feat: add privacy router and zero-cost safeguards

src/javis/memory/usage_store.py

@@ -0,0 +1,114 @@
+"""Metadata-only provider audit and local usage limits."""
+
+from __future__ import annotations
+
+import sqlite3
+from contextlib import closing
+from dataclasses import dataclass
+from datetime import UTC, date, datetime
+from pathlib import Path
+
+
+class UsageStoreError(RuntimeError):
+    """Provider metadata could not be stored or read."""
+
+
+@dataclass(frozen=True, slots=True)
+class ProviderEvent:
+    provider: str
+    model: str
+    success: bool
+    error_category: str | None
+    fallback: bool
+    privacy_policy: str
+    input_tokens: int | None = None
+    output_tokens: int | None = None
+
+
+class SQLiteUsageStore:
+    def __init__(self, database_path: Path) -> None:
+        self.database_path = database_path
+        try:
+            self.database_path.parent.mkdir(parents=True, exist_ok=True)
+            with closing(self._connect()) as connection:
+                connection.execute(
+                    """
+                    CREATE TABLE IF NOT EXISTS provider_events (
+                        id INTEGER PRIMARY KEY AUTOINCREMENT,
+                        occurred_at TEXT NOT NULL,
+                        provider TEXT NOT NULL,
+                        model TEXT NOT NULL,
+                        success INTEGER NOT NULL,
+                        error_category TEXT,
+                        fallback INTEGER NOT NULL,
+                        privacy_policy TEXT NOT NULL,
+                        input_tokens INTEGER,
+                        output_tokens INTEGER
+                    )
+                    """
+                )
+                connection.execute(
+                    """
+                    CREATE INDEX IF NOT EXISTS idx_provider_events_time_provider
+                    ON provider_events(occurred_at, provider)
+                    """
+                )
+                connection.commit()
+        except (OSError, sqlite3.Error) as exc:
+            raise UsageStoreError(
+                f"Die Nutzungsmetadatenbank kann nicht geöffnet werden: {database_path}"
+            ) from exc
+
+    def _connect(self) -> sqlite3.Connection:
+        return sqlite3.connect(self.database_path, timeout=10)
+
+    def record(self, event: ProviderEvent) -> None:
+        try:
+            with closing(self._connect()) as connection:
+                connection.execute(
+                    """
+                    INSERT INTO provider_events (
+                        occurred_at, provider, model, success, error_category,
+                        fallback, privacy_policy, input_tokens, output_tokens
+                    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+                    """,
+                    (
+                        datetime.now(UTC).isoformat(timespec="seconds"),
+                        event.provider,
+                        event.model,
+                        int(event.success),
+                        event.error_category,
+                        int(event.fallback),
+                        event.privacy_policy,
+                        event.input_tokens,
+                        event.output_tokens,
+                    ),
+                )
+                connection.commit()
+        except sqlite3.Error as exc:
+            raise UsageStoreError("Nutzungsmetadaten konnten nicht gespeichert werden.") from exc
+
+    def cloud_requests_on(self, day: date | None = None) -> int:
+        return self._count(day or datetime.now(UTC).date(), "provider = 'gemini'")
+
+    def local_fallbacks_on(self, day: date | None = None) -> int:
+        return self._count(
+            day or datetime.now(UTC).date(),
+            "provider = 'ollama' AND fallback = 1",
+        )
+
+    def _count(self, day: date, condition: str) -> int:
+        start = f"{day.isoformat()}T00:00:00+00:00"
+        end = f"{day.isoformat()}T23:59:59+00:00"
+        try:
+            with closing(self._connect()) as connection:
+                row = connection.execute(
+                    f"""
+                    SELECT COUNT(*) FROM provider_events
+                    WHERE occurred_at BETWEEN ? AND ? AND {condition}
+                    """,
+                    (start, end),
+                ).fetchone()
+        except sqlite3.Error as exc:
+            raise UsageStoreError("Nutzungsmetadaten konnten nicht gelesen werden.") from exc
+        return int(row[0])