Release 1.4.2: load-only dialog when nothing is selected

With neither mode derivable (nothing selected, no marker rectangles,
no config) the dialog now opens anyway instead of failing with an
error figure: both radios disabled with their reasons, OK/Save
disabled, Load config… live - a saved config can bootstrap the run.

README: note that macOS/NixOS field tests last ran with plugin v1.3.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HjSRLWQ8ywBBYyakvr3YTx

README.md

@@ -45,8 +45,8 @@ SWIG API. Requires KiCad **10.0.1+**.
 | Platform                    | Status | Verified by |
 |-----------------------------|:------:|-------------|
 | Windows                     |   ✅   | development platform, full suite before every release |
-| macOS                       |   ✅   | field-tested in KiCad 10 |
-| NixOS                       |   ✅   | field-tested in KiCad 10 ([setup](docs/NIXOS.md)) |
+| macOS                       |   ✅   | field-tested in KiCad 10 (last on plugin v1.3) |
+| NixOS                       |   ✅   | field-tested in KiCad 10 (last on plugin v1.3, [setup](docs/NIXOS.md)) |
 | Debian 12                   |   ✅   | CI test suite in container |
 | Ubuntu 24.04                |   ✅   | CI test suite in container |
 | Fedora (latest)             |   ✅   | CI test suite in container |
@@ -57,16 +57,17 @@ rasterizer, and the platform-fallback regressions — headless against
 the real pip wheels of each Linux row, including the
 `PySide6.QtWidgets` import probe that decides the matplotlib backend.
 What CI *cannot* do is launch KiCad itself, so "runs inside KiCad"
-remains field-tested (Windows continuously, macOS and NixOS per
-release).
+remains field-tested (Windows continuously; macOS and NixOS last
+field-tested with plugin v1.3 — later versions are covered there by
+the test suites only).
 
 ## Setup (one-time)
 
 The plugin is developed and tested on **Windows**; **macOS works**
-(field-tested on KiCad 10 after a round of mac-specific fixes), and
-**Linux works** (field-tested on NixOS — the hardest Linux to run pip
-wheels on; mainstream FHS distributions should be no harder, reports
-welcome). KiCad builds the plugin a private Python venv from
+(field-tested on KiCad 10 after a round of mac-specific fixes, last
+with plugin v1.3), and **Linux works** (field-tested on NixOS — the
+hardest Linux to run pip wheels on, last with plugin v1.3; mainstream
+FHS distributions should be no harder, reports welcome). KiCad builds the plugin a private Python venv from
 `requirements.txt` on every platform, from pre-built wheels only, no
 compiler needed. Steps 1–4 are the same everywhere; OS specifics are
 spelled out per step and in *Platform notes* below.
@@ -110,7 +111,8 @@ spelled out per step and in *Platform notes* below.
 - **Windows** is the development and test platform — everything in
   this README was exercised here. KiCad's bundled Python is 3.13, so
   the venv gets the current dependency stack.
-- **macOS** — **works** (field-tested on KiCad 10). Requires
+- **macOS** — **works** (field-tested on KiCad 10, last with plugin
+  v1.3). Requires
   macOS 12+ (KiCad's own minimum; Intel and Apple Silicon — the dmg
   is universal). KiCad's bundled Python is **3.9**, so pip resolves
   an older stack (numpy 2.0, scipy 1.13, matplotlib 3.9,
@@ -119,8 +121,9 @@ spelled out per step and in *Platform notes* below.
   Plot and dialog windows may open **behind** the KiCad window (they
   are raised best-effort) — check the Dock if nothing seems to appear
   after a solve.
-- **Linux** — **works** (field-tested on NixOS, KiCad 10; mainstream
-  distributions are audited but not yet field-tested). The venv uses
+- **Linux** — **works** (field-tested on NixOS, KiCad 10, last with
+  plugin v1.3; mainstream distributions are audited but not yet
+  field-tested). The venv uses
   the system Python (3.9+), so the stack matches your distribution.
   On **ARM64 (aarch64)** there are no pyamg wheels —
   `requirements.txt` skips pyamg there and the solver falls back to
@@ -236,7 +239,10 @@ the picked file. **Save config…** asks for the target file name each
 time (pre-filled with the loaded config), so writing back and saving
 a variant under a new `fill_res_config.<name>.json` are both one
 click — a name outside the auto-load set prints a reminder that it
-needs Load config….
+needs Load config…. The dialog opens even when nothing on the board
+yields a setup (nothing selected, no marker rectangles, no config):
+load-only, with both mode radios disabled and their reasons shown, so
+**Load config…** can bootstrap the run.
 
 **Precedence**: `config.py` constants < config file < dialog edits.
 The file pre-fills the dialog; what the dialog shows is what runs. A

docs/release-notes/v1.4.2.md

@@ -0,0 +1,11 @@
+Launching with nothing usable on the board no longer dead-ends: when
+neither mode can be derived (nothing selected, no marker rectangles,
+no config), the dialog now opens anyway - load-only - instead of
+failing with an error figure.
+
+- Both mode radios are unchecked and disabled with their reasons
+  shown; OK and Save config... are disabled too. Load config... (and
+  Cancel) stay live, so a saved config can bootstrap the run without
+  first selecting pads or drawing marker rectangles.
+- A loaded file re-derives everything exactly as if it had been
+  present at launch - mode, net, terminals, values.

fill_resistance/__init__.py

@@ -4,4 +4,4 @@ __version__ is the runtime source of truth (metadata.json and
 pyproject.toml are not deployed with the plugin); a test keeps the
 three in sync.
 """
-__version__ = "1.4.1"
+__version__ = "1.4.2"

fill_resistance/dialog.py

@@ -26,7 +26,11 @@ Two run modes share the dialog, chosen by a radio at the top:
 
 "Load config…" swaps the whole setup for another config file: ask()
 then returns a LoadRequest instead of a Selection and main re-derives
-everything from that file and reopens the dialog.
+everything from that file and reopens the dialog. The dialog even
+opens with NO runnable mode at all (nothing selected, no marker
+rectangles, no config) - load-only: both radios unchecked and
+disabled with their reasons, OK/Save disabled - so a saved config can
+bootstrap the run.
 
 Row identity is POSITIONAL: the tables never sort or reorder, so
 main.py zips Selection.pdn_rows with its own parallel terminal list.
@@ -205,16 +209,28 @@ class _Dialog(QDialog):
         self.mode_pdn = QRadioButton("PDN")
         self.mode_classic.setEnabled(self._classic_ok)
         self.mode_pdn.setEnabled(self._pdn_ok)
-        start_pdn = self._pdn_ok and (not self._classic_ok
-                                      or start_mode == "pdn")
-        (self.mode_pdn if start_pdn else self.mode_classic).setChecked(True)
-        reason = None
+        # with NEITHER mode derivable (nothing selected, no marker
+        # rectangles, no config terminals) the dialog still opens
+        # LOAD-ONLY: no radio checked, OK/Save disabled below - so
+        # "Load config…" can pull in a saved setup instead of the
+        # launch dying with an error figure
+        self._no_mode = not (self._classic_ok or self._pdn_ok)
+        if not self._no_mode:
+            start_pdn = self._pdn_ok and (not self._classic_ok
+                                          or start_mode == "pdn")
+            (self.mode_pdn if start_pdn
+             else self.mode_classic).setChecked(True)
+        reasons = []
         if not self._classic_ok and classic_reason:
-            reason = f"Classic unavailable: {classic_reason}"
+            reasons.append(f"Classic unavailable: {classic_reason}")
             self.mode_classic.setToolTip(classic_reason)
-        elif not self._pdn_ok and pdn_reason:
-            reason = f"PDN unavailable: {pdn_reason}"
+        if not self._pdn_ok and pdn_reason:
+            reasons.append(f"PDN unavailable: {pdn_reason}")
             self.mode_pdn.setToolTip(pdn_reason)
+        if self._no_mode and load_dir is not None:
+            reasons.append("Load config… below can still set up a run "
+                           "from a saved config file.")
+        reason = "\n".join(reasons) if reasons else None
 
         # --- shared form #1 --------------------------------------------
         form1 = QFormLayout()
@@ -387,14 +403,23 @@ class _Dialog(QDialog):
         buttons = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
         buttons.accepted.connect(self._try_accept)
         buttons.rejected.connect(self.reject)
+        self.ok_button = buttons.button(QDialogButtonBox.Ok)
+        self.load_button = None
+        self.save_button = None
         if load_dir is not None:
-            load_btn = buttons.addButton("Load config…",
-                                         QDialogButtonBox.ActionRole)
-            load_btn.clicked.connect(self._load_config)
+            self.load_button = buttons.addButton(
+                "Load config…", QDialogButtonBox.ActionRole)
+            self.load_button.clicked.connect(self._load_config)
         if save_callback is not None:
-            save_btn = buttons.addButton("Save config…",
-                                         QDialogButtonBox.ActionRole)
-            save_btn.clicked.connect(self._save_config)
+            self.save_button = buttons.addButton(
+                "Save config…", QDialogButtonBox.ActionRole)
+            self.save_button.clicked.connect(self._save_config)
+        if self._no_mode:
+            # nothing to run or to save until a load re-derives; Load
+            # config… and Cancel stay live
+            self.ok_button.setEnabled(False)
+            if self.save_button is not None:
+                self.save_button.setEnabled(False)
 
         content = QWidget()
         lay = QVBoxLayout(content)
@@ -405,11 +430,12 @@ class _Dialog(QDialog):
         mode_row.addWidget(self.mode_pdn)
         mode_row.addStretch(1)
         lay.addLayout(mode_row)
+        self.reason_label = None
         if reason is not None:
-            rl = QLabel(reason)
-            rl.setWordWrap(True)
-            rl.setStyleSheet("color: gray; font-size: 10px;")
-            lay.addWidget(rl)
+            self.reason_label = QLabel(reason)
+            self.reason_label.setWordWrap(True)
+            self.reason_label.setStyleSheet("color: gray; font-size: 10px;")
+            lay.addWidget(self.reason_label)
         lay.addLayout(form1)
         if self.classic_section is not None:
             lay.addWidget(self.classic_section)
@@ -997,7 +1023,9 @@ def ask(candidates: dict[str, list[str]], layer_order: list[str],
     config file); pdn: the PDN terminal setup (editable tables);
     pdn_candidates: net candidates for PDN mode (classic uses
     `candidates`); classic_reason / pdn_reason: why a mode is
-    unavailable (its radio is disabled with the reason shown);
+    unavailable (its radio is disabled with the reason shown; with
+    BOTH unavailable the dialog opens load-only - OK and Save disabled
+    until Load config… returns a LoadRequest);
     save_callback(selection, target_path) -> saved name string enables
     the "Save config…" button in both modes (the file name is asked
     per save, seeded with save_target); load_dir (the board directory)

fill_resistance/main.py

@@ -7,7 +7,10 @@ config's terminal set) -> gather fills -> dialog with a Classic/PDN
 mode selector (classic: the two-contact form; PDN: editable per-role
 terminal tables) -> extract vias -> solve -> figures + report. The
 dialog's "Load config…" button loops back to the derivation with the
-picked file, so a run can be set up from any saved config.
+picked file, so a run can be set up from any saved config - and the
+dialog opens even when NEITHER mode is derivable (nothing selected, no
+marker rectangles, no config): load-only, both radios disabled with
+their reasons, so a saved config can bootstrap the run.
 
 Every failure is reported twice: on stdout (lands in the KiCad status-bar
 warning list) and as a matplotlib error figure, so it cannot be missed.
@@ -101,8 +104,10 @@ def main() -> None:
                     configfile.apply_physics(cfg)
 
                 # BOTH terminal derivations always run; a failure only
-                # disables that mode's radio (with the reason shown) - the
-                # launch dies only when neither mode is possible
+                # disables that mode's radio (with the reason shown).
+                # Even with neither mode possible the dialog still
+                # opens - load-only - so "Load config…" works without
+                # first selecting pads or drawing marker rectangles
                 classic_reason = pdn_reason = None
                 es1: list = []
                 es2: list = []
@@ -210,9 +215,13 @@ def main() -> None:
                               f"workable supply+load copper; PDN "
                               f"candidates: {', '.join(pdn_nets)}")
                 if classic_reason is not None and pdn_reason is not None:
-                    raise SelectionError(
-                        f"{classic_reason}\n(PDN mode is also "
-                        f"unavailable: {pdn_reason})")
+                    # nothing runnable right now: the dialog opens with
+                    # both radios and OK/Save disabled, offering only
+                    # Load config… (and Cancel) - a loaded file then
+                    # re-derives everything through the loop below
+                    print(f"note: classic mode unavailable: "
+                          f"{classic_reason}")
+                    print(f"note: PDN mode unavailable: {pdn_reason}")
                 buildups = board_io.gather_mask_buildups(board)
             except ApiError as e:
                 raise UserFacingError(

metadata.json

@@ -17,7 +17,7 @@
     },
     "versions": [
         {
-            "version": "1.4.1",
+            "version": "1.4.2",
             "status": "stable",
             "kicad_version": "10.0",
             "runtime": "ipc"

pyproject.toml

@@ -3,7 +3,7 @@
 # the dependency list there in sync with [project.dependencies].
 [project]
 name = "fill-resistance"
-version = "1.4.1"
+version = "1.4.2"
 description = "DC resistance of copper zone fills and traces between two contacts (KiCad 10 plugin)"
 license = "GPL-3.0-or-later"
 requires-python = ">=3.11"

tests/test_dialog.py

@@ -590,6 +590,55 @@ def test_load_button_cancelled_picker_does_nothing(app, tmp_path,
     assert not dlg.error_label.isVisible()
 
 
+# --- no runnable mode: the load-only dialog ----------------------------------
+
+def _no_mode_dlg(app, load_dir=None, save_callback=None):
+    """Neither mode derivable (nothing selected, no marker rects, no
+    config): main opens the dialog anyway so a config can be loaded."""
+    return _Dialog({}, ORDER, "", "", "", "auto", "auto",
+                   buildup_layers=[], pdn=None, pdn_candidates={},
+                   classic_reason="nothing selected",
+                   pdn_reason="no rectangles found",
+                   save_callback=save_callback, load_dir=load_dir)
+
+
+def test_no_mode_opens_load_only(app, tmp_path):
+    dlg = _no_mode_dlg(app, load_dir=tmp_path,
+                       save_callback=lambda *_a: "x")
+    assert not dlg.mode_classic.isEnabled()
+    assert not dlg.mode_pdn.isEnabled()
+    # no mode is even checked - there is nothing to run
+    assert not dlg.mode_classic.isChecked()
+    assert not dlg.mode_pdn.isChecked()
+    assert not dlg.ok_button.isEnabled()
+    assert not dlg.save_button.isEnabled()
+    assert dlg.load_button.isEnabled()
+    # both reasons and the load hint are shown together
+    text = dlg.reason_label.text()
+    assert "nothing selected" in text
+    assert "no rectangles found" in text
+    assert "Load config…" in text
+
+
+def test_no_mode_load_config_still_works(app, tmp_path, monkeypatch):
+    path = tmp_path / "fill_res_config.saved.json"
+    path.write_text('{"version": 1}', encoding="utf-8")
+    monkeypatch.setattr(dialog_mod, "QFileDialog", _FakePicker)
+    _FakePicker.result = (str(path), "json")
+    dlg = _no_mode_dlg(app, load_dir=tmp_path)
+    dlg._load_config()
+    assert dlg._load_request == path
+    assert dlg.result() == QDialog.Accepted
+
+
+def test_available_modes_keep_ok_and_save_enabled(app, tmp_path):
+    dlg = _dlg(app, pdn=_setup(), save_callback=lambda *_a: "x",
+               load_dir=tmp_path)
+    assert dlg.ok_button.isEnabled()
+    assert dlg.save_button.isEnabled()
+    assert dlg.load_button.isEnabled()
+
+
 # --- save button -------------------------------------------------------------
 
 def _patch_save(monkeypatch, name):

uv.lock

@@ -216,7 +216,7 @@ wheels = [
 
 [[package]]
 name = "fill-resistance"
-version = "1.4.1"
+version = "1.4.2"
 source = { virtual = "." }
 dependencies = [
     { name = "kicad-python" },