Implement LLM-WP-0007: Kimi K3 default and EUR spend reporting

Add moonshotai/kimi-k3 as OpenRouter basemodel default after live smoke,
USD→EUR cost conversion, append-only usage ledger, and CLI run/cost/spend
week commands with token and euro reporting.

tests/test_usage.py

@@ -0,0 +1,127 @@
+from datetime import datetime
+from zoneinfo import ZoneInfo
+
+import pytest
+
+from llm_connect.models import LLMResponse
+from llm_connect.usage import (
+    UsageEvent,
+    UsageLedger,
+    default_usage_ledger_path,
+    event_from_response,
+    maybe_record_usage,
+    suppress_auto_usage_record,
+    week_window,
+)
+
+
+def test_default_ledger_path_env_and_xdg():
+    assert default_usage_ledger_path(env={"LLM_CONNECT_USAGE_LEDGER": "/tmp/u.jsonl"}) == (
+        __import__("pathlib").Path("/tmp/u.jsonl")
+    )
+    path = default_usage_ledger_path(env={"XDG_DATA_HOME": "/tmp/xdg"})
+    assert path.as_posix().endswith("llm-connect/usage.jsonl")
+    assert "xdg" in path.as_posix()
+
+
+def test_usage_ledger_append_and_sum_range(tmp_path):
+    ledger = UsageLedger(tmp_path / "usage.jsonl")
+    berlin = ZoneInfo("Europe/Berlin")
+    monday = datetime(2026, 8, 3, 10, 0, tzinfo=berlin)  # Monday
+    sunday = datetime(2026, 8, 2, 12, 0, tzinfo=berlin)  # previous Sunday
+
+    ledger.append(
+        UsageEvent(
+            provider="openrouter",
+            model_id="moonshotai/kimi-k3",
+            prompt_tokens=100,
+            completion_tokens=50,
+            total_tokens=150,
+            cost_usd=0.001,
+            cost_eur=0.00092,
+            cost_source="rate_table:moonshotai/kimi-k3",
+            fx_source="snapshot:2026-08-03",
+            source="cli",
+            recorded_at=monday,
+        )
+    )
+    ledger.append(
+        UsageEvent(
+            provider="openrouter",
+            model_id="moonshotai/kimi-k3",
+            prompt_tokens=10,
+            completion_tokens=5,
+            total_tokens=15,
+            cost_usd=0.0001,
+            cost_eur=0.000092,
+            cost_source="rate_table:moonshotai/kimi-k3",
+            source="cli",
+            recorded_at=sunday,
+        )
+    )
+
+    start, end = week_window(
+        "current",
+        now=datetime(2026, 8, 5, 18, 0, tzinfo=berlin),
+        tz="Europe/Berlin",
+    )
+    summary = ledger.sum_range(start, end)
+
+    assert summary.event_count == 1
+    assert summary.prompt_tokens == 100
+    assert summary.total_tokens == 150
+    assert summary.cost_eur == pytest.approx(0.00092)
+
+    last_start, last_end = week_window(
+        "last",
+        now=datetime(2026, 8, 5, 18, 0, tzinfo=berlin),
+        tz="Europe/Berlin",
+    )
+    last_summary = ledger.sum_range(last_start, last_end)
+    assert last_summary.event_count == 1
+    assert last_summary.total_tokens == 15
+
+
+def test_week_window_current_and_last():
+    berlin = ZoneInfo("Europe/Berlin")
+    now = datetime(2026, 8, 5, 15, 30, tzinfo=berlin)  # Wednesday
+    start, end = week_window("current", now=now, tz="Europe/Berlin")
+    assert start.weekday() == 0
+    assert start.hour == 0
+    assert end == now
+
+    last_start, last_end = week_window("last", now=now, tz="Europe/Berlin")
+    assert (last_end - last_start).days == 7
+    assert last_end == start
+
+
+def test_event_from_response_estimates_kimi_cost():
+    response = LLMResponse(
+        content="hi",
+        model="moonshotai/kimi-k3",
+        usage={"prompt_tokens": 1000, "completion_tokens": 1000, "total_tokens": 2000},
+    )
+    event = event_from_response(response, provider="openrouter", source="cli", fx=1.0)
+
+    assert event.cost_usd == pytest.approx(0.018)
+    assert event.cost_eur == pytest.approx(0.018)
+    assert event.cost_source == "rate_table:moonshotai/kimi-k3"
+
+
+def test_maybe_record_usage_opt_in(tmp_path, monkeypatch):
+    ledger = tmp_path / "usage.jsonl"
+    monkeypatch.setenv("LLM_CONNECT_USAGE_LEDGER", str(ledger))
+    response = LLMResponse(
+        content="x",
+        model="moonshotai/kimi-k3",
+        usage={"prompt_tokens": 10, "completion_tokens": 5, "total_tokens": 15},
+        metadata={"provider": "openrouter"},
+    )
+
+    event = maybe_record_usage(response, provider="openrouter", source="library")
+    assert event is not None
+    assert ledger.is_file()
+    assert UsageLedger(ledger).read_all()[0].source == "library"
+
+    with suppress_auto_usage_record():
+        assert maybe_record_usage(response, provider="openrouter", source="library") is None