Web-runtime guard for non-Pyodide-compatible toolboxes

src/lib/components/dialogs/ToolboxManagerDialog.svelte

@@ -2,6 +2,7 @@
 	import { onDestroy } from 'svelte';
 	import Icon from '$lib/components/icons/Icon.svelte';
 	import { tooltip } from '$lib/components/Tooltip.svelte';
+	import { getBackendType } from '$lib/pyodide/backend';
 	import DialogShell from './shared/DialogShell.svelte';
 	import {
 		TOOLBOX_CATALOG,
@@ -80,8 +81,13 @@
 	let activeOverrideRow = $state<string | null>(null);
 	const SHAPE_OPTIONS = ['pill', 'rect', 'mixed'] as const;
 
+	// True when running in the browser (Pyodide) backend: installs are then
+	// limited to pure-Python / Pyodide-compatible packages.
+	let isWebRuntime = $state(false);
+
 	$effect(() => {
 		if (!open) return;
+		isWebRuntime = getBackendType() === 'pyodide';
 		if (editing) {
 			startEdit(editing);
 		} else {
@@ -508,6 +514,17 @@
 							network requests, read clipboard data, or consume CPU and memory.
 						</p>
 						<p>Only continue if you trust the source.</p>
+						{#if isWebRuntime}
+							<div class="web-note">
+								<Icon name="info" size={14} />
+								<span>
+									You're using the PathView web app. Installs run through Pyodide in the browser,
+									so only pure-Python toolboxes (or packages Pyodide ships pre-built) work here.
+									For toolboxes with compiled dependencies, use the standalone
+									<code>pip install pathview</code> desktop app.
+								</span>
+							</div>
+						{/if}
 						<div class="source-recap">
 							{#if resolvedSource?.type === 'pypi'}
 								<code>pip install {resolvedSource.pkg}{resolvedSource.version ? `==${resolvedSource.version}` : ''}</code>
@@ -940,6 +957,30 @@
 		color: var(--text-muted);
 	}
 
+	/* Web-runtime (Pyodide) install limitation notice on the trust step */
+	.web-note {
+		display: flex;
+		gap: var(--space-sm);
+		padding: var(--space-sm) var(--space-md);
+		background: var(--accent-bg);
+		border: 1px solid color-mix(in srgb, var(--accent) 35%, transparent);
+		border-radius: var(--radius-sm);
+		font-size: var(--font-base);
+		line-height: 1.5;
+		color: var(--text-muted);
+	}
+
+	.web-note :global(svg) {
+		flex-shrink: 0;
+		margin-top: 2px;
+		color: var(--accent);
+	}
+
+	.web-note code {
+		font-family: var(--font-mono);
+		color: var(--text-muted);
+	}
+
 	.spinner-row {
 		display: flex;
 		align-items: center;

src/lib/toolbox/installer.ts

@@ -78,6 +78,40 @@ function pyStr(s: string): string {
 	return JSON.stringify(s);
 }
 
+/**
+ * Turn a raw micropip failure into a web-version-aware message.
+ *
+ * The web app runs Python through Pyodide, which can only install
+ * pure-Python wheels (or packages Pyodide ships pre-built). Toolboxes with
+ * compiled/native code fail here even though they install fine in the
+ * standalone (pip-backed) PathView. `_pv_install_micropip` tags those
+ * failures with `PV_INCOMPATIBLE`, so we give a useful hint instead of
+ * surfacing a raw traceback. Genuine failures pass through unchanged.
+ */
+function reframePyodideInstallError(spec: string, err: unknown): Error {
+	const raw = err instanceof Error ? err.message : String(err);
+	if (!raw.includes('PV_INCOMPATIBLE')) {
+		// Network error, bad spec, etc. — pass through, just strip our tag.
+		return new Error(raw.replace(/PV_INSTALL_ERROR:\s*/, ''));
+	}
+	const detail = raw.split('PV_INCOMPATIBLE:').pop()?.trim() || raw;
+	return new Error(
+		`"${spec}" can't be installed in the PathView web app.\n` +
+			`\n` +
+			`The web version runs Python in your browser via Pyodide, which can\n` +
+			`only install pure-Python packages (or packages Pyodide ships\n` +
+			`pre-built). This toolbox needs compiled or native code that isn't\n` +
+			`available in the browser.\n` +
+			`\n` +
+			`To use it, install the standalone PathView desktop app:\n` +
+			`    pip install pathview\n` +
+			`    pathview\n` +
+			`It runs a real Python environment and can install any pip package.\n` +
+			`\n` +
+			`micropip: ${detail}`
+	);
+}
+
 /**
  * Install a package. Skips when `importPath` is given and the module is
  * already importable (saves a round-trip + download).
@@ -94,8 +128,13 @@ export async function installPackage(spec: string, importPath?: string): Promise
 	}
 	const backend = getBackendType();
 	if (backend === 'pyodide') {
-		// runPythonAsync supports top-level await for micropip.install
-		await exec(`await _pv_install_micropip(${pyStr(spec)})`);
+		// runPythonAsync supports top-level await for micropip.install.
+		// Reframe Pyodide-incompatibility failures into an actionable hint.
+		try {
+			await exec(`await _pv_install_micropip(${pyStr(spec)})`);
+		} catch (e) {
+			throw reframePyodideInstallError(spec, e);
+		}
 	} else {
 		// Flask / remote: real CPython, use subprocess pip (sync)
 		await exec(`_pv_install_pip(${pyStr(spec)})`);

src/lib/toolbox/python.ts

@@ -34,9 +34,29 @@ def _pv_already_installed(import_path):
 
 
 async def _pv_install_micropip(spec):
-    """Pyodide-side install via micropip (top-level await)."""
+    """Pyodide-side install via micropip (top-level await).
+
+    micropip can only install pure-Python wheels (or packages Pyodide
+    ships pre-built), so toolboxes with compiled/native code fail here
+    even though they install fine in the standalone (pip-backed) build.
+    On failure we classify the error and prefix it with PV_INCOMPATIBLE
+    (browser-runtime limitation) or PV_INSTALL_ERROR (genuine failure)
+    so the JS side can show a useful hint instead of a raw traceback."""
     import micropip
-    await micropip.install(spec, keep_going=True)
+    try:
+        await micropip.install(spec, keep_going=True)
+    except Exception as e:
+        msg = str(e)
+        low = msg.lower()
+        incompatible = (
+            "pure python" in low
+            or "can't find" in low
+            or "cannot find" in low
+            or "no matching distribution" in low
+            or "no known package" in low
+        )
+        tag = "PV_INCOMPATIBLE" if incompatible else "PV_INSTALL_ERROR"
+        raise RuntimeError(tag + ": " + msg)
     return {"ok": True, "spec": spec, "via": "micropip"}