feat: auto-discover Power BI Desktop port, making -d optional on connect

README.md

@@ -41,11 +41,13 @@ Install and set up pbi-cli from https://github.com/MinaSaad1/pbi-cli.git
 **Or install manually (two commands):**
 
 ```bash
-pipx install pbi-cli-tool           # 1. Install (handles PATH automatically)
-pbi connect -d localhost:54321      # 2. Connect (auto-downloads binary + installs skills)
+pipx install pbi-cli-tool    # 1. Install (handles PATH automatically)
+pbi connect                  # 2. Auto-detects Power BI Desktop, downloads binary, installs skills
 ```
 
-That's it. The first `connect` automatically downloads the MCP binary and installs Claude Code skills. Open Claude Code and start asking.
+That's it. Open Power BI Desktop with a `.pbix` file, run `pbi connect`, and everything is set up automatically. Open Claude Code and start asking.
+
+You can also specify the port manually: `pbi connect -d localhost:54321`
 
 > **Requires:** Python 3.10+ and Power BI Desktop (local) or a Fabric workspace (cloud).
 

src/pbi_cli/commands/connection.py

@@ -23,7 +23,12 @@ from pbi_cli.main import PbiContext, pass_context
 
 
 @click.command()
-@click.option("--data-source", "-d", required=True, help="Data source (e.g., localhost:54321).")
+@click.option(
+    "--data-source",
+    "-d",
+    default=None,
+    help="Data source (e.g., localhost:54321). Auto-detected if omitted.",
+)
 @click.option("--catalog", "-C", default="", help="Initial catalog / dataset name.")
 @click.option(
     "--name", "-n", default=None, help="Name for this connection (auto-generated if omitted)."
@@ -33,11 +38,21 @@ from pbi_cli.main import PbiContext, pass_context
 )
 @pass_context
 def connect(
-    ctx: PbiContext, data_source: str, catalog: str, name: str | None, connection_string: str
+    ctx: PbiContext,
+    data_source: str | None,
+    catalog: str,
+    name: str | None,
+    connection_string: str,
 ) -> None:
-    """Connect to a Power BI instance via data source."""
+    """Connect to a Power BI instance via data source.
+
+    If --data-source is omitted, auto-detects a running Power BI Desktop instance.
+    """
     _ensure_ready()
 
+    if data_source is None:
+        data_source = _auto_discover_data_source()
+
     conn_name = name or _auto_name(data_source)
 
     request: dict[str, object] = {
@@ -233,6 +248,27 @@ def connections_last(ctx: PbiContext) -> None:
         )
 
 
+def _auto_discover_data_source() -> str:
+    """Auto-detect a running Power BI Desktop instance.
+
+    Raises click.ClickException if no instance is found.
+    """
+    from pbi_cli.core.output import print_info
+    from pbi_cli.utils.platform import discover_pbi_port
+
+    port = discover_pbi_port()
+    if port is None:
+        raise click.ClickException(
+            "No running Power BI Desktop instance found.\n"
+            "  1. Open Power BI Desktop and load a .pbix file\n"
+            "  2. Run 'pbi connect' again, or specify manually: pbi connect -d localhost:<port>"
+        )
+
+    data_source = f"localhost:{port}"
+    print_info(f"Auto-detected Power BI Desktop on {data_source}")
+    return data_source
+
+
 def _ensure_ready() -> None:
     """Auto-setup binary and skills if not already done.
 

src/pbi_cli/utils/platform.py

@@ -57,6 +57,46 @@ def ensure_executable(path: Path) -> None:
         path.chmod(current | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
 
 
+def discover_pbi_port() -> int | None:
+    """Find the port of a running Power BI Desktop instance.
+
+    Power BI Desktop writes its XMLA port to a file at:
+    %LOCALAPPDATA%/Microsoft/Power BI Desktop/AnalysisServicesWorkspaces/
+        AnalysisServicesWorkspace_*/Data/msmdsrv.port.txt
+
+    Returns the port number, or None if Power BI Desktop is not running.
+    """
+    if platform.system() != "Windows":
+        return None
+
+    import os
+
+    local_app_data = os.environ.get("LOCALAPPDATA", "")
+    if not local_app_data:
+        return None
+
+    workspaces_dir = (
+        Path(local_app_data) / "Microsoft" / "Power BI Desktop" / "AnalysisServicesWorkspaces"
+    )
+    if not workspaces_dir.exists():
+        return None
+
+    # Find all port files, pick the most recently modified (latest instance)
+    port_files = sorted(
+        workspaces_dir.glob("*/Data/msmdsrv.port.txt"),
+        key=lambda p: p.stat().st_mtime,
+        reverse=True,
+    )
+    if not port_files:
+        return None
+
+    try:
+        port_text = port_files[0].read_text(encoding="utf-8").strip()
+        return int(port_text)
+    except (ValueError, OSError):
+        return None
+
+
 def find_vscode_extension_binary() -> Path | None:
     """Look for the binary in the VS Code extension install directory.