feat(chat): save and view chat history — admin-only saved_chats, History page, open-a-chat return

app/models.py

@@ -17,6 +17,11 @@ Data model — see ``.agent/PLAN.md`` §Data Model:
                       directories) the Sync button and import_docs
                       import (phase 35; ``kind`` discriminator added in
                       phase 38).
+* ``saved_chats``    — owner-saved chat conversations: one row per
+                      explicitly Saved conversation (auto-``title`` +
+                      the ``bor.chat.v1`` message list as JSONB, phase
+                      14 shape) — phase 50; ``/api/chat`` stays
+                      stateless.
 """
 from __future__ import annotations
 
@@ -35,7 +40,7 @@ from sqlalchemy import (
     UniqueConstraint,
     func,
 )
-from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from app.config import get_settings
@@ -162,3 +167,33 @@ class GitSource(Base):
     #: Unique — Postgres treats NULLs as distinct under a unique index.
     path: Mapped[str | None] = mapped_column(Text, unique=True)
     added_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+
+
+class SavedChat(Base):
+    """One owner-saved chat conversation (phase 50).
+
+    Only conversations the owner explicitly **Saves** are stored —
+    ``/api/chat`` itself stays stateless (A10, owner-locked extension
+    2026-08-29) and nothing is stored about a conversation that was not
+    saved. ``messages`` holds the exact ``bor.chat.v1`` localStorage
+    record shape (phase 14 — raw text, never HTML), so a saved chat
+    restores pixel-identical through the existing
+    ``renderStoredMessage`` path. No share-related columns here —
+    phase 51 adds ``share_token`` in migration 0009.
+    """
+
+    __tablename__ = "saved_chats"
+
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    #: Auto-title (the first question, API-side). Plain column on purpose:
+    #: a future rename needs no migration.
+    title: Mapped[str] = mapped_column(String(500))
+    #: ``list[dict]`` in the ``bor.chat.v1`` record shape
+    #: (``{who, text, sources?, deflected?, suggestions?, thinking?,
+    #: tools?, stopped?}``); the API always supplies a list, so no
+    #: default is needed.
+    messages: Mapped[list] = mapped_column(JSONB)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
+    )