step B.1 complete: WS context + frame schemas

app/core/ws_context.py

@@ -0,0 +1,68 @@
+"""WebSocket client executor context.
+
+Holds a per-request async callback that tools call to execute CRUD
+operations on the Electron client's local SQLite / LanceDB databases.
+The callback sends a `tool_call` WS frame and awaits the `tool_result`.
+"""
+
+from __future__ import annotations
+
+from contextvars import ContextVar
+from typing import Any, Callable, Coroutine
+from uuid import uuid4
+
+# Holds the execute callback for the current WS session.
+# Set by the chat WS handler before the orchestrator runs; cleared after.
+_client_executor: ContextVar[Callable[[dict], Coroutine[Any, Any, dict]]] = ContextVar(
+    "_client_executor"
+)
+
+
+def set_client_executor(fn: Callable[[dict], Coroutine[Any, Any, dict]]) -> None:
+    """Bind *fn* as the executor for the current async context (task/coroutine)."""
+    _client_executor.set(fn)
+
+
+def clear_client_executor() -> None:
+    """Remove the executor binding (best-effort; ContextVar resets on task exit)."""
+    try:
+        _client_executor.set(None)  # type: ignore[arg-type]
+    except Exception:
+        pass
+
+
+async def execute_on_client(
+    action: str,
+    table: str | None = None,
+    data: dict[str, Any] | None = None,
+    filters: dict[str, Any] | None = None,
+    vector: list[float] | None = None,
+    limit: int | None = None,
+) -> dict[str, Any]:
+    """Send a CRUD/vector operation to the Electron client and return the result.
+
+    Builds a ``tool_call`` payload, invokes the per-session WS callback,
+    and returns the ``tool_result`` dict from Electron.
+
+    Raises ``RuntimeError`` if no executor is set (i.e. called outside a WS session).
+    """
+    callback = _client_executor.get(None)
+    if callback is None:
+        raise RuntimeError(
+            "execute_on_client() called outside a WebSocket session — "
+            "no client executor is set."
+        )
+
+    payload: dict[str, Any] = {"id": str(uuid4()), "action": action}
+    if table is not None:
+        payload["table"] = table
+    if data is not None:
+        payload["data"] = data
+    if filters is not None:
+        payload["filters"] = {k: v for k, v in filters.items() if v is not None}
+    if vector is not None:
+        payload["vector"] = vector
+    if limit is not None:
+        payload["limit"] = limit
+
+    return await callback(payload)

app/schemas.py

@@ -5,6 +5,7 @@ Mirrors the TypeScript types from the Electron app (src/shared/api-types.ts).
 
 from __future__ import annotations
 
+from enum import Enum
 from typing import Any, Literal
 
 from pydantic import BaseModel, Field
@@ -155,3 +156,54 @@ class PluginListResponse(BaseModel):
 
 class PluginInstallRequest(BaseModel):
     plugin_id: str
+
+
+# ── WebSocket Frame Protocol ──────────────────────────────────────────
+
+class WsFrameType(str, Enum):
+    chat_request = "chat_request"
+    text_chunk = "text_chunk"
+    tool_call = "tool_call"
+    tool_result = "tool_result"
+    final = "final"
+    ping = "ping"
+
+
+class WsToolCall(BaseModel):
+    """Server → Client: requests a CRUD/vector operation on the local DB."""
+
+    type: Literal[WsFrameType.tool_call] = WsFrameType.tool_call
+    id: str
+    action: str
+    table: str | None = None
+    data: dict[str, Any] | None = None
+    filters: dict[str, Any] | None = None
+    vector: list[float] | None = None
+    limit: int | None = None
+
+
+class WsToolResult(BaseModel):
+    """Client → Server: result of a CRUD/vector operation."""
+
+    type: Literal[WsFrameType.tool_result] = WsFrameType.tool_result
+    id: str
+    row: dict[str, Any] | None = None
+    rows: list[dict[str, Any]] | None = None
+    results: list[dict[str, Any]] | None = None
+    deleted: bool | None = None
+    ok: bool | None = None
+    error: str | None = None
+
+
+class WsTextChunk(BaseModel):
+    """Server → Client: incremental LLM response text."""
+
+    type: Literal[WsFrameType.text_chunk] = WsFrameType.text_chunk
+    text: str
+
+
+class WsFinal(BaseModel):
+    """Server → Client: signals end of response with the complete text."""
+
+    type: Literal[WsFrameType.final] = WsFrameType.final
+    response: str