diff --git a/backend/apps/agents/agents.py b/backend/apps/agents/agents.py
index a6c078dc..fe0864d6 100644
--- a/backend/apps/agents/agents.py
+++ b/backend/apps/agents/agents.py
@@ -487,7 +487,7 @@ async def probe_model(body: dict):
         from backend.apps.agents.providers.registry import (
             resolve_model_id_for_sdk,
             get_api_type,
-            _find_builtin_model,
+            find_builtin_model,
             _NINEROUTER_MODEL_PREFIXES,
         )
         from backend.apps.settings.settings import load_settings
@@ -495,7 +495,7 @@ async def probe_model(body: dict):
         settings = load_settings()
         api_type = get_api_type(short_name)
         resolved = resolve_model_id_for_sdk(short_name, settings)
-        entry = _find_builtin_model(short_name) or {}
+        entry = find_builtin_model(short_name) or {}
         route = entry.get("route")
         connection_mode = getattr(settings, "connection_mode", "own_key")
 
@@ -774,14 +774,14 @@ async def list_models():
                 result[f"OpenRouter · {pretty}"] = entries
 
     # Custom OpenAI-compatible providers (Ollama Cloud, Together, etc); addressed via custom/<slug>/<model_id>.
-    from backend.apps.agents.providers.registry import _custom_provider_slug_for_lookup
+    from backend.apps.agents.providers.registry import custom_provider_slug_for_lookup
     for cp in (getattr(settings, "custom_providers", None) or []):
         cp_name = (getattr(cp, "name", "") or "").strip()
         cp_base_url = (getattr(cp, "base_url", "") or "").strip()
         cp_models = getattr(cp, "models", None) or []
         if not cp_name or not cp_base_url or not cp_models:
             continue
-        slug = _custom_provider_slug_for_lookup(cp_name)
+        slug = custom_provider_slug_for_lookup(cp_name)
         entries: list[dict] = []
         for m in cp_models:
             bare = (m.get("value") or m.get("id") or "").strip()
diff --git a/backend/apps/agents/browser/browser_agent.py b/backend/apps/agents/browser/browser_agent.py
index d6d0ddb7..8edf48ac 100644
--- a/backend/apps/agents/browser/browser_agent.py
+++ b/backend/apps/agents/browser/browser_agent.py
@@ -445,7 +445,7 @@ async def run_browser_agent(
     from backend.apps.settings.settings import load_settings
     from backend.apps.settings.credentials import get_anthropic_client_for_model
     from backend.apps.agents.providers.registry import (
-        _find_builtin_model,
+        find_builtin_model,
         resolve_model_id_for_sdk,
         resolve_aux_model,
     )
@@ -457,7 +457,7 @@ async def run_browser_agent(
     # type, etc.) through 9Router's claude→openai translator is UNVERIFIED , 
     # if translation is poor, the user should manually switch this session
     # back to Claude in the model picker.
-    if _find_builtin_model(model) is not None:
+    if find_builtin_model(model) is not None:
         api_model = resolve_model_id_for_sdk(model, browser_settings)
     else:
         # Unknown model string; fall back to whatever aux model is available
diff --git a/backend/apps/agents/core/mcp_preflight.py b/backend/apps/agents/core/mcp_preflight.py
index de58feed..b779f4eb 100644
--- a/backend/apps/agents/core/mcp_preflight.py
+++ b/backend/apps/agents/core/mcp_preflight.py
@@ -79,7 +79,7 @@ _PATH_LIKE = re.compile(r"^[./~]|/[\w\-]+/|\.[a-zA-Z]{1,5}\b")
 _SHELL_PREFIX = re.compile(r"^\s*[\$!/]")
 
 
-def _is_obviously_local(prompt: str) -> bool:
+def p_is_obviously_local(prompt: str) -> bool:
     """True for prompts that obviously can't benefit from MCP (very short, shell-ish, single path)."""
     s = prompt.strip()
     if len(s) < 8:
@@ -100,21 +100,21 @@ async def run_preflight(prompt: str, timeout_s: float = 8.0, task_id: str | None
     if not prompt or not prompt.strip():
         return default
 
-    if _is_obviously_local(prompt):
+    if p_is_obviously_local(prompt):
         return default
 
     try:
         settings = load_settings()
-        available = _build_available_shortlist(settings)
+        available = p_build_available_shortlist(settings)
 
         result = await asyncio.wait_for(
-            _call_classifier(settings, prompt, available, task_id),
+            p_call_classifier(settings, prompt, available, task_id),
             timeout=timeout_s,
         )
         # Re-validate ids against the curated shortlist so hallucinations can't reach the frontend.
         valid_ids = {e["id"] for e in CURATED_SHORTLIST}
         result["suggestions"] = [
-            _decorate(s, available) for s in result.get("suggestions", [])
+            p_decorate(s, available) for s in result.get("suggestions", [])
             if isinstance(s, dict) and s.get("id") in valid_ids
         ]
         result["suggestions"] = [s for s in result["suggestions"] if s is not None]
@@ -131,7 +131,7 @@ async def run_preflight(prompt: str, timeout_s: float = 8.0, task_id: str | None
         return default
 
 
-def _build_available_shortlist(settings) -> list[CuratedEntry]:
+def p_build_available_shortlist(settings) -> list[CuratedEntry]:
     """Curated entries that are NOT currently enabled and NOT dismissed."""
     try:
         enabled_names = {t.name for t in load_all_tools() if getattr(t, "enabled", False)}
@@ -158,7 +158,7 @@ def offer_for_gated_server(server_name: str, settings) -> CuratedEntry | None:
     # ("Google Workspace"). Match on the slug of both sides so neither form is a load-bearing string.
     slug = _sanitize_server_name(server_name)
     entry = next(
-        (e for e in _build_available_shortlist(settings) if _sanitize_server_name(e["id"]) == slug),
+        (e for e in p_build_available_shortlist(settings) if _sanitize_server_name(e["id"]) == slug),
         None,
     )
     if entry is None:
@@ -166,7 +166,7 @@ def offer_for_gated_server(server_name: str, settings) -> CuratedEntry | None:
     return {"id": entry["id"], "title": entry["title"], "description": entry["description"], "reason": ""}
 
 
-def _decorate(llm_suggestion: dict, available: list[CuratedEntry]) -> dict | None:
+def p_decorate(llm_suggestion: dict, available: list[CuratedEntry]) -> dict | None:
     """Expand an LLM-returned {id, reason} into the full frontend shape."""
     entry = next((e for e in available if e["id"] == llm_suggestion["id"]), None)
     if entry is None:
@@ -179,7 +179,7 @@ def _decorate(llm_suggestion: dict, available: list[CuratedEntry]) -> dict | Non
     }
 
 
-async def _call_classifier(settings, prompt: str, available: list[CuratedEntry], task_id: str | None = None) -> dict:
+async def p_call_classifier(settings, prompt: str, available: list[CuratedEntry], task_id: str | None = None) -> dict:
     """One aux-model call, returns validated JSON {is_vague, suggestions}."""
     aux_model, _base = await resolve_aux_model(settings, preferred_tier="haiku")
     client = get_anthropic_client_for_model(settings, aux_model)
diff --git a/backend/apps/agents/core/openai_passthrough.py b/backend/apps/agents/core/openai_passthrough.py
index dc5ac2fd..22edaf30 100644
--- a/backend/apps/agents/core/openai_passthrough.py
+++ b/backend/apps/agents/core/openai_passthrough.py
@@ -31,7 +31,7 @@ _HOP_HEADERS = {
 }
 
 
-def _is_gpt5(model: str) -> bool:
+def p_is_gpt5(model: str) -> bool:
     m = (model or "").strip().lower()
     if not m:
         return False
@@ -52,7 +52,7 @@ _GPT5_UNSUPPORTED_PARAMS = (
 )
 
 
-def _scrub_gpt5_params(body: bytes) -> bytes:
+def scrub_gpt5_params(body: bytes) -> bytes:
     """For GPT-5: rename max_tokens→max_completion_tokens and drop the sampling
     params the reasoning models reject. Bytes in/out, never raises."""
     if not body:
@@ -61,7 +61,7 @@ def _scrub_gpt5_params(body: bytes) -> bytes:
         parsed = json.loads(body)
     except Exception:
         return body
-    if not isinstance(parsed, dict) or not _is_gpt5(str(parsed.get("model") or "")):
+    if not isinstance(parsed, dict) or not p_is_gpt5(str(parsed.get("model") or "")):
         return body
     mutated = False
     if "max_tokens" in parsed:
@@ -85,7 +85,7 @@ def _scrub_gpt5_params(body: bytes) -> bytes:
 )
 async def passthrough(rest: str, request: Request):
     body = await request.body()
-    body = _scrub_gpt5_params(body)
+    body = scrub_gpt5_params(body)
 
     forward_headers: dict[str, str] = {}
     for k, v in request.headers.items():
diff --git a/backend/apps/agents/core/seq_log.py b/backend/apps/agents/core/seq_log.py
index fcd1ea39..e52b54da 100644
--- a/backend/apps/agents/core/seq_log.py
+++ b/backend/apps/agents/core/seq_log.py
@@ -143,7 +143,7 @@ class SeqLogStore:
                 pass
 
 
-def _default_persist_dir() -> Optional[str]:
+def p_default_persist_dir() -> Optional[str]:
     try:
         from backend.config.paths import DATA_ROOT
         return os.path.join(DATA_ROOT, "agents", "terminal_events")
@@ -151,4 +151,4 @@ def _default_persist_dir() -> Optional[str]:
         return None
 
 
-seq_log = SeqLogStore(persist_dir=_default_persist_dir())
+seq_log = SeqLogStore(persist_dir=p_default_persist_dir())
diff --git a/backend/apps/agents/manager/RunSupportMixin.py b/backend/apps/agents/manager/RunSupportMixin.py
index 2e92d5bd..bd6f57d6 100644
--- a/backend/apps/agents/manager/RunSupportMixin.py
+++ b/backend/apps/agents/manager/RunSupportMixin.py
@@ -267,7 +267,7 @@ class RunSupportMixin:
             return
 
         try:
-            from backend.apps.agents.providers.registry import _find_builtin_model as find_builtin_model
+            from backend.apps.agents.providers.registry import find_builtin_model as find_builtin_model
             entry = find_builtin_model(session.model)
             if not entry or entry.get("api") != "anthropic":
                 return  # other providers handle caching automatically
diff --git a/backend/apps/agents/manager/provider_env.py b/backend/apps/agents/manager/provider_env.py
index c0971104..527c0581 100644
--- a/backend/apps/agents/manager/provider_env.py
+++ b/backend/apps/agents/manager/provider_env.py
@@ -28,7 +28,7 @@ async def configure_provider_env(
     from backend.apps.agents.providers.registry import _NINEROUTER_MODEL_PREFIXES as NINEROUTER_MODEL_PREFIXES
     resolved_is_9router = isinstance(resolved_model, str) and resolved_model.startswith(NINEROUTER_MODEL_PREFIXES)
 
-    from backend.apps.agents.providers.registry import _find_builtin_model as find_builtin_model
+    from backend.apps.agents.providers.registry import find_builtin_model as find_builtin_model
     model_entry = find_builtin_model(session.model)
     is_pinned_api_route = (
         model_entry is not None
@@ -81,7 +81,7 @@ async def configure_provider_env(
                     "providers need 9Router to translate the Anthropic "
                     "protocol, install Node.js and restart the app."
                 )
-        from backend.apps.agents.providers.registry import _find_custom_provider_for_value as find_custom_provider_for_value
+        from backend.apps.agents.providers.registry import find_custom_provider_for_value as find_custom_provider_for_value
         cp = find_custom_provider_for_value(global_settings, session.model)
         env = {
             "ANTHROPIC_API_KEY": "9router",
diff --git a/backend/apps/agents/providers/pricing.py b/backend/apps/agents/providers/pricing.py
index 63035aa3..c985a655 100644
--- a/backend/apps/agents/providers/pricing.py
+++ b/backend/apps/agents/providers/pricing.py
@@ -185,7 +185,7 @@ MODEL_TIERS: dict[str, tuple[int, int, int]] = {
 }
 
 
-def _heuristic_tiers(label: str, output_cost_per_1m: float, reasoning: bool) -> tuple[int, int, int]:
+def heuristic_tiers(label: str, output_cost_per_1m: float, reasoning: bool) -> tuple[int, int, int]:
     """Fallback tier scoring for models not in MODEL_TIERS. Tries to
     extract a parameter count from the label (8B/70B/235B/etc.) and
     use that as a stronger size signal than cost alone, since open-
@@ -310,7 +310,7 @@ def compute_tiers(
         if c in MODEL_TIERS:
             return MODEL_TIERS[c]
 
-    return _heuristic_tiers(label, output_cost_per_1m, reasoning)
+    return heuristic_tiers(label, output_cost_per_1m, reasoning)
 
 
 def compute_billing_kind(
diff --git a/backend/apps/agents/providers/registry.py b/backend/apps/agents/providers/registry.py
index 3ef184a8..17e4bb6f 100644
--- a/backend/apps/agents/providers/registry.py
+++ b/backend/apps/agents/providers/registry.py
@@ -21,7 +21,7 @@ from .openrouter import (
 from .pricing import (
     compute_billing_kind,
     compute_tiers,
-    _heuristic_tiers,
+    heuristic_tiers,
 )
 from .thinking import thinking_params_for
 
@@ -155,7 +155,7 @@ BUILTIN_MODELS: dict[str, list[dict[str, Any]]] = {
 _CUSTOM_VALUE_PREFIX = "custom/"
 
 
-def _custom_provider_slug_for_lookup(name: str) -> str:
+def custom_provider_slug_for_lookup(name: str) -> str:
     """Mirror nine_router._custom_provider_slug; duplicated here to avoid
     importing from nine_router (circular: nine_router imports from settings)."""
     import re
@@ -163,7 +163,7 @@ def _custom_provider_slug_for_lookup(name: str) -> str:
     return s or "custom"
 
 
-def _find_custom_provider_for_value(settings, value: str):
+def find_custom_provider_for_value(settings, value: str):
     """Look up the CustomProvider whose slug matches the slug encoded in a
     `custom/<slug>/<model_id>` picker value. Returns None if no match."""
     if not isinstance(value, str) or not value.startswith(_CUSTOM_VALUE_PREFIX):
@@ -173,12 +173,12 @@ def _find_custom_provider_for_value(settings, value: str):
     if not slug:
         return None
     for cp in getattr(settings, "custom_providers", None) or []:
-        if _custom_provider_slug_for_lookup(getattr(cp, "name", "")) == slug:
+        if custom_provider_slug_for_lookup(getattr(cp, "name", "")) == slug:
             return cp
     return None
 
 
-def _find_builtin_model(short_name: str) -> dict | None:
+def find_builtin_model(short_name: str) -> dict | None:
     """Look up a model entry by its short `value`.
 
     OpenRouter entries (prefixed `or:<vendor>/<model>`) and custom-provider
@@ -223,11 +223,11 @@ def _find_builtin_model(short_name: str) -> dict | None:
 
 
 def get_api_type(short_name: str) -> str:
-    entry = _find_builtin_model(short_name)
+    entry = find_builtin_model(short_name)
     return (entry or {}).get("api", "anthropic")
 
 
-def _antigravity_connected() -> bool:
+def p_antigravity_connected() -> bool:
     """True if a live Antigravity OAuth lane exists in 9Router. Synchronous
     probe (this resolver is sync) with a tight timeout; any hiccup reads as
     'no' so a slow/absent 9Router never blocks model resolution for long."""
@@ -249,7 +249,7 @@ def _antigravity_connected() -> bool:
 
 def resolve_model_id_for_sdk(short_name: str, settings: AppSettings) -> str:
     """Short model name → id string for ClaudeAgentOptions."""
-    entry = _find_builtin_model(short_name)
+    entry = find_builtin_model(short_name)
     if entry is None:
         return short_name
     if entry.get("route") == "cc":
@@ -294,7 +294,7 @@ def resolve_model_id_for_sdk(short_name: str, settings: AppSettings) -> str:
         if isinstance(rid, str) and rid.startswith("gc/"):
             suffix = rid[len("gc/"):]
             ag_suffix = _ANTIGRAVITY_MAP.get(suffix)
-            if ag_suffix and _antigravity_connected():
+            if ag_suffix and p_antigravity_connected():
                 return "ag/" + ag_suffix
             if getattr(settings, "google_api_key", None):
                 return "gemini/" + suffix
diff --git a/backend/apps/agents/session_credential.py b/backend/apps/agents/session_credential.py
index 1facfad3..5951f7d5 100644
--- a/backend/apps/agents/session_credential.py
+++ b/backend/apps/agents/session_credential.py
@@ -25,9 +25,9 @@ from typing import Any, Literal, TYPE_CHECKING
 
 from backend.apps.agents.providers.registry import (
     _CUSTOM_VALUE_PREFIX,
-    _custom_provider_slug_for_lookup,
-    _find_builtin_model,
-    _find_custom_provider_for_value,
+    custom_provider_slug_for_lookup,
+    find_builtin_model,
+    find_custom_provider_for_value,
     get_api_type,
 )
 
@@ -73,9 +73,9 @@ class PoweringCredential:
 
 
 def _custom_slug_for_model(model_value: str, settings: AppSettings) -> str | None:
-    cp = _find_custom_provider_for_value(settings, model_value)
+    cp = find_custom_provider_for_value(settings, model_value)
     if cp is not None:
-        return _custom_provider_slug_for_lookup(getattr(cp, "name", ""))
+        return custom_provider_slug_for_lookup(getattr(cp, "name", ""))
     # Fall back to the slug encoded in the picker value itself.
     if isinstance(model_value, str) and model_value.startswith(_CUSTOM_VALUE_PREFIX):
         slug = model_value[len(_CUSTOM_VALUE_PREFIX):].partition("/")[0]
@@ -89,7 +89,7 @@ def resolve_powering_credential(model_value: str, settings: AppSettings) -> Powe
     `model_value` is the session's short model name (e.g. "opus-4-8", "sonnet-api",
     "custom/lmstudio/llama"), exactly what AgentSession.model holds.
     """
-    entry = _find_builtin_model(model_value)
+    entry = find_builtin_model(model_value)
     api = (entry or {}).get("api") or get_api_type(model_value)
     route = (entry or {}).get("route")
     mode = getattr(settings, "connection_mode", "own_key")
@@ -166,7 +166,7 @@ def _powering_custom_slug_present(new_providers: Any, slug: str) -> bool:
         return False
     for cp in new_providers:
         name = cp.get("name") if isinstance(cp, dict) else getattr(cp, "name", None)
-        if name and _custom_provider_slug_for_lookup(name) == slug:
+        if name and custom_provider_slug_for_lookup(name) == slug:
             return True
     return False
 
diff --git a/backend/apps/agents/tools/ssrf_guard.py b/backend/apps/agents/tools/ssrf_guard.py
index c641844a..099f5338 100644
--- a/backend/apps/agents/tools/ssrf_guard.py
+++ b/backend/apps/agents/tools/ssrf_guard.py
@@ -46,7 +46,7 @@ _BLOCKED_V6_NETS = [
 ]
 
 
-async def _resolve_host_async(host: str) -> list[str]:
+async def p_resolve_host_async(host: str) -> list[str]:
     """Resolve host to all IPs (v4 + v6) without blocking the event loop."""
     loop = asyncio.get_event_loop()
     try:
@@ -56,7 +56,7 @@ async def _resolve_host_async(host: str) -> list[str]:
     return list({info[4][0] for info in infos})
 
 
-def _is_forbidden_ip(ip_str: str) -> bool:
+def p_is_forbidden_ip(ip_str: str) -> bool:
     """True iff this IP is in a blocked range. Loopback is allowed (see module docstring)."""
     try:
         ip = ipaddress.ip_address(ip_str)
@@ -88,17 +88,17 @@ async def assert_safe_url(url: str) -> str:
 
     try:
         ipaddress.ip_address(host)
-        if _is_forbidden_ip(host):
+        if p_is_forbidden_ip(host):
             raise SSRFBlocked(f"URL host {host} is in a blocked range.")
         return url
     except ValueError:
         pass
 
-    resolved = await _resolve_host_async(host)
+    resolved = await p_resolve_host_async(host)
     if not resolved:
         raise SSRFBlocked(f"No DNS records for {host}.")
     for ip in resolved:
-        if _is_forbidden_ip(ip):
+        if p_is_forbidden_ip(ip):
             raise SSRFBlocked(f"Host {host} resolves to forbidden IP {ip}.")
     return url
 
diff --git a/backend/apps/agents/tools/web.py b/backend/apps/agents/tools/web.py
index 6e2a74a7..492613e9 100644
--- a/backend/apps/agents/tools/web.py
+++ b/backend/apps/agents/tools/web.py
@@ -66,7 +66,7 @@ def should_register_web_mcp(
     no Claude connection), and a subscription-route Claude model on a non-Pro account (the
     built-in WebSearch's aux haiku call 401s). Pro pool is deliberately NOT counted for a
     non-Claude primary: spending it on WebSearch would drain the user's Claude turns."""
-    from backend.apps.agents.providers.registry import _find_builtin_model as find_builtin_model
+    from backend.apps.agents.providers.registry import find_builtin_model as find_builtin_model
 
     m = router_model_id if isinstance(router_model_id, str) else ""
     primary_is_claude = m.startswith("cc/") or (
@@ -93,13 +93,13 @@ def should_register_web_mcp(
     return not has_anthropic_path
 
 
-def _truncate(text: str, limit: int = _MAX_OUTPUT_BYTES) -> str:
+def p_truncate(text: str, limit: int = _MAX_OUTPUT_BYTES) -> str:
     if len(text) > limit:
         return text[:limit] + "\n... (output truncated)"
     return text
 
 
-def _strip_html(raw_html: str) -> str:
+def p_strip_html(raw_html: str) -> str:
     """Naive but effective HTML to plain-text conversion."""
     text = re.sub(r"<(script|style)[^>]*>.*?</\1>", "", raw_html, flags=re.DOTALL | re.IGNORECASE)
     text = re.sub(r"<[^>]+>", " ", text)
@@ -206,14 +206,14 @@ class WebSearchTool(BaseTool):
             if "/y.js?" in raw_url or "ad_provider=" in raw_url or "ad_domain=" in raw_url:
                 continue
 
-            title = _strip_html(link_match.group(2)).strip()
+            title = p_strip_html(link_match.group(2)).strip()
 
             snippet_match = re.search(
                 r'<a[^>]*class="[^"]*result__snippet[^"]*"[^>]*>(.*?)</a>',
                 block,
                 flags=re.DOTALL,
             )
-            snippet = _strip_html(snippet_match.group(1)).strip() if snippet_match else ""
+            snippet = p_strip_html(snippet_match.group(1)).strip() if snippet_match else ""
 
             # DDG wraps URLs in a redirect; extract the real one.
             real_url_match = re.search(r"uddg=([^&]+)", raw_url)
@@ -291,11 +291,11 @@ class WebFetchTool(BaseTool):
             except Exception:
                 text = None
             if not text:
-                text = _strip_html(resp.text)
+                text = p_strip_html(resp.text)
         else:
             text = resp.text
 
-        text = _truncate(text)
+        text = p_truncate(text)
 
         header = f"Contents of {url}:"
         if prompt:
diff --git a/backend/tests/test_browser_agent_loop.py b/backend/tests/test_browser_agent_loop.py
index 5f4bfcd9..221740c7 100644
--- a/backend/tests/test_browser_agent_loop.py
+++ b/backend/tests/test_browser_agent_loop.py
@@ -71,7 +71,7 @@ def _install(monkeypatch, primary, aux):
     import backend.apps.agents.agent_manager as am_mod
 
     monkeypatch.setattr(settings_mod, "load_settings", lambda: {"fake": True}, raising=True)
-    monkeypatch.setattr(reg_mod, "_find_builtin_model", lambda m: object(), raising=True)
+    monkeypatch.setattr(reg_mod, "find_builtin_model", lambda m: object(), raising=True)
     monkeypatch.setattr(reg_mod, "resolve_model_id_for_sdk", lambda m, s: "primary-x", raising=True)
 
     async def _aux_resolve(s, preferred_tier="haiku"):
diff --git a/backend/tests/test_mcp_offer.py b/backend/tests/test_mcp_offer.py
index 6c58cc8c..9889e50a 100644
--- a/backend/tests/test_mcp_offer.py
+++ b/backend/tests/test_mcp_offer.py
@@ -80,7 +80,7 @@ def _stub_classifier(is_vague, ids):
 def test_preflight_default_suppresses_suggestions_on_concrete_prompt(monkeypatch):
     # Launch path: a concrete (non-vague) prompt must NOT interrupt with a card.
     monkeypatch.setattr(pf, "load_all_tools", lambda: [])
-    monkeypatch.setattr(pf, "_call_classifier", _stub_classifier(False, ["Google Workspace"]))
+    monkeypatch.setattr(pf, "p_call_classifier", _stub_classifier(False, ["Google Workspace"]))
     out = asyncio.run(run_preflight("refactor foo.ts to use the new client", timeout_s=5))
     assert out["suggestions"] == []
 
@@ -89,7 +89,7 @@ def test_preflight_require_vague_false_keeps_suggestions(monkeypatch):
     # MCPSearch path: the agent already proved it needs an integration, so keep the suggestion
     # even though the prompt is concrete (is_vague False).
     monkeypatch.setattr(pf, "load_all_tools", lambda: [])
-    monkeypatch.setattr(pf, "_call_classifier", _stub_classifier(False, ["Google Workspace"]))
+    monkeypatch.setattr(pf, "p_call_classifier", _stub_classifier(False, ["Google Workspace"]))
     out = asyncio.run(run_preflight("check my unread emails", timeout_s=5, require_vague=False))
     assert [s["id"] for s in out["suggestions"]] == ["Google Workspace"]
     assert set(out["suggestions"][0].keys()) == OFFER_SHAPE
@@ -98,6 +98,6 @@ def test_preflight_require_vague_false_keeps_suggestions(monkeypatch):
 def test_preflight_require_vague_false_still_drops_hallucinated_ids(monkeypatch):
     # require_vague=False must NOT loosen the vetted-id revalidation: a made-up id is still dropped.
     monkeypatch.setattr(pf, "load_all_tools", lambda: [])
-    monkeypatch.setattr(pf, "_call_classifier", _stub_classifier(False, ["TotallyFakeServer"]))
+    monkeypatch.setattr(pf, "p_call_classifier", _stub_classifier(False, ["TotallyFakeServer"]))
     out = asyncio.run(run_preflight("do the thing", timeout_s=5, require_vague=False))
     assert out["suggestions"] == []
diff --git a/backend/tests/test_streaming_harness.py b/backend/tests/test_streaming_harness.py
index 29dcea78..af4e6110 100644
--- a/backend/tests/test_streaming_harness.py
+++ b/backend/tests/test_streaming_harness.py
@@ -65,7 +65,7 @@ def _capture_env(monkeypatch, settings, api_type, resolved_model, model_entry):
     monkeypatch.setattr(am, "load_settings", lambda: settings, raising=True)
     monkeypatch.setattr(reg, "get_api_type", lambda model: api_type, raising=True)
     monkeypatch.setattr(reg, "resolve_model_id_for_sdk", lambda model, s: resolved_model, raising=True)
-    monkeypatch.setattr(reg, "_find_builtin_model", lambda model: model_entry, raising=True)
+    monkeypatch.setattr(reg, "find_builtin_model", lambda model: model_entry, raising=True)
     captured = {}
 
     async def capturing_query(*args, **kwargs):
@@ -172,7 +172,7 @@ def test_loop_builds_direct_anthropic_key_env(monkeypatch):
     monkeypatch.setattr(am, "load_settings", lambda: settings, raising=True)
     monkeypatch.setattr(reg, "get_api_type", lambda model: "anthropic", raising=True)
     monkeypatch.setattr(reg, "resolve_model_id_for_sdk", lambda model, s: "claude-sonnet-4-6", raising=True)
-    monkeypatch.setattr(reg, "_find_builtin_model", lambda model: None, raising=True)
+    monkeypatch.setattr(reg, "find_builtin_model", lambda model: None, raising=True)
 
     captured = {}
 
diff --git a/backend/tests/test_v2_invariants.py b/backend/tests/test_v2_invariants.py
index 6cd0ca45..9a61513f 100644
--- a/backend/tests/test_v2_invariants.py
+++ b/backend/tests/test_v2_invariants.py
@@ -582,15 +582,15 @@ def test_resolve_sdk_gemini_prefers_antigravity_over_api_key():
     from backend.apps.settings.models import AppSettings
     s = AppSettings()
     s.google_api_key = "ai-studio-key"
-    with patch.object(registry, "_antigravity_connected", return_value=True):
+    with patch.object(registry, "p_antigravity_connected", return_value=True):
         # flash IS AG-serveable -> AG wins over the key
         assert registry.resolve_model_id_for_sdk("gemini-3-flash", s) == "ag/gemini-3-flash"
-    with patch.object(registry, "_antigravity_connected", return_value=False):
+    with patch.object(registry, "p_antigravity_connected", return_value=False):
         # AG not connected -> key
         assert registry.resolve_model_id_for_sdk("gemini-3-flash", s) == "gemini/gemini-3-flash-preview"
     # No key, no AG -> gc/ subscription lane untouched
     s2 = AppSettings()
-    with patch.object(registry, "_antigravity_connected", return_value=False):
+    with patch.object(registry, "p_antigravity_connected", return_value=False):
         assert registry.resolve_model_id_for_sdk("gemini-3-flash", s2) == "gc/gemini-3-flash-preview"
 
 
@@ -1254,13 +1254,13 @@ def test_get_api_type_openai():
 
 
 def test_find_builtin_model_returns_none_for_unknown():
-    from backend.apps.agents.providers.registry import _find_builtin_model
-    assert _find_builtin_model("not-a-real-model-xyz") is None
+    from backend.apps.agents.providers.registry import find_builtin_model
+    assert find_builtin_model("not-a-real-model-xyz") is None
 
 
 def test_find_builtin_model_returns_dict_for_known():
-    from backend.apps.agents.providers.registry import _find_builtin_model
-    sonnet = _find_builtin_model("sonnet")
+    from backend.apps.agents.providers.registry import find_builtin_model
+    sonnet = find_builtin_model("sonnet")
     assert sonnet is not None
     assert sonnet.get("api") == "anthropic"
 
@@ -1766,20 +1766,20 @@ def test_gpt5_param_scrub_drops_unsupported_sampling_knobs():
     Live-confirmed the 400s against the OpenAI API 2026-06-14."""
     import json
     from backend.apps.agents.proxy.anthropic_proxy import _scrub_request_for_openai_gpt5
-    from backend.apps.agents.core.openai_passthrough import _scrub_gpt5_params
+    from backend.apps.agents.core.openai_passthrough import scrub_gpt5_params
     dirty = json.dumps({"model": "gpt-5", "messages": [{"role": "user", "content": "hi"}],
                         "max_tokens": 200, "temperature": 0, "top_p": 0.9,
                         "frequency_penalty": 0.5, "presence_penalty": 0.1, "logprobs": True}).encode()
-    for fn in (_scrub_request_for_openai_gpt5, _scrub_gpt5_params):
+    for fn in (_scrub_request_for_openai_gpt5, scrub_gpt5_params):
         out = json.loads(fn(dirty))
         assert out.get("max_completion_tokens") == 200 and "max_tokens" not in out, fn.__name__
         for k in ("temperature", "top_p", "frequency_penalty", "presence_penalty", "logprobs"):
             assert k not in out, f"{fn.__name__} left {k}"
     # temperature==1 is the one allowed value; don't over-strip it
-    assert json.loads(_scrub_gpt5_params(json.dumps(
+    assert json.loads(scrub_gpt5_params(json.dumps(
         {"model": "gpt-5", "temperature": 1}).encode())).get("temperature") == 1
     # non-gpt-5 models are untouched
-    assert json.loads(_scrub_gpt5_params(json.dumps(
+    assert json.loads(scrub_gpt5_params(json.dumps(
         {"model": "gpt-4o", "temperature": 0, "top_p": 0.5}).encode())) == \
         {"model": "gpt-4o", "temperature": 0, "top_p": 0.5}
 
@@ -2300,8 +2300,8 @@ def test_custom_provider_value_synthesises_route_api_entry():
     api='custom' entry whose model_id is the 9Router routing string
     `cp-<slug>/<bare>`. agent_manager keys on api='custom' and resolved_model
     must be the cp- prefixed string for 9Router to forward correctly."""
-    from backend.apps.agents.providers.registry import _find_builtin_model
-    entry = _find_builtin_model("custom/ollama-cloud/gpt-oss:120b")
+    from backend.apps.agents.providers.registry import find_builtin_model
+    entry = find_builtin_model("custom/ollama-cloud/gpt-oss:120b")
     assert entry is not None
     assert entry.get("api") == "custom"
     assert entry.get("route") == "api"
@@ -2320,28 +2320,28 @@ def test_custom_provider_value_with_multi_segment_model_id():
     """Model ids may contain '/' (e.g. meta-llama/llama-3-70b-instruct on
     Together AI). Synthesis must use partition on the FIRST '/' so the
     rest of the model id stays intact."""
-    from backend.apps.agents.providers.registry import _find_builtin_model
-    entry = _find_builtin_model("custom/together-ai/meta-llama/llama-3-70b-instruct")
+    from backend.apps.agents.providers.registry import find_builtin_model
+    entry = find_builtin_model("custom/together-ai/meta-llama/llama-3-70b-instruct")
     assert entry is not None
     assert entry.get("model_id") == "cp-together-ai/meta-llama/llama-3-70b-instruct"
 
 
 def test_custom_provider_lookup_finds_entry_by_slug():
-    """_find_custom_provider_for_value must slugify the same way as the
+    """find_custom_provider_for_value must slugify the same way as the
     UI/sync layer so name 'Ollama Cloud' resolves to the value
     'custom/ollama-cloud/...'."""
-    from backend.apps.agents.providers.registry import _find_custom_provider_for_value
+    from backend.apps.agents.providers.registry import find_custom_provider_for_value
     from backend.apps.settings.models import AppSettings, CustomProvider
     s = AppSettings(custom_providers=[
         CustomProvider(name="Ollama Cloud", base_url="https://ollama.com/v1", api_key="x"),
         CustomProvider(name="Together AI", base_url="https://api.together.xyz/v1", api_key="y"),
     ])
-    cp = _find_custom_provider_for_value(s, "custom/ollama-cloud/gpt-oss:120b")
+    cp = find_custom_provider_for_value(s, "custom/ollama-cloud/gpt-oss:120b")
     assert cp is not None and cp.name == "Ollama Cloud"
-    cp2 = _find_custom_provider_for_value(s, "custom/together-ai/meta-llama/llama-3-70b")
+    cp2 = find_custom_provider_for_value(s, "custom/together-ai/meta-llama/llama-3-70b")
     assert cp2 is not None and cp2.name == "Together AI"
     # Unknown slug → None.
-    assert _find_custom_provider_for_value(s, "custom/nonexistent/whatever") is None
+    assert find_custom_provider_for_value(s, "custom/nonexistent/whatever") is None
 
 
 def test_get_context_window_custom_provider_value_format():
@@ -2365,22 +2365,22 @@ def test_custom_provider_slug_is_url_safe():
     """The slug must be alnum-and-dash only, it's used both as the 9Router
     prefix and as a URL path segment. Spaces, slashes, and special chars
     must all be folded to dashes."""
-    from backend.apps.agents.providers.registry import _custom_provider_slug_for_lookup
-    assert _custom_provider_slug_for_lookup("Ollama Cloud") == "ollama-cloud"
-    assert _custom_provider_slug_for_lookup("My/Local LM!!!") == "my-local-lm"
-    assert _custom_provider_slug_for_lookup("") == "custom"
-    assert _custom_provider_slug_for_lookup("   ") == "custom"
+    from backend.apps.agents.providers.registry import custom_provider_slug_for_lookup
+    assert custom_provider_slug_for_lookup("Ollama Cloud") == "ollama-cloud"
+    assert custom_provider_slug_for_lookup("My/Local LM!!!") == "my-local-lm"
+    assert custom_provider_slug_for_lookup("") == "custom"
+    assert custom_provider_slug_for_lookup("   ") == "custom"
 
 
 def test_custom_provider_slug_unicode_collapses_safely():
     """Unicode names are folded to ASCII-safe dashes; emojis/accents drop."""
-    from backend.apps.agents.providers.registry import _custom_provider_slug_for_lookup
+    from backend.apps.agents.providers.registry import custom_provider_slug_for_lookup
     # Accented chars get stripped (regex is [a-zA-Z0-9-] only).
-    assert _custom_provider_slug_for_lookup("Tögether AI 🚀") == "t-gether-ai"
+    assert custom_provider_slug_for_lookup("Tögether AI 🚀") == "t-gether-ai"
     # Pure-emoji name → fallback "custom".
-    assert _custom_provider_slug_for_lookup("🚀💎") == "custom"
+    assert custom_provider_slug_for_lookup("🚀💎") == "custom"
     # Trailing/leading dashes get stripped.
-    assert _custom_provider_slug_for_lookup("---weird---") == "weird"
+    assert custom_provider_slug_for_lookup("---weird---") == "weird"
 
 
 def test_custom_provider_slug_does_not_collide_with_routing_prefixes():
@@ -2388,8 +2388,8 @@ def test_custom_provider_slug_does_not_collide_with_routing_prefixes():
     built-in prefixes (cc/, cx/, gc/, ag/, gemini/, openrouter/) used by
     resolved_is_9router. cp- starts with 'c' and dash so it can't be
     confused with cc/, but verify the dispatch logic agrees."""
-    from backend.apps.agents.providers.registry import _find_builtin_model
-    entry = _find_builtin_model("custom/cc/whatever")  # adversarial slug "cc"
+    from backend.apps.agents.providers.registry import find_builtin_model
+    entry = find_builtin_model("custom/cc/whatever")  # adversarial slug "cc"
     assert entry is not None
     routed = entry["model_id"]
     assert routed == "cp-cc/whatever"
@@ -2402,7 +2402,7 @@ def test_custom_provider_models_with_special_chars():
     (deepseek 'deepseek-v3.1'), version suffixes (':free'), and slashes
     (Together 'meta-llama/Llama-3-70B'). All must round-trip without
     being mangled."""
-    from backend.apps.agents.providers.registry import _find_builtin_model
+    from backend.apps.agents.providers.registry import find_builtin_model
     cases = [
         "custom/ollama/gpt-oss:120b",
         "custom/together/meta-llama/Llama-3.3-70B-Instruct",
@@ -2411,7 +2411,7 @@ def test_custom_provider_models_with_special_chars():
         "custom/groq/llama-3.3-70b-versatile",
     ]
     for v in cases:
-        e = _find_builtin_model(v)
+        e = find_builtin_model(v)
         assert e is not None, f"failed: {v}"
         # Bare-model portion is everything after first slash after the slug.
         rest = v[len("custom/"):]
@@ -2421,12 +2421,12 @@ def test_custom_provider_models_with_special_chars():
 
 def test_custom_provider_value_with_invalid_format_returns_none():
     """Malformed picker values (no slug, no model) must not synthesise a
-    bogus entry, they should miss _find_builtin_model entirely so the
+    bogus entry, they should miss find_builtin_model entirely so the
     dispatch loop falls through to the 'unknown model' branch."""
-    from backend.apps.agents.providers.registry import _find_builtin_model
-    assert _find_builtin_model("custom/") is None
-    assert _find_builtin_model("custom/onlyslug") is None
-    assert _find_builtin_model("custom//onlymodel") is None  # empty slug
+    from backend.apps.agents.providers.registry import find_builtin_model
+    assert find_builtin_model("custom/") is None
+    assert find_builtin_model("custom/onlyslug") is None
+    assert find_builtin_model("custom//onlymodel") is None  # empty slug
 
 
 def test_custom_provider_get_api_type_returns_custom():
@@ -2486,10 +2486,10 @@ def test_custom_provider_two_providers_get_distinct_slugs():
     """Two custom providers with different display names must produce
     two different slugs / routing prefixes, otherwise 9Router will route
     both to whichever connection was created last."""
-    from backend.apps.agents.providers.registry import _custom_provider_slug_for_lookup
-    a = _custom_provider_slug_for_lookup("Ollama Cloud")
-    b = _custom_provider_slug_for_lookup("Together AI")
-    c = _custom_provider_slug_for_lookup("Groq")
+    from backend.apps.agents.providers.registry import custom_provider_slug_for_lookup
+    a = custom_provider_slug_for_lookup("Ollama Cloud")
+    b = custom_provider_slug_for_lookup("Together AI")
+    c = custom_provider_slug_for_lookup("Groq")
     assert len({a, b, c}) == 3
 
 
@@ -2500,10 +2500,10 @@ def test_custom_provider_slug_collision_after_sanitize():
     test just documents that post-slug collisions DO collide and the
     UI-level uniqueness check (in Settings.tsx) is the right enforcement
     layer, backend resolution would always pick the first match."""
-    from backend.apps.agents.providers.registry import _custom_provider_slug_for_lookup
-    assert _custom_provider_slug_for_lookup("Ollama Cloud") == \
-           _custom_provider_slug_for_lookup("ollama-cloud") == \
-           _custom_provider_slug_for_lookup("OLLAMA cloud")
+    from backend.apps.agents.providers.registry import custom_provider_slug_for_lookup
+    assert custom_provider_slug_for_lookup("Ollama Cloud") == \
+           custom_provider_slug_for_lookup("ollama-cloud") == \
+           custom_provider_slug_for_lookup("OLLAMA cloud")
 
 
 def test_list_models_includes_complete_custom_providers_excludes_incomplete():
@@ -2634,11 +2634,11 @@ def test_custom_provider_resolve_aux_model_unaffected():
 def test_custom_provider_with_very_long_name_still_works():
     """No upper bound on name length anywhere in the pipeline. Verify a
     250-char name slugs cleanly."""
-    from backend.apps.agents.providers.registry import _custom_provider_slug_for_lookup, _find_builtin_model
+    from backend.apps.agents.providers.registry import custom_provider_slug_for_lookup, find_builtin_model
     long_name = "a" * 250
-    slug = _custom_provider_slug_for_lookup(long_name)
+    slug = custom_provider_slug_for_lookup(long_name)
     assert slug == long_name
-    entry = _find_builtin_model(f"custom/{slug}/some-model")
+    entry = find_builtin_model(f"custom/{slug}/some-model")
     assert entry is not None
     assert entry["model_id"] == f"cp-{slug}/some-model"
 
diff --git a/backend/tests/test_web_mcp_decision.py b/backend/tests/test_web_mcp_decision.py
index b5f1b40f..fe782667 100644
--- a/backend/tests/test_web_mcp_decision.py
+++ b/backend/tests/test_web_mcp_decision.py
@@ -12,7 +12,7 @@ def _call(**kw):
     base = dict(model="m", router_model_id="cc/opus", api_type="anthropic",
                 anthropic_api_key=None, connection_mode="own_key")
     base.update(kw)
-    with patch("backend.apps.agents.providers.registry._find_builtin_model", return_value=None):
+    with patch("backend.apps.agents.providers.registry.find_builtin_model", return_value=None):
         return should_register_web_mcp(**base)
 
 
@@ -40,7 +40,7 @@ def test_subscription_route_claude_non_pro_registers():
 
 def test_direct_anthropic_api_route_uses_native_path():
     entry = {"route": "api", "api": "anthropic"}
-    with patch("backend.apps.agents.providers.registry._find_builtin_model", return_value=entry):
+    with patch("backend.apps.agents.providers.registry.find_builtin_model", return_value=entry):
         out = should_register_web_mcp(
             model="claude-x", router_model_id="claude-3-5-api", api_type="anthropic",
             anthropic_api_key="sk-ant-xxx", connection_mode="own_key",