Power-Agent · qian-harvard · Jun 14, 2026 · Jun 14, 2026
diff --git a/ANDES/andes_mcp.py b/ANDES/andes_mcp.py
@@ -354,8 +354,8 @@ def load_network_from_json(
     Accepts the ``json`` string returned by the powerio server's parse_case or
     case_to_json tools. Converts the network to MATPOWER format, writes it to
     out_path (use a .m extension), and returns the path along with component
-    counts. Pass out_path to run_power_flow to run the simulation. Requires the
-    powerio extra (pip install 'powermcp[powerio]').
+    counts. Pass out_path to run_power_flow to run the simulation. powerio is a
+    core dependency, so this is always available.
 
     Args:
         network_json: The JSON transport string from powerio
@@ -399,8 +399,8 @@ def load_network_from_any(
 
     Reads MATPOWER .m, PSS/E .raw (v33), PowerWorld .aux, PowerModels JSON, or
     egret JSON via powerio and writes a MATPOWER file to out_path (use a .m
-    extension). Pass out_path to run_power_flow to run the simulation. Requires
-    the powerio extra (pip install 'powermcp[powerio]').
+    extension). Pass out_path to run_power_flow to run the simulation. powerio
+    is a core dependency, so this is always available.
 
     Args:
         file_path: Path to the source case file

diff --git a/Egret/egret_mcp.py b/Egret/egret_mcp.py
@@ -214,8 +214,8 @@ def load_model_from_any(file_path: str, source_format: Optional[str] = None) ->
     egret JSON via powerio, converts it to egret JSON, validates it as an
     egret ModelData, and stages it to a temp file. Pass the returned
     `case_file` path to solve_ac_opf, solve_dc_opf, or
-    solve_unit_commitment_problem. Requires the powerio extra
-    (pip install 'powermcp[powerio]').
+    solve_unit_commitment_problem. powerio is a core dependency, so this is
+    always available.
 
     Args:
         file_path: Path to the case file
@@ -254,8 +254,8 @@ def load_model_from_json(network_json: str) -> Dict[str, Any]:
     case_to_json tools, so a case parsed once there feeds egret without
     re-reading the file. Converts it to egret JSON, validates it as an egret
     ModelData, and stages it to a temp file. Pass the returned `case_file`
-    path to the solver tools. Requires the powerio extra
-    (pip install 'powermcp[powerio]').
+    path to the solver tools. powerio is a core dependency, so this is always
+    available.
 
     Args:
         network_json: The JSON transport string from powerio

diff --git a/PyPSA/pypsa_mcp.py b/PyPSA/pypsa_mcp.py
@@ -727,8 +727,8 @@ def import_case_from_any(
     .nc extension); pass that path as network_name to the other tools. PyPSA's
     ppc import drops generator cost data; anything else it cannot represent is
     listed in the returned warnings. Branches with rating 0 are imported with
-    s_nom 0 unless overwrite_zero_s_nom supplies a value. Requires the powerio
-    extra (pip install 'powermcp[powerio]').
+    s_nom 0 unless overwrite_zero_s_nom supplies a value. powerio is a core
+    dependency, so this is always available.
 
     Args:
         file_path: Path to the case file
@@ -776,8 +776,8 @@ def import_case_from_json(
     a file around or re-parsing it. Expects source-valued tables (MW, degrees)
     as parse_case emits them, not the per-unit normalize_case form. Writes the
     network to output_path (use a .nc extension); pass that path as
-    network_name to the other tools. Requires the powerio extra
-    (pip install 'powermcp[powerio]').
+    network_name to the other tools. powerio is a core dependency, so this is
+    always available.
 
     Args:
         network_json: The JSON transport string from powerio

diff --git a/README.md b/README.md
@@ -72,12 +72,12 @@ PowerMCP installs as a single Python package with an interactive CLI. Python 3.1
 pip install powermcp
 ```
 
-The base install includes the two open-source engines that need no extra setup — **pandapower** and **PyPSA**. Every other tool is opt-in via an extra:
+The base install includes the open-source engines that need no extra setup — **pandapower**, **PyPSA**, and **PowerIO** (the cross-server case-conversion substrate). Every other tool is opt-in via an extra:
 
 ```bash
 pip install powermcp[psse]              # add PSS/E support
 pip install powermcp[andes,opendss]     # add several tools at once
-pip install powermcp[opensource]        # all open-source tools (ANDES, Egret, OpenDSS, surge, HOPE, LTSpice, PowerIO)
+pip install powermcp[opensource]        # all open-source tools (ANDES, Egret, OpenDSS, surge, HOPE, LTSpice)
 pip install powermcp[all]               # everything (closed-source tools still need the local software)
 ```
 
@@ -87,7 +87,7 @@ pip install powermcp[all]               # everything (closed-source tools still
 powermcp install
 ```
 
-The wizard lets you pick tools (pandapower + PyPSA pre-selected), captures the local install path for any closed-source/EXE-based tools you choose (PSS/E, PSLF, PowerFactory, PSCAD, LTSpice), installs the right extras, and writes the MCP client configuration for **Claude Desktop**, **Claude Code**, and the **Codex CLI**. Use `--dry-run` to preview the changes, or `--yes` for a non-interactive core install.
+The wizard lets you pick tools (pandapower + PyPSA + PowerIO pre-selected), captures the local install path for any closed-source/EXE-based tools you choose (PSS/E, PSLF, PowerFactory, PSCAD, LTSpice), installs the right extras, and writes the MCP client configuration for **Claude Desktop**, **Claude Code**, and the **Codex CLI**. Use `--dry-run` to preview the changes, or `--yes` for a non-interactive core install.
 
 In the interactive picker, move with ↑/↓ and **press SPACE to toggle each tool** before ENTER (ENTER alone keeps only the preselected tools). Prefer not to use the checkbox? Choose tools directly:
 
@@ -126,7 +126,7 @@ These tools wrap commercial or locally-installed software, so PowerMCP stores th
 
 ### Case conversion between servers (PowerIO)
 
-The `powerio` extra adds a conversion server backed by [powerio](https://github.com/eigenergy/powerio). It parses MATPOWER `.m`, PSS/E `.raw`, PowerWorld `.aux`, PowerModels JSON, and egret JSON into one format neutral network, converts between those formats with fidelity warnings, and builds the sparse matrices solvers need (B', B'', Y_bus, PTDF, LODF, Laplacian, LACPF).
+PowerMCP ships a conversion server backed by [powerio](https://github.com/eigenergy/powerio) as a **core dependency** (no extra needed). It parses MATPOWER `.m`, PSS/E `.raw`, PowerWorld `.aux`, PowerModels JSON, and egret JSON into one format neutral network, converts between those formats with fidelity warnings, and builds the sparse matrices solvers need (B', B'', Y_bus, PTDF, LODF, Laplacian, LACPF).
 
 Its JSON transport is the exchange format between PowerMCP servers: parse a case once, pass the returned `json` string between tool calls, and load it anywhere.
 

diff --git a/pandapower/panda_mcp.py b/pandapower/panda_mcp.py
@@ -387,7 +387,7 @@ def load_network_from_any(file_path: str, source_format: Optional[str] = None) -
     Reads MATPOWER .m, PSS/E .raw (v33), PowerWorld .aux, PowerModels JSON, or
     egret JSON via powerio and converts it to a pandapower network, replacing
     the currently loaded one. Use this for case formats load_network does not
-    accept. Requires the powerio extra (pip install 'powermcp[powerio]').
+    accept. powerio is a core dependency, so this is always available.
 
     Args:
         file_path: Path to the case file
@@ -422,8 +422,8 @@ def load_network_from_json(network_json: str) -> Dict[str, Any]:
     case_to_json tools, so a case parsed once there loads here without passing
     a file around or re-parsing it. Expects source-valued tables (MW, degrees)
     as parse_case emits them, not the per-unit normalize_case form. Replaces
-    the currently loaded network. Requires the powerio extra
-    (pip install 'powermcp[powerio]').
+    the currently loaded network. powerio is a core dependency, so this is
+    always available.
 
     Args:
         network_json: The JSON transport string from powerio
@@ -452,7 +452,7 @@ def export_network_to_format(to_format: str) -> Dict[str, Any]:
     Converts the loaded network to MATPOWER tables and serializes them with
     powerio. to_format is a powerio format name: matpower (m),
     powermodels-json (pm), egret-json (egret), psse (raw), powerworld (aux).
-    Requires the powerio extra (pip install 'powermcp[powerio]').
+    powerio is a core dependency, so this is always available.
 
     Args:
         to_format: Target format name

diff --git a/powermcp/registry.py b/powermcp/registry.py
@@ -131,10 +131,10 @@ def resolve_module_root(self) -> Path:
             external_solvers=("Julia",),
         ),
         Tool(
-            "powerio", "PowerIO", "open-source", windows_only=False, extra="powerio",
+            "powerio", "PowerIO", "open-source", windows_only=False, extra=None,
             server_dir="powerio", run_kind="script", entry_rel="powerio_mcp.py",
             probe="powerio",
-            notes="Format-neutral case conversion and matrix builder; the JSON transport is the cross-server exchange format.",
+            notes="Format-neutral case conversion and matrix builder; the JSON transport is the cross-server exchange format. Core dependency: it is the cross-server exchange substrate the pandapower/Egret/PyPSA/ANDES bridges build on.",
         ),
         # ---- CLOSED-SOURCE / VENDOR ----
         Tool(
@@ -205,7 +205,11 @@ def resolve_module_root(self) -> Path:
 }
 
 # Tools installed by a bare `pip install powermcp` and pre-checked in the wizard.
-CORE: tuple[str, ...] = ("pandapower", "pypsa")
+# powerio is core because it is the cross-server exchange substrate (the
+# pandapower/Egret/PyPSA/ANDES bridges all build on its JSON transport) and is
+# cheap: abi3 wheels, zero required runtime deps, extras resolving to numpy
+# (core) + scipy (transitive via pandapower).
+CORE: tuple[str, ...] = ("pandapower", "pypsa", "powerio")
 
 
 def get_tool(name: str) -> "Tool":

diff --git a/pyproject.toml b/pyproject.toml
@@ -36,6 +36,11 @@ dependencies = [
     "numpy>=1.24",
     "pandas>=2.0",
     "mcp>=1.0",
+    # powerio is the cross-server exchange substrate (the pandapower/Egret/PyPSA/
+    # ANDES bridges build on its JSON transport), and is cheap to require: abi3
+    # wheels for five platforms, zero required runtime deps, [mcp,matrix] adding
+    # only scipy (already transitive via pandapower) on top of mcp+numpy.
+    "powerio[mcp,matrix]>=0.1.1",
     # CLI / installer toolkit:
     "typer>=0.12",
     "questionary>=2.0",
@@ -53,7 +58,8 @@ opendss    = ["py_dss_toolkit"]
 ltspice    = ["PyLTSpice", "matplotlib"]
 surge      = ["surge-py>=0.1.5; python_version >= '3.12' and python_version < '3.15'"]
 hope       = ["PyYAML>=6.0"]
-powerio    = ["powerio[mcp,matrix]>=0.1.1"]
+# powerio moved to core `dependencies`; the extra is gone (a bare
+# `pip install powermcp` now always provides the conversion server).
 # --- closed-source / vendor tool engines ---
 powerworld = ["esa", "numba"]                   # esa auto-discovers a running Simulator via COM.
                                                 # numba is required: esa 1.3.5's no-numba code path
@@ -65,7 +71,7 @@ psse       = []                                 # vendor `psspy` not on PyPI —
 pslf       = ["pandas"]                         # vendor `PSLF_PYTHON` not on PyPI — path captured in config.toml
 powerfactory = ["fastmcp>=2.0", "numpy>=1.26", "matplotlib>=3.8", "pandas>=1.5"]  # vendor `powerfactory` not on PyPI
 # --- convenience groups ---
-opensource = ["powermcp[andes]", "powermcp[egret]", "powermcp[opendss]", "powermcp[ltspice]", "powermcp[surge]", "powermcp[hope]", "powermcp[powerio]"]
+opensource = ["powermcp[andes]", "powermcp[egret]", "powermcp[opendss]", "powermcp[ltspice]", "powermcp[surge]", "powermcp[hope]"]
 windows    = ["powermcp[pscad-windows]", "powermcp[powerworld]", "powermcp[powerfactory]", "powermcp[psse]", "powermcp[pslf]"]
 all        = ["powermcp[opensource]", "powermcp[powerworld]", "powermcp[powerfactory]", "powermcp[pscad-windows]", "powermcp[psse]", "powermcp[pslf]"]
 

diff --git a/tests/test_powerio_server.py b/tests/test_powerio_server.py
@@ -1,7 +1,8 @@
 """Tests for the powerio conversion server, the PyPSA bridge, and the
 registry/runner wiring.
 
-The whole module skips when powerio is not installed (it is an opt-in extra).
+powerio is a core dependency, so it is normally present; the importorskip below
+stays as insurance for stripped-down environments.
 The FastMCP-decorated tools stay ordinary callables, so we exercise them
 in-process without a transport. The launch test lives here rather than in
 test_runner.py so it skips with the rest of the module.
@@ -236,7 +237,7 @@ def test_pypsa_import_missing_file(tmp_path):
 def test_registry_entry():
     t = TOOLS["powerio"]
     assert t.kind == "open-source"
-    assert t.extra == "powerio"
+    assert t.extra is None  # promoted to a core dependency (issue #30)
     assert t.run_kind == "script"
     assert t.windows_only is False
     assert t.probe == "powerio"

diff --git a/tests/test_registry.py b/tests/test_registry.py
@@ -9,7 +9,7 @@
 
 
 def test_core_tools_present_and_have_no_extra():
-    assert set(CORE) == {"pandapower", "pypsa"}
+    assert set(CORE) == {"pandapower", "pypsa", "powerio"}
     for name in CORE:
         assert TOOLS[name].extra is None