fix(web): bound the /api/model/info context-length probe

get_model_info called get_model_context_length inline. The resolver
chain runs several sequential provider probes, each with its own
multi-second timeout, so an unreachable model.base_url held the
response for tens of seconds. Bound the whole chain to a 5s budget on
a throwaway worker thread; on timeout the response degrades to
auto_context_length=0 while the abandoned probe finishes on its own.

Fixes https://github.com/NousResearch/hermes-agent/issues/63214 (backend half)

hermes_cli/web_routers/models.py

@@ -5,6 +5,7 @@ Extracted from ``hermes_cli.web_server``; helpers/state that tests monkeypatch o
 """
 
 import asyncio
+import concurrent.futures
 import logging
 from typing import Optional
 
@@ -50,6 +51,41 @@ def _load_config_scoped(profile: Optional[str]) -> dict:
         return load_config()
 
 
+# Blocking budget for /api/model/info's context-length resolution. The resolver
+# chain (agent.model_metadata.get_model_context_length) runs several sequential
+# provider probes, each with its own multi-second timeout, so an unreachable or
+# blackholed model.base_url can hold this response for tens of seconds — and the
+# Desktop Model Settings page waits on it (#63214).
+_MODEL_INFO_PROBE_BUDGET_S = 5.0
+
+
+def _bounded_context_length_probe(model: str, base_url: str, provider: str) -> int:
+    """``get_model_context_length`` with the route's blocking budget.
+
+    On timeout the abandoned probe keeps running in its worker thread (bounded
+    by its own per-request timeouts) while the response degrades to
+    ``auto_context_length = 0`` ("auto-detected: unknown").
+    """
+    from agent.model_metadata import get_model_context_length
+
+    pool = concurrent.futures.ThreadPoolExecutor(max_workers=1, thread_name_prefix="model-info-probe")
+    try:
+        return pool.submit(
+            get_model_context_length, model=model, base_url=base_url, provider=provider,
+            config_context_length=None
+        ).result(timeout=_MODEL_INFO_PROBE_BUDGET_S)
+    except concurrent.futures.TimeoutError:
+        _log.warning(
+            "GET /api/model/info: context-length probe for %r at %s exceeded %.1fs — returning unknown",
+            model, base_url or "<default>", _MODEL_INFO_PROBE_BUDGET_S,
+        )
+        return 0
+    finally:
+        # wait=False: never block the response (or interpreter exit) on the
+        # abandoned probe.
+        pool.shutdown(wait=False)
+
+
 @router.get("/api/model/info")
 def get_model_info(profile: Optional[str] = None):
     """Resolved metadata for the configured model: auto-detected vs configured
@@ -65,10 +101,10 @@ def get_model_info(profile: Optional[str] = None):
             return dict(_EMPTY_MODEL_INFO, provider=provider)
 
         try:
-            from agent.model_metadata import get_model_context_length
-            # config_context_length=None: ignore the override — we want the auto value
-            auto_ctx = get_model_context_length(model=model_name, base_url=base_url, provider=provider,
-                                                config_context_length=None)
+            # config_context_length=None: ignore the override — we want the auto value.
+            # Bounded: the resolver's provider probes can hang for tens of seconds
+            # when model.base_url is unreachable (#63214).
+            auto_ctx = _bounded_context_length_probe(model_name, base_url, provider)
         except Exception:
             auto_ctx = 0
 

tests/hermes_cli/test_model_info_probe_timeout.py

@@ -0,0 +1,67 @@
+"""/api/model/info must bound its context-length probe (#63214).
+
+The resolver chain (``agent.model_metadata.get_model_context_length``) runs
+several sequential provider probes, each with its own multi-second timeout, so
+an unreachable ``model.base_url`` held the response for tens of seconds — and
+the Desktop Model Settings page, which awaits this endpoint inside one
+``Promise.all``, showed loading skeletons indefinitely.
+"""
+
+from __future__ import annotations
+
+import time
+
+
+def _config(model: str, provider: str, base_url: str) -> dict:
+    return {"model": {"default": model, "provider": provider, "base_url": base_url}}
+
+
+def test_model_info_degrades_when_the_context_probe_exceeds_its_budget(monkeypatch):
+    from hermes_cli.web_routers import models as router
+
+    monkeypatch.setattr(
+        router, "_load_config_scoped",
+        lambda profile: _config("some-model", "custom-proxy", "http://localhost:9/v1"),
+    )
+    monkeypatch.setattr(router, "_MODEL_INFO_PROBE_BUDGET_S", 0.2)
+
+    import agent.model_metadata as metadata
+
+    def _hanging_probe(model, base_url="", api_key="", config_context_length=None, provider="", custom_providers=None):
+        time.sleep(1.0)
+        raise AssertionError("the abandoned probe should never be awaited")
+
+    monkeypatch.setattr(metadata, "get_model_context_length", _hanging_probe)
+
+    started = time.monotonic()
+    info = router.get_model_info()
+    elapsed = time.monotonic() - started
+
+    # The response degrades to "auto context unknown" instead of hanging…
+    assert info["model"] == "some-model"
+    assert info["provider"] == "custom-proxy"
+    assert info["auto_context_length"] == 0
+    # …and it returns within the (shrunk) budget, not the probe's 1s sleep.
+    assert elapsed < 0.9
+
+
+def test_model_info_surfaces_the_context_value_when_the_probe_is_fast(monkeypatch):
+    from hermes_cli.web_routers import models as router
+
+    monkeypatch.setattr(
+        router, "_load_config_scoped",
+        lambda profile: _config("some-model", "custom-proxy", "http://localhost:9/v1"),
+    )
+
+    import agent.model_metadata as metadata
+
+    def _fast_probe(model, base_url="", api_key="", config_context_length=None, provider="", custom_providers=None):
+        return 131072
+
+    monkeypatch.setattr(metadata, "get_model_context_length", _fast_probe)
+
+    info = router.get_model_info()
+
+    assert info["model"] == "some-model"
+    assert info["auto_context_length"] == 131072
+    assert info["effective_context_length"] == 131072