Let qdk-chemistry supply pyscf in the venv command

source/vscode/resources/qdk-learning/courses/chemistry-qpe/requirements.txt

@@ -2,4 +2,3 @@ qdk-chemistry[jupyter]>=2.1.0
 # Pinned to 6.x: ipykernel 7 can leave notebooks hanging on the first cell.
 # Remove once https://github.com/microsoft/qdk/issues/3662 is fixed.
 ipykernel>=6.0,<7
-pyscf>=2.9.0,<2.12.1

source/vscode/src/pythonEnvs.ts

@@ -12,94 +12,138 @@ import { CopilotToolError } from "./gh-copilot/types.js";
 
 const pythonEnvsNotInstalledMsg = `The Python Environments extension (${EXTENSION_ID}) is not installed or is disabled.`;
 
+/**
+ * A package offered in the venv picker. `label` is display text only; the
+ * requirement passed to pip is built from the fields below, so a version
+ * constraint never leaks into the UI.
+ */
+interface PackagePickItem extends vscode.QuickPickItem {
+  /** Distribution name, e.g. `qdk-chemistry`. */
+  packageName: string;
+  /** Extras to request, e.g. `["jupyter"]`. */
+  extras?: string[];
+  /** Version constraint, e.g. `>=6.0,<7`. */
+  versionSpecifier?: string;
+}
+
 // All packages offered in the command palette picker (in display order)
-const packagePickItems: vscode.QuickPickItem[] = [
+const packagePickItems: PackagePickItem[] = [
   {
     label: "qdk",
+    packageName: "qdk",
     description: "Quantum Development Kit (core)",
     detail: "Compile, simulate, and estimate resources for quantum programs",
     picked: true,
   },
   {
     label: "qdk[azure]",
+    packageName: "qdk",
+    extras: ["azure"],
     description: "QDK optional support for Azure Quantum",
     detail: "Submit jobs to Azure Quantum hardware and cloud simulators",
     picked: false,
   },
   {
     label: "qdk[cirq]",
+    packageName: "qdk",
+    extras: ["cirq"],
     description: "QDK optional support for Cirq",
     detail: "Interop with Cirq via qdk.cirq",
     picked: false,
   },
   {
     label: "qdk[jupyter]",
+    packageName: "qdk",
+    extras: ["jupyter"],
     description: "QDK optional support for Jupyter notebooks",
     detail:
       "Enable Q# code cells and interactive quantum widgets in Jupyter notebooks",
     picked: true,
   },
   {
     label: "qdk[qiskit]",
+    packageName: "qdk",
+    extras: ["qiskit"],
     description: "QDK optional support for Qiskit",
     detail: "Interop with Qiskit via qdk.qiskit",
     picked: false,
   },
   {
     label: "qdk-chemistry",
-    description: "Microsoft Quantum Development Kit for Chemistry",
-    detail: "End-to-end toolkit for quantum chemistry",
+    packageName: "qdk-chemistry",
+    description: "Microsoft Quantum Development Kit for Chemistry (core)",
+    detail: "Chemistry library only, without the notebook or PySCF plugins",
     picked: false,
   },
   {
-    label: "pyscf",
-    description: "Python-based Simulations of Chemistry Framework",
+    // The `jupyter` extra pulls in `plugins`, which is where qdk-chemistry
+    // bounds pyscf. Without it pyscf would be left unconstrained.
+    label: "qdk-chemistry[jupyter]",
+    packageName: "qdk-chemistry",
+    extras: ["jupyter"],
+    description: "QDK/Chemistry optional support for Jupyter notebooks",
     detail:
-      "Collection of electronic structure methods for molecules and periodic solids",
+      "Add the notebook and simulation plugins, including PySCF. Required by the chemistry course.",
     picked: false,
   },
   {
+    label: "ipykernel",
+    packageName: "ipykernel",
     // Pinned to 6.x: ipykernel 7 can leave notebooks hanging on the first cell.
     // Remove once https://github.com/microsoft/qdk/issues/3662 is fixed.
-    label: "ipykernel<7",
+    versionSpecifier: ">=6.0,<7",
     description: "Jupyter kernel",
     detail: "Enable Jupyter notebook functionality in VS Code",
     picked: true,
   },
   {
     label: "ipympl",
+    packageName: "ipympl",
     description: "Interactive Matplotlib widgets",
     detail: "Enable interactive plots in Jupyter notebooks",
     picked: true,
   },
 ];
 
-// pyscf doesn't support Windows
-function getAvailablePackagePickItems(): vscode.QuickPickItem[] {
-  return packagePickItems.filter(
-    (item) => item.label !== "pyscf" || process.platform !== "win32",
-  );
-}
+/**
+ * Build the pip requirements for the selected items, merging selections that
+ * name the same package so ticking `qdk` and `qdk[jupyter]` installs
+ * `qdk[jupyter]` rather than passing both. Selection order is preserved.
+ */
+function toRequirements(selected: readonly PackagePickItem[]): string[] {
+  const order: string[] = [];
+  const byName = new Map<
+    string,
+    { extras: string[]; versionSpecifiers: string[] }
+  >();
 
-// Merge selected qdk extras (e.g. qdk + qdk[azure] + qdk[jupyter]) into one specifier.
-function coalesceQdkExtras(packages: string[]): string[] {
-  const extras: string[] = [];
-  const rest: string[] = [];
-  let hasQdk = false;
-  for (const pkg of packages) {
-    if (pkg === "qdk") {
-      hasQdk = true;
-    } else if (pkg.startsWith("qdk[") && pkg.endsWith("]")) {
-      hasQdk = true;
-      extras.push(...pkg.slice(4, -1).split(","));
-    } else {
-      rest.push(pkg);
+  for (const item of selected) {
+    let merged = byName.get(item.packageName);
+    if (!merged) {
+      merged = { extras: [], versionSpecifiers: [] };
+      byName.set(item.packageName, merged);
+      order.push(item.packageName);
+    }
+    for (const extra of item.extras ?? []) {
+      if (!merged.extras.includes(extra)) {
+        merged.extras.push(extra);
+      }
+    }
+    // Constraints from every selected row are kept, so pinning two rows of the
+    // same package narrows the range instead of silently dropping one.
+    if (
+      item.versionSpecifier &&
+      !merged.versionSpecifiers.includes(item.versionSpecifier)
+    ) {
+      merged.versionSpecifiers.push(item.versionSpecifier);
     }
   }
-  if (hasQdk) {
-    rest.unshift(extras.length > 0 ? `qdk[${extras.join(",")}]` : "qdk");
-  }
-  return rest;
+
+  return order.map((name) => {
+    const { extras, versionSpecifiers } = byName.get(name)!;
+    const extrasPart = extras.length > 0 ? `[${extras.join(",")}]` : "";
+    return `${name}${extrasPart}${versionSpecifiers.join(",")}`;
+  });
 }
 
 async function getPythonEnvsApi(): Promise<PythonEnvironmentApi | undefined> {
@@ -212,13 +256,9 @@ export async function createQuantumVenv(): Promise<{ action: string }> {
   }
 
   // Don't interrupt the chat by showing a picker - just use the defaults
-  const selectedPackages = getAvailablePackagePickItems().filter(
-    (item) => item.picked,
-  );
+  const selectedPackages = packagePickItems.filter((item) => item.picked);
 
-  const packagesToInstall = coalesceQdkExtras(
-    selectedPackages.map((item) => item.label),
-  );
+  const packagesToInstall = toRequirements(selectedPackages);
 
   const existingEnv = await getEnvInFolder(api, root);
   if (existingEnv) {
@@ -296,7 +336,7 @@ export async function createQuantumVenvForCommand(): Promise<void> {
   }
 
   const selectedPackages = await vscode.window.showQuickPick(
-    getAvailablePackagePickItems().map((item) => ({ ...item })),
+    packagePickItems.map((item) => ({ ...item })),
     {
       canPickMany: true,
       placeHolder: "Select packages to install",
@@ -306,9 +346,7 @@ export async function createQuantumVenvForCommand(): Promise<void> {
     return;
   }
 
-  const packagesToInstall = coalesceQdkExtras(
-    selectedPackages.map((item) => item.label),
-  );
+  const packagesToInstall = toRequirements(selectedPackages);
 
   try {
     if (existingEnv) {