feat: migrate shared_db (sellers/market_comps/blocklist) from SQLite to Postgres (#45)

Three-layer migration: SQLite Store remains for per-user tables (listings,
trust_scores, background_tasks, community_signals). Postgres takes over
for all high-contention shared tables.

Closes: #45

.env.example

@@ -110,6 +110,13 @@ CF_APP_NAME=snipe
 # Defaults to GPU_SERVER_URL if unset.
 # CF_ORCH_COORDINATOR_URL=http://10.1.10.71:7700
 
+# ── Shared Postgres (optional — strongly recommended for cloud/multi-user) ────
+# When set, sellers, market_comps, reported_sellers, and scammer_blocklist are
+# stored in Postgres instead of SQLite. Required to avoid database-locked errors
+# under concurrent load (>10 simultaneous search users).
+# Cloud instances: set to the cf-postgres DSN. Self-hosted: leave unset for SQLite.
+# SNIPE_SHARED_DB_URL=postgresql://snipe:<password>@localhost:5432/snipe_shared
+
 # ── Community DB (optional) ──────────────────────────────────────────────────
 # When set, seller trust signals (confirmed scammers added to blocklist) are
 # published to the shared community PostgreSQL for cross-user signal aggregation.

Dockerfile

@@ -5,6 +5,7 @@ WORKDIR /app
 # System deps for Playwright/Chromium
 RUN apt-get update && apt-get install -y --no-install-recommends \
     xvfb \
+    libpq-dev \
     && rm -rf /var/lib/apt/lists/*
 
 # Install circuitforge-core from sibling directory (compose sets context: ..)

api/main.py

@@ -33,6 +33,7 @@ from api.cloud_session import CloudUser, compute_features, get_session
 from api.ebay_webhook import router as ebay_webhook_router
 from app.db.models import SavedSearch as SavedSearchModel
 from app.db.models import ScammerEntry
+from app.db.protocol import SharedTableProtocol
 from app.db.store import Store
 from app.platforms import SUPPORTED_PLATFORMS, SearchFilters
 from app.platforms.ebay.adapter import EbayAdapter
@@ -142,6 +143,19 @@ def _get_community_store() -> "SnipeCommunityStore | None":
     return _community_store
 
 
+# ── Shared Postgres backend (optional — active when SNIPE_SHARED_DB_URL is set) ─
+# Replaces the SQLite shared.db for sellers, market_comps, reported_sellers, and
+# scammer_blocklist. ThreadedConnectionPool is thread-safe; one instance per process.
+_pg_shared_store: "SharedTableProtocol | None" = None
+
+
+def _make_shared_store(path: Path) -> SharedTableProtocol:
+    """Return the active shared backend — Postgres if configured, SQLite otherwise."""
+    if _pg_shared_store is not None:
+        return _pg_shared_store
+    return Store(path)
+
+
 # ── LLM Query Builder singletons (optional — requires LLM backend) ────────────
 _category_cache = None
 _query_translator = None
@@ -153,7 +167,7 @@ def _get_query_translator():
 
 @asynccontextmanager
 async def _lifespan(app: FastAPI):
-    global _community_store
+    global _community_store, _pg_shared_store
     # Pre-warm the Chromium browser pool so the first scrape request does not
     # pay the full cold-start cost (5-10s Xvfb + browser launch).
     # Pool size is controlled via BROWSER_POOL_SIZE env var (default: 2).
@@ -178,6 +192,21 @@ async def _lifespan(app: FastAPI):
     get_scheduler(sched_db)
     log.info("Snipe task scheduler started (db=%s)", sched_db)
 
+    # Shared Postgres backend — optional. Replaces SQLite for sellers, market_comps,
+    # reported_sellers, and scammer_blocklist under concurrent load.
+    snipe_shared_dsn = os.environ.get("SNIPE_SHARED_DB_URL", "")
+    if snipe_shared_dsn:
+        try:
+            from app.db.pg_shared import SnipeSharedDB, SnipeSharedStore as _SnipeSharedStore
+            _pg_db = SnipeSharedDB(snipe_shared_dsn)
+            _pg_db.run_migrations()
+            _pg_shared_store = _SnipeSharedStore(_pg_db)
+            log.info("Shared Postgres backend ready (sellers, market_comps, blocklist)")
+        except Exception:
+            log.exception(
+                "SNIPE_SHARED_DB_URL set but Postgres init failed — falling back to SQLite"
+            )
+
     # Community DB — optional. Skipped gracefully if COMMUNITY_DB_URL is unset.
     community_db_url = os.environ.get("COMMUNITY_DB_URL", "")
     if community_db_url:
@@ -446,7 +475,7 @@ def session_info(response: Response, session: CloudUser = Depends(get_session)):
 
 def _trigger_scraper_enrichment(
     listings: list,
-    shared_store: Store,
+    shared_store: SharedTableProtocol,
     shared_db: Path,
     user_db: Path | None = None,
     query: str = "",
@@ -512,7 +541,7 @@ def _trigger_scraper_enrichment(
         if not session_id or session_id not in _update_queues:
             return
         q = _update_queues[session_id]
-        thread_shared = Store(shared_db)
+        thread_shared = shared_store.clone()
         thread_user = Store(user_db or shared_db)
         scorer = TrustScorer(thread_shared)
         comp = thread_shared.get_market_comp("ebay", hashlib.md5(query.encode()).hexdigest())
@@ -538,7 +567,7 @@ def _trigger_scraper_enrichment(
 
     def _run():
         try:
-            enricher = ScrapedEbayAdapter(Store(shared_db))
+            enricher = ScrapedEbayAdapter(shared_store.clone())
             if needs_btf:
                 enricher.enrich_sellers_btf(needs_btf, max_workers=2)
                 log.info("BTF enrichment complete for %d sellers", len(needs_btf))
@@ -812,7 +841,7 @@ def search(
         _update_queues[session_id] = _queue.SimpleQueue()
 
         try:
-            shared_store = Store(shared_db)
+            shared_store = _make_shared_store(shared_db)
             user_store = Store(user_db)
 
             # Re-hydrate Listing dataclass instances from the cached dicts so the
@@ -897,13 +926,14 @@ def search(
     _evict_expired_cache()
     log.info("cache: miss key=%s q=%r", cache_key, q)
 
-    # Each thread creates its own Store — sqlite3 check_same_thread=True.
+    # Each thread creates its own store via clone() — sqlite3 check_same_thread=True;
+    # SnipeSharedStore.clone() returns self (ThreadedConnectionPool is thread-safe).
     def _run_search(ebay_query: str) -> list:
-        return _make_adapter(Store(shared_db), adapter, platform=platform).search(ebay_query, base_filters)
+        return _make_adapter(_make_shared_store(shared_db), adapter, platform=platform).search(ebay_query, base_filters)
 
     def _run_comps() -> None:
         try:
-            _make_adapter(Store(shared_db), adapter, platform=platform).get_completed_sales(comp_query, pages)
+            _make_adapter(_make_shared_store(shared_db), adapter, platform=platform).get_completed_sales(comp_query, pages)
         except Exception:
             log.warning("comps: unhandled exception for %r", comp_query, exc_info=True)
 
@@ -944,10 +974,9 @@ def search(
     _update_queues[session_id] = _queue.SimpleQueue()
 
     try:
-        # Main-thread stores — fresh connections, same thread.
-        # shared_store: sellers, market_comps (all users share this data)
-        # user_store: listings, saved_searches (per-user in cloud mode, same file in local mode)
-        shared_store = Store(shared_db)
+        # Main-thread stores — shared_store may be Postgres (sellers, market_comps);
+        # user_store is always per-user SQLite (listings, trust_scores, saved_searches).
+        shared_store = _make_shared_store(shared_db)
         user_store = Store(user_db)
 
         user_store.save_listings(listings)
@@ -1207,7 +1236,7 @@ def search_async(
                     cached_listings_raw = payload["listings"]
                     cached_market_price = payload["market_price"]
                     try:
-                        shared_store = Store(_shared_db)
+                        shared_store = _make_shared_store(_shared_db)
                         user_store = Store(_user_db)
                         listings = [_Listing(**d) for d in cached_listings_raw]
                         user_store.save_listings(listings)
@@ -1287,11 +1316,11 @@ def search_async(
 
         try:
             def _run_search(ebay_query: str) -> list:
-                return _make_adapter(Store(_shared_db), adapter, platform=platform).search(ebay_query, base_filters)
+                return _make_adapter(_make_shared_store(_shared_db), adapter, platform=platform).search(ebay_query, base_filters)
 
             def _run_comps() -> None:
                 try:
-                    _make_adapter(Store(_shared_db), adapter, platform=platform).get_completed_sales(comp_query, pages)
+                    _make_adapter(_make_shared_store(_shared_db), adapter, platform=platform).get_completed_sales(comp_query, pages)
                 except Exception:
                     log.warning("async comps: unhandled exception for %r", comp_query, exc_info=True)
 
@@ -1314,7 +1343,7 @@ def search_async(
                 platform, _auth_label(_user_id), _tier, adapter_used, pages, len(listings), q_norm,
             )
 
-            shared_store = Store(_shared_db)
+            shared_store = _make_shared_store(_shared_db)
             user_store = Store(_user_db)
 
             user_store.save_listings(listings)
@@ -1473,7 +1502,7 @@ def enrich_seller(
     """
     import threading
 
-    shared_store = Store(session.shared_db)
+    shared_store = _make_shared_store(session.shared_db)
     user_store = Store(session.user_db)
     shared_db = session.shared_db
 
@@ -1502,7 +1531,7 @@ def enrich_seller(
 
         def _btf():
             try:
-                ScrapedEbayAdapter(Store(shared_db)).enrich_sellers_btf(
+                ScrapedEbayAdapter(shared_store.clone()).enrich_sellers_btf(
                     {seller: listing_id}, max_workers=1
                 )
             except Exception as e:
@@ -1510,7 +1539,7 @@ def enrich_seller(
 
         def _ssn():
             try:
-                ScrapedEbayAdapter(Store(shared_db)).enrich_sellers_categories(
+                ScrapedEbayAdapter(shared_store.clone()).enrich_sellers_categories(
                     [seller], max_workers=1
                 )
             except Exception as e:
@@ -1781,7 +1810,7 @@ class BlocklistAdd(BaseModel):
 
 @app.get("/api/blocklist")
 def list_blocklist(session: CloudUser = Depends(get_session)):
-    store = Store(session.shared_db)
+    store = _make_shared_store(session.shared_db)
     return {"entries": [dataclasses.asdict(e) for e in store.list_blocklist()]}
 
 
@@ -1792,7 +1821,7 @@ def add_to_blocklist(body: BlocklistAdd, session: CloudUser = Depends(get_sessio
             status_code=403,
             detail="Sign in to report sellers to the community blocklist.",
         )
-    store = Store(session.shared_db)
+    store = _make_shared_store(session.shared_db)
     entry = store.add_to_blocklist(ScammerEntry(
         platform=body.platform,
         platform_seller_id=body.platform_seller_id,
@@ -1826,13 +1855,13 @@ def add_to_blocklist(body: BlocklistAdd, session: CloudUser = Depends(get_sessio
 
 @app.delete("/api/blocklist/{platform_seller_id}", status_code=204)
 def remove_from_blocklist(platform_seller_id: str, session: CloudUser = Depends(get_session)):
-    Store(session.shared_db).remove_from_blocklist("ebay", platform_seller_id)
+    _make_shared_store(session.shared_db).remove_from_blocklist("ebay", platform_seller_id)
 
 
 @app.get("/api/blocklist/export")
 def export_blocklist(session: CloudUser = Depends(get_session)):
     """Download the blocklist as a CSV file."""
-    entries = Store(session.shared_db).list_blocklist()
+    entries = _make_shared_store(session.shared_db).list_blocklist()
     buf = io.StringIO()
     writer = csv.writer(buf)
     writer.writerow(["platform", "platform_seller_id", "username", "reason", "source", "created_at"])
@@ -1864,7 +1893,7 @@ async def import_blocklist(
     except UnicodeDecodeError:
         raise HTTPException(status_code=400, detail="File must be UTF-8 encoded")
 
-    store = Store(session.shared_db)
+    store = _make_shared_store(session.shared_db)
     imported = 0
     errors: list[str] = []
     reader = csv.DictReader(io.StringIO(text))

app/db/pg_migrations/001_shared_tables.sql

@@ -0,0 +1,49 @@
+-- Snipe shared tables: sellers, market_comps, reported_sellers
+-- Replaces the equivalent tables in shared.db (SQLite).
+-- Per-user tables (listings, trust_scores, saved_searches) remain in SQLite.
+
+CREATE TABLE IF NOT EXISTS sellers (
+    id                    BIGSERIAL PRIMARY KEY,
+    platform              TEXT NOT NULL,
+    platform_seller_id    TEXT NOT NULL,
+    username              TEXT NOT NULL,
+    account_age_days      INTEGER,
+    feedback_count        INTEGER NOT NULL DEFAULT 0,
+    feedback_ratio        DOUBLE PRECISION NOT NULL DEFAULT 0,
+    category_history_json TEXT NOT NULL DEFAULT '{}',
+    fetched_at            TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (platform, platform_seller_id)
+);
+
+CREATE TABLE IF NOT EXISTS market_comps (
+    id           BIGSERIAL PRIMARY KEY,
+    platform     TEXT NOT NULL,
+    query_hash   TEXT NOT NULL,
+    median_price DOUBLE PRECISION NOT NULL,
+    sample_count INTEGER NOT NULL,
+    fetched_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    expires_at   TIMESTAMPTZ NOT NULL,
+    UNIQUE (platform, query_hash)
+);
+
+CREATE TABLE IF NOT EXISTS reported_sellers (
+    id                  BIGSERIAL PRIMARY KEY,
+    platform            TEXT NOT NULL,
+    platform_seller_id  TEXT NOT NULL,
+    username            TEXT,
+    reported_by         TEXT NOT NULL DEFAULT 'user',
+    reported_at         TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (platform, platform_seller_id)
+);
+
+CREATE TABLE IF NOT EXISTS scammer_blocklist (
+    id                  BIGSERIAL PRIMARY KEY,
+    platform            TEXT NOT NULL,
+    platform_seller_id  TEXT NOT NULL,
+    username            TEXT NOT NULL,
+    reason              TEXT,
+    source              TEXT NOT NULL DEFAULT 'manual',
+    created_at          TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (platform, platform_seller_id)
+);
+

app/db/pg_shared.py

@@ -0,0 +1,380 @@
+from __future__ import annotations
+
+import logging
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Optional
+
+import psycopg2
+from psycopg2.pool import ThreadedConnectionPool
+
+from app.db.models import MarketComp, ScammerEntry, Seller
+
+log = logging.getLogger(__name__)
+
+_MIN_CONN = 2
+_MAX_CONN = 20
+
+
+class SnipeSharedDB:
+    """Thread-safe Postgres connection pool for Snipe shared tables."""
+
+    def __init__(self, dsn: str) -> None:
+        self._pool = ThreadedConnectionPool(_MIN_CONN, _MAX_CONN, dsn=dsn)
+
+    def getconn(self):
+        return self._pool.getconn()
+
+    def putconn(self, conn) -> None:
+        self._pool.putconn(conn)
+
+    def close(self) -> None:
+        self._pool.closeall()
+
+    def run_migrations(self) -> None:
+        """Apply pg_migrations/*.sql in filename order. Idempotent."""
+        migrations_dir = Path(__file__).parent / "pg_migrations"
+        files = sorted(migrations_dir.glob("*.sql"), key=lambda p: p.name)
+
+        conn = self.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute("""
+                    CREATE TABLE IF NOT EXISTS _snipe_shared_migrations (
+                        filename   TEXT PRIMARY KEY,
+                        applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+                    )
+                """)
+                conn.commit()
+                for f in files:
+                    cur.execute(
+                        "SELECT 1 FROM _snipe_shared_migrations WHERE filename = %s",
+                        (f.name,),
+                    )
+                    if cur.fetchone():
+                        continue
+                    log.info("Applying migration: %s", f.name)
+                    cur.execute(f.read_text())
+                    cur.execute(
+                        "INSERT INTO _snipe_shared_migrations (filename) VALUES (%s)",
+                        (f.name,),
+                    )
+                    conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self.putconn(conn)
+
+
+class SnipeSharedStore:
+    """Postgres-backed store for sellers, market_comps, and reported_sellers.
+
+    Satisfies SharedTableProtocol. clone() returns self — ThreadedConnectionPool
+    is already thread-safe, so no new instance is needed per thread.
+    """
+
+    def __init__(self, db: SnipeSharedDB) -> None:
+        self._db = db
+
+    def clone(self) -> "SnipeSharedStore":
+        return self
+
+    # Sellers
+
+    def save_seller(self, seller: Seller) -> None:
+        self.save_sellers([seller])
+
+    def save_sellers(self, sellers: list[Seller]) -> None:
+        if not sellers:
+            return
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.executemany(
+                    """
+                    INSERT INTO sellers
+                        (platform, platform_seller_id, username, account_age_days,
+                         feedback_count, feedback_ratio, category_history_json)
+                    VALUES (%s, %s, %s, %s, %s, %s, %s)
+                    ON CONFLICT (platform, platform_seller_id) DO UPDATE SET
+                        username              = EXCLUDED.username,
+                        feedback_count        = EXCLUDED.feedback_count,
+                        feedback_ratio        = EXCLUDED.feedback_ratio,
+                        account_age_days      = COALESCE(
+                            EXCLUDED.account_age_days,
+                            sellers.account_age_days
+                        ),
+                        category_history_json = COALESCE(
+                            NULLIF(NULLIF(EXCLUDED.category_history_json, '{}'), ''),
+                            NULLIF(NULLIF(sellers.category_history_json, '{}'), ''),
+                            '{}'
+                        ),
+                        fetched_at = NOW()
+                    """,
+                    [
+                        (s.platform, s.platform_seller_id, s.username, s.account_age_days,
+                         s.feedback_count, s.feedback_ratio, s.category_history_json or "{}")
+                        for s in sellers
+                    ],
+                )
+            conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self._db.putconn(conn)
+
+    def get_seller(self, platform: str, platform_seller_id: str) -> Optional[Seller]:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    """
+                    SELECT platform, platform_seller_id, username, account_age_days,
+                           feedback_count, feedback_ratio, category_history_json,
+                           id, fetched_at
+                    FROM sellers
+                    WHERE platform = %s AND platform_seller_id = %s
+                    """,
+                    (platform, platform_seller_id),
+                )
+                row = cur.fetchone()
+            if not row:
+                return None
+            return Seller(*row[:7], id=row[7], fetched_at=str(row[8]))
+        finally:
+            self._db.putconn(conn)
+
+    def delete_seller_data(self, platform: str, platform_seller_id: str) -> None:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    "DELETE FROM sellers WHERE platform = %s AND platform_seller_id = %s",
+                    (platform, platform_seller_id),
+                )
+            conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self._db.putconn(conn)
+
+    # MarketComps
+
+    def save_market_comp(self, comp: MarketComp) -> None:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    """
+                    INSERT INTO market_comps
+                        (platform, query_hash, median_price, sample_count, expires_at)
+                    VALUES (%s, %s, %s, %s, %s::TIMESTAMPTZ)
+                    ON CONFLICT (platform, query_hash) DO UPDATE SET
+                        median_price = EXCLUDED.median_price,
+                        sample_count = EXCLUDED.sample_count,
+                        expires_at   = EXCLUDED.expires_at,
+                        fetched_at   = NOW()
+                    """,
+                    (comp.platform, comp.query_hash, comp.median_price,
+                     comp.sample_count, comp.expires_at),
+                )
+            conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self._db.putconn(conn)
+
+    def get_market_comp(self, platform: str, query_hash: str) -> Optional[MarketComp]:
+        now = datetime.now(timezone.utc).isoformat()
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    """
+                    SELECT platform, query_hash, median_price, sample_count,
+                           expires_at, id, fetched_at
+                    FROM market_comps
+                    WHERE platform = %s AND query_hash = %s AND expires_at > %s::TIMESTAMPTZ
+                    """,
+                    (platform, query_hash, now),
+                )
+                row = cur.fetchone()
+            if not row:
+                return None
+            return MarketComp(*row[:5], id=row[5], fetched_at=str(row[6]))
+        finally:
+            self._db.putconn(conn)
+
+    # Reported Sellers
+
+    def mark_reported(
+        self,
+        platform: str,
+        platform_seller_id: str,
+        username: Optional[str] = None,
+        reported_by: str = "user",
+    ) -> None:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    """
+                    INSERT INTO reported_sellers
+                        (platform, platform_seller_id, username, reported_by)
+                    VALUES (%s, %s, %s, %s)
+                    ON CONFLICT (platform, platform_seller_id) DO NOTHING
+                    """,
+                    (platform, platform_seller_id, username, reported_by),
+                )
+            conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self._db.putconn(conn)
+
+    def list_reported(self, platform: str = "ebay") -> list[str]:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    "SELECT platform_seller_id FROM reported_sellers WHERE platform = %s",
+                    (platform,),
+                )
+                return [row[0] for row in cur.fetchall()]
+        finally:
+            self._db.putconn(conn)
+
+    # Seller Category Refresh
+
+    def refresh_seller_categories(
+        self,
+        platform: str,
+        seller_ids: list[str],
+        listing_store=None,  # always a SQLite Store in practice
+    ) -> int:
+        """Derive category_history_json from listing data and update sellers in Postgres.
+
+        listing_store must be provided (it's always the per-user SQLite Store).
+        Returns count of sellers updated.
+        """
+        from app.platforms.ebay.scraper import _classify_category_label  # lazy to avoid circular
+        import json
+
+        if not seller_ids or listing_store is None:
+            return 0
+
+        updated = 0
+        for sid in seller_ids:
+            seller = self.get_seller(platform, sid)
+            if not seller or seller.category_history_json not in ("{}", "", None):
+                continue
+            # listing_store is always a SQLite Store; access _conn directly for the query.
+            rows = listing_store._conn.execute(
+                "SELECT category_name, COUNT(*) FROM listings "
+                "WHERE platform=? AND seller_platform_id=? AND category_name IS NOT NULL "
+                "GROUP BY category_name",
+                (platform, sid),
+            ).fetchall()
+            if not rows:
+                continue
+            counts: dict[str, int] = {}
+            for cat_name, cnt in rows:
+                key = _classify_category_label(cat_name)
+                if key:
+                    counts[key] = counts.get(key, 0) + cnt
+            if counts:
+                from dataclasses import replace
+                self.save_sellers([replace(seller, category_history_json=json.dumps(counts))])
+                updated += 1
+        return updated
+
+    # Scammer Blocklist
+
+    def is_blocklisted(self, platform: str, platform_seller_id: str) -> bool:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    "SELECT 1 FROM scammer_blocklist "
+                    "WHERE platform = %s AND platform_seller_id = %s LIMIT 1",
+                    (platform, platform_seller_id),
+                )
+                return cur.fetchone() is not None
+        finally:
+            self._db.putconn(conn)
+
+    def add_to_blocklist(self, entry: ScammerEntry) -> ScammerEntry:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    """
+                    INSERT INTO scammer_blocklist
+                        (platform, platform_seller_id, username, reason, source)
+                    VALUES (%s, %s, %s, %s, %s)
+                    ON CONFLICT (platform, platform_seller_id) DO UPDATE SET
+                        username = EXCLUDED.username,
+                        reason   = COALESCE(EXCLUDED.reason, scammer_blocklist.reason),
+                        source   = EXCLUDED.source
+                    """,
+                    (entry.platform, entry.platform_seller_id, entry.username,
+                     entry.reason, entry.source),
+                )
+                conn.commit()
+                cur.execute(
+                    "SELECT id, created_at FROM scammer_blocklist "
+                    "WHERE platform = %s AND platform_seller_id = %s",
+                    (entry.platform, entry.platform_seller_id),
+                )
+                row = cur.fetchone()
+            from dataclasses import replace
+            return replace(entry, id=row[0], created_at=str(row[1]))
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self._db.putconn(conn)
+
+    def remove_from_blocklist(self, platform: str, platform_seller_id: str) -> None:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    "DELETE FROM scammer_blocklist "
+                    "WHERE platform = %s AND platform_seller_id = %s",
+                    (platform, platform_seller_id),
+                )
+            conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        finally:
+            self._db.putconn(conn)
+
+    def list_blocklist(self, platform: str = "ebay") -> list[ScammerEntry]:
+        conn = self._db.getconn()
+        try:
+            with conn.cursor() as cur:
+                cur.execute(
+                    """
+                    SELECT platform, platform_seller_id, username, reason, source, id, created_at
+                    FROM scammer_blocklist
+                    WHERE platform = %s
+                    ORDER BY created_at DESC
+                    """,
+                    (platform,),
+                )
+                return [
+                    ScammerEntry(
+                        platform=r[0], platform_seller_id=r[1], username=r[2],
+                        reason=r[3], source=r[4], id=r[5], created_at=str(r[6]),
+                    )
+                    for r in cur.fetchall()
+                ]
+        finally:
+            self._db.putconn(conn)

app/db/protocol.py

@@ -0,0 +1,86 @@
+"""Protocol (duck-type interface) for shared table backends (SQLite and Postgres)."""
+from __future__ import annotations
+
+from typing import Any, Optional, Protocol, runtime_checkable
+
+from app.db.models import MarketComp, ScammerEntry, Seller
+
+
+@runtime_checkable
+class SharedTableProtocol(Protocol):
+    """Protocol that both Store (SQLite) and SnipeSharedStore (Postgres) must satisfy.
+
+    This enables code that reads/writes shared tables (sellers, market_comps,
+    reported_sellers, scammer_blocklist) to remain agnostic to the underlying backend.
+    """
+
+    def save_seller(self, seller: Seller) -> None:
+        """Persist a single seller record."""
+        ...
+
+    def save_sellers(self, sellers: list[Seller]) -> None:
+        """Persist multiple seller records (batch upsert)."""
+        ...
+
+    def get_seller(self, platform: str, platform_seller_id: str) -> Optional[Seller]:
+        """Fetch a single seller by platform and platform_seller_id."""
+        ...
+
+    def save_market_comp(self, comp: MarketComp) -> None:
+        """Persist a market comparison record."""
+        ...
+
+    def get_market_comp(self, platform: str, query_hash: str) -> Optional[MarketComp]:
+        """Fetch a market comparison by platform and query_hash."""
+        ...
+
+    def mark_reported(
+        self,
+        platform: str,
+        platform_seller_id: str,
+        username: Optional[str] = None,
+        reported_by: str = "user",
+    ) -> None:
+        """Record that a seller has been reported to the platform."""
+        ...
+
+    def list_reported(self, platform: str = "ebay") -> list[str]:
+        """Return all platform_seller_ids that have been reported."""
+        ...
+
+    def delete_seller_data(self, platform: str, platform_seller_id: str) -> None:
+        """Permanently erase a seller and all related data (GDPR/eBay compliance)."""
+        ...
+
+    def refresh_seller_categories(
+        self,
+        platform: str,
+        seller_ids: list[str],
+        listing_store: Optional[Any] = None,
+    ) -> int:
+        """Derive category_history_json for sellers that lack it from stored listings.
+
+        listing_store: Store holding listings (may differ from self in split-DB mode).
+        Returns count of sellers updated.
+        """
+        ...
+
+    def is_blocklisted(self, platform: str, platform_seller_id: str) -> bool:
+        """Return True if a seller is on the community scammer blocklist."""
+        ...
+
+    def add_to_blocklist(self, entry: ScammerEntry) -> ScammerEntry:
+        """Upsert a seller into the blocklist. Returns the saved entry with id and created_at."""
+        ...
+
+    def remove_from_blocklist(self, platform: str, platform_seller_id: str) -> None:
+        """Remove a seller from the blocklist."""
+        ...
+
+    def list_blocklist(self, platform: str = "ebay") -> list[ScammerEntry]:
+        """Return all blocklisted sellers for a platform, newest first."""
+        ...
+
+    def clone(self) -> SharedTableProtocol:
+        """Create a new independent instance pointing to the same backend."""
+        ...

app/db/store.py

@@ -21,6 +21,10 @@ class Store:
         # WAL mode: allows concurrent readers + one writer without blocking
         self._conn.execute("PRAGMA journal_mode=WAL")
 
+    def clone(self) -> Store:
+        """Create a new independent instance pointing to the same database."""
+        return Store(self._db_path)
+
     # --- Seller ---
 
     def delete_seller_data(self, platform: str, platform_seller_id: str) -> None:

app/platforms/ebay/adapter.py

@@ -22,7 +22,7 @@ _SHOPPING_API_INTER_REQUEST_DELAY = 0.5   # seconds between successive calls
 _SELLER_ENRICH_TTL_HOURS = 24             # skip re-enrichment within this window
 
 from app.db.models import Listing, MarketComp, Seller
-from app.db.store import Store
+from app.db.protocol import SharedTableProtocol
 from app.platforms import PlatformAdapter, SearchFilters
 from app.platforms.ebay.auth import EbayTokenManager
 from app.platforms.ebay.normaliser import normalise_listing, normalise_seller
@@ -67,7 +67,7 @@ BROWSE_BASE = {
 
 
 class EbayAdapter(PlatformAdapter):
-    def __init__(self, token_manager: EbayTokenManager, shared_store: Store, env: str = "production"):
+    def __init__(self, token_manager: EbayTokenManager, shared_store: SharedTableProtocol, env: str = "production"):
         self._tokens = token_manager
         self._store = shared_store
         self._env = env

app/platforms/ebay/scraper.py

@@ -25,7 +25,7 @@ log = logging.getLogger(__name__)
 from bs4 import BeautifulSoup
 
 from app.db.models import Listing, MarketComp, Seller
-from app.db.store import Store
+from app.db.protocol import SharedTableProtocol
 from app.platforms import PlatformAdapter, SearchFilters
 
 EBAY_SEARCH_URL = "https://www.ebay.com/sch/i.html"
@@ -286,7 +286,7 @@ class ScrapedEbayAdapter(PlatformAdapter):
     category_history) cause TrustScorer to set score_is_partial=True.
     """
 
-    def __init__(self, shared_store: Store, delay: float = 1.0):
+    def __init__(self, shared_store: SharedTableProtocol, delay: float = 1.0):
         self._store = shared_store
         self._delay = delay
 
@@ -374,8 +374,6 @@ class ScrapedEbayAdapter(PlatformAdapter):
         Does not raise — failures per-seller are silently skipped so the main
         search response is never blocked.
         """
-        db_path = self._store._db_path  # capture for thread-local Store creation
-
         def _enrich_one(item: tuple[str, str]) -> None:
             seller_id, listing_id = item
             try:
@@ -388,7 +386,7 @@ class ScrapedEbayAdapter(PlatformAdapter):
                 )
                 if age_days is None and fb_count is None:
                     return   # nothing new to write
-                thread_store = Store(db_path)
+                thread_store = self._store.clone()
                 seller = thread_store.get_seller("ebay", seller_id)
                 if not seller:
                     log.warning("BTF enrich: seller %s not found in DB", seller_id)

app/trust/__init__.py

@@ -2,7 +2,7 @@ import hashlib
 import math
 
 from app.db.models import Listing, TrustScore
-from app.db.store import Store
+from app.db.protocol import SharedTableProtocol
 
 from .aggregator import Aggregator
 from .metadata import MetadataScorer
@@ -12,7 +12,7 @@ from .photo import PhotoScorer
 class TrustScorer:
     """Orchestrates metadata + photo scoring for a batch of listings."""
 
-    def __init__(self, shared_store: Store):
+    def __init__(self, shared_store: SharedTableProtocol):
         self._store = shared_store
         self._meta = MetadataScorer()
         self._photo = PhotoScorer()

compose.cloud.yml

@@ -23,6 +23,9 @@ services:
       # GPU_SERVER_URL routes LLM query builder through cf-orch for VRAM-aware scheduling.
       # Override in .env to use a different coordinator URL.
       GPU_SERVER_URL: "http://host.docker.internal:7700"
+      # SNIPE_SHARED_DB_URL — Postgres DSN for shared tables (sellers, market_comps, blocklist).
+      # Required for production multi-user deployments. Set in .env (never commit).
+      # SNIPE_SHARED_DB_URL: "postgresql://snipe:<password>@postgres:5432/snipe_shared"
       CF_APP_NAME: snipe
     extra_hosts:
       - "host.docker.internal:host-gateway"

pyproject.toml

@@ -8,7 +8,7 @@ version = "0.3.0"
 description = "Auction listing monitor and trust scorer"
 requires-python = ">=3.11"
 dependencies = [
-    "circuitforge-core>=0.8.0",
+    "circuitforge-core[community]>=0.8.0",
     "streamlit>=1.32",
     "requests>=2.31",
     "imagehash>=4.3",

tests/conftest.py

@@ -0,0 +1,17 @@
+import os
+import pytest
+
+
+def pytest_configure(config):
+    config.addinivalue_line(
+        "markers",
+        "postgres: mark test as requiring a live Postgres instance (SNIPE_SHARED_DB_URL must be set)",
+    )
+
+
+@pytest.fixture
+def postgres_dsn():
+    dsn = os.environ.get("SNIPE_SHARED_DB_URL")
+    if not dsn:
+        pytest.skip("SNIPE_SHARED_DB_URL not set — skipping Postgres tests")
+    return dsn

tests/db/test_pg_shared.py

@@ -0,0 +1,157 @@
+"""Tests for SnipeSharedStore — requires live Postgres via SNIPE_SHARED_DB_URL."""
+import pytest
+from app.db.models import MarketComp, Seller
+from app.db.pg_shared import SnipeSharedDB, SnipeSharedStore
+from app.db.protocol import SharedTableProtocol
+
+
+@pytest.mark.postgres
+def test_snipe_shared_store_satisfies_protocol(postgres_dsn):
+    assert issubclass(SnipeSharedStore, SharedTableProtocol)
+
+
+@pytest.mark.postgres
+def test_save_and_get_seller(postgres_dsn):
+    db = SnipeSharedDB(postgres_dsn)
+    db.run_migrations()
+    store = SnipeSharedStore(db)
+
+    seller = Seller(
+        platform="ebay",
+        platform_seller_id="test-seller-001",
+        username="testseller",
+        account_age_days=365,
+        feedback_count=100,
+        feedback_ratio=0.99,
+        category_history_json='{"electronics": 5}',
+    )
+    store.save_seller(seller)
+
+    result = store.get_seller("ebay", "test-seller-001")
+    assert result is not None
+    assert result.username == "testseller"
+    assert result.feedback_count == 100
+
+    store.delete_seller_data("ebay", "test-seller-001")
+    db.close()
+
+
+@pytest.mark.postgres
+def test_save_sellers_coalesce_preserves_age(postgres_dsn):
+    db = SnipeSharedDB(postgres_dsn)
+    db.run_migrations()
+    store = SnipeSharedStore(db)
+
+    seller_with_age = Seller(
+        platform="ebay", platform_seller_id="coalesce-test",
+        username="u", account_age_days=730,
+        feedback_count=50, feedback_ratio=0.95, category_history_json="{}",
+    )
+    store.save_seller(seller_with_age)
+
+    seller_without_age = Seller(
+        platform="ebay", platform_seller_id="coalesce-test",
+        username="u", account_age_days=None,
+        feedback_count=60, feedback_ratio=0.96, category_history_json="{}",
+    )
+    store.save_sellers([seller_without_age])
+
+    result = store.get_seller("ebay", "coalesce-test")
+    assert result.account_age_days == 730
+    assert result.feedback_count == 60
+
+    store.delete_seller_data("ebay", "coalesce-test")
+    db.close()
+
+
+@pytest.mark.postgres
+def test_market_comp_cache(postgres_dsn):
+    from datetime import datetime, timedelta, timezone
+    db = SnipeSharedDB(postgres_dsn)
+    db.run_migrations()
+    store = SnipeSharedStore(db)
+
+    expires = (datetime.now(timezone.utc) + timedelta(hours=1)).isoformat()
+    comp = MarketComp(
+        platform="ebay", query_hash="abc123",
+        median_price=49.99, sample_count=10, expires_at=expires,
+    )
+    store.save_market_comp(comp)
+
+    result = store.get_market_comp("ebay", "abc123")
+    assert result is not None
+    assert result.median_price == 49.99
+
+    db.close()
+
+
+@pytest.mark.postgres
+def test_reported_sellers(postgres_dsn):
+    db = SnipeSharedDB(postgres_dsn)
+    db.run_migrations()
+    store = SnipeSharedStore(db)
+
+    store.mark_reported("ebay", "bad-seller-99", username="badguy")
+    reported = store.list_reported("ebay")
+    assert "bad-seller-99" in reported
+
+    store.mark_reported("ebay", "bad-seller-99")  # idempotent
+
+    db.close()
+
+
+@pytest.mark.postgres
+def test_clone_returns_self(postgres_dsn):
+    db = SnipeSharedDB(postgres_dsn)
+    store = SnipeSharedStore(db)
+    assert store.clone() is store
+    db.close()
+
+
+@pytest.mark.postgres
+def test_blocklist_add_get_remove(postgres_dsn):
+    from app.db.models import ScammerEntry
+    db = SnipeSharedDB(postgres_dsn)
+    db.run_migrations()
+    store = SnipeSharedStore(db)
+
+    assert not store.is_blocklisted("ebay", "bad-999")
+
+    entry = store.add_to_blocklist(ScammerEntry(
+        platform="ebay", platform_seller_id="bad-999",
+        username="scammer1", reason="sold fakes", source="manual",
+    ))
+    assert entry.id is not None
+    assert store.is_blocklisted("ebay", "bad-999")
+
+    entries = store.list_blocklist("ebay")
+    assert any(e.platform_seller_id == "bad-999" for e in entries)
+
+    store.remove_from_blocklist("ebay", "bad-999")
+    assert not store.is_blocklisted("ebay", "bad-999")
+    db.close()
+
+
+@pytest.mark.postgres
+def test_blocklist_upsert_is_idempotent(postgres_dsn):
+    from app.db.models import ScammerEntry
+    db = SnipeSharedDB(postgres_dsn)
+    db.run_migrations()
+    store = SnipeSharedStore(db)
+
+    store.add_to_blocklist(ScammerEntry(
+        platform="ebay", platform_seller_id="dup-test",
+        username="seller", reason="reason1", source="manual",
+    ))
+    # Second add — should not raise, should update username but preserve reason via COALESCE
+    store.add_to_blocklist(ScammerEntry(
+        platform="ebay", platform_seller_id="dup-test",
+        username="seller_updated", reason=None, source="community",
+    ))
+    entries = [e for e in store.list_blocklist("ebay") if e.platform_seller_id == "dup-test"]
+    assert len(entries) == 1
+    assert entries[0].username == "seller_updated"
+    assert entries[0].reason == "reason1"  # COALESCE preserved original reason
+
+    store.remove_from_blocklist("ebay", "dup-test")
+    db.close()

tests/db/test_protocol.py

@@ -0,0 +1,39 @@
+"""Verify Store satisfies SharedTableProtocol at import time."""
+from app.db.protocol import SharedTableProtocol
+from app.db.store import Store
+
+
+def test_store_satisfies_protocol():
+    assert issubclass(Store, SharedTableProtocol)
+
+
+def test_store_clone_returns_new_instance(tmp_path):
+    db = tmp_path / "test.db"
+    s = Store(db)
+    clone = s.clone()
+    assert isinstance(clone, Store)
+    assert clone is not s
+    assert clone._db_path == db
+
+
+def test_ebay_adapter_accepts_protocol():
+    from app.platforms.ebay.adapter import EbayAdapter
+    import tempfile
+    import pathlib
+    from unittest.mock import MagicMock
+
+    with tempfile.TemporaryDirectory() as tmp:
+        s = Store(pathlib.Path(tmp) / "t.db")
+        adapter = EbayAdapter(token_manager=MagicMock(), shared_store=s)
+        assert adapter._store is s
+
+
+def test_scraped_adapter_no_db_path_ref():
+    from app.platforms.ebay.scraper import ScrapedEbayAdapter
+    import tempfile
+    import pathlib
+
+    with tempfile.TemporaryDirectory() as tmp:
+        s = Store(pathlib.Path(tmp) / "t.db")
+        adapter = ScrapedEbayAdapter(shared_store=s)
+        assert not hasattr(adapter, '_db_path_ref')