mini") == "gpt-4o-mini"
+    assert _match("o1-mini") == "o1-mini"
+    assert _match("o1-pro") == "o1-pro"
+    assert _match("o3-mini") == "o3-mini"
+
+
+@pytest.mark.skipif(not _HAS_NODE, reason="node binary not on PATH")
+def test_base_model_and_unknown():
+    assert _match("gpt-4o-2024-08-06") == "gpt-4o"
+    assert _match("some-unknown-model") is None