Add support for ENV based HF_TOKEN.

app/model_downloader/constants.py

@@ -17,6 +17,15 @@ AUTH_SCHEME_HEADER = "header"
 AUTH_SCHEME_QUERY = "query"
 AUTH_SCHEMES = (AUTH_SCHEME_BEARER, AUTH_SCHEME_HEADER, AUTH_SCHEME_QUERY)
 
+# Hosts for which a bearer token can be sourced from the environment when no
+# stored credential matches. Values are the env var names to try, in order.
+# Only consulted during auto-resolve for an exact host match over https, so the
+# same per-hop boundary rules apply (e.g. the token is dropped on a redirect to
+# a CDN host). Kept here so the host->env-var mapping lives in one place.
+ENV_TOKEN_HOSTS = {
+    "huggingface.co": ("HF_TOKEN", "HUGGING_FACE_HUB_TOKEN"),
+}
+
 
 class DownloadStatus:
     QUEUED = "queued"

app/model_downloader/credentials/resolver.py

@@ -10,6 +10,7 @@ which is exactly what these hubs expect.
 from __future__ import annotations
 
 import asyncio
+import os
 from dataclasses import dataclass, field
 from typing import Optional
 from urllib.parse import urlencode, urlsplit, urlunsplit
@@ -18,6 +19,7 @@ from app.model_downloader.constants import (
     AUTH_SCHEME_BEARER,
     AUTH_SCHEME_HEADER,
     AUTH_SCHEME_QUERY,
+    ENV_TOKEN_HOSTS,
 )
 from app.model_downloader.credentials.store import normalize_host
 from app.model_downloader.database import queries
@@ -89,6 +91,14 @@ def _resolve_sync(
     for sub in queries.list_subdomain_credentials():
         if sub.enabled and _matches(sub, hop_host):
             return _build_auth(sub)
+
+    # Env fallback: only for an exact host match, and only after the DB lookups
+    # miss, so a user-set credential always takes precedence. The token is never
+    # persisted; it is read fresh from the environment on each hop.
+    for var in ENV_TOKEN_HOSTS.get(hop_host, ()):
+        token = os.environ.get(var)
+        if token:
+            return RequestAuth(headers={"Authorization": f"Bearer {token}"})
     return None
 
 

tests-unit/model_downloader_test/test_credentials.py

@@ -108,3 +108,59 @@ def test_resolver_never_crosses_host_boundary():
         finally:
             await CREDENTIAL_STORE.delete(view.id)
     asyncio.run(_run())
+
+
+# ----- env-based HF token fallback -----
+
+
+def test_env_token_fallback_attaches_when_no_db_credential(monkeypatch):
+    monkeypatch.setenv("HF_TOKEN", "env_hf_token")
+
+    async def _run():
+        # exact host over https -> env token attached
+        auth = await resolver.resolve_auth_for_hop("huggingface.co", "https")
+        assert auth is not None
+        assert auth.headers["Authorization"] == "Bearer env_hf_token"
+        # non-https hop -> never attached
+        assert await resolver.resolve_auth_for_hop("huggingface.co", "http") is None
+        # CDN redirect host -> dropped (exact-host only)
+        assert await resolver.resolve_auth_for_hop("cdn-lfs.huggingface.co", "https") is None
+    asyncio.run(_run())
+
+
+def test_env_token_secondary_var_is_honored(monkeypatch):
+    monkeypatch.delenv("HF_TOKEN", raising=False)
+    monkeypatch.setenv("HUGGING_FACE_HUB_TOKEN", "env_hub_token")
+
+    async def _run():
+        auth = await resolver.resolve_auth_for_hop("huggingface.co", "https")
+        assert auth is not None
+        assert auth.headers["Authorization"] == "Bearer env_hub_token"
+    asyncio.run(_run())
+
+
+def test_db_credential_takes_precedence_over_env(monkeypatch):
+    monkeypatch.setenv("HF_TOKEN", "env_hf_token")
+
+    async def _run():
+        view = await CREDENTIAL_STORE.upsert("huggingface.co", "db_secret_key")
+        try:
+            auth = await resolver.resolve_auth_for_hop("huggingface.co", "https")
+            assert auth is not None
+            assert auth.headers["Authorization"] == "Bearer db_secret_key"
+        finally:
+            await CREDENTIAL_STORE.delete(view.id)
+    asyncio.run(_run())
+
+
+def test_env_token_does_not_leak_into_explicit_path(monkeypatch):
+    monkeypatch.setenv("HF_TOKEN", "env_hf_token")
+
+    async def _run():
+        # An explicit credential id that doesn't resolve must stay None; the env
+        # fallback only applies to the auto-resolve branch.
+        auth = await resolver.resolve_auth_for_hop(
+            "huggingface.co", "https", explicit_credential_id="does-not-exist"
+        )
+        assert auth is None
+    asyncio.run(_run())