diff --git a/examples/hello-world/.gitignore b/examples/hello-world/.gitignore
index 3c0f0280..c764e5aa 100644
--- a/examples/hello-world/.gitignore
+++ b/examples/hello-world/.gitignore
@@ -1 +1,2 @@
+baselines
 sde-prep
diff --git a/examples/hello-world/package.json b/examples/hello-world/package.json
index 161fbb65..8e643f27 100644
--- a/examples/hello-world/package.json
+++ b/examples/hello-world/package.json
@@ -6,6 +6,7 @@
   "scripts": {
     "build": "sde bundle",
     "dev": "sde dev",
+    "save-baseline": "sde-check baseline --save",
     "serve": "sirv ./sde-prep/check-report"
   },
   "dependencies": {
diff --git a/examples/sample-check-app/src/index.ts b/examples/sample-check-app/src/index.ts
index ccb7a97c..3db945dc 100644
--- a/examples/sample-check-app/src/index.ts
+++ b/examples/sample-check-app/src/index.ts
@@ -25,6 +25,8 @@ if (suiteSummaryJson) {
 const checkOptions = getConfigOptions(baselineBundle() as Bundle, currentBundle() as Bundle)
 
 // Initialize the root Svelte component
-const appShell = initAppShell(checkOptions, suiteSummary)
+const appShell = initAppShell(checkOptions, {
+  suiteSummary
+})
 
 export default appShell
diff --git a/examples/template-default/.gitignore b/examples/template-default/.gitignore
index f5c47214..5a2a8e83 100644
--- a/examples/template-default/.gitignore
+++ b/examples/template-default/.gitignore
@@ -1,3 +1,4 @@
+baselines
 sde-prep
 *.vdf
 *.vdfx
diff --git a/examples/template-default/package.json b/examples/template-default/package.json
index f5723216..214dc073 100644
--- a/examples/template-default/package.json
+++ b/examples/template-default/package.json
@@ -6,7 +6,7 @@
   "scripts": {
     "build": "sde bundle",
     "dev": "sde dev",
-    "start": "sde dev"
+    "save-baseline": "sde-check baseline --save"
   },
   "workspaces": [
     "packages/core",
diff --git a/examples/template-minimal/.gitignore b/examples/template-minimal/.gitignore
index 3c0f0280..c764e5aa 100644
--- a/examples/template-minimal/.gitignore
+++ b/examples/template-minimal/.gitignore
@@ -1 +1,2 @@
+baselines
 sde-prep
diff --git a/examples/template-minimal/package.json b/examples/template-minimal/package.json
index 7f0ec704..e0cde93f 100644
--- a/examples/template-minimal/package.json
+++ b/examples/template-minimal/package.json
@@ -5,7 +5,8 @@
   "type": "module",
   "scripts": {
     "build": "sde bundle",
-    "dev": "sde dev"
+    "dev": "sde dev",
+    "save-baseline": "sde-check baseline --save"
   },
   "dependencies": {
     "@sdeverywhere/build": "^0.2.0",
diff --git a/packages/check-ui-shell/src/_shared/stores.ts b/packages/check-ui-shell/src/_shared/stores.ts
new file mode 100644
index 00000000..0c2deb89
--- /dev/null
+++ b/packages/check-ui-shell/src/_shared/stores.ts
@@ -0,0 +1,36 @@
+// Copyright (c) 2022 Climate Interactive / New Venture Fund
+
+import type { Writable } from 'svelte/store'
+import { writable } from 'svelte/store'
+
+/**
+ * Return a Svelte writable store that is backed by local storage.
+ */
+export function localStorageWritableBoolean(key: string, defaultValue: boolean): Writable<boolean> {
+  const initialStringValue = localStorage.getItem(key)
+  let initialValue: boolean
+  if (initialStringValue !== undefined) {
+    initialValue = initialStringValue === '1'
+  } else {
+    initialValue = defaultValue
+  }
+
+  let currentValue = initialValue
+  const { subscribe, set } = writable(initialValue)
+
+  const _set = (newValue: boolean) => {
+    currentValue = newValue
+    localStorage.setItem(key, newValue ? '1' : '0')
+    set(newValue)
+  }
+
+  const _update = (updater: (value: boolean) => boolean) => {
+    _set(updater(currentValue))
+  }
+
+  return {
+    subscribe,
+    set: _set,
+    update: _update
+  }
+}
diff --git a/packages/check-ui-shell/src/app-init.ts b/packages/check-ui-shell/src/app-init.ts
index 812c67ee..e67d1c9e 100644
--- a/packages/check-ui-shell/src/app-init.ts
+++ b/packages/check-ui-shell/src/app-init.ts
@@ -7,12 +7,15 @@ import { initAppModel } from './model/app-model'
 import { default as AppShell } from './app-shell.svelte'
 import { AppViewModel } from './app-vm'
 
-export function initAppShell(
-  configOptions: ConfigOptions,
-  suiteSummary?: SuiteSummary,
-  containerId = 'app-shell-container'
-): AppShell {
+export interface AppShellOptions {
+  suiteSummary?: SuiteSummary
+  containerId?: string
+  bundleNames?: string[]
+}
+
+export function initAppShell(configOptions: ConfigOptions, appShellOptions?: AppShellOptions): AppShell {
   // Initialize the root Svelte component
+  const containerId = appShellOptions?.containerId || 'app-shell-container'
   const appShell = new AppShell({
     target: document.getElementById(containerId),
     props: {
@@ -23,8 +26,17 @@ export function initAppShell(
   // Initialize the app model asynchronously
   initAppModel(configOptions)
     .then(appModel => {
-      // Create the app view model and update the AppShell component
-      const appViewModel = new AppViewModel(appModel, suiteSummary)
+      // Create the app view model
+      const appViewModel = new AppViewModel(appModel, appShellOptions?.suiteSummary)
+
+      if (appShellOptions?.bundleNames) {
+        // Set the list of available bundle names
+        // TODO: Pass these to AppViewModel constructor instead of setting them here
+        appViewModel.headerViewModel.bundleNamesL.set(appShellOptions.bundleNames)
+        appViewModel.headerViewModel.bundleNamesR.set(appShellOptions.bundleNames)
+      }
+
+      // Update the AppShell component
       appShell.$set({
         appViewModel
       })
diff --git a/packages/check-ui-shell/src/components/check/summary/check-summary-row-vm.ts b/packages/check-ui-shell/src/components/check/summary/check-summary-row-vm.ts
index 0da21102..958aec61 100644
--- a/packages/check-ui-shell/src/components/check/summary/check-summary-row-vm.ts
+++ b/packages/check-ui-shell/src/components/check/summary/check-summary-row-vm.ts
@@ -31,7 +31,8 @@ export function row(
   rowClass: string,
   status: CheckStatus,
   content: string,
-  graphBoxViewModel?: CheckSummaryGraphBoxViewModel
+  graphBoxViewModel?: CheckSummaryGraphBoxViewModel,
+  graphVisible = false
 ): CheckSummaryRowViewModel {
   const whitespace = '&ensp;'.repeat(2 + indent * 4)
   const statusChar = charForStatus(status)
@@ -42,6 +43,6 @@ export function row(
     status,
     span,
     graphBoxViewModel,
-    graphVisible: writable(false)
+    graphVisible: writable(graphVisible)
   }
 }
diff --git a/packages/check-ui-shell/src/components/check/summary/check-summary-test-vm.ts b/packages/check-ui-shell/src/components/check/summary/check-summary-test-vm.ts
index e2c0f444..a871357c 100644
--- a/packages/check-ui-shell/src/components/check/summary/check-summary-test-vm.ts
+++ b/packages/check-ui-shell/src/components/check/summary/check-summary-test-vm.ts
@@ -24,6 +24,8 @@ export function createCheckSummaryTestViewModel(
   dataCoordinator: CheckDataCoordinator,
   test: CheckTestReport
 ): CheckSummaryTestViewModel {
+  let expandedFirstGraph = false
+
   const rows: CheckSummaryRowViewModel[] = []
   const testRow = row(0, 'test', test.status, test.name)
   for (const scenario of test.scenarios) {
@@ -32,6 +34,7 @@ export function createCheckSummaryTestViewModel(
       rows.push(row(2, 'dataset', dataset.status, datasetMessage(dataset, bold)))
       for (const predicate of dataset.predicates) {
         let graphBoxViewModel: CheckSummaryGraphBoxViewModel
+        let graphVisible = false
         if (scenario.checkScenario.scenario && dataset.checkDataset.datasetKey) {
           graphBoxViewModel = new CheckSummaryGraphBoxViewModel(
             dataCoordinator,
@@ -39,8 +42,22 @@ export function createCheckSummaryTestViewModel(
             dataset.checkDataset.datasetKey,
             predicate
           )
+          if (!expandedFirstGraph && predicate.result.status === 'failed') {
+            // Expand the graph for the first failing check
+            expandedFirstGraph = true
+            graphVisible = true
+          }
         }
-        rows.push(row(3, 'predicate', predicate.result.status, predicateMessage(predicate, bold), graphBoxViewModel))
+        rows.push(
+          row(
+            3,
+            'predicate',
+            predicate.result.status,
+            predicateMessage(predicate, bold),
+            graphBoxViewModel,
+            graphVisible
+          )
+        )
       }
     }
   }
diff --git a/packages/check-ui-shell/src/components/header/header-vm.ts b/packages/check-ui-shell/src/components/header/header-vm.ts
index f586f234..e841893f 100644
--- a/packages/check-ui-shell/src/components/header/header-vm.ts
+++ b/packages/check-ui-shell/src/components/header/header-vm.ts
@@ -3,10 +3,13 @@
 import type { Writable } from 'svelte/store'
 import { writable } from 'svelte/store'
 import type { CompareConfig } from '@sdeverywhere/check-core'
+import { localStorageWritableBoolean } from '../../_shared/stores'
 
 export interface HeaderViewModel {
   nameL?: string
   nameR?: string
+  bundleNamesL: Writable<string[]>
+  bundleNamesR: Writable<string[]>
   thresholds?: string[]
   simplifyScenarios?: Writable<boolean>
 }
@@ -15,7 +18,12 @@ export function createHeaderViewModel(
   compareConfig: CompareConfig | undefined,
   includeSimplifyScenarios: boolean
 ): HeaderViewModel {
-  const simplifyScenarios: Writable<boolean> = includeSimplifyScenarios ? writable(true) : undefined
+  let simplifyScenarios: Writable<boolean>
+  if (includeSimplifyScenarios) {
+    simplifyScenarios = localStorageWritableBoolean('sde-check-simplify-scenarios', true)
+  } else {
+    simplifyScenarios = undefined
+  }
 
   // Only include the comparison-related header elements if the compare
   // config is defined
@@ -31,11 +39,15 @@ export function createHeaderViewModel(
     return {
       nameL: compareConfig.bundleL.name,
       nameR: compareConfig.bundleR.name,
+      bundleNamesL: writable([compareConfig.bundleL.name]),
+      bundleNamesR: writable([compareConfig.bundleR.name]),
       thresholds: thresholdStrings,
       simplifyScenarios
     }
   } else {
     return {
+      bundleNamesL: writable([]),
+      bundleNamesR: writable([]),
       simplifyScenarios
     }
   }
diff --git a/packages/check-ui-shell/src/components/header/header.pug b/packages/check-ui-shell/src/components/header/header.pug
new file mode 100644
index 00000000..474388de
--- /dev/null
+++ b/packages/check-ui-shell/src/components/header/header.pug
@@ -0,0 +1,13 @@
+//- Copyright (c) 2021-2022 Climate Interactive / New Venture Fund
+
+//- Note: These mixins are kept in an external pug file to work around a
+//- Svelte issue related to `each` and TypeScript, see:
+//-   https://github.com/sveltejs/svelte-preprocess/issues/207
+
+mixin optionsL
+  +each(`$bundleNamesL as name`)
+    option(selected!='{name === viewModel.nameL}') { name }
+
+mixin optionsR
+  +each(`$bundleNamesR as name`)
+    option(selected!='{name === viewModel.nameR}') { name }
diff --git a/packages/check-ui-shell/src/components/header/header.svelte b/packages/check-ui-shell/src/components/header/header.svelte
index 78830fa8..09a99e75 100644
--- a/packages/check-ui-shell/src/components/header/header.svelte
+++ b/packages/check-ui-shell/src/components/header/header.svelte
@@ -11,6 +11,8 @@ import type { HeaderViewModel } from './header-vm'
 export let viewModel: HeaderViewModel
 const simplifyScenarios = viewModel.simplifyScenarios
 const thresholds = viewModel.thresholds
+const bundleNamesL = viewModel.bundleNamesL
+const bundleNamesR = viewModel.bundleNamesR
 
 const dispatch = createEventDispatcher()
 
@@ -18,6 +20,24 @@ function onHome() {
   dispatch('command', { cmd: 'show-summary' })
 }
 
+function onSelectBundle(kind: string, name: string): void {
+  const changeEvent = new CustomEvent('sde-check-bundle', {
+    detail: {
+      kind,
+      name
+    }
+  })
+  document.dispatchEvent(changeEvent)
+}
+
+function onSelectBundleL(e: Event) {
+  onSelectBundle('left', (e.target as HTMLSelectElement).value)
+}
+
+function onSelectBundleR(e: Event) {
+  onSelectBundle('right', (e.target as HTMLSelectElement).value)
+}
+
 </script>
 
 
@@ -26,6 +46,8 @@ function onHome() {
 <!-- TEMPLATE -->
 <template lang='pug'>
 
+include header.pug
+
 .header-container
   .header-content
     .header-group
@@ -35,12 +57,20 @@ function onHome() {
       .header-group
         input.checkbox(type='checkbox' name='simplify-toggle' bind:checked!='{$simplifyScenarios}')
         label(for='simplify-toggle') Simplify Scenarios
-    +if('viewModel.nameL')
+    +if('viewModel.nameL || $bundleNamesL.length > 1')
       .spacer-fixed
       .header-group
         .label Comparing:
-        .label.dataset-color-0 {viewModel.nameL}
-        .label.dataset-color-1 {viewModel.nameR}
+        +if('$bundleNamesL.length > 1')
+          select.selector.dataset-color-0(on:change!='{onSelectBundleL}')
+            +optionsL
+          +else
+            .label.dataset-color-0 {viewModel.nameL}
+        +if('$bundleNamesR.length > 1')
+          select.selector.dataset-color-1(on:change!='{onSelectBundleR}')
+            +optionsR
+          +else
+            .label.dataset-color-1 {viewModel.nameR}
       .spacer-fixed
       .header-group
         .label Thresholds:
@@ -91,6 +121,24 @@ function onHome() {
 .label:not(:last-child)
   margin-right: 1rem
 
+select
+  margin-right: 1rem
+  font-family: Roboto, sans-serif
+  font-size: 1em
+  // XXX: Remove browser-provided background, but preserve arrow; based on:
+  //   https://stackoverflow.com/a/57510283
+  -webkit-appearance: none
+  -moz-appearance: none
+  appearance: none
+  padding: .2rem 1.6rem .2rem .4rem
+  background: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='100' height='100' fill='%23555'><polygon points='0,0 100,0 50,60'/></svg>") no-repeat
+  background-size: .8rem
+  background-position: calc(100% - .4rem) 70%
+  background-repeat: no-repeat
+  background-color: #353535
+  border: none
+  border-radius: .4rem
+
 .line
   min-height: 1px
   margin-bottom: 1rem
diff --git a/packages/check-ui-shell/src/components/stats/stats-table-vm.ts b/packages/check-ui-shell/src/components/stats/stats-table-vm.ts
index a15a327d..7f275e40 100644
--- a/packages/check-ui-shell/src/components/stats/stats-table-vm.ts
+++ b/packages/check-ui-shell/src/components/stats/stats-table-vm.ts
@@ -24,6 +24,14 @@ export function createStatsTableViewModel(
     return n === 0 ? '' : `${signed(n, 1)}%`
   }
 
+  function pctChange(s0: number, s1: number): number {
+    if (s0 !== 0) {
+      return ((s1 - s0) / s0) * 100
+    } else {
+      return 0
+    }
+  }
+
   const modelSpecL = compareConfig.bundleL.model.modelSpec
   const modelSpecR = compareConfig.bundleR.model.modelSpec
 
@@ -38,17 +46,17 @@ export function createStatsTableViewModel(
   const modelSizeL = modelSpecL.modelSizeInBytes
   const modelSizeR = modelSpecR.modelSizeInBytes
   const modelSizeChange = modelSizeR - modelSizeL
-  const modelSizePctChange = ((modelSizeR - modelSizeL) / modelSizeL) * 100
+  const modelSizePctChange = pctChange(modelSizeL, modelSizeR)
 
   const dataSizeL = modelSpecL.dataSizeInBytes
   const dataSizeR = modelSpecR.dataSizeInBytes
   const dataSizeChange = dataSizeR - dataSizeL
-  const dataSizePctChange = ((dataSizeR - dataSizeL) / dataSizeL) * 100
+  const dataSizePctChange = pctChange(dataSizeL, dataSizeR)
 
   const avgTimeL = perfReportL.avgTime || 0
   const avgTimeR = perfReportR.avgTime || 0
   const avgTimeChange = avgTimeR - avgTimeL
-  const avgTimePctChange = avgTimeL > 0 ? ((avgTimeR - avgTimeL) / avgTimeL) * 100 : 0
+  const avgTimePctChange = pctChange(avgTimeL, avgTimeR)
 
   const minTimeL = perfReportL.minTime
   const minTimeR = perfReportR.minTime
diff --git a/packages/check-ui-shell/src/global.css b/packages/check-ui-shell/src/global.css
index d46923fd..7111806a 100644
--- a/packages/check-ui-shell/src/global.css
+++ b/packages/check-ui-shell/src/global.css
@@ -56,8 +56,8 @@ sub {
  */
 
 :root {
-  --dataset-0: deepskyblue;
-  --dataset-1: crimson;
+  --dataset-0: crimson;
+  --dataset-1: deepskyblue;
   --bucket-0: green;
   --bucket-1: orange;
   --bucket-2: orangered;
diff --git a/packages/check-ui-shell/types/index.d.ts b/packages/check-ui-shell/types/index.d.ts
index 1bc4d4d4..61441e6b 100644
--- a/packages/check-ui-shell/types/index.d.ts
+++ b/packages/check-ui-shell/types/index.d.ts
@@ -2,8 +2,10 @@
 
 import type { ConfigOptions, SuiteSummary } from '@sdeverywhere/check-core'
 
-export function initAppShell(
-  configOptions: ConfigOptions,
-  suiteSummary?: SuiteSummary,
-  containerId = 'app-shell-container'
-): unknown
+export interface AppShellOptions {
+  suiteSummary?: SuiteSummary
+  containerId?: string
+  bundleNames?: string[]
+}
+
+export function initAppShell(configOptions: ConfigOptions, appShellOptions?: AppShellOptions): unknown
diff --git a/packages/plugin-check/bin/sde-check.js b/packages/plugin-check/bin/sde-check.js
new file mode 100755
index 00000000..bd8f7ed1
--- /dev/null
+++ b/packages/plugin-check/bin/sde-check.js
@@ -0,0 +1,60 @@
+#!/usr/bin/env node
+
+/*
+ * This is the entrypoint for the `sde-check` CLI, which provides commands
+ * that work in conjunction with `@sdeverywhere/plugin-check`.
+ */
+
+import { copyFileSync, existsSync, mkdirSync } from 'fs'
+import { join as joinPath } from 'path'
+
+function printUsage() {
+  console.log()
+  console.log('Usage:')
+  console.log('  sim-check baseline --save\t\tcopy the latest bundle to the `baselines` directory')
+  // console.log('  sim-check baseline --clear-all\tremove all bundles from the `baselines` directory')
+  console.log()
+}
+
+function timestamp() {
+  const padL = (nr, len = 2, chr = `0`) => `${nr}`.padStart(len, chr)
+
+  const d = new Date()
+  const year = d.getFullYear()
+  const month = padL(d.getMonth() + 1)
+  const day = padL(d.getDate())
+  const hours = padL(d.getHours())
+  const minutes = padL(d.getMinutes())
+  const seconds = padL(d.getSeconds())
+
+  return `${year}-${month}-${day}--${hours}-${minutes}-${seconds}`
+}
+
+const args = process.argv.slice(2)
+if (args.length !== 2 || args[0] !== 'baseline') {
+  printUsage()
+  process.exit(1)
+}
+
+if (args[1] !== '--save') {
+  printUsage()
+  process.exit(1)
+}
+
+// TODO: For now we make a number of assumptions (e.g., that the bundle will be copied to
+// the `baselines` directory under the current working directory, that the bundle filename
+// will contain the current timestamp); should make these configurable
+const prepDir = joinPath(process.cwd(), 'sde-prep')
+const srcBundleFile = joinPath(prepDir, 'check-bundle.js')
+if (!existsSync(srcBundleFile)) {
+  console.error(`ERROR: No 'check-bundle.js' file found in 'sde-prep' directory`)
+  process.exit(1)
+}
+
+const baselinesDir = joinPath(process.cwd(), 'baselines')
+if (!existsSync(baselinesDir)) {
+  mkdirSync(baselinesDir, { recursive: true })
+}
+
+const dstBundleFile = joinPath(baselinesDir, `${timestamp()}.js`)
+copyFileSync(srcBundleFile, dstBundleFile)
diff --git a/packages/plugin-check/package.json b/packages/plugin-check/package.json
index 47f6fa71..41163c0b 100644
--- a/packages/plugin-check/package.json
+++ b/packages/plugin-check/package.json
@@ -2,6 +2,7 @@
   "name": "@sdeverywhere/plugin-check",
   "version": "0.1.5",
   "files": [
+    "bin/**",
     "dist/**",
     "template-bundle/**",
     "template-report/**",
@@ -18,6 +19,9 @@
       "require": "./dist/index.cjs"
     }
   },
+  "bin": {
+    "sde-check": "bin/sde-check.js"
+  },
   "scripts": {
     "clean": "rm -rf dist",
     "lint": "eslint src --ext .ts --max-warnings 0",
@@ -33,11 +37,13 @@
   },
   "dependencies": {
     "@rollup/plugin-node-resolve": "^13.3.0",
+    "@rollup/plugin-replace": "^4.0.0",
     "@sdeverywhere/check-core": "^0.1.0",
     "@sdeverywhere/check-ui-shell": "^0.1.1",
     "@sdeverywhere/runtime": "^0.1.0",
     "@sdeverywhere/runtime-async": "^0.1.0",
     "assert-never": "^1.2.1",
+    "chokidar": "^3.5.3",
     "picocolors": "^1.0.0",
     "rollup": "^2.76.0",
     "vite": "^3.1.3"
diff --git a/packages/plugin-check/src/plugin.ts b/packages/plugin-check/src/plugin.ts
index f63cd77e..155b3cf1 100644
--- a/packages/plugin-check/src/plugin.ts
+++ b/packages/plugin-check/src/plugin.ts
@@ -6,6 +6,8 @@ import { fileURLToPath } from 'url'
 import type { InlineConfig, ViteDevServer } from 'vite'
 import { build, createServer } from 'vite'
 
+import chokidar from 'chokidar'
+
 import type { BuildContext, ModelSpec, Plugin, ResolvedConfig } from '@sdeverywhere/build'
 
 import type { Bundle, SuiteSummary } from '@sdeverywhere/check-core'
@@ -35,7 +37,7 @@ class CheckPlugin implements Plugin {
   async watch(config: ResolvedConfig): Promise<void> {
     if (this.options?.testConfigPath === undefined) {
       // Test config was not provided, so generate a default config in watch mode.
-      // The test template uses import.meta.importGlob so that checks are re-run
+      // The test template uses import.meta.glob so that checks are re-run
       // automatically when the *.check.yaml files are changed.
       await this.genTestConfig(config, 'watch')
     }
@@ -47,6 +49,29 @@ class CheckPlugin implements Plugin {
     const viteConfig = this.createViteConfigForReport(config, testOptions, undefined)
     const server: ViteDevServer = await createServer(viteConfig)
     await server.listen()
+
+    // XXX: Currently Vite doesn't reload the page if a file is added/removed
+    // in the baselines directory (Vite's import.meta.glob handling doesn't
+    // seem to do this automatically), so as a workaround, watch the baselines
+    // directory and restart the server if files are added/removed
+    // TODO: The same problem also applies to the glob for `.check.yaml` files
+    // in the test config, so we should also reload if files match/unmatch
+    // the `.check.yaml` glob
+    // TODO: Use the baselines directory from the config
+    const baselinesDir = 'baselines'
+    const watcher = chokidar.watch(baselinesDir, {
+      // Watch paths are resolved relative to the project root directory
+      cwd: config.rootDir,
+      // Don't send initial "file added" events
+      ignoreInitial: true,
+      // XXX: Include a delay, otherwise on macOS we sometimes get multiple
+      // change events when a file is saved just once
+      awaitWriteFinish: {
+        stabilityThreshold: 200
+      }
+    })
+    watcher.on('add', () => server.restart())
+    watcher.on('unlink', () => server.restart())
   }
 
   // TODO: Note that this plugin runs as a `postBuild` step because it currently
@@ -186,6 +211,7 @@ class CheckPlugin implements Plugin {
   ): InlineConfig {
     return createViteConfigForReport(
       this.options,
+      config.rootDir,
       config.prepDir,
       testOptions.currentBundleName,
       testOptions.currentBundlePath,
diff --git a/packages/plugin-check/src/vite-config-for-bundle.ts b/packages/plugin-check/src/vite-config-for-bundle.ts
index 01e5f189..9c166623 100644
--- a/packages/plugin-check/src/vite-config-for-bundle.ts
+++ b/packages/plugin-check/src/vite-config-for-bundle.ts
@@ -1,12 +1,14 @@
 // Copyright (c) 2022 Climate Interactive / New Venture Fund
 
-import type { ModelSpec } from '@sdeverywhere/build'
+import { existsSync, statSync } from 'fs'
 import { dirname, join as joinPath, relative, resolve as resolvePath } from 'path'
 import { fileURLToPath } from 'url'
 
 import type { InlineConfig, Plugin as VitePlugin } from 'vite'
 import { nodeResolve } from '@rollup/plugin-node-resolve'
 
+import type { ModelSpec } from '@sdeverywhere/build'
+
 import { sdeNameForVensimVarName } from './var-names'
 
 const __filename = fileURLToPath(import.meta.url)
@@ -22,7 +24,7 @@ const __dirname = dirname(__filename)
  * TODO: This could be simplified by using `vite-plugin-virtual` but that
  * doesn't seem to be working correctly in an ESM setting
  */
-function injectModelSpec(modelSpec: ModelSpec): VitePlugin {
+function injectModelSpec(prepDir: string, modelSpec: ModelSpec): VitePlugin {
   // Include the SDE variable ID with each spec
   const inputSpecs = modelSpec.inputs.map(i => {
     return {
@@ -37,11 +39,33 @@ function injectModelSpec(modelSpec: ModelSpec): VitePlugin {
     }
   })
 
+  function stagedFileSize(filename: string): number {
+    const path = joinPath(prepDir, 'staged', 'model', filename)
+    if (existsSync(path)) {
+      return statSync(path).size
+    } else {
+      return 0
+    }
+  }
+
+  // The size (in bytes) of the `wasm-model.js` file
+  // TODO: Ideally we would measure the size of the raw WASM binary, but currently
+  // we inline it as a base64 blob inside the JS file, so we take the size of the
+  // whole JS file as the second best option
+  const modelSizeInBytes = stagedFileSize('wasm-model.js')
+
+  // The size (in bytes) of the `static-data.ts` file
+  // TODO: Ideally we would measure the size of the minified JS file here, or
+  // at least ignore things like whitespace
+  const dataSizeInBytes = stagedFileSize('static-data.ts')
+
   const moduleSrc = `
 export const startTime = ${modelSpec.startTime};
 export const endTime = ${modelSpec.endTime};
 export const inputSpecs = ${JSON.stringify(inputSpecs)};
 export const outputSpecs = ${JSON.stringify(outputSpecs)};
+export const modelSizeInBytes = ${modelSizeInBytes};
+export const dataSizeInBytes = ${dataSizeInBytes};
 `
 
   const virtualModuleId = 'virtual:model-spec'
@@ -122,7 +146,7 @@ export async function createViteConfigForBundle(prepDir: string, modelSpec: Mode
 
     plugins: [
       // Use a virtual module plugin to inject the model spec values
-      injectModelSpec(modelSpec)
+      injectModelSpec(prepDir, modelSpec)
     ],
 
     build: {
diff --git a/packages/plugin-check/src/vite-config-for-report.ts b/packages/plugin-check/src/vite-config-for-report.ts
index d491a5c8..b30ff548 100644
--- a/packages/plugin-check/src/vite-config-for-report.ts
+++ b/packages/plugin-check/src/vite-config-for-report.ts
@@ -3,7 +3,8 @@
 import { dirname, relative, join as joinPath, resolve as resolvePath } from 'path'
 import { fileURLToPath } from 'url'
 
-import type { Alias, InlineConfig } from 'vite'
+import type { Alias, InlineConfig, PluginOption } from 'vite'
+import replace from '@rollup/plugin-replace'
 
 import type { SuiteSummary } from '@sdeverywhere/check-core'
 
@@ -14,6 +15,7 @@ const __dirname = dirname(__filename)
 
 export function createViteConfigForReport(
   options: CheckPluginOptions | undefined,
+  projDir: string,
   prepDir: string,
   currentBundleName: string,
   currentBundlePath: string,
@@ -23,6 +25,17 @@ export function createViteConfigForReport(
   // Use `template-report` as the root directory for the report project
   const root = resolvePath(__dirname, '..', 'template-report')
 
+  // Include `baselines/*.js` files under the configured project root directory.  This
+  // glob path apparently must be a relative path (relative to the `template-report/src`
+  // directory where the glob is used).
+  const templateSrcDir = resolvePath(root, 'src')
+  const relProjDir = relative(templateSrcDir, projDir)
+  // XXX: The glob pattern must use forward slashes only, so on Windows we need to
+  // convert backslashes to slashes
+  const relProjDirPath = relProjDir.replaceAll('\\', '/')
+  // TODO: Use baselinesDir from options
+  const baselinesPath = `${relProjDirPath}/baselines/*.js`
+
   // Calculate output directory relative to the template root
   let reportPath: string
   if (options?.reportPath) {
@@ -155,6 +168,20 @@ export function createViteConfigForReport(
       __CURRENT_NAME__: JSON.stringify(currentBundleName)
     },
 
+    plugins: [
+      // Inject special values into the generated JS
+      // TODO: We currently have to use `@rollup/plugin-replace` instead of Vite's
+      // built-in `define` feature because the latter does not seem to run before
+      // the glob handler (which requires the glob to be injected as a literal)
+      replace({
+        preventAssignment: true,
+        values: {
+          // Inject the path for baseline bundles
+          __BASELINE_BUNDLES_PATH__: JSON.stringify(baselinesPath)
+        }
+      }) as PluginOption
+    ],
+
     build: {
       // Write output files to the configured directory (instead of the default `dist`);
       // note that this must be relative to the project `root`
diff --git a/packages/plugin-check/template-bundle/src/bundle.ts b/packages/plugin-check/template-bundle/src/bundle.ts
index 880046bc..23f0ba11 100644
--- a/packages/plugin-check/template-bundle/src/bundle.ts
+++ b/packages/plugin-check/template-bundle/src/bundle.ts
@@ -21,7 +21,7 @@ import type { Input } from './inputs'
 import { getInputVars, setInputsForScenario } from './inputs'
 import { getOutputVars } from './outputs'
 
-import { startTime, endTime, inputSpecs, outputSpecs } from 'virtual:model-spec'
+import { startTime, endTime, inputSpecs, outputSpecs, modelSizeInBytes, dataSizeInBytes } from 'virtual:model-spec'
 
 import modelWorkerJs from '@_model_worker_/worker.js?raw'
 
@@ -31,14 +31,6 @@ import modelWorkerJs from '@_model_worker_/worker.js?raw'
 // have different version numbers.
 const VERSION = 1
 
-// The size (in bytes) of the model file(s), injected at build time.
-const __MODEL_SIZE_IN_BYTES__ = 1
-const modelSizeInBytes = __MODEL_SIZE_IN_BYTES__
-
-// The size (in bytes) of the data file(s), injected at build time.
-const __DATA_SIZE_IN_BYTES__ = 1
-const dataSizeInBytes = __DATA_SIZE_IN_BYTES__
-
 export class BundleModel implements CheckBundleModel {
   private readonly inputs: InputValue[]
   private outputs: Outputs
diff --git a/packages/plugin-check/template-bundle/src/empty-model-spec.ts b/packages/plugin-check/template-bundle/src/empty-model-spec.ts
index 6c8b03e8..9eb9d633 100644
--- a/packages/plugin-check/template-bundle/src/empty-model-spec.ts
+++ b/packages/plugin-check/template-bundle/src/empty-model-spec.ts
@@ -13,3 +13,5 @@ export const startTime = 0
 export const endTime = 0
 export const inputSpecs: InputSpec[] = []
 export const outputSpecs: OutputSpec[] = []
+export const modelSizeInBytes = 0
+export const dataSizeInBytes = 0
diff --git a/packages/plugin-check/template-report/index.html b/packages/plugin-check/template-report/index.html
index d81e410f..c8a08842 100644
--- a/packages/plugin-check/template-report/index.html
+++ b/packages/plugin-check/template-report/index.html
@@ -13,6 +13,16 @@
       rel="stylesheet"
     />
 
+    <style>
+      /*
+       * TODO: This avoids white flash when page reloads (due to the CSS bundled with
+       * check-ui-shell being loaded asynchronously); should fix this
+       */
+      body {
+        background-color: #272727;
+      }
+    </style>
+
     <script type="module" src="./src/index.ts"></script>
   </head>
 
diff --git a/packages/plugin-check/template-report/src/env.d.ts b/packages/plugin-check/template-report/src/env.d.ts
index c201691b..f8d487ae 100644
--- a/packages/plugin-check/template-report/src/env.d.ts
+++ b/packages/plugin-check/template-report/src/env.d.ts
@@ -2,6 +2,7 @@
 
 // These values are injected by Vite at build time, so we need to
 // declare types for them here
+declare const __BASELINE_BUNDLES_PATH__: string
 declare const __BASELINE_NAME__: string
 declare const __CURRENT_NAME__: string
 declare const __SUITE_SUMMARY_JSON__: string
diff --git a/packages/plugin-check/template-report/src/index.ts b/packages/plugin-check/template-report/src/index.ts
index 5352264f..72660846 100644
--- a/packages/plugin-check/template-report/src/index.ts
+++ b/packages/plugin-check/template-report/src/index.ts
@@ -14,17 +14,73 @@ import { createBundle as createBaselineBundle } from '@_baseline_bundle_'
 import { createBundle as createCurrentBundle } from '@_current_bundle_'
 import { getConfigOptions } from '@_test_config_'
 
-// For "production" builds, load the summary from a JSON file that
-// was generated as part of the build process.  This makes the
-// report load almost immediately instead of running all the checks
-// in the user's browser.
-const suiteSummaryJson = __SUITE_SUMMARY_JSON__
-let suiteSummary: SuiteSummary
-if (suiteSummaryJson) {
-  suiteSummary = JSON.parse(suiteSummaryJson) as SuiteSummary
+function loadBundleName(key: string): string | undefined {
+  if (import.meta.hot) {
+    return localStorage.getItem(`sde-check-selected-bundle-${key}`)
+  } else {
+    return undefined
+  }
+}
+
+function saveBundleName(key: string, value: string): void {
+  if (import.meta.hot) {
+    localStorage.setItem(`sde-check-selected-bundle-${key}`, value)
+  }
+}
+
+// For local development mode, load the list of available baseline bundles
+type BundleModule = {
+  createBundle(): Bundle
 }
+type LoadBundle = () => Promise<Bundle>
+const availableBundles: { [key: string]: LoadBundle } = {}
+let bundleNames: string[]
+let selectedBaselineBundleName: string
+let selectedCurrentBundleName: string
+const baselinesPath = __BASELINE_BUNDLES_PATH__
+if (import.meta.hot && baselinesPath) {
+  // Restore the previously selected bundles (from before the page was reloaded)
+  selectedBaselineBundleName = loadBundleName('baseline')
+  selectedCurrentBundleName = loadBundleName('current')
+
+  // Get the available baseline bundles
+  const bundlesGlob = import.meta.glob(__BASELINE_BUNDLES_PATH__, {
+    eager: false
+  })
+  const baselineBundleNames: string[] = []
+  for (const bundleKey of Object.keys(bundlesGlob)) {
+    const loadBundle = bundlesGlob[bundleKey]
+    const bundlePathParts = bundleKey.split('/')
+    const bundleFileName = bundlePathParts[bundlePathParts.length - 1]
+    const bundleName = bundleFileName.replace('.js', '')
+    baselineBundleNames.push(bundleName)
+    availableBundles[bundleName] = async () => {
+      const module = (await loadBundle()) as BundleModule
+      return module.createBundle() as Bundle
+    }
+  }
+
+  // Alphabetize (reversed, so that newer dates are at the top of the list)
+  baselineBundleNames.sort((a, b) => {
+    return b.toLowerCase().localeCompare(a.toLowerCase())
+  })
+
+  // Always include the "current" bundle as the first option, followed by
+  // the alphabetized bundle names
+  bundleNames = ['current', ...baselineBundleNames]
+}
+
+async function initForProduction(): Promise<void> {
+  // For "production" builds, load the summary from a JSON file that
+  // was generated as part of the build process.  This makes the
+  // report load almost immediately instead of running all the checks
+  // in the user's browser.
+  const suiteSummaryJson = __SUITE_SUMMARY_JSON__
+  let suiteSummary: SuiteSummary
+  if (suiteSummaryJson) {
+    suiteSummary = JSON.parse(suiteSummaryJson) as SuiteSummary
+  }
 
-async function init() {
   // Load the bundles used by the model check/compare configuration.  We
   // always initialize the "current" bundle.
   const bundleR: Bundle = createCurrentBundle()
@@ -47,10 +103,85 @@ async function init() {
   })
 
   // Initialize the root Svelte component
-  initAppShell(checkOptions, suiteSummary)
+  initAppShell(checkOptions, {
+    suiteSummary
+  })
+}
 
-  // Initialize the overlay element used to show builder messages/errors
-  initOverlay()
+async function initForLocal(): Promise<void> {
+  async function createBundle(requestedName: string | undefined): Promise<[Bundle, string]> {
+    if (requestedName === undefined) {
+      requestedName = 'current'
+    }
+
+    // See if there is a bundle available for the requested name
+    let bundle: Bundle
+    let bundleName: string
+    if (requestedName in availableBundles) {
+      // Load the bundle for the requested name
+      const loadBundle = availableBundles[requestedName]
+      bundle = await loadBundle()
+      bundleName = requestedName
+    } else {
+      // Load the "current" bundle
+      bundle = createCurrentBundle()
+      bundleName = 'current'
+    }
+    return [bundle, bundleName]
+  }
+
+  const [bundleL, nameL] = await createBundle(selectedBaselineBundleName)
+  const [bundleR, nameR] = await createBundle(selectedCurrentBundleName)
+
+  // Prepare the model check/compare configuration
+  const checkOptions = await getConfigOptions(bundleL, bundleR, {
+    nameL,
+    nameR
+  })
+
+  // Initialize the root Svelte component
+  initAppShell(checkOptions, {
+    bundleNames
+  })
+}
+
+async function initBundlesAndUI() {
+  // Prepare options differently if in local development mode
+  if (import.meta.hot) {
+    await initForLocal()
+  } else {
+    await initForProduction()
+  }
 }
 
-init()
+// Initialize the overlay element used to show builder messages/errors
+initOverlay()
+
+// Initialize the bundles and user interface
+initBundlesAndUI()
+
+if (import.meta.hot) {
+  // Reload everything when the user chooses a new baseline or current bundle
+  document.addEventListener('sde-check-bundle', e => {
+    // Change the selected bundle
+    const info = (e as CustomEvent).detail
+    if (info.kind === 'left') {
+      saveBundleName('baseline', info.name)
+      selectedBaselineBundleName = info.name
+    } else {
+      saveBundleName('current', info.name)
+      selectedCurrentBundleName = info.name
+    }
+
+    // Before switching bundles, clear out the app-shell-container element
+    const container = document.getElementById('app-shell-container')
+    while (container.firstChild) {
+      container.removeChild(container.firstChild)
+    }
+
+    // TODO: Release resources associated with active bundles
+
+    // Reinitialize using the chosen bundles
+    initBundlesAndUI()
+  })
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 495d8537..762c7841 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -257,6 +257,7 @@ importers:
   packages/plugin-check:
     specifiers:
       '@rollup/plugin-node-resolve': ^13.3.0
+      '@rollup/plugin-replace': ^4.0.0
       '@sdeverywhere/build': '*'
       '@sdeverywhere/check-core': ^0.1.0
       '@sdeverywhere/check-ui-shell': ^0.1.1
@@ -264,16 +265,19 @@ importers:
       '@sdeverywhere/runtime-async': ^0.1.0
       '@types/node': ^16.11.7
       assert-never: ^1.2.1
+      chokidar: ^3.5.3
       picocolors: ^1.0.0
       rollup: ^2.76.0
       vite: ^3.1.3
     dependencies:
       '@rollup/plugin-node-resolve': 13.3.0_rollup@2.76.0
+      '@rollup/plugin-replace': 4.0.0_rollup@2.76.0
       '@sdeverywhere/check-core': link:../check-core
       '@sdeverywhere/check-ui-shell': link:../check-ui-shell
       '@sdeverywhere/runtime': link:../runtime
       '@sdeverywhere/runtime-async': link:../runtime-async
       assert-never: 1.2.1
+      chokidar: 3.5.3
       picocolors: 1.0.0
       rollup: 2.76.0
       vite: 3.1.3
@@ -525,6 +529,19 @@ packages:
       rollup: 2.76.0
     dev: false
 
+  /@rollup/plugin-replace/4.0.0_rollup@2.76.0:
+    resolution: {integrity: sha512-+rumQFiaNac9y64OHtkHGmdjm7us9bo1PlbgQfdihQtuNxzjpaB064HbRnewUOggLQxVCCyINfStkgmBeQpv1g==}
+    peerDependencies:
+      rollup: ^1.20.0 || ^2.0.0
+    peerDependenciesMeta:
+      rollup:
+        optional: true
+    dependencies:
+      '@rollup/pluginutils': 3.1.0_rollup@2.76.0
+      magic-string: 0.25.9
+      rollup: 2.76.0
+    dev: false
+
   /@rollup/pluginutils/3.1.0_rollup@2.76.0:
     resolution: {integrity: sha512-GksZ6pr6TpIjHm8h9lSQ8pi8BE9VeubNT0OMJ3B5uZJ8pz73NPiqOtCog/x2/QzM1ENChPKxMDhiQuRHsqc+lg==}
     engines: {node: '>= 8.0.0'}
@@ -2477,7 +2494,6 @@ packages:
     resolution: {integrity: sha512-RmF0AsMzgt25qzqqLc1+MbHmhdx0ojF2Fvs4XnOqz2ZOBXzzkEwc/dJQZCYHAn7v1jbVOjAZfK8msRn4BxO4VQ==}
     dependencies:
       sourcemap-codec: 1.4.8
-    dev: true
 
   /magic-string/0.26.4:
     resolution: {integrity: sha512-e5uXtVJ22aEpK9u1+eQf0fSxHeqwyV19K+uGnlROCxUhzwRip9tBsaMViK/0vC3viyPd5Gtucp3UmEp/Q2cPTQ==}
@@ -3294,7 +3310,6 @@ packages:
 
   /sourcemap-codec/1.4.8:
     resolution: {integrity: sha512-9NykojV5Uih4lgo5So5dtw+f0JgJX30KCNI8gwhz2J9A15wD0Ml6tjHKwf6fTSa6fAdVBdZeNOs9eJ71qCk8vA==}
-    dev: true
 
   /spdx-correct/3.1.1:
     resolution: {integrity: sha512-cOYcUWwhCuHCXi49RhFRCyJEK3iPj1Ziz9DpViV3tbZOwXD49QzIN3MpOLJNxh2qwq2lJJZaKMVw9qNi4jTC0w==}