worker: idalib worker + WorkerClient (drop-in for IDAClient) — migration step 1

First concrete step off the mcp HTTP transport. Instead of reimplementing ~25
tools, reuse ida-pro-mcp's tool *functions* verbatim and replace only the
transport + process management:

* idatui/worker.py — opens ONE database in-process on the main thread (as idalib
  requires), imports ida_pro_mcp (which registers every stock + our patched-in
  custom tool against MCP_SERVER), then serves MCP_SERVER.tools.methods[name]
  (**args) over a unix socket with length-prefixed pickle. Serial on the main
  thread (idalib is single-threaded; tools run inline through execute_sync).
  Session-management tools (idb_open/idb_save/server_health/idb_list) are shimmed
  since the worker *is* the single session.
* idatui/worker_client.py — WorkerClient exposes the exact surface the app/domain
  use on the client (call/call_envelope/connect/set_db/resolve_db/list_sessions/
  health/keepalive/close) and returns byte-identical payloads (the worker calls
  the same functions IDAClient.call ultimately hits). So domain.py and the app
  are UNCHANGED — you just construct a WorkerClient instead of an IDAClient.
  Calls are serialized under a lock over one socket; keepalive is a no-op (the
  worker is ours and never idles out).

Not wired into the app yet — the mcp path is fully intact.

Verified without idalib: pickle framing round-trips arbitrary payloads incl raw
bytes; WorkerClient has full IDAClient surface; call_envelope produces the
result.structuredContent shape domain.decompile() reads. The idalib E2E
(experiments/worker_smoke.py drives the real domain.Program read path through the
worker) is written but couldn't run here — this sandbox has degraded to reaping
any idalib spawn; the underlying unix-socket protocol already ran clean in the
inproc_spike bench (~50us/call), and the worker dispatches the same tool
functions the HTTP path does, so shapes match by construction.

Next: stand up progress reporting during analysis, then flip _connect/_reconnect
to build a WorkerClient behind a flag and run the pilot suite against it.

2 files changed, 325 insertions, 0 deletions

diff --git a/idatui/worker.py b/idatui/worker.py
new file mode 100644
index 0000000..d5fab20
--- /dev/null
+++ b/idatui/worker.py
@@ -0,0 +1,160 @@
+"""idatui's own idalib worker — the replacement for the ida-pro-mcp supervisor.
+
+Opens ONE database in-process (on the main thread, as idalib requires) and
+serves ida-pro-mcp's *tool functions* over a unix socket with length-prefixed
+pickle. Same tool implementations as the MCP path (we call
+``MCP_SERVER.tools.methods[name](**args)`` directly), so return shapes are
+byte-identical — but with ~50us/call instead of the HTTP path's ~5ms, and no
+supervisor / HTTP / JSON / 50KB-truncation machinery.
+
+    python -m idatui.worker <sock_path> <binary_path>
+
+The socket only appears once the database is open + analyzed, so a client can
+poll ``connect()`` to know when the worker is ready. Requests are served
+serially on the main thread (idalib is single-threaded; every tool runs inline
+through its own execute_sync, which is a no-op on the main thread).
+
+Protocol (both directions length-prefixed: 4-byte big-endian len + pickle):
+    request  = (tool_name: str, kwargs: dict)
+    response = (ok: bool, result_or_error)
+    tool_name == "__shutdown__" ends the worker.
+"""
+from __future__ import annotations
+
+import os
+import pickle
+import socket
+import struct
+import sys
+import uuid
+
+
+# --------------------------------------------------------------------------- #
+# framing
+# --------------------------------------------------------------------------- #
+def _recvn(sock: socket.socket, n: int) -> bytes | None:
+    buf = bytearray()
+    while len(buf) < n:
+        chunk = sock.recv(n - len(buf))
+        if not chunk:
+            return None
+        buf += chunk
+    return bytes(buf)
+
+
+def send(sock: socket.socket, obj) -> None:
+    data = pickle.dumps(obj, protocol=pickle.HIGHEST_PROTOCOL)
+    sock.sendall(struct.pack(">I", len(data)) + data)
+
+
+def recv(sock: socket.socket):
+    hdr = _recvn(sock, 4)
+    if hdr is None:
+        return None
+    (n,) = struct.unpack(">I", hdr)
+    body = _recvn(sock, n)
+    return None if body is None else pickle.loads(body)
+
+
+# --------------------------------------------------------------------------- #
+# worker
+# --------------------------------------------------------------------------- #
+def _open_and_register(binpath: str):
+    """Open the DB (main thread) then import ida-pro-mcp so every @tool registers
+    against this live database. Returns (tools_dict, module_name, save_fn)."""
+    import idapro
+    idapro.enable_console_messages(False)
+    rc = idapro.open_database(binpath, run_auto_analysis=True)
+    if rc:
+        raise RuntimeError(f"open_database({binpath!r}) failed rc={rc}")
+
+    # importing the package registers all api_*/patched tools against MCP_SERVER
+    from ida_pro_mcp.ida_mcp import MCP_SERVER  # noqa: WPS433
+
+    import ida_nalt
+    module = os.path.basename(ida_nalt.get_root_filename() or binpath)
+
+    def save():
+        import idc
+        try:
+            idc.save_database(idc.get_idb_path(), 0)
+        except Exception:  # noqa: BLE001
+            import ida_loader, ida_pro  # noqa: WPS433
+            ida_loader.save_database(idc.get_idb_path(), 0)
+
+    return MCP_SERVER.tools.methods, module, save
+
+
+def serve(sockpath: str, binpath: str) -> None:
+    tools, module, save = _open_and_register(binpath)
+    sid = uuid.uuid4().hex[:8]
+
+    def dispatch(name: str, args: dict):
+        args = dict(args)
+        args.pop("database", None)  # single-DB worker: no session routing
+        # session-management shims (were the supervisor's job):
+        if name in ("idb_open",):
+            return {"success": True,
+                    "session": {"session_id": sid, "module": module,
+                                "input_path": binpath}}
+        if name in ("idb_save", "save"):
+            save()
+            return {"success": True}
+        if name in ("server_health", "ping", "health", "state"):
+            return {"module": module, "ok": True, "session_id": sid}
+        if name in ("idb_list",):
+            return {"sessions": [{"session_id": sid, "module": module,
+                                  "input_path": binpath}]}
+        fn = tools.get(name)
+        if fn is None:
+            raise KeyError(f"unknown tool: {name!r}")
+        return fn(**args)
+
+    try:
+        os.unlink(sockpath)
+    except OSError:
+        pass
+    srv = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    srv.bind(sockpath)
+    srv.listen(8)
+    try:
+        while True:
+            conn, _ = srv.accept()
+            try:
+                while True:
+                    req = recv(conn)
+                    if req is None:
+                        break
+                    name, args = req
+                    if name == "__shutdown__":
+                        return
+                    try:
+                        send(conn, (True, dispatch(name, args)))
+                    except Exception as e:  # noqa: BLE001 -- report, keep serving
+                        send(conn, (False, f"{type(e).__name__}: {e}"))
+            except (ConnectionError, OSError):
+                pass
+            finally:
+                conn.close()
+    finally:
+        try:
+            import idapro
+            idapro.close_database(save=False)
+        except Exception:  # noqa: BLE001
+            pass
+        try:
+            os.unlink(sockpath)
+        except OSError:
+            pass
+
+
+def main(argv=None) -> None:
+    argv = argv if argv is not None else sys.argv[1:]
+    if len(argv) < 2:
+        sys.stderr.write("usage: python -m idatui.worker <sock> <binary>\n")
+        raise SystemExit(2)
+    serve(argv[0], argv[1])
+
+
+if __name__ == "__main__":
+    main()
diff --git a/idatui/worker_client.py b/idatui/worker_client.py
new file mode 100644
index 0000000..49da8fa
--- /dev/null
+++ b/idatui/worker_client.py
@@ -0,0 +1,165 @@
+"""WorkerClient — a drop-in replacement for ``IDAClient`` backed by our own
+idalib worker (``idatui.worker``) over a unix socket instead of ida-pro-mcp's
+HTTP/JSON transport.
+
+It exposes exactly the surface the app/domain use on the client
+(``call``/``call_envelope``/``connect``/``set_db``/``resolve_db``/
+``list_sessions``/``health``/``keepalive``/``close``) and returns byte-identical
+payloads (the worker calls the same tool functions), so ``domain.py`` and the
+app are unchanged — you just construct a WorkerClient instead of an IDAClient.
+
+Concurrency: the app fires calls from several worker threads over one client;
+the worker is single-threaded, so calls are serialized under a lock (the worker
+processes one tool at a time anyway — and at ~50us/call that's free).
+"""
+from __future__ import annotations
+
+import os
+import socket
+import subprocess
+import sys
+import threading
+import time
+import uuid
+from typing import Any
+
+from .client import IDAToolError, IDAConnectionError, Session
+from .worker import recv as _recv
+from .worker import send as _send
+
+
+class _NoopKeepAlive:
+    """The worker is ours and never idles out, so keepalive is a no-op."""
+
+    def __init__(self) -> None:
+        self.beats = self.failures = 0
+
+    def start(self):
+        return self
+
+    def stop(self) -> None:
+        pass
+
+
+class WorkerClient:
+    def __init__(self, binary_path: str, *, ttl: int = 0,
+                 python: str | None = None) -> None:
+        self._bin = os.path.abspath(os.path.expanduser(binary_path))
+        self._python = python or sys.executable
+        self._sock_path = f"/tmp/idatui-worker-{os.getpid()}-{uuid.uuid4().hex[:8]}.sock"
+        self._proc: subprocess.Popen | None = None
+        self._sock: socket.socket | None = None
+        self._sid = uuid.uuid4().hex[:8]
+        self._lock = threading.Lock()       # serialize socket use
+        self._spawn_lock = threading.Lock()
+
+    # -- lifecycle --------------------------------------------------------- #
+    def connect(self, timeout: float = 1800.0, progress=None) -> "WorkerClient":
+        """Spawn the worker (opens + analyzes the DB) and connect once ready."""
+        with self._spawn_lock:
+            if self._sock is not None:
+                return self
+            if self._proc is None or self._proc.poll() is not None:
+                self._proc = subprocess.Popen(
+                    [self._python, "-m", "idatui.worker",
+                     self._sock_path, self._bin],
+                    cwd=os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
+                )
+            deadline = time.time() + timeout
+            t0 = time.time()
+            while time.time() < deadline:
+                try:
+                    s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+                    s.connect(self._sock_path)
+                    self._sock = s
+                    return self
+                except OSError:
+                    if self._proc.poll() is not None:
+                        raise IDAConnectionError(
+                            f"worker exited during startup (code "
+                            f"{self._proc.returncode})")
+                    if progress:
+                        progress(f"auto-analyzing {os.path.basename(self._bin)}… "
+                                 f"({int(time.time() - t0)}s)")
+                    time.sleep(0.2)
+            raise IDAConnectionError("worker did not become ready in time")
+
+    def close(self) -> None:
+        with self._lock:
+            s = self._sock
+            self._sock = None
+            if s is not None:
+                try:
+                    _send(s, ("__shutdown__", {}))
+                except Exception:  # noqa: BLE001
+                    pass
+                try:
+                    s.close()
+                except Exception:  # noqa: BLE001
+                    pass
+        if self._proc is not None:
+            try:
+                self._proc.terminate()
+                self._proc.wait(timeout=5)
+            except Exception:  # noqa: BLE001
+                try:
+                    self._proc.kill()
+                except Exception:  # noqa: BLE001
+                    pass
+
+    # -- the call surface -------------------------------------------------- #
+    def call(self, tool: str, *, timeout: float | None = None, **args) -> Any:
+        if self._sock is None:
+            self.connect()
+        with self._lock:
+            s = self._sock
+            if s is None:
+                raise IDAConnectionError("worker connection is closed")
+            try:
+                _send(s, (tool, args))
+                reply = _recv(s)
+            except (OSError, ConnectionError) as e:
+                self._sock = None
+                raise IDAConnectionError(f"worker transport failed: {e}") from e
+        if reply is None:
+            self._sock = None
+            raise IDAConnectionError("worker closed the connection")
+        ok, payload = reply
+        if not ok:
+            raise IDAToolError(tool, str(payload))
+        return payload
+
+    def call_envelope(self, tool: str, *, timeout: float | None = None,
+                      **args) -> dict:
+        # domain.decompile() reads result.structuredContent — mirror that shape.
+        return {"result": {"structuredContent": self.call(tool, timeout=timeout,
+                                                           **args)}}
+
+    # -- session shims (single-DB worker) --------------------------------- #
+    def set_db(self, db: str | None) -> None:
+        if db:
+            self._sid = db
+
+    def resolve_db(self) -> str:
+        return self._sid
+
+    def list_sessions(self) -> list[Session]:
+        return [Session(session_id=self._sid,
+                        filename=os.path.basename(self._bin),
+                        input_path=self._bin, is_active=True)]
+
+    def health(self) -> dict:
+        try:
+            return self.call("server_health")
+        except IDAToolError:
+            return {"module": os.path.basename(self._bin), "ok": True}
+
+    def keepalive(self, interval: float = 120.0) -> _NoopKeepAlive:
+        return _NoopKeepAlive()
+
+    # context manager parity with IDAClient
+    def __enter__(self) -> "WorkerClient":
+        return self.connect()
+
+    def __exit__(self, *exc) -> None:
+        self.close()