feat(tiktok): add tiktok.user_search verb for account discovery

Video/general search is login-walled for anonymous sessions, but the Users
tab (/api/search/user) returns public account records without a redirect, so
this exposes the one reliably-unblocked search path. A keyword yields
TikTokProfileItems (name, followers, bio, verification), deduped per query,
capped, and degraded to an ErrorItem when a query is empty/withheld.

Reuses the browser capture (generalized over XHR markers + extractor) and the
shared profile item shape. Billed per account on a new TIKTOK_USER meter
(TIKTOK_MICROS_PER_USER), surfaced on the chat subagent alongside tiktok.scrape.

surfsense_backend/tests/unit/capabilities/tiktok/test_registry.py

@@ -10,6 +10,10 @@ from app.capabilities import (
 from app.capabilities.core import BillingUnit
 from app.capabilities.core.store import get_capability
 from app.capabilities.tiktok.scrape.schemas import ScrapeInput, ScrapeOutput
+from app.capabilities.tiktok.user_search.schemas import (
+    UserSearchInput,
+    UserSearchOutput,
+)
 
 pytestmark = pytest.mark.unit
 
@@ -21,3 +25,12 @@ def test_tiktok_scrape_is_registered_and_billed_per_video():
     assert cap.input_schema is ScrapeInput
     assert cap.output_schema is ScrapeOutput
     assert cap.billing_unit is BillingUnit.TIKTOK_VIDEO
+
+
+def test_tiktok_user_search_is_registered_and_billed_per_profile():
+    cap = get_capability("tiktok.user_search")
+
+    assert cap.name == "tiktok.user_search"
+    assert cap.input_schema is UserSearchInput
+    assert cap.output_schema is UserSearchOutput
+    assert cap.billing_unit is BillingUnit.TIKTOK_USER

surfsense_backend/tests/unit/capabilities/tiktok/user_search/test_executor.py

@@ -0,0 +1,49 @@
+"""``tiktok.user_search`` executor: verb input → search args → typed profile items.
+
+Boundary mocked: the proprietary search actor (injected fake). NOT mocked: the
+verb's own payload→args forwarding and the dict→TikTokProfileItem wrapping.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from app.capabilities.tiktok.user_search.executor import build_user_search_executor
+from app.capabilities.tiktok.user_search.schemas import (
+    UserSearchInput,
+    UserSearchOutput,
+)
+
+pytestmark = pytest.mark.unit
+
+
+class _FakeSearch:
+    """Records the queries + kwargs it was called with; returns canned items."""
+
+    def __init__(self, items: list[dict]):
+        self._items = items
+        self.calls: list[tuple[list[str], int, int | None]] = []
+
+    async def __call__(
+        self, queries: list[str], *, per_query: int, limit: int | None = None
+    ) -> list[dict]:
+        self.calls.append((queries, per_query, limit))
+        return self._items
+
+
+async def test_forwards_queries_and_limits_and_wraps_items():
+    search = _FakeSearch([{"id": "1", "name": "nasa"}])
+    execute = build_user_search_executor(search_fn=search)
+
+    out = await execute(
+        UserSearchInput(queries=["nasa"], results_per_query=7, max_items=25)
+    )
+
+    assert isinstance(out, UserSearchOutput)
+    assert len(out.items) == 1
+    assert out.items[0].name == "nasa"
+
+    (queries, per_query, limit) = search.calls[0]
+    assert queries == ["nasa"]
+    assert per_query == 7
+    assert limit == 25

surfsense_backend/tests/unit/capabilities/tiktok/user_search/test_schemas.py

@@ -0,0 +1,49 @@
+"""``tiktok.user_search`` input guards and billing: a query is required, bounded,
+and ErrorItems are surfaced free."""
+
+from __future__ import annotations
+
+import pytest
+from pydantic import ValidationError
+
+from app.capabilities.tiktok.scrape.schemas import MAX_TIKTOK_ITEMS, MAX_TIKTOK_SOURCES
+from app.capabilities.tiktok.user_search.schemas import (
+    UserSearchInput,
+    UserSearchOutput,
+)
+
+pytestmark = pytest.mark.unit
+
+
+def test_rejects_input_with_no_query():
+    with pytest.raises(ValidationError):
+        UserSearchInput(queries=[])
+
+
+def test_defaults_and_bounds():
+    payload = UserSearchInput(queries=["nasa"])
+    assert payload.max_items == 10
+    assert payload.results_per_query == 10
+    assert payload.estimated_units == 10
+    with pytest.raises(ValidationError):
+        UserSearchInput(queries=["nasa"], max_items=0)
+    with pytest.raises(ValidationError):
+        UserSearchInput(queries=["nasa"], max_items=MAX_TIKTOK_ITEMS + 1)
+
+
+def test_rejects_more_queries_than_the_cap():
+    too_many = [f"q{i}" for i in range(MAX_TIKTOK_SOURCES + 1)]
+    with pytest.raises(ValidationError):
+        UserSearchInput(queries=too_many)
+
+
+def test_error_items_are_not_billed():
+    # Real accounts count; ErrorItems (empty/withheld queries) are surfaced free.
+    out = UserSearchOutput(
+        items=[
+            {"id": "1", "name": "nasa"},
+            {"errorCode": "no_users", "input": "ghost", "error": "empty"},
+        ]
+    )
+    assert len(out.items) == 2
+    assert out.billable_units == 1