diff --git a/src/dashboard/store.py b/src/dashboard/store.py
index 69fc565..ffd97e6 100644
--- a/src/dashboard/store.py
+++ b/src/dashboard/store.py
@@ -1,4 +1,23 @@
+"""Persistent chat message store backed by SQLite.
+
+Provides the same API as the original in-memory MessageLog so all callers
+(dashboard routes, chat_api, thinking, briefing) work without changes.
+
+Data lives in ``data/chat.db`` — survives server restarts.
+A configurable retention policy (default 500 messages) keeps the DB lean.
+"""
+
+import sqlite3
+import threading
 from dataclasses import dataclass
+from pathlib import Path
+
+# ── Data dir — resolved relative to repo root (two levels up from this file) ──
+_REPO_ROOT = Path(__file__).resolve().parents[2]
+DB_PATH: Path = _REPO_ROOT / "data" / "chat.db"
+
+# Maximum messages to retain (oldest pruned on append)
+MAX_MESSAGES: int = 500
 
 
 @dataclass
@@ -9,25 +28,106 @@ class Message:
     source: str = "browser"  # "browser" | "api" | "telegram" | "discord" | "system"
 
 
-class MessageLog:
-    """In-memory chat history for the lifetime of the server process."""
+def _get_conn(db_path: Path | None = None) -> sqlite3.Connection:
+    """Open (or create) the chat database and ensure schema exists."""
+    path = db_path or DB_PATH
+    path.parent.mkdir(parents=True, exist_ok=True)
+    conn = sqlite3.connect(str(path), check_same_thread=False)
+    conn.row_factory = sqlite3.Row
+    conn.execute("PRAGMA journal_mode=WAL")
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS chat_messages (
+            id        INTEGER PRIMARY KEY AUTOINCREMENT,
+            role      TEXT NOT NULL,
+            content   TEXT NOT NULL,
+            timestamp TEXT NOT NULL,
+            source    TEXT NOT NULL DEFAULT 'browser'
+        )
+    """)
+    conn.commit()
+    return conn
 
-    def __init__(self) -> None:
-        self._entries: list[Message] = []
+
+class MessageLog:
+    """SQLite-backed chat history — drop-in replacement for the old in-memory list."""
+
+    def __init__(self, db_path: Path | None = None) -> None:
+        self._db_path = db_path or DB_PATH
+        self._lock = threading.Lock()
+        self._conn: sqlite3.Connection | None = None
+
+    # Lazy connection — opened on first use, not at import time.
+    def _ensure_conn(self) -> sqlite3.Connection:
+        if self._conn is None:
+            self._conn = _get_conn(self._db_path)
+        return self._conn
 
     def append(self, role: str, content: str, timestamp: str, source: str = "browser") -> None:
-        self._entries.append(
-            Message(role=role, content=content, timestamp=timestamp, source=source)
-        )
+        with self._lock:
+            conn = self._ensure_conn()
+            conn.execute(
+                "INSERT INTO chat_messages (role, content, timestamp, source) VALUES (?, ?, ?, ?)",
+                (role, content, timestamp, source),
+            )
+            conn.commit()
+            self._prune(conn)
 
     def all(self) -> list[Message]:
-        return list(self._entries)
+        with self._lock:
+            conn = self._ensure_conn()
+            rows = conn.execute(
+                "SELECT role, content, timestamp, source FROM chat_messages ORDER BY id"
+            ).fetchall()
+        return [
+            Message(
+                role=r["role"], content=r["content"], timestamp=r["timestamp"], source=r["source"]
+            )
+            for r in rows
+        ]
+
+    def recent(self, limit: int = 50) -> list[Message]:
+        """Return the *limit* most recent messages (oldest-first)."""
+        with self._lock:
+            conn = self._ensure_conn()
+            rows = conn.execute(
+                "SELECT role, content, timestamp, source FROM chat_messages "
+                "ORDER BY id DESC LIMIT ?",
+                (limit,),
+            ).fetchall()
+        return [
+            Message(
+                role=r["role"], content=r["content"], timestamp=r["timestamp"], source=r["source"]
+            )
+            for r in reversed(rows)
+        ]
 
     def clear(self) -> None:
-        self._entries.clear()
+        with self._lock:
+            conn = self._ensure_conn()
+            conn.execute("DELETE FROM chat_messages")
+            conn.commit()
+
+    def _prune(self, conn: sqlite3.Connection) -> None:
+        """Keep at most MAX_MESSAGES rows, deleting the oldest."""
+        count = conn.execute("SELECT COUNT(*) FROM chat_messages").fetchone()[0]
+        if count > MAX_MESSAGES:
+            excess = count - MAX_MESSAGES
+            conn.execute(
+                "DELETE FROM chat_messages WHERE id IN "
+                "(SELECT id FROM chat_messages ORDER BY id LIMIT ?)",
+                (excess,),
+            )
+            conn.commit()
+
+    def close(self) -> None:
+        if self._conn is not None:
+            self._conn.close()
+            self._conn = None
 
     def __len__(self) -> int:
-        return len(self._entries)
+        with self._lock:
+            conn = self._ensure_conn()
+            return conn.execute("SELECT COUNT(*) FROM chat_messages").fetchone()[0]
 
 
 # Module-level singleton shared across the app
diff --git a/tests/conftest.py b/tests/conftest.py
index 1c8eea6..5c2be15 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -55,13 +55,27 @@ os.environ["TIMMY_SKIP_EMBEDDINGS"] = "1"
 
 
 @pytest.fixture(autouse=True)
-def reset_message_log():
-    """Clear the in-memory chat log before and after every test."""
-    from dashboard.store import message_log
+def reset_message_log(tmp_path):
+    """Redirect chat DB to temp dir and clear before/after every test."""
+    import dashboard.store as _store_mod
 
-    message_log.clear()
+    original_db_path = _store_mod.DB_PATH
+    tmp_chat_db = tmp_path / "chat.db"
+    _store_mod.DB_PATH = tmp_chat_db
+
+    # Close existing singleton connection and point it at tmp DB
+    _store_mod.message_log.close()
+    _store_mod.message_log._db_path = tmp_chat_db
+    _store_mod.message_log._conn = None
+
+    _store_mod.message_log.clear()
     yield
-    message_log.clear()
+    _store_mod.message_log.clear()
+    _store_mod.message_log.close()
+
+    _store_mod.DB_PATH = original_db_path
+    _store_mod.message_log._db_path = original_db_path
+    _store_mod.message_log._conn = None
 
 
 @pytest.fixture(autouse=True)
diff --git a/tests/dashboard/test_chat_persistence.py b/tests/dashboard/test_chat_persistence.py
new file mode 100644
index 0000000..cea4084
--- /dev/null
+++ b/tests/dashboard/test_chat_persistence.py
@@ -0,0 +1,125 @@
+"""Tests for SQLite-backed chat persistence (issue #46)."""
+
+from dashboard.store import Message, MessageLog
+
+
+def test_persistence_across_instances(tmp_path):
+    """Messages survive creating a new MessageLog pointing at the same DB."""
+    db = tmp_path / "chat.db"
+    log1 = MessageLog(db_path=db)
+    log1.append(role="user", content="hello", timestamp="10:00:00", source="browser")
+    log1.append(role="agent", content="hi back", timestamp="10:00:01", source="browser")
+    log1.close()
+
+    # New instance — simulates server restart
+    log2 = MessageLog(db_path=db)
+    msgs = log2.all()
+    assert len(msgs) == 2
+    assert msgs[0].role == "user"
+    assert msgs[0].content == "hello"
+    assert msgs[1].role == "agent"
+    assert msgs[1].content == "hi back"
+    log2.close()
+
+
+def test_retention_policy(tmp_path):
+    """Oldest messages are pruned when count exceeds MAX_MESSAGES."""
+    import dashboard.store as store_mod
+
+    original_max = store_mod.MAX_MESSAGES
+    store_mod.MAX_MESSAGES = 5  # Small limit for testing
+
+    try:
+        db = tmp_path / "chat.db"
+        log = MessageLog(db_path=db)
+        for i in range(8):
+            log.append(role="user", content=f"msg-{i}", timestamp=f"10:00:{i:02d}")
+
+        assert len(log) == 5
+        msgs = log.all()
+        # Oldest 3 should have been pruned
+        assert msgs[0].content == "msg-3"
+        assert msgs[-1].content == "msg-7"
+        log.close()
+    finally:
+        store_mod.MAX_MESSAGES = original_max
+
+
+def test_clear_removes_all(tmp_path):
+    db = tmp_path / "chat.db"
+    log = MessageLog(db_path=db)
+    log.append(role="user", content="data", timestamp="12:00:00")
+    assert len(log) == 1
+    log.clear()
+    assert len(log) == 0
+    assert log.all() == []
+    log.close()
+
+
+def test_recent_returns_limited_newest(tmp_path):
+    db = tmp_path / "chat.db"
+    log = MessageLog(db_path=db)
+    for i in range(10):
+        log.append(role="user", content=f"msg-{i}", timestamp=f"10:00:{i:02d}")
+
+    recent = log.recent(limit=3)
+    assert len(recent) == 3
+    # Should be oldest-first within the window
+    assert recent[0].content == "msg-7"
+    assert recent[1].content == "msg-8"
+    assert recent[2].content == "msg-9"
+    log.close()
+
+
+def test_source_field_persisted(tmp_path):
+    db = tmp_path / "chat.db"
+    log = MessageLog(db_path=db)
+    log.append(role="user", content="from api", timestamp="10:00:00", source="api")
+    log.append(role="user", content="from tg", timestamp="10:00:01", source="telegram")
+    log.close()
+
+    log2 = MessageLog(db_path=db)
+    msgs = log2.all()
+    assert msgs[0].source == "api"
+    assert msgs[1].source == "telegram"
+    log2.close()
+
+
+def test_message_dataclass_defaults():
+    m = Message(role="user", content="hi", timestamp="12:00:00")
+    assert m.source == "browser"
+
+
+def test_empty_db_returns_empty(tmp_path):
+    db = tmp_path / "chat.db"
+    log = MessageLog(db_path=db)
+    assert log.all() == []
+    assert len(log) == 0
+    assert log.recent() == []
+    log.close()
+
+
+def test_concurrent_appends(tmp_path):
+    """Multiple threads can append without corrupting data."""
+    import threading
+
+    db = tmp_path / "chat.db"
+    log = MessageLog(db_path=db)
+    errors = []
+
+    def writer(thread_id):
+        try:
+            for i in range(20):
+                log.append(role="user", content=f"t{thread_id}-{i}", timestamp="10:00:00")
+        except Exception as e:
+            errors.append(e)
+
+    threads = [threading.Thread(target=writer, args=(t,)) for t in range(4)]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    assert not errors
+    assert len(log) == 80
+    log.close()