add script to customize model slugs in models.json

scripts/generate_prefixed_model_catalog.py

@@ -0,0 +1,144 @@
+#!/usr/bin/env python3
+"""Fetch a Codex models.json from a public GitHub tag and prefix model slugs.
+
+Example:
+  python scripts/generate_prefixed_model_catalog.py \
+    --tag 0.104.0 \
+    --prefix custom/ \
+    --out ./models.custom.json
+
+This custom models.json can be used to override the default models.json used
+by Codex via the `model_catalog_json` config option.
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import sys
+import urllib.error
+import urllib.request
+from pathlib import Path
+
+
+REPO = "openai/codex"
+RAW_MODELS_URL = "https://raw.githubusercontent.com/{repo}/{tag}/codex-rs/core/models.json"
+HTTP_TIMEOUT_SECONDS = 15.0
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description=(
+            "Fetch codex-rs/core/models.json for a public openai/codex tag and prefix model slugs."
+        )
+    )
+    parser.add_argument("--tag", required=True, help="Git tag/branch/commit to fetch")
+    parser.add_argument(
+        "--prefix",
+        required=True,
+        help="Prefix to add to each model slug (e.g. 'custom/' or 'gateway/')",
+    )
+    parser.add_argument("--out", required=True, help="Output path for the generated JSON")
+    return parser.parse_args()
+
+
+def fetch_catalog(repo: str, tag: str, timeout_seconds: float) -> tuple[str, dict]:
+    url = RAW_MODELS_URL.format(repo=repo, tag=tag)
+    request = urllib.request.Request(
+        url,
+        headers={"User-Agent": "codex-model-catalog-prefixer/1"},
+    )
+    with urllib.request.urlopen(request, timeout=timeout_seconds) as response:
+        payload = response.read()
+    return url, json.loads(payload.decode("utf-8"))
+
+
+def normalize_tag(tag: str) -> str:
+    if tag.startswith("rust-"):
+        return tag
+    if tag.startswith("v"):
+        return f"rust-{tag}"
+    return f"rust-v{tag}"
+
+
+def prefixed(prefix: str, value: str) -> str:
+    if value.startswith(prefix):
+        return value
+    return f"{prefix}{value}"
+
+
+def rewrite_catalog(catalog: dict, prefix: str) -> dict[str, int]:
+    models = catalog.get("models")
+    if not isinstance(models, list):
+        raise ValueError("expected JSON object with a top-level 'models' list")
+
+    slug_updates = 0
+    upgrade_updates = 0
+
+    for idx, model in enumerate(models):
+        if not isinstance(model, dict):
+            raise ValueError(f"models[{idx}] is not an object")
+
+        slug = model.get("slug")
+        if not isinstance(slug, str):
+            raise ValueError(f"models[{idx}].slug is missing or not a string")
+
+        new_slug = prefixed(prefix, slug)
+        if new_slug != slug:
+            model["slug"] = new_slug
+            slug_updates += 1
+
+        upgrade = model.get("upgrade")
+        if isinstance(upgrade, dict):
+            upgrade_model = upgrade.get("model")
+            if isinstance(upgrade_model, str):
+                new_upgrade_model = prefixed(prefix, upgrade_model)
+                if new_upgrade_model != upgrade_model:
+                    upgrade["model"] = new_upgrade_model
+                    upgrade_updates += 1
+
+    return {
+        "models": len(models),
+        "slug_updates": slug_updates,
+        "upgrade_model_updates": upgrade_updates,
+    }
+
+
+def main() -> int:
+    args = parse_args()
+    if not args.prefix:
+        print("error: --prefix must not be empty", file=sys.stderr)
+        return 2
+    tag = normalize_tag(args.tag)
+
+    try:
+        source_url, catalog = fetch_catalog(REPO, tag, HTTP_TIMEOUT_SECONDS)
+        stats = rewrite_catalog(catalog, args.prefix)
+    except urllib.error.HTTPError as err:
+        print(f"error: failed to fetch models.json ({err.code}): {err.url}", file=sys.stderr)
+        return 1
+    except urllib.error.URLError as err:
+        print(f"error: network error while fetching models.json: {err}", file=sys.stderr)
+        return 1
+    except json.JSONDecodeError as err:
+        print(f"error: fetched file is not valid JSON: {err}", file=sys.stderr)
+        return 1
+    except ValueError as err:
+        print(f"error: unexpected models.json shape: {err}", file=sys.stderr)
+        return 1
+
+    out_path = Path(args.out)
+    out_path.parent.mkdir(parents=True, exist_ok=True)
+    out_path.write_text(json.dumps(catalog, indent=2) + "\n", encoding="utf-8")
+
+    print(f"Fetched: {source_url}")
+    print(f"Wrote:   {out_path}")
+    print(
+        "Models: {models} (updated {slug_updates}); upgrade.model updated: "
+        "{upgrade_model_updates}".format(**stats)
+    )
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())