generated from coulomb/repo-seed
session-memory Phase 0: Tier1/Tier2 store (T03)
- session_memory/core/store.py: SQLite rows + blob-dir bodies, idempotent ingest on (session_uid,seq), Tier1/Tier2 usage accounting, evict_raw that drops raw but preserves the digest; watermark columns authoritative - tests/test_store.py: ingest idempotency, accounting, eviction invariant Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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session_memory/core/store.py
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225
session_memory/core/store.py
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"""Two-tier store (design §3, §8).
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Tier 1 (bulky, evictable): ``Session`` + ``SessionEvent`` rows in SQLite, with
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event bodies written out-of-line as files under a blob dir (referenced by
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``payload_ref``). Tier 2 (compact, durable): per-session ``digest`` rows.
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Writes are idempotent on ``(session_uid, seq)`` for events and on
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``session_uid`` for sessions/digests, so sweeps are safely re-runnable. Eviction
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(:meth:`evict_raw`) deletes Tier 1 rows + blobs but keeps the session row and its
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Tier 2 digest — the invariant that makes budget-based retention non-lossy.
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"""
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from __future__ import annotations
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import json
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import os
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import re
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import sqlite3
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from datetime import datetime, timezone
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from typing import Any, Optional
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from .schema import Cost, Session, SessionEvent
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_SAFE = re.compile(r"[^A-Za-z0-9._-]+")
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def _now() -> str:
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return datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
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class Store:
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def __init__(self, db_path: str, blob_dir: str):
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self.db_path = db_path
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self.blob_dir = blob_dir
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os.makedirs(os.path.dirname(db_path) or ".", exist_ok=True)
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os.makedirs(blob_dir, exist_ok=True)
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self.db = sqlite3.connect(db_path)
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self.db.row_factory = sqlite3.Row
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self.db.execute("PRAGMA journal_mode=WAL")
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self._init_schema()
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def close(self) -> None:
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self.db.close()
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def __enter__(self) -> "Store":
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return self
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def __exit__(self, *exc) -> None:
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self.close()
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def _init_schema(self) -> None:
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self.db.executescript(
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"""
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CREATE TABLE IF NOT EXISTS sessions (
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session_uid TEXT PRIMARY KEY,
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json TEXT NOT NULL,
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analyzed_at TEXT,
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evicted_at TEXT
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);
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CREATE TABLE IF NOT EXISTS events (
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session_uid TEXT NOT NULL,
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seq INTEGER NOT NULL,
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json TEXT NOT NULL,
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PRIMARY KEY (session_uid, seq)
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);
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CREATE TABLE IF NOT EXISTS blobs (
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ref TEXT PRIMARY KEY,
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session_uid TEXT NOT NULL,
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path TEXT NOT NULL,
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nbytes INTEGER NOT NULL
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);
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CREATE TABLE IF NOT EXISTS digests (
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session_uid TEXT PRIMARY KEY,
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json TEXT NOT NULL,
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nbytes INTEGER NOT NULL
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);
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CREATE INDEX IF NOT EXISTS ix_events_uid ON events(session_uid);
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CREATE INDEX IF NOT EXISTS ix_blobs_uid ON blobs(session_uid);
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"""
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)
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self.db.commit()
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# ---- Tier 1 writes -----------------------------------------------------
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def upsert_session(self, s: Session) -> None:
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self.db.execute(
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"INSERT INTO sessions(session_uid, json, analyzed_at, evicted_at) "
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"VALUES(?,?,?,?) ON CONFLICT(session_uid) DO UPDATE SET "
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"json=excluded.json, analyzed_at=excluded.analyzed_at, evicted_at=excluded.evicted_at",
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(s.session_uid, s.to_json(), s.analyzed_at, s.evicted_at),
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)
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self.db.commit()
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def upsert_events(self, events: list[SessionEvent]) -> int:
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rows = [(e.session_uid, e.seq, e.to_json()) for e in events]
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self.db.executemany(
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"INSERT INTO events(session_uid, seq, json) VALUES(?,?,?) "
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"ON CONFLICT(session_uid, seq) DO UPDATE SET json=excluded.json",
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rows,
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)
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self.db.commit()
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return len(rows)
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def write_blobs(self, session_uid: str, blobs: dict[str, str]) -> int:
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"""Write event bodies as files; record path + size. Returns bytes written."""
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total = 0
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sub = os.path.join(self.blob_dir, _SAFE.sub("_", session_uid))
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os.makedirs(sub, exist_ok=True)
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for ref, body in blobs.items():
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data = body.encode("utf-8")
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fname = _SAFE.sub("_", ref) + ".txt"
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path = os.path.join(sub, fname)
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with open(path, "w", encoding="utf-8") as f:
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f.write(body)
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self.db.execute(
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"INSERT INTO blobs(ref, session_uid, path, nbytes) VALUES(?,?,?,?) "
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"ON CONFLICT(ref) DO UPDATE SET path=excluded.path, nbytes=excluded.nbytes",
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(ref, session_uid, path, len(data)),
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)
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total += len(data)
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self.db.commit()
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return total
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def ingest(self, bundle) -> None:
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"""Persist a full Normalized bundle (session + events + blobs)."""
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s = bundle.session
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if s.ingested_at is None:
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s.ingested_at = _now()
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self.upsert_session(s)
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self.upsert_events(bundle.events)
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self.write_blobs(s.session_uid, bundle.blobs)
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# ---- Tier 2 (digest) ---------------------------------------------------
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def write_digest(self, session_uid: str, digest: dict[str, Any], analyzed_at: Optional[str] = None) -> None:
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payload = json.dumps(digest, sort_keys=True)
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self.db.execute(
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"INSERT INTO digests(session_uid, json, nbytes) VALUES(?,?,?) "
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"ON CONFLICT(session_uid) DO UPDATE SET json=excluded.json, nbytes=excluded.nbytes",
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(session_uid, payload, len(payload.encode("utf-8"))),
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)
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self.db.execute(
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"UPDATE sessions SET analyzed_at=? WHERE session_uid=?",
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(analyzed_at or _now(), session_uid),
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)
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self.db.commit()
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def get_digest(self, session_uid: str) -> Optional[dict[str, Any]]:
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row = self.db.execute("SELECT json FROM digests WHERE session_uid=?", (session_uid,)).fetchone()
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return json.loads(row["json"]) if row else None
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# ---- reads -------------------------------------------------------------
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def get_session(self, session_uid: str) -> Optional[Session]:
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row = self.db.execute(
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"SELECT json, analyzed_at, evicted_at FROM sessions WHERE session_uid=?", (session_uid,)
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).fetchone()
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return self._row_to_session(row) if row else None
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def list_sessions(self) -> list[Session]:
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rows = self.db.execute("SELECT json, analyzed_at, evicted_at FROM sessions")
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return [self._row_to_session(r) for r in rows]
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@staticmethod
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def _row_to_session(row) -> Session:
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"""Rebuild a Session, treating the watermark columns as authoritative."""
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s = Session.from_json(row["json"])
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s.analyzed_at = row["analyzed_at"]
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s.evicted_at = row["evicted_at"]
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return s
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def get_events(self, session_uid: str) -> list[SessionEvent]:
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rows = self.db.execute(
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"SELECT json FROM events WHERE session_uid=? ORDER BY seq", (session_uid,)
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).fetchall()
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return [SessionEvent.from_json(r["json"]) for r in rows]
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def count_events(self, session_uid: str) -> int:
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return self.db.execute(
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"SELECT COUNT(*) c FROM events WHERE session_uid=?", (session_uid,)
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).fetchone()["c"]
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# ---- usage accounting (drives retention) -------------------------------
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def tier1_usage_bytes(self) -> int:
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"""Bytes held in Tier 1: event-row JSON + blob bytes for non-evicted sessions."""
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row = self.db.execute(
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"SELECT COALESCE(SUM(LENGTH(json)),0) b FROM events e "
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"WHERE NOT EXISTS (SELECT 1 FROM sessions s "
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"WHERE s.session_uid=e.session_uid AND s.evicted_at IS NOT NULL)"
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).fetchone()
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blob = self.db.execute("SELECT COALESCE(SUM(nbytes),0) b FROM blobs").fetchone()
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return int(row["b"]) + int(blob["b"])
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def session_tier1_bytes(self, session_uid: str) -> int:
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ev = self.db.execute(
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"SELECT COALESCE(SUM(LENGTH(json)),0) b FROM events WHERE session_uid=?", (session_uid,)
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).fetchone()["b"]
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bl = self.db.execute(
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"SELECT COALESCE(SUM(nbytes),0) b FROM blobs WHERE session_uid=?", (session_uid,)
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).fetchone()["b"]
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return int(ev) + int(bl)
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def tier2_usage_bytes(self) -> int:
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return int(self.db.execute("SELECT COALESCE(SUM(nbytes),0) b FROM digests").fetchone()["b"])
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# ---- eviction ----------------------------------------------------------
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def evict_raw(self, session_uid: str) -> int:
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"""Drop Tier 1 raw (events + blob files) for a session; keep digest + row.
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Sets ``evicted_at``. Returns bytes freed. Safe to call on an
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already-evicted session (no-op-ish).
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"""
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freed = self.session_tier1_bytes(session_uid)
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for r in self.db.execute("SELECT path FROM blobs WHERE session_uid=?", (session_uid,)).fetchall():
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try:
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os.remove(r["path"])
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except FileNotFoundError:
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pass
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self.db.execute("DELETE FROM blobs WHERE session_uid=?", (session_uid,))
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self.db.execute("DELETE FROM events WHERE session_uid=?", (session_uid,))
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self.db.execute("UPDATE sessions SET evicted_at=? WHERE session_uid=?", (_now(), session_uid))
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self.db.commit()
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return freed
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