fix watchlist remove (was undone by auto-populate); add watch toggle on ticker page

Removing a ticker did nothing because get_watchlist re-runs auto_populate on
every read, instantly re-adding any top-ranked ticker the user had just removed.
Removals are now tombstoned as a "dismissed" entry_type: auto-population skips
them, the list hides them, and a later manual add revives the row. Also exposes
an Add/Remove-watchlist toggle in the ticker detail header.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/unit/test_watchlist_service.py

@@ -0,0 +1,104 @@
+"""Tests for watchlist remove → dismiss → revive behaviour.
+
+Regression cover for the bug where removing a top-ranked ticker did nothing,
+because get_watchlist re-runs auto_populate on every read and would instantly
+re-add it. Removals are now tombstoned as "dismissed" so auto-population skips
+them; a later manual add revives the row.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+
+import pytest
+from sqlalchemy import select
+
+from app.models.score import CompositeScore
+from app.models.ticker import Ticker
+from app.models.user import User
+from app.models.watchlist import WatchlistEntry
+from app.services.watchlist_service import (
+    DISMISSED,
+    add_manual_entry,
+    auto_populate,
+    get_watchlist,
+    remove_entry,
+)
+
+# Plain (committing) session — the watchlist service commits, so the rolling-back
+# db_session fixture would fight it. Reuse the shared in-memory engine.
+from tests.conftest import _test_session_factory  # type: ignore
+
+
+@pytest.fixture
+async def session():
+    async with _test_session_factory() as s:
+        yield s
+
+
+async def _seed(session) -> tuple[int, list[int]]:
+    user = User(username="u", password_hash="x", role="user", has_access=True)
+    session.add(user)
+    await session.flush()
+
+    now = datetime.now(timezone.utc)
+    ticker_ids: list[int] = []
+    for i, sym in enumerate(["AAA", "BBB", "CCC"]):
+        t = Ticker(symbol=sym)
+        session.add(t)
+        await session.flush()
+        ticker_ids.append(t.id)
+        session.add(
+            CompositeScore(
+                ticker_id=t.id,
+                score=90.0 - i,  # AAA highest
+                is_stale=False,
+                weights_json="{}",
+                computed_at=now,
+            )
+        )
+    await session.commit()
+    return user.id, ticker_ids
+
+
+async def test_remove_dismisses_and_survives_auto_populate(session):
+    user_id, _ = await _seed(session)
+
+    await auto_populate(session, user_id)
+    await session.commit()
+
+    rows = await get_watchlist(session, user_id)
+    assert {r["symbol"] for r in rows} == {"AAA", "BBB", "CCC"}
+
+    # Remove a top-ranked ticker, then force another auto-population pass.
+    await remove_entry(session, user_id, "AAA")
+    await auto_populate(session, user_id)
+    await session.commit()
+
+    rows = await get_watchlist(session, user_id)
+    symbols = {r["symbol"] for r in rows}
+    assert "AAA" not in symbols
+    assert symbols == {"BBB", "CCC"}
+
+    # The row is tombstoned, not deleted.
+    res = await session.execute(
+        select(WatchlistEntry).join(Ticker).where(Ticker.symbol == "AAA")
+    )
+    entry = res.scalar_one()
+    assert entry.entry_type == DISMISSED
+
+
+async def test_manual_add_revives_dismissed(session):
+    user_id, _ = await _seed(session)
+    await auto_populate(session, user_id)
+    await session.commit()
+
+    await remove_entry(session, user_id, "AAA")
+
+    # Re-adding the dismissed ticker should succeed (not DuplicateError) and
+    # reappear as a manual entry.
+    revived = await add_manual_entry(session, user_id, "AAA")
+    assert revived.entry_type == "manual"
+
+    rows = await get_watchlist(session, user_id)
+    assert "AAA" in {r["symbol"] for r in rows}