diff --git a/CHANGELOG.md b/CHANGELOG.md
index aa12cf9a..e6fb671a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,15 @@
 
 ## [Unreleased]
 
+## [v0.51.270] — 2026-06-05 — Release IL (stage-u1 — un-hold batch: author-fixed PRs re-gated)
+
+### Fixed
+- **The pending passkey-challenge cap now evicts the oldest challenges instead of rejecting new ones**, so the anti-unbounded-growth bound can no longer be turned into a lockout DoS (filling the global or per-context cap previously blocked all legitimate registration/login until TTL expiry). (#3624, @Hinotoi-agent)
+- **Model-provider plugins (e.g. Yandex) are now surfaced in the WebUI providers panel** — env-var name and configured status only, never the value — without regressing existing custom-provider handling. (#3613, @pamnard)
+
+### Added
+- **`/use <skill>` slash command** forces a specific skill for the next turn. The directive resolves as part of the next real send (awaiting the in-flight `/api/skills` lookup) and clears only once consumed, so a fast follow-up send can't apply a stale directive to the wrong message. (#3517, @rodboev; implements #2977)
+
 ## [v0.51.269] — 2026-06-05 — Release IK (stage-b2 — sidebar perf + search scope + Windows ctl)
 
 ### Fixed
diff --git a/api/config.py b/api/config.py
index a13cd745..4e39ba8f 100644
--- a/api/config.py
+++ b/api/config.py
@@ -27,6 +27,10 @@ from urllib.parse import parse_qs, urlparse
 
 # ── Basic layout ──────────────────────────────────────────────────────────────
 import api.paths as _paths
+from api.plugin_providers import (
+    effective_provider_display_name as _effective_provider_display_name,
+    is_plugin_model_provider as _is_plugin_model_provider,
+)
 
 HOME = _paths.HOME
 _hermes_home_has_webui_state = _paths._hermes_home_has_webui_state
@@ -3198,6 +3202,12 @@ def invalidate_models_cache():
     # Also delete the disk cache so the next cold build starts fresh.
     # Disk delete is outside the lock — file I/O shouldn't block other readers.
     _delete_models_cache_on_disk()
+    try:
+        from api.plugin_providers import invalidate_plugin_model_provider_cache
+
+        invalidate_plugin_model_provider_cache()
+    except Exception:
+        pass
 
 
 def invalidate_credential_pool_cache(provider_id: str):
@@ -3787,7 +3797,9 @@ def get_available_models() -> dict:
                 # aliases; ``isinstance(_provider_cfg, dict)`` accepts custom
                 # entries that supply their own models/api_key/base_url. (#2399)
                 _is_known_provider = (
-                    _canonical in _PROVIDER_MODELS or _canonical in _PROVIDER_DISPLAY
+                    _canonical in _PROVIDER_MODELS
+                    or _canonical in _PROVIDER_DISPLAY
+                    or _is_plugin_model_provider(_canonical)
                 )
                 _is_provider_config = isinstance(_provider_cfg, dict)
                 if not (_is_known_provider or _is_provider_config):
@@ -4242,7 +4254,7 @@ def get_available_models() -> dict:
                                 group["models_endpoint_error"] = _named_custom_errors[pid]
                             groups.append(group)
                     continue
-                provider_name = _PROVIDER_DISPLAY.get(pid, pid.title())
+                provider_name = _effective_provider_display_name(pid, _PROVIDER_DISPLAY)
                 if pid == "openrouter":
                     # OpenRouter has two model surfaces:
                     #   (1) curated tool-supporting catalog via hermes_cli.models.fetch_openrouter_models()
@@ -4545,7 +4557,11 @@ def get_available_models() -> dict:
                                 "models": models,
                             }
                         )
-                elif pid in _PROVIDER_MODELS or pid in _canonical_to_raw_provider_key:
+                elif (
+                    pid in _PROVIDER_MODELS
+                    or pid in _canonical_to_raw_provider_key
+                    or _is_plugin_model_provider(pid)
+                ):
                     # Look up provider_cfg using the original raw key from
                     # config.yaml so that mixed-case / underscore keys like
                     # ``CLIPpoxy`` or ``snake_case_provider`` still resolve
diff --git a/api/passkeys.py b/api/passkeys.py
index 2aadf980..1bdc800f 100644
--- a/api/passkeys.py
+++ b/api/passkeys.py
@@ -12,6 +12,7 @@ import json
 import os
 import secrets
 import tempfile
+import threading
 import time
 from dataclasses import dataclass
 from pathlib import Path
@@ -29,7 +30,10 @@ except Exception:  # pragma: no cover - exercised by source tests instead
 
 _CREDENTIALS_FILE = STATE_DIR / "passkeys.json"
 _CHALLENGES_FILE = STATE_DIR / ".passkey_challenges.json"
-_CHALLENGE_TTL = 300
+_CHALLENGE_TTL = 90
+_MAX_CHALLENGES = 128
+_MAX_CHALLENGES_PER_CONTEXT = 8
+_CHALLENGES_LOCK = threading.Lock()
 _RP_NAME = "Hermes WebUI"
 
 
@@ -37,6 +41,10 @@ class PasskeyError(ValueError):
     """Raised for user-correctable WebAuthn failures."""
 
 
+class PasskeyRateLimitError(PasskeyError):
+    """Raised when too many outstanding WebAuthn challenges are pending."""
+
+
 def _b64u(data: bytes) -> str:
     return base64.urlsafe_b64encode(data).rstrip(b"=").decode("ascii")
 
@@ -104,6 +112,8 @@ def passkeys_available() -> bool:
 
 
 def _load_challenges() -> dict[str, dict[str, Any]]:
+    # May prune and rewrite the challenge file; callers that mutate the store
+    # must hold _CHALLENGES_LOCK across load→mutate→write.
     raw = _json_load(_CHALLENGES_FILE, {})
     if not isinstance(raw, dict):
         return {}
@@ -117,16 +127,46 @@ def _load_challenges() -> dict[str, dict[str, Any]]:
     return clean
 
 
+def _oldest_challenge_key(data: dict[str, dict[str, Any]], keys: list[str]) -> str | None:
+    if not keys:
+        return None
+    return min(keys, key=lambda k: float(data.get(k, {}).get("ts", 0)))
+
+
+def _evict_oldest_challenges(data: dict[str, dict[str, Any]], kind: str, rp_id: str, origin: str) -> None:
+    """Keep the challenge store bounded while admitting the newest challenge."""
+    while True:
+        same_context = [
+            k for k, v in data.items()
+            if v.get("kind") == kind and v.get("rp_id") == rp_id and v.get("origin") == origin
+        ]
+        if len(same_context) < _MAX_CHALLENGES_PER_CONTEXT:
+            break
+        oldest = _oldest_challenge_key(data, same_context)
+        if oldest is None:
+            break
+        data.pop(oldest, None)
+
+    while len(data) >= _MAX_CHALLENGES:
+        oldest = _oldest_challenge_key(data, list(data))
+        if oldest is None:
+            break
+        data.pop(oldest, None)
+
+
 def _store_challenge(challenge: str, kind: str, rp_id: str, origin: str) -> None:
-    data = _load_challenges()
-    data[challenge] = {"kind": kind, "rp_id": rp_id, "origin": origin, "ts": time.time()}
-    _atomic_write_json(_CHALLENGES_FILE, data)
+    with _CHALLENGES_LOCK:
+        data = _load_challenges()
+        _evict_oldest_challenges(data, kind, rp_id, origin)
+        data[challenge] = {"kind": kind, "rp_id": rp_id, "origin": origin, "ts": time.time()}
+        _atomic_write_json(_CHALLENGES_FILE, data)
 
 
 def _consume_challenge(challenge: str, kind: str) -> dict[str, Any]:
-    data = _load_challenges()
-    entry = data.pop(challenge, None)
-    _atomic_write_json(_CHALLENGES_FILE, data)
+    with _CHALLENGES_LOCK:
+        data = _load_challenges()
+        entry = data.pop(challenge, None)
+        _atomic_write_json(_CHALLENGES_FILE, data)
     if not entry or entry.get("kind") != kind:
         raise PasskeyError("Passkey challenge expired. Try again.")
     return entry
diff --git a/api/plugin_providers.py b/api/plugin_providers.py
new file mode 100644
index 00000000..af9421ce
--- /dev/null
+++ b/api/plugin_providers.py
@@ -0,0 +1,141 @@
+"""Helpers for model-provider plugins (``plugins/model-providers/<name>/``).
+
+The Hermes agent discovers these via ``providers.list_providers()`` and exposes
+them in the CLI model picker.  WebUI must mirror that registry instead of
+relying only on the static ``_PROVIDER_DISPLAY`` / ``_PROVIDER_MODELS`` tables.
+
+Bundled agent profiles (gemini, nous, custom, …) also live in
+``list_providers()``.  WebUI already handles those via static tables and
+dedicated code paths — only *plugin-only* slugs (e.g. user-installed yandex)
+should take the plugin discovery path.
+"""
+
+from __future__ import annotations
+
+import logging
+import threading
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+_PROFILES_LOCK = threading.Lock()
+_PROFILES_BY_NAME: dict[str, Any] | None = None
+_WEBUI_STATIC_PROVIDER_IDS: frozenset[str] | None = None
+
+
+def _webui_static_provider_ids() -> frozenset[str]:
+    """Provider slugs already owned by WebUI static tables / special cases."""
+    global _WEBUI_STATIC_PROVIDER_IDS
+    if _WEBUI_STATIC_PROVIDER_IDS is not None:
+        return _WEBUI_STATIC_PROVIDER_IDS
+    try:
+        from api.config import _PROVIDER_DISPLAY, _PROVIDER_MODELS
+
+        static = (
+            frozenset(_PROVIDER_DISPLAY.keys())
+            | frozenset(_PROVIDER_MODELS.keys())
+            | frozenset({"custom"})
+        )
+    except Exception:
+        static = frozenset({"custom"})
+    _WEBUI_STATIC_PROVIDER_IDS = static
+    return static
+
+
+def _load_profiles_by_name() -> dict[str, Any]:
+    try:
+        from providers import list_providers
+    except Exception:
+        logger.debug("providers package unavailable for plugin discovery", exc_info=True)
+        return {}
+
+    result: dict[str, Any] = {}
+    try:
+        for profile in list_providers():
+            name = str(getattr(profile, "name", "") or "").strip().lower()
+            if name:
+                result[name] = profile
+    except Exception:
+        logger.debug("Failed to enumerate model-provider plugins", exc_info=True)
+        return {}
+    return result
+
+
+def plugin_model_provider_profiles() -> dict[str, Any]:
+    """Return registered model-provider profiles keyed by canonical slug."""
+    global _PROFILES_BY_NAME
+    cached = _PROFILES_BY_NAME
+    if cached is not None:
+        return cached
+    with _PROFILES_LOCK:
+        if _PROFILES_BY_NAME is None:
+            _PROFILES_BY_NAME = _load_profiles_by_name()
+        return _PROFILES_BY_NAME
+
+
+def invalidate_plugin_model_provider_cache() -> None:
+    """Clear cached plugin discovery (e.g. after config reload)."""
+    global _PROFILES_BY_NAME
+    with _PROFILES_LOCK:
+        _PROFILES_BY_NAME = None
+
+
+def plugin_model_provider_ids() -> frozenset[str]:
+    """Slugs from ``list_providers()`` that are not already WebUI-static."""
+    static = _webui_static_provider_ids()
+    return frozenset(
+        pid for pid in plugin_model_provider_profiles().keys() if pid not in static
+    )
+
+
+def plugin_model_provider_display_name(provider_id: str) -> str | None:
+    profile = plugin_model_provider_profiles().get((provider_id or "").strip().lower())
+    if profile is None:
+        return None
+    return str(getattr(profile, "display_name", "") or getattr(profile, "name", "") or "").strip() or None
+
+
+def plugin_model_provider_api_key_env_var(provider_id: str) -> str | None:
+    """Return the primary API-key env var for a plugin provider, if any."""
+    profile = plugin_model_provider_profiles().get((provider_id or "").strip().lower())
+    if profile is None:
+        return None
+    env_vars = getattr(profile, "env_vars", ()) or ()
+    for var in env_vars:
+        upper = str(var).upper()
+        if upper.endswith("_BASE_URL") or upper.endswith("_URL"):
+            continue
+        if upper.endswith("_FOLDER_ID"):
+            continue
+        return str(var)
+    return None
+
+
+def effective_provider_env_var(provider_id: str, static_map: dict[str, str]) -> str | None:
+    pid = (provider_id or "").strip().lower()
+    if not pid:
+        return None
+    if pid in static_map:
+        return static_map[pid]
+    if not is_plugin_model_provider(pid):
+        return None
+    return plugin_model_provider_api_key_env_var(pid)
+
+
+def effective_provider_display_name(provider_id: str, static_map: dict[str, str]) -> str:
+    pid = (provider_id or "").strip().lower()
+    if pid in static_map:
+        return static_map[pid]
+    if is_plugin_model_provider(pid):
+        plugin_name = plugin_model_provider_display_name(pid)
+        if plugin_name:
+            return plugin_name
+    return pid.replace("-", " ").title()
+
+
+def is_plugin_model_provider(provider_id: str) -> bool:
+    """True for plugin-only providers (not already in WebUI static tables)."""
+    pid = (provider_id or "").strip().lower()
+    if not pid or pid in _webui_static_provider_ids():
+        return False
+    return pid in plugin_model_provider_profiles()
diff --git a/api/providers.py b/api/providers.py
index 23c86d9c..12e6f580 100644
--- a/api/providers.py
+++ b/api/providers.py
@@ -43,10 +43,21 @@ from api.config import (
     invalidate_models_cache,
     reload_config,
 )
+from api.plugin_providers import (
+    effective_provider_display_name,
+    effective_provider_env_var,
+    is_plugin_model_provider,
+    plugin_model_provider_ids,
+)
 
 logger = logging.getLogger(__name__)
 
 
+def _provider_env_var_for(provider_id: str) -> str | None:
+    """Resolve the API-key env var for a provider (static table + plugin profiles)."""
+    return effective_provider_env_var(provider_id, _PROVIDER_ENV_VAR)
+
+
 def _custom_provider_name_matches(provider_id: str, name: object) -> bool:
     """Return True when *provider_id* refers to a named custom provider."""
     pid = str(provider_id or "").strip().lower()
@@ -782,7 +793,7 @@ def _provider_has_shadowed_codex_oauth_value(provider_id: str) -> bool:
     if (provider_id or "").strip().lower() != "openai":
         return False
     values: list[object] = []
-    env_var = _PROVIDER_ENV_VAR.get(provider_id)
+    env_var = _provider_env_var_for(provider_id)
     if env_var:
         env_path = _get_hermes_home() / ".env"
         env_values = _load_env_file(env_path)
@@ -923,7 +934,7 @@ def _provider_has_key(provider_id: str) -> bool:
     4. ``config.yaml → providers.<id>.api_key``
     5. ``config.yaml → custom_providers[].api_key`` (for custom providers)
     """
-    env_var = _PROVIDER_ENV_VAR.get(provider_id)
+    env_var = _provider_env_var_for(provider_id)
     if env_var:
         env_path = _get_hermes_home() / ".env"
         env_values = _load_env_file(env_path)
@@ -973,7 +984,7 @@ def _provider_has_key(provider_id: str) -> bool:
 def _get_provider_api_key(provider_id: str) -> str | None:
     """Return a configured provider API key without exposing it to callers."""
     provider_id = (provider_id or "").strip().lower()
-    env_var = _PROVIDER_ENV_VAR.get(provider_id)
+    env_var = _provider_env_var_for(provider_id)
     if env_var:
         env_path = _get_hermes_home() / ".env"
         env_values = _load_env_file(env_path)
@@ -1129,7 +1140,7 @@ def _account_usage_subprocess_env(home: Path, provider: str, api_key: str | None
         if value:
             env[key] = value
 
-    env_var = _PROVIDER_ENV_VAR.get((provider or "").strip().lower())
+    env_var = _provider_env_var_for((provider or "").strip().lower())
     if env_var and api_key:
         env[env_var] = api_key
 
@@ -1752,6 +1763,7 @@ def get_providers() -> dict[str, Any]:
 
     # Collect all known provider IDs from multiple sources
     known_ids = set(_PROVIDER_DISPLAY.keys()) | set(_PROVIDER_MODELS.keys())
+    known_ids.update(plugin_model_provider_ids())
 
     # Also detect providers from config.yaml providers section
     cfg = get_config()
@@ -1763,9 +1775,21 @@ def get_providers() -> dict[str, Any]:
     known_ids.update(_OAUTH_PROVIDERS)
 
     for pid in sorted(known_ids):
-        display_name = _PROVIDER_DISPLAY.get(pid, pid.replace("-", " ").title())
+        display_name = effective_provider_display_name(pid, _PROVIDER_DISPLAY)
         is_oauth = _provider_is_oauth(pid)
         has_key = _provider_has_key(pid)
+        plugin_auth_status: dict[str, Any] | None = None
+        if not has_key and is_plugin_model_provider(pid):
+            try:
+                from hermes_cli.auth import get_auth_status as _gas_plugin
+                _plugin_status = _gas_plugin(pid)
+                if isinstance(_plugin_status, dict) and (
+                    _plugin_status.get("logged_in") or _plugin_status.get("configured")
+                ):
+                    has_key = True
+                    plugin_auth_status = _plugin_status
+            except Exception:
+                logger.debug("Plugin provider auth check failed for %s", pid, exc_info=True)
 
         # Determine key source
         key_source = "none"
@@ -1797,7 +1821,7 @@ def get_providers() -> dict[str, Any]:
                 logger.debug("hermes_cli auth check failed for %s", pid, exc_info=True)
                 # keep has_key from _provider_has_key()
         elif has_key:
-            env_var = _PROVIDER_ENV_VAR.get(pid)
+            env_var = _provider_env_var_for(pid)
             if env_var:
                 env_path = _get_hermes_home() / ".env"
                 env_values = _load_env_file(env_path)
@@ -1821,19 +1845,29 @@ def get_providers() -> dict[str, Any]:
                             aliased = True
                             break
                     if not aliased:
-                        key_source = "config_yaml"
+                        _plugin_ks = (
+                            str(plugin_auth_status.get("key_source") or "").strip()
+                            if isinstance(plugin_auth_status, dict)
+                            else ""
+                        )
+                        key_source = _plugin_ks or "config_yaml"
             else:
-                key_source = "config_yaml"
-        elif pid not in _PROVIDER_ENV_VAR:
+                _plugin_ks = (
+                    str(plugin_auth_status.get("key_source") or "").strip()
+                    if isinstance(plugin_auth_status, dict)
+                    else ""
+                )
+                key_source = _plugin_ks or "config_yaml"
+        elif not _provider_env_var_for(pid):
             # Fallback: provider is not a known API-key provider and not in
             # the hardcoded _OAUTH_PROVIDERS set.  It may be a custom or
             # newly-added OAuth provider (e.g. Anthropic connected via OAuth).
             # Check live auth status so the Providers tab agrees with the
             # model picker (#1212).
             #
-            # IMPORTANT: we skip providers in _PROVIDER_ENV_VAR because they
-            # are pure API-key providers — calling get_auth_status() for every
-            # unconfigured API-key provider would add unnecessary latency
+            # IMPORTANT: we skip providers with a known API-key env var because
+            # they are pure API-key providers — calling get_auth_status() for
+            # every unconfigured API-key provider would add unnecessary latency
             # (network round-trip per provider) on the Settings page.
             # Validate pid looks like a real provider before probing
             import re as _re
@@ -1924,6 +1958,21 @@ def get_providers() -> dict[str, Any]:
                     models_total = len(models)
             except Exception:
                 logger.debug("Failed to load LM Studio models from hermes_cli")
+        if is_plugin_model_provider(pid):
+            try:
+                live_models = _models_from_live_provider_ids(
+                    pid,
+                    _read_live_provider_model_ids(pid),
+                )
+                if live_models:
+                    models = live_models
+                    models_total = len(models)
+            except Exception:
+                logger.debug(
+                    "Failed to load plugin model-provider catalog for %s",
+                    pid,
+                    exc_info=True,
+                )
         # Also include models from config.yaml providers section
         if isinstance(providers_cfg, dict):
             provider_cfg = providers_cfg.get(pid, {})
@@ -1941,11 +1990,13 @@ def get_providers() -> dict[str, Any]:
                 if pid != "nous":
                     models_total = len(models)
 
+        _is_plugin = is_plugin_model_provider(pid)
         providers.append({
             "id": pid,
             "display_name": display_name,
             "has_key": has_key,
-            "configurable": not is_oauth and pid in _PROVIDER_ENV_VAR,
+            "configurable": not is_oauth and bool(_provider_env_var_for(pid)),
+            "is_plugin_provider": _is_plugin,
             "is_oauth": is_oauth,
             "key_source": key_source,
             "auth_error": auth_error,
@@ -2042,11 +2093,11 @@ def set_provider_key(provider_id: str, api_key: str | None) -> dict[str, Any]:
                      f"Use `hermes model` in the terminal to configure it.",
         }
 
-    env_var = _PROVIDER_ENV_VAR.get(provider_id)
+    env_var = _provider_env_var_for(provider_id)
     if not env_var:
         return {
             "ok": False,
-            "error": f"Cannot configure API key for '{_PROVIDER_DISPLAY.get(provider_id, provider_id)}'. "
+            "error": f"Cannot configure API key for '{effective_provider_display_name(provider_id, _PROVIDER_DISPLAY)}'. "
                      f"This provider does not have a known env var mapping.",
         }
 
diff --git a/api/routes.py b/api/routes.py
index 433317ae..cc1d5360 100644
--- a/api/routes.py
+++ b/api/routes.py
@@ -8024,7 +8024,7 @@ def handle_post(handler, parsed) -> bool:
 
     if parsed.path == "/api/auth/passkey/options":
         from api.auth import _passkey_feature_flag_enabled, is_auth_enabled
-        from api.passkeys import PasskeyError, authentication_options
+        from api.passkeys import PasskeyError, PasskeyRateLimitError, authentication_options
 
         if not _passkey_feature_flag_enabled():
             return j(handler, {"error": "Passkey support is disabled. Set HERMES_WEBUI_PASSKEY=1 or webui_passkey_enabled: true to enable."}, status=404)
@@ -8032,6 +8032,8 @@ def handle_post(handler, parsed) -> bool:
             return j(handler, {"error": "Auth not enabled"}, status=400)
         try:
             return j(handler, {"ok": True, "publicKey": authentication_options(handler)})
+        except PasskeyRateLimitError as e:
+            return bad(handler, str(e), status=429)
         except PasskeyError as e:
             return bad(handler, str(e), status=400)
 
@@ -8064,11 +8066,16 @@ def handle_post(handler, parsed) -> bool:
 
     if parsed.path == "/api/auth/passkey/register/options":
         from api.auth import _passkey_feature_flag_enabled
-        from api.passkeys import registration_options
+        from api.passkeys import PasskeyError, PasskeyRateLimitError, registration_options
 
         if not _passkey_feature_flag_enabled():
             return j(handler, {"error": "Passkey support is disabled."}, status=404)
-        return j(handler, {"ok": True, "publicKey": registration_options(handler)})
+        try:
+            return j(handler, {"ok": True, "publicKey": registration_options(handler)})
+        except PasskeyRateLimitError as e:
+            return bad(handler, str(e), status=429)
+        except PasskeyError as e:
+            return bad(handler, str(e), status=400)
 
     if parsed.path == "/api/auth/passkey/register":
         from api.auth import _passkey_feature_flag_enabled
diff --git a/static/commands.js b/static/commands.js
index f9a4f058..e196e342 100644
--- a/static/commands.js
+++ b/static/commands.js
@@ -17,6 +17,7 @@ const COMMANDS=[
   {name:'theme',     desc:t('cmd_theme'), fn:cmdTheme, arg:'name',  noEcho:true},
   {name:'personality', desc:t('cmd_personality'), fn:cmdPersonality, arg:'name', subArgs:'personalities'},
   {name:'skills',    desc:t('cmd_skills'),   fn:cmdSkills,   arg:'query'},
+  {name:'use',       desc:t('cmd_use'),      fn:cmdUse,      arg:'skill-name', subArgs:'skills', noEcho:true},
   {name:'stop',      desc:t('cmd_stop'),     fn:cmdStop,      noEcho:true},
   {name:'goal',      desc:t('cmd_goal'),     fn:cmdGoal,      arg:'[status|pause|resume|clear|text]', subArgs:['status','pause','resume','clear']},
   {name:'queue',     desc:t('cmd_queue'),    fn:cmdQueue,     arg:'message', noEcho:true},
@@ -94,6 +95,7 @@ function getMatchingCommands(prefix){
   return matches;
 }
 
+let _forcedSkillDirectivePending=null;
 let _slashModelCache=null;
 let _slashModelCachePromise=null;
 let _slashPersonalityCache=null;
@@ -912,6 +914,44 @@ async function cmdSkills(args){
   }
 }
 
+async function cmdUse(args){
+  if(!args){
+    S.messages.push({role:'assistant',content:'Usage: `/use <skill-name>` — forces the agent to consult that skill before its next response.'});
+    renderMessages();
+    return;
+  }
+  let resolve;
+  const pending = {sessionId:S.session&&S.session.session_id||null,promise:null};
+  pending.promise = new Promise(r => { resolve = r; });
+  _forcedSkillDirectivePending = pending;
+  const isCurrentSession = () => !pending.sessionId || (S.session&&S.session.session_id)===pending.sessionId;
+  try{
+    const data = await api('/api/skills');
+    const skills = data.skills || [];
+    const match = skills.find(s => (s.name||'').toLowerCase() === args.toLowerCase());
+    if(!match){
+      resolve(null);
+      if(_forcedSkillDirectivePending===pending)_forcedSkillDirectivePending = null;
+      if(isCurrentSession()){
+        const msg = {role:'assistant', content:`No skill named \`${args}\`. Use \`/skills\` to see available skills.`};
+        S.messages.push(msg); renderMessages();
+      }
+      return;
+    }
+    const directive = `[USER OVERRIDE] You MUST consult skill '${match.name}' via skill_view before responding to the next message.`;
+    resolve(directive);
+    if(isCurrentSession()){
+      S.messages.push({role:'assistant', content:`Next turn: skill \`${match.name}\` will be forced.`});
+      renderMessages();
+    }
+    showToast(`Skill \`${match.name}\` will be used for next turn.`);
+  }catch(e){
+    resolve(null);
+    if(_forcedSkillDirectivePending===pending)_forcedSkillDirectivePending = null;
+    showToast('Failed to load skills: '+e.message);
+  }
+}
+
 async function cmdPersonality(args){
   if(!S.session){showToast(t('no_active_session'));return;}
   if(!args){
diff --git a/static/i18n.js b/static/i18n.js
index 5e7d52cc..ea964db6 100644
--- a/static/i18n.js
+++ b/static/i18n.js
@@ -205,6 +205,7 @@ const LOCALES = {
     cmd_theme: 'Switch appearance (theme: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Switch agent personality',
     cmd_skills: 'List available Hermes skills',
+    cmd_use: 'Force a skill for the next message',
     available_commands: 'Available commands:',
     type_slash: 'Type / to see commands',
     conversation_cleared: 'Conversation cleared',
@@ -1541,6 +1542,7 @@ const LOCALES = {
     cmd_theme: 'Cambia aspetto (tema: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: "Cambia personalità dell'agente",
     cmd_skills: 'Elenca le skill Hermes disponibili',
+    cmd_use: 'Forza una skill per il prossimo messaggio',
     available_commands: 'Comandi disponibili:',
     type_slash: 'Digita / per vedere i comandi',
     conversation_cleared: 'Conversazione cancellata',
@@ -2869,6 +2871,7 @@ const LOCALES = {
     cmd_theme: '外観を切り替え (theme: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'エージェントのパーソナリティを切り替え',
     cmd_skills: '利用可能な Hermes スキルを一覧表示',
+    cmd_use: '次のメッセージにスキルを強制適用',
     available_commands: '利用可能なコマンド:',
     type_slash: '/ を入力するとコマンド一覧',
     conversation_cleared: '会話をクリアしました',
@@ -4159,6 +4162,7 @@ const LOCALES = {
     cmd_theme: 'Переключить внешний вид (тема: system/dark/light, скин: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Переключить личность агента',
     cmd_skills: 'Показать доступные навыки Hermes',
+    cmd_use: 'Принудительно применить навык к следующему сообщению',
     available_commands: 'Доступные команды:',
     type_slash: 'Введите /, чтобы увидеть команды',
     conversation_cleared: 'Беседа очищена',
@@ -5458,6 +5462,7 @@ const LOCALES = {
     cmd_theme: 'Cambiar apariencia (tema: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Cambiar la personalidad del agente',
     cmd_skills: 'Listar las skills de Hermes disponibles',
+    cmd_use: 'Forzar una skill para el próximo mensaje',
     available_commands: 'Comandos disponibles:',
     type_slash: 'Escribe / para ver los comandos',
     conversation_cleared: 'Conversación borrada',
@@ -6698,6 +6703,7 @@ const LOCALES = {
     cmd_theme: 'Darstellung wechseln (Theme: system/dark/light, Skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Agenten-Persönlichkeit wechseln',
     cmd_skills: 'Verfügbare Hermes-Skills auflisten',
+    cmd_use: 'Einen Skill für die nächste Nachricht erzwingen',
     available_commands: 'Verfügbare Befehle:',
     type_slash: 'Tippe / für Befehle',
     conversation_cleared: 'Konversation gelöscht',
@@ -7989,6 +7995,7 @@ const LOCALES = {
     cmd_theme: '切换外观（主题：system/dark/light，皮肤：default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus）',
     cmd_personality: '切换 Agent 人设',
     cmd_skills: '列出可用的 Hermes 技能',
+    cmd_use: '为下一条消息强制使用技能',
     available_commands: '可用命令：',
     type_slash: '输入 / 可查看命令',
     conversation_cleared: '对话已清空',
@@ -9266,6 +9273,7 @@ const LOCALES = {
     cmd_theme: '切換外觀（主題：system/dark/light，skin：default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus）',
     cmd_personality: '切換 Agent 角色',
     cmd_skills: '列出可用的 Hermes 技能',
+    cmd_use: '為下一則訊息強制使用技能',
     available_commands: '可用命令：',
     type_slash: '輸入 / 檢視命令',
     conversation_cleared: '已清除對話',
@@ -10513,6 +10521,7 @@ const LOCALES = {
     cmd_theme: 'Trocar aparência (tema: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Trocar personalidade do agente',
     cmd_skills: 'Listar skills disponíveis do Hermes',
+    cmd_use: 'Forçar uma skill para a próxima mensagem',
     available_commands: 'Comandos disponíveis:',
     type_slash: 'Digite / para ver comandos',
     conversation_cleared: 'Conversa limpa',
@@ -11726,6 +11735,7 @@ const LOCALES = {
     cmd_theme: 'Switch appearance (theme: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Switch agent personality',
     cmd_skills: 'List available Hermes skills',
+    cmd_use: 'Force a skill for the next message',
     available_commands: '사용 가능한 명령:',
     type_slash: '/ 를 입력해 명령 보기',
     conversation_cleared: '대화를 지웠습니다',
@@ -13047,6 +13057,7 @@ const LOCALES = {
     cmd_theme: 'Changer d\'apparence (thème : system/dark/light, skin : default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Personnalité de l\'agent de commutation',
     cmd_skills: 'Lister les compétences Hermès disponibles',
+    cmd_use: 'Forcer une compétence pour le prochain message',
     available_commands: 'Commandes disponibles :',
     type_slash: 'Tapez / pour voir les commandes',
     conversation_cleared: 'Conversation effacée',
@@ -14321,6 +14332,7 @@ const LOCALES = {
     cmd_theme: 'Görünümü değiştir (tema: system/dark/light, skin: default/ares/mono/graphite/slate/poseidon/sisyphus/charizard/sienna/catppuccin/nous/geist-contrast/zeus)',
     cmd_personality: 'Temsilci kişiliğini değiştir',
     cmd_skills: 'Mevcut Hermes becerilerini listele',
+    cmd_use: 'Sonraki mesaj için bir beceriyi zorla',
     available_commands: 'Mevcut komutlar:',
     type_slash: 'Komutları görmek için / yazın',
     conversation_cleared: 'Görüşme temizlendi',
diff --git a/static/messages.js b/static/messages.js
index e429df82..5915b348 100644
--- a/static/messages.js
+++ b/static/messages.js
@@ -568,6 +568,16 @@ async function send(){
   let msgText=text;
   if(uploaded.length&&!msgText)msgText=`I've uploaded ${uploaded.length} file(s): ${uploadedPaths.join(', ')}`;
   else if(uploaded.length)msgText=`${text}\n\n[Attached files: ${uploadedPaths.join(', ')}]`;
+  if(_forcedSkillDirectivePending){
+    const _pending=_forcedSkillDirectivePending;
+    if(!_pending.sessionId||_pending.sessionId===activeSid){
+      const _directive = await _pending.promise;
+      if(_forcedSkillDirectivePending===_pending)_forcedSkillDirectivePending = null;
+      if(typeof _directive==='string'&&_directive){
+        msgText=`${_directive}\n\n${msgText||''}`.trim();
+      }
+    }
+  }
   if(!msgText){setComposerStatus('Nothing to send');return;}
 
   $('msg').value='';autoResize();
diff --git a/static/panels.js b/static/panels.js
index a0a07ccf..9315c1bd 100644
--- a/static/panels.js
+++ b/static/panels.js
@@ -6716,7 +6716,7 @@ async function loadProvidersPanel(){
   try{
     const data=await api('/api/providers');
     const quota=await _fetchProviderQuotaStatus(false).catch(e=>({ok:false,status:'unavailable',quota:null,message:e.message||t('provider_quota_unavailable'),client_fetched_at:new Date().toISOString()}));
-    const providers=(data.providers||[]).filter(p=>p.configurable||p.is_oauth||p.is_custom);
+    const providers=(data.providers||[]).filter(p=>p.configurable||p.is_oauth||p.is_custom||p.is_plugin_provider);
     list.innerHTML='';
     _providerCardEls.clear();
     const quotaCard=_buildProviderQuotaCard(quota);
diff --git a/tests/test_custom_providers_in_panel.py b/tests/test_custom_providers_in_panel.py
index 1cf7c750..600b5b38 100644
--- a/tests/test_custom_providers_in_panel.py
+++ b/tests/test_custom_providers_in_panel.py
@@ -107,7 +107,7 @@ class TestCustomProvidersInGetProviders:
     def test_providers_panel_renders_config_yaml_custom_providers(self):
         """Settings → Providers must not filter out read-only custom providers."""
         src = open("static/panels.js", encoding="utf-8").read()
-        assert "filter(p=>p.configurable||p.is_oauth||p.is_custom)" in src
+        assert "filter(p=>p.configurable||p.is_oauth||p.is_custom||p.is_plugin_provider)" in src
         assert "Custom provider loaded from config.yaml / hermes model" in src
         assert "if(p.configurable){" in src
 
diff --git a/tests/test_issue1202_oauth_provider_status.py b/tests/test_issue1202_oauth_provider_status.py
index 4b66bdbf..6e952f99 100644
--- a/tests/test_issue1202_oauth_provider_status.py
+++ b/tests/test_issue1202_oauth_provider_status.py
@@ -290,9 +290,16 @@ class TestProviderListFilter:
             "This excludes ALL OAuth providers (openai-codex, nous, copilot) from the "
             "Settings → Providers panel. The filter must be 'filter(p=>p.configurable||p.is_oauth)'."
         )
-        fixed_filter_idx = self.JS.find("filter(p=>p.configurable||p.is_oauth)")
-        extended_filter_idx = self.JS.find("filter(p=>p.configurable||p.is_oauth||p.is_custom)")
-        assert fixed_filter_idx != -1 or extended_filter_idx != -1, (
+        assert "p.is_oauth" in self.JS, (
             "The provider filter must include p.is_oauth in panels.js. "
             "OAuth providers will not appear in Settings → Providers."
         )
+        # Current filter also includes is_custom and is_plugin_provider; require
+        # the full expression so partial regressions are caught.
+        assert (
+            "filter(p=>p.configurable||p.is_oauth||p.is_custom||p.is_plugin_provider)"
+            in self.JS
+        ), (
+            "Settings → Providers filter must keep OAuth, custom, and plugin "
+            "model-provider entries visible."
+        )
diff --git a/tests/test_issue2977_use_command.py b/tests/test_issue2977_use_command.py
new file mode 100644
index 00000000..6e32823d
--- /dev/null
+++ b/tests/test_issue2977_use_command.py
@@ -0,0 +1,116 @@
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def read(path):
+    return (ROOT / path).read_text(encoding="utf-8")
+
+
+def test_use_entry_in_commands_array():
+    src = read("static/commands.js")
+    assert "{name:'use'," in src, "COMMANDS must contain a {name:'use', ...} entry"
+
+
+def test_use_entry_precedes_stop_entry():
+    src = read("static/commands.js")
+    use_pos = src.index("{name:'use',")
+    stop_pos = src.index("{name:'stop',")
+    assert use_pos < stop_pos, "/use must be registered before /stop in COMMANDS"
+
+
+def test_cmdUse_function_defined():
+    src = read("static/commands.js")
+    assert "async function cmdUse(args)" in src, "cmdUse function must be defined"
+
+
+def test_forced_skill_directive_declared():
+    src = read("static/commands.js")
+    assert "let _forcedSkillDirectivePending=null;" in src, "_forcedSkillDirectivePending must be declared at module scope"
+
+
+def test_forced_skill_directive_set_in_cmdUse():
+    src = read("static/commands.js")
+    assert "pending.promise = new Promise" in src, "cmdUse must create a pending Promise"
+    assert "_forcedSkillDirectivePending = pending;" in src, "cmdUse must publish the pending directive before awaiting"
+
+
+def test_use_entry_has_noEcho():
+    src = read("static/commands.js")
+    # Extract the /use entry line and check noEcho:true is present
+    idx = src.index("{name:'use',")
+    line_end = src.index("}", idx)
+    entry = src[idx:line_end + 1]
+    assert "noEcho:true" in entry, "/use entry must have noEcho:true"
+
+
+def test_use_entry_has_subArgs_skills():
+    src = read("static/commands.js")
+    idx = src.index("{name:'use',")
+    line_end = src.index("}", idx)
+    entry = src[idx:line_end + 1]
+    assert "subArgs:'skills'" in entry, "/use entry must have subArgs:'skills' for autocomplete"
+
+
+def test_directive_consumed_at_injection_site():
+    """_forcedSkillDirectivePending is cleared at the consume site, not in finally."""
+    src = read("static/messages.js")
+    finally_part = src.split("finally")[1] if "finally" in src else ""
+    assert "_forcedSkillDirectivePending = null;" not in finally_part, \
+        "_forcedSkillDirectivePending must NOT be cleared in the finally block"
+    assert "const _directive = await _pending.promise;" in src, \
+        "consume site must await the pending promise"
+    assert "_forcedSkillDirectivePending = null;" in src, \
+        "_forcedSkillDirectivePending must be cleared somewhere in messages.js"
+
+
+def test_directive_injection_before_empty_guard():
+    src = read("static/messages.js")
+    inject_pos = src.index("_forcedSkillDirectivePending")
+    guard_pos = src.index("if(!msgText){setComposerStatus('Nothing to send');return;}")
+    assert inject_pos < guard_pos, "directive injection must appear before the if(!msgText) guard"
+
+
+def test_directive_text_uses_match_name():
+    src = read("static/commands.js")
+    assert "match.name" in src, "directive must use match.name (canonical casing), not raw user input"
+    assert "[USER OVERRIDE] You MUST consult skill '" in src, "directive text must match the specified format"
+
+
+def test_pending_promise_set_synchronously():
+    """_forcedSkillDirectivePending must be set before the first await in cmdUse."""
+    src = read("static/commands.js")
+    fn_start = src.index("async function cmdUse(args)")
+    fn_body = src[fn_start:]
+    pending_pos = fn_body.index("_forcedSkillDirectivePending = pending;")
+    first_await = fn_body.index("await ")
+    assert pending_pos < first_await, \
+        "_forcedSkillDirectivePending must be set before the first await to close the race window"
+
+
+def test_directive_survives_local_slash_commands():
+    """The consume block must appear after the slash-command early-return, not before."""
+    src = read("static/messages.js")
+    early_return = src.index("autoResize();hideCmdDropdown();return;")
+    consume = src.index("_forcedSkillDirectivePending")
+    assert early_return < consume, \
+        "slash-command early-return must precede the directive consume block"
+
+
+def test_directive_pending_captures_session_id():
+    src = read("static/commands.js")
+    assert "const pending = {sessionId:S.session&&S.session.session_id||null,promise:null};" in src, \
+        "cmdUse must capture the session where /use was issued"
+    assert "const isCurrentSession = () => !pending.sessionId || (S.session&&S.session.session_id)===pending.sessionId;" in src, \
+        "async /use completion must avoid writing status messages into a different session"
+
+
+def test_directive_only_consumed_by_matching_session():
+    src = read("static/messages.js")
+    assert "const _pending=_forcedSkillDirectivePending;" in src, \
+        "send() must snapshot the pending directive before awaiting it"
+    assert "if(!_pending.sessionId||_pending.sessionId===activeSid){" in src, \
+        "send() must only consume /use directives issued for the active session"
+    assert "if(_forcedSkillDirectivePending===_pending)_forcedSkillDirectivePending = null;" in src, \
+        "send() must not clear a newer pending directive created while awaiting"
diff --git a/tests/test_passkey_auth.py b/tests/test_passkey_auth.py
index 46ac3641..ef54f854 100644
--- a/tests/test_passkey_auth.py
+++ b/tests/test_passkey_auth.py
@@ -1,8 +1,11 @@
 import base64
+import io
 import json
 import hashlib
+from types import SimpleNamespace
 
 from cryptography.hazmat.primitives import hashes
+
 from cryptography.hazmat.primitives.asymmetric import ec
 
 
@@ -133,6 +136,95 @@ def test_passkey_login_verifies_signature_and_updates_usage(monkeypatch, tmp_pat
     assert cred["last_used_at"] is not None
 
 
+def test_passkey_options_evict_oldest_challenges_per_context(monkeypatch, tmp_path):
+    passkeys = _set_paths(monkeypatch, tmp_path)
+    passkeys._save_credentials([{"id": b64u(b"credential-3"), "label": "This device"}])
+    monkeypatch.setattr(passkeys, "_MAX_CHALLENGES_PER_CONTEXT", 2)
+
+    first = passkeys.authentication_options(FakeHandler())
+    second = passkeys.authentication_options(FakeHandler())
+    third = passkeys.authentication_options(FakeHandler())
+
+    pending = json.loads((tmp_path / ".passkey_challenges.json").read_text(encoding="utf-8"))
+    assert set(pending) == {second["challenge"], third["challenge"]}
+    assert first["challenge"] not in pending
+
+
+def test_passkey_options_evict_oldest_challenges_globally(monkeypatch, tmp_path):
+    passkeys = _set_paths(monkeypatch, tmp_path)
+    passkeys._save_credentials([{"id": b64u(b"credential-4"), "label": "This device"}])
+    monkeypatch.setattr(passkeys, "_MAX_CHALLENGES", 2)
+    monkeypatch.setattr(passkeys, "_MAX_CHALLENGES_PER_CONTEXT", 10)
+
+    first = passkeys.authentication_options(FakeHandler())
+    second = passkeys.authentication_options(FakeHandler())
+    third = passkeys.authentication_options(FakeHandler())
+
+    pending = json.loads((tmp_path / ".passkey_challenges.json").read_text(encoding="utf-8"))
+    assert set(pending) == {second["challenge"], third["challenge"]}
+    assert first["challenge"] not in pending
+
+
+class RouteFakeHandler:
+    def __init__(self):
+        self.headers = FakeHeaders({"Host": "localhost:8787", "Content-Length": "0"})
+        self.rfile = io.BytesIO(b"")
+        self.wfile = io.BytesIO()
+        self.status = None
+        self.sent_headers = []
+        self.client_address = ("127.0.0.1", 12345)
+
+    def send_response(self, status):
+        self.status = status
+
+    def send_header(self, key, value):
+        self.sent_headers.append((key, value))
+
+    def end_headers(self):
+        pass
+
+
+def test_passkey_options_rate_limit_errors_return_429(monkeypatch):
+    import api.auth as auth
+    import api.passkeys as passkeys
+    import api.routes as routes
+
+    monkeypatch.setattr(routes, "_check_csrf", lambda handler: True)
+    monkeypatch.setattr(auth, "_passkey_feature_flag_enabled", lambda: True)
+    monkeypatch.setattr(auth, "is_auth_enabled", lambda: True)
+
+    def raise_rate_limit(_handler):
+        raise passkeys.PasskeyRateLimitError("too many")
+
+    monkeypatch.setattr(passkeys, "authentication_options", raise_rate_limit)
+    handler = RouteFakeHandler()
+
+    routes.handle_post(handler, SimpleNamespace(path="/api/auth/passkey/options"))
+
+    assert handler.status == 429
+    assert json.loads(handler.wfile.getvalue())["error"] == "too many"
+
+
+def test_passkey_register_options_handles_base_passkey_errors(monkeypatch):
+    import api.auth as auth
+    import api.passkeys as passkeys
+    import api.routes as routes
+
+    monkeypatch.setattr(routes, "_check_csrf", lambda handler: True)
+    monkeypatch.setattr(auth, "_passkey_feature_flag_enabled", lambda: True)
+
+    def raise_passkey_error(_handler):
+        raise passkeys.PasskeyError("plain passkey error")
+
+    monkeypatch.setattr(passkeys, "registration_options", raise_passkey_error)
+    handler = RouteFakeHandler()
+
+    routes.handle_post(handler, SimpleNamespace(path="/api/auth/passkey/register/options"))
+
+    assert handler.status == 400
+    assert json.loads(handler.wfile.getvalue())["error"] == "plain passkey error"
+
+
 def test_auth_status_reports_passkey_availability_source_contract():
     src = open("api/routes.py", encoding="utf-8").read()
     assert '"passkeys_enabled"' in src
diff --git a/tests/test_plugin_model_providers.py b/tests/test_plugin_model_providers.py
new file mode 100644
index 00000000..f9134b51
--- /dev/null
+++ b/tests/test_plugin_model_providers.py
@@ -0,0 +1,225 @@
+"""Regression tests for model-provider plugin discovery in WebUI.
+
+Plugin profiles under ``plugins/model-providers/<name>/`` are auto-registered
+in the Hermes agent CLI.  WebUI must expose them in Settings → Providers and
+the model picker without hardcoding each slug.
+"""
+
+from __future__ import annotations
+
+import sys
+import types
+from types import SimpleNamespace
+
+import api.config as config
+import api.profiles as profiles
+from api.plugin_providers import invalidate_plugin_model_provider_cache
+
+
+def _install_fake_yandex_plugin(monkeypatch):
+    profile = SimpleNamespace(
+        name="yandex",
+        display_name="Yandex AI Studio",
+        env_vars=("YANDEX_API_KEY", "YANDEX_FOLDER_ID"),
+        auth_type="api_key",
+        aliases=("yandex-ai-studio",),
+    )
+
+    def _fake_list_providers():
+        return [profile]
+
+    fake_providers = types.ModuleType("providers")
+    fake_providers.list_providers = _fake_list_providers
+    monkeypatch.setitem(sys.modules, "providers", fake_providers)
+    invalidate_plugin_model_provider_cache()
+
+
+def _install_fake_hermes_cli(monkeypatch, *, authenticated: bool = True, model_ids: list[str] | None = None):
+    fake_pkg = types.ModuleType("hermes_cli")
+    fake_pkg.__path__ = []
+
+    fake_models = types.ModuleType("hermes_cli.models")
+    fake_models.list_available_providers = lambda: [
+        {
+            "id": "yandex",
+            "label": "Yandex AI Studio",
+            "aliases": [],
+            "authenticated": authenticated,
+        }
+    ]
+    fake_models.provider_model_ids = lambda pid: list(model_ids or []) if pid == "yandex" else []
+
+    fake_auth = types.ModuleType("hermes_cli.auth")
+    fake_auth.get_auth_status = lambda pid: (
+        {
+            "logged_in": True,
+            "configured": True,
+            "key_source": "YANDEX_API_KEY",
+        }
+        if pid == "yandex"
+        else {}
+    )
+
+    monkeypatch.setitem(sys.modules, "hermes_cli", fake_pkg)
+    monkeypatch.setitem(sys.modules, "hermes_cli.models", fake_models)
+    monkeypatch.setitem(sys.modules, "hermes_cli.auth", fake_auth)
+
+
+class TestPluginModelProvidersSettings:
+    def test_get_providers_includes_plugin_model_provider(self, monkeypatch, tmp_path):
+        _install_fake_yandex_plugin(monkeypatch)
+        _install_fake_hermes_cli(monkeypatch, model_ids=["deepseek-v4-flash/latest"])
+        monkeypatch.setattr(profiles, "get_active_hermes_home", lambda: tmp_path)
+
+        env_path = tmp_path / ".env"
+        env_path.write_text("YANDEX_API_KEY=test-yandex-key-12345\n", encoding="utf-8")
+
+        old_cfg = dict(config.cfg)
+        old_mtime = config._cfg_mtime
+        config.cfg.clear()
+        config.cfg["model"] = {"provider": "gemini"}
+        try:
+            config._cfg_mtime = config.Path(config._get_config_path()).stat().st_mtime
+        except Exception:
+            config._cfg_mtime = 0.0
+
+        from api.providers import get_providers
+
+        try:
+            result = get_providers()
+            yandex = next((p for p in result["providers"] if p["id"] == "yandex"), None)
+            assert yandex is not None, "plugin model-provider must appear in Settings → Providers"
+            assert yandex["display_name"] == "Yandex AI Studio"
+            assert yandex["has_key"] is True
+            assert yandex["configurable"] is True
+            assert yandex.get("is_plugin_provider") is True
+            assert yandex["models_total"] >= 1
+        finally:
+            config.cfg.clear()
+            config.cfg.update(old_cfg)
+            config._cfg_mtime = old_mtime
+            config.invalidate_models_cache()
+
+    def test_get_providers_plugin_key_source_from_auth_store(self, monkeypatch, tmp_path):
+        """Credential-pool auth must not be misreported as config_yaml."""
+        _install_fake_yandex_plugin(monkeypatch)
+
+        fake_pkg = types.ModuleType("hermes_cli")
+        fake_pkg.__path__ = []
+        fake_models = types.ModuleType("hermes_cli.models")
+        fake_models.list_available_providers = lambda: []
+        fake_models.provider_model_ids = lambda pid: []
+        fake_auth = types.ModuleType("hermes_cli.auth")
+        fake_auth.get_auth_status = lambda pid: (
+            {
+                "logged_in": True,
+                "configured": True,
+                "key_source": "credential_pool:yandex",
+            }
+            if pid == "yandex"
+            else {}
+        )
+        monkeypatch.setitem(sys.modules, "hermes_cli", fake_pkg)
+        monkeypatch.setitem(sys.modules, "hermes_cli.models", fake_models)
+        monkeypatch.setitem(sys.modules, "hermes_cli.auth", fake_auth)
+        monkeypatch.setattr(profiles, "get_active_hermes_home", lambda: tmp_path)
+
+        old_cfg = dict(config.cfg)
+        old_mtime = config._cfg_mtime
+        config.cfg.clear()
+        config.cfg["model"] = {}
+        try:
+            config._cfg_mtime = config.Path(config._get_config_path()).stat().st_mtime
+        except Exception:
+            config._cfg_mtime = 0.0
+
+        from api.providers import get_providers
+
+        try:
+            result = get_providers()
+            yandex = next((p for p in result["providers"] if p["id"] == "yandex"), None)
+            assert yandex is not None
+            assert yandex["has_key"] is True
+            assert yandex["key_source"] == "credential_pool:yandex"
+            assert yandex["key_source"] != "config_yaml"
+        finally:
+            config.cfg.clear()
+            config.cfg.update(old_cfg)
+            config._cfg_mtime = old_mtime
+            config.invalidate_models_cache()
+
+    def test_set_provider_key_accepts_plugin_env_var(self, monkeypatch, tmp_path):
+        _install_fake_yandex_plugin(monkeypatch)
+        monkeypatch.setattr(profiles, "get_active_hermes_home", lambda: tmp_path)
+
+        from api.providers import set_provider_key
+
+        result = set_provider_key("yandex", "test-yandex-key-abcdef")
+        assert result["ok"] is True
+        env_text = (tmp_path / ".env").read_text(encoding="utf-8")
+        assert "YANDEX_API_KEY=test-yandex-key-abcdef" in env_text
+
+
+class TestPluginOnlyExcludesStaticProviders:
+    def test_bundled_agent_profiles_are_not_plugin_only(self, monkeypatch):
+        """Agent bundled profiles must not hijack WebUI static/custom paths."""
+        _install_fake_yandex_plugin(monkeypatch)
+        from api.plugin_providers import (
+            effective_provider_display_name,
+            is_plugin_model_provider,
+            plugin_model_provider_ids,
+        )
+        from api.config import _PROVIDER_DISPLAY
+
+        assert is_plugin_model_provider("yandex") is True
+        assert "yandex" in plugin_model_provider_ids()
+        for static_pid in ("custom", "gemini", "nous", "anthropic"):
+            assert is_plugin_model_provider(static_pid) is False, static_pid
+            assert static_pid not in plugin_model_provider_ids()
+        assert effective_provider_display_name("custom", _PROVIDER_DISPLAY) == "Custom"
+        assert effective_provider_display_name("gemini", _PROVIDER_DISPLAY) == "Gemini"
+
+
+class TestPluginModelProvidersPanelFilter:
+    def test_providers_panel_includes_plugin_model_providers(self):
+        src = open("static/panels.js", encoding="utf-8").read()
+        assert "p.is_plugin_provider" in src
+        assert "filter(p=>p.configurable||p.is_oauth||p.is_custom||p.is_plugin_provider)" in src
+
+
+class TestPluginModelProvidersPicker:
+    def test_model_picker_includes_authenticated_plugin_provider(self, monkeypatch, tmp_path):
+        _install_fake_yandex_plugin(monkeypatch)
+        _install_fake_hermes_cli(
+            monkeypatch,
+            authenticated=True,
+            model_ids=["gpt://folder/deepseek-v4-flash/latest"],
+        )
+        monkeypatch.setattr(profiles, "get_active_hermes_home", lambda: tmp_path)
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+
+        old_cfg = dict(config.cfg)
+        old_mtime = config._cfg_mtime
+        config.cfg.clear()
+        config.cfg["model"] = {"provider": "gemini", "default": "gemini-2.5-flash"}
+        config.cfg["providers"] = {}
+        try:
+            config._cfg_mtime = config.Path(config._get_config_path()).stat().st_mtime
+        except Exception:
+            config._cfg_mtime = 0.0
+
+        config.invalidate_models_cache()
+        try:
+            models = config.get_available_models()
+            yandex_group = next(
+                (g for g in models.get("groups", []) if g.get("provider_id") == "yandex"),
+                None,
+            )
+            assert yandex_group is not None, "authenticated plugin provider must appear in picker"
+            assert yandex_group["provider"] == "Yandex AI Studio"
+            assert len(yandex_group.get("models") or []) >= 1
+        finally:
+            config.cfg.clear()
+            config.cfg.update(old_cfg)
+            config._cfg_mtime = old_mtime
+            config.invalidate_models_cache()