feat(daemon): add IPC transport module

Newline-delimited JSON over Unix socket (macOS/Linux, chmod 600, UID-checked
via SO_PEERCRED/getpeereid) with TCP loopback fallback on Windows. Port written
to ~/.pyra/daemon.port for Windows clients. Sync send_command() wrapper for CLI.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_daemon_ipc.py

@@ -0,0 +1,162 @@
+"""Unit tests for the IPC layer."""
+
+from __future__ import annotations
+
+import asyncio
+import os
+import sys
+import tempfile
+from pathlib import Path
+
+import pytest
+
+from pyra.daemon.ipc import (
+    IpcClient,
+    IpcMessage,
+    IpcResponse,
+    IpcServer,
+    decode_message,
+    encode_message,
+    is_unix_socket,
+)
+
+
+@pytest.fixture
+def sock_path():
+    """Short socket path that fits within macOS's 104-char AF_UNIX limit."""
+    with tempfile.TemporaryDirectory(dir="/tmp") as d:
+        yield Path(d) / "t.sock"
+
+
+# ── Protocol encode / decode ──────────────────────────────────────────────────
+
+def test_encode_appends_newline() -> None:
+    data = encode_message({"cmd": "ping"})
+    assert data.endswith(b"\n")
+
+
+def test_encode_is_valid_json() -> None:
+    import json
+    data = encode_message({"cmd": "status", "extra": 42})
+    assert json.loads(data) == {"cmd": "status", "extra": 42}
+
+
+def test_decode_roundtrip() -> None:
+    msg: IpcMessage = {"cmd": "stop"}
+    assert decode_message(encode_message(msg)) == msg
+
+
+def test_decode_strips_newline() -> None:
+    assert decode_message(b'{"cmd": "stop"}\n')["cmd"] == "stop"
+
+
+def test_decode_raises_on_bad_json() -> None:
+    with pytest.raises(ValueError, match="Invalid IPC message"):
+        decode_message(b"not json\n")
+
+
+def test_decode_raises_on_empty_line() -> None:
+    with pytest.raises(ValueError):
+        decode_message(b"\n")
+
+
+# ── is_unix_socket ────────────────────────────────────────────────────────────
+
+def test_is_unix_socket_matches_platform() -> None:
+    if sys.platform == "win32":
+        assert not is_unix_socket()
+    else:
+        assert is_unix_socket()
+
+
+# ── Server + client roundtrip (Unix only) ─────────────────────────────────────
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Unix socket test")
+async def test_server_client_ping(sock_path: Path) -> None:
+    async def handler(msg: IpcMessage) -> IpcResponse:
+        return {"ok": True, "data": {"pong": True}}
+
+    server = IpcServer(sock_path, handler)
+    await server.start()
+    try:
+        resp = await IpcClient(sock_path).send({"cmd": "ping"})
+        assert resp["ok"] is True
+        assert resp["data"]["pong"] is True
+    finally:
+        await server.stop()
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Unix socket test")
+async def test_server_echoes_error_for_bad_json(sock_path: Path) -> None:
+    async def handler(msg: IpcMessage) -> IpcResponse:
+        return {"ok": True, "data": {}}
+
+    server = IpcServer(sock_path, handler)
+    await server.start()
+    try:
+        reader, writer = await asyncio.open_unix_connection(str(sock_path))
+        writer.write(b"not valid json\n")
+        await writer.drain()
+        line = await asyncio.wait_for(reader.readline(), timeout=3.0)
+        resp = decode_message(line)
+        assert resp["ok"] is False
+        assert "error" in resp["data"]
+    finally:
+        try:
+            writer.close()
+        except Exception:
+            pass
+        await server.stop()
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Unix socket test")
+async def test_handler_response_returned_to_client(sock_path: Path) -> None:
+    async def handler(msg: IpcMessage) -> IpcResponse:
+        if msg.get("cmd") == "status":
+            return {"ok": True, "data": {"uptime": 99.0}}
+        return {"ok": False, "data": {"error": "unknown"}}
+
+    server = IpcServer(sock_path, handler)
+    await server.start()
+    try:
+        resp = await IpcClient(sock_path).send({"cmd": "status"})
+        assert resp["ok"] is True
+        assert resp["data"]["uptime"] == 99.0
+
+        resp2 = await IpcClient(sock_path).send({"cmd": "bogus"})
+        assert resp2["ok"] is False
+    finally:
+        await server.stop()
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Unix socket test")
+async def test_client_raises_when_no_server(sock_path: Path) -> None:
+    client = IpcClient(sock_path)
+    with pytest.raises((ConnectionRefusedError, FileNotFoundError, OSError)):
+        await client.send({"cmd": "ping"})
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Unix socket test")
+async def test_socket_file_chmod_600(sock_path: Path) -> None:
+    async def handler(msg: IpcMessage) -> IpcResponse:
+        return {"ok": True, "data": {}}
+
+    server = IpcServer(sock_path, handler)
+    await server.start()
+    try:
+        mode = oct(sock_path.stat().st_mode & 0o777)
+        assert mode == oct(0o600), f"Expected 0o600, got {mode}"
+    finally:
+        await server.stop()
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Unix socket test")
+async def test_stop_removes_socket_file(sock_path: Path) -> None:
+    async def handler(msg: IpcMessage) -> IpcResponse:
+        return {"ok": True, "data": {}}
+
+    server = IpcServer(sock_path, handler)
+    await server.start()
+    assert sock_path.exists()
+    await server.stop()
+    assert not sock_path.exists()