feat: session modes (Talk/Cash) + live session HUD

Lyra now switches register based on what she's doing at the table instead of
being a wishy-washy companion mid-session.

Modes (lyra/modes.py):
- Talk (default companion) + Cash (live cash copilot); a mode = prompt card +
  tool allow-list. Tool gating via tools.specs(allow=).
- Two-register Cash voice: act-first one-line logging when fed facts; full warm
  companion voice for strategy / tilt / mental game.
- mode persisted per chat session (new sessions.mode column); auto-switch into
  Cash when start_session fires; UI forces cloud backend in Cash (tools only
  fire there).

Stack tracking + HUD:
- log_stack tool + poker_stack_log table; live net while sitting (stack - buy-in).
- poker.hud() bundle; /session HUD page (stack sparkline, hands, villains, notes,
  stats) polling /session/data every 5s; Talk/Cash switcher + Session nav.

Endpoints: /session, /session/data, GET/POST /sessions/{id}/mode, /modes.
tests/test_modes.py (gating, mode roundtrip, stack/HUD); 36 tests green. v0.3.0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_modes.py

@@ -0,0 +1,108 @@
+"""Conversation modes: tool gating, mode persistence, stack tracking + HUD."""
+from __future__ import annotations
+
+import importlib
+
+import pytest
+
+
+@pytest.fixture
+def lyra(tmp_path, monkeypatch):
+    monkeypatch.setenv("LYRA_DB_PATH", str(tmp_path / "test.db"))
+    from lyra import llm
+    monkeypatch.setattr(llm, "embed", lambda texts: [[0.1, 0.2, 0.3] for _ in texts])
+    import lyra.memory as memory
+    importlib.reload(memory)
+    import lyra.poker as poker
+    importlib.reload(poker)
+    import lyra.modes as modes
+    importlib.reload(modes)
+    import lyra.tools as tools
+    importlib.reload(tools)
+    return memory, poker, modes, tools
+
+
+def _names(specs):
+    return {s["function"]["name"] for s in specs}
+
+
+def test_tool_gating_by_mode(lyra):
+    _, _, modes, tools = lyra
+    talk = _names(tools.specs(modes.TALK.tools))
+    cash = _names(tools.specs(modes.CASH.tools))
+
+    # Cash is the full live toolset.
+    assert {"log_hand", "log_stack", "analyze_spot", "end_session"} <= cash
+    # Talk hides the live write tools...
+    assert "log_hand" not in talk and "log_stack" not in talk
+    # ...but keeps her agency + read-only lookups + the session entry point.
+    assert {"journal_write", "note", "player_profile", "start_session"} <= talk
+    # No allow-list = every registered tool.
+    assert _names(tools.specs()) == set(tools.TOOLS)
+
+
+def test_every_mode_tool_exists(lyra):
+    _, _, modes, tools = lyra
+    for mode in modes.MODES.values():
+        assert set(mode.tools) <= set(tools.TOOLS), f"{mode.key} references unknown tools"
+
+
+def test_mode_resolution_and_persistence(lyra):
+    memory, _, modes, _ = lyra
+    assert modes.get(None).key == modes.DEFAULT
+    assert modes.get("nonsense").key == modes.DEFAULT
+    assert modes.get("poker_cash") is modes.CASH
+
+    memory.ensure_session("s1")
+    assert memory.get_session_mode("s1") is None  # unset -> caller applies default
+    memory.set_session_mode("s1", "poker_cash")
+    assert memory.get_session_mode("s1") == "poker_cash"
+    # set on an unknown session creates the row
+    memory.set_session_mode("s2", "conversation")
+    assert memory.get_session_mode("s2") == "conversation"
+
+
+def test_stack_log_and_live_net(lyra):
+    _, poker, _, _ = lyra
+    poker.start_session(venue="Meadows", stakes="2/5", buy_in=500)
+    assert poker.current_stack() is None  # nothing logged yet
+
+    st = poker.log_stack(700)
+    assert st["current"] == 700 and st["net"] == 200  # up 200 on a 500 buy-in
+    poker.log_stack(350)
+    assert poker.current_stack() == 350
+    assert poker.stack_state()["net"] == -150
+    assert len(poker.stack_log()) == 2
+
+
+def test_log_stack_requires_live_session(lyra):
+    _, poker, _, _ = lyra
+    with pytest.raises(ValueError):
+        poker.log_stack(300)
+
+
+def test_hud_bundle(lyra):
+    _, poker, _, _ = lyra
+    assert poker.hud() is None  # no session -> nothing to show
+
+    sid = poker.start_session(venue="Meadows", stakes="2/5", game="NLH", buy_in=500)
+    poker.log_stack(620)
+    poker.log_hand(position="BTN", hole_cards="AKs", result=120, tag="confidence")
+    poker.add_read(note="3bets light from the SB", name="Round Mike", seat="SB")
+
+    hud = poker.hud()
+    assert hud["session"]["id"] == sid and hud["session"]["stakes"] == "2/5"
+    assert hud["stack"]["current"] == 620 and hud["stack"]["net"] == 120
+    assert len(hud["stack"]["log"]) == 1
+    assert len(hud["hands"]) == 1 and hud["hands"][0]["hole_cards"] == "AKs"
+    assert any(v["name"] == "Round Mike" for v in hud["villains"])
+    assert hud["stats"]["hands_logged"] == 1
+
+
+def test_log_stack_tool_handler(lyra):
+    _, poker, _, tools = lyra
+    poker.start_session(stakes="1/3", buy_in=300)
+    out = tools.dispatch("log_stack", {"amount": 450}, {})
+    assert "450" in out and "150" in out  # confirms stack + live net
+    # graceful when there's no number
+    assert "number" in tools.dispatch("log_stack", {}, {}).lower()