diff --git a/.agents/session-log.md b/.agents/session-log.md
index e5d229b..392eb68 100644
--- a/.agents/session-log.md
+++ b/.agents/session-log.md
@@ -389,7 +389,8 @@
 - 2026-04-10: Completed issue #342 primary workbench ownership. The renderer now marks workbench-heavy surfaces explicitly and collapses the outer support lane plus internal two-column workbench grids earlier, so `Runs`, `Compare`, `Candidates`, `Run Detail`, and `Paper Ops` stop holding two side rails at the same laptop-width breakpoint. Validation passed with `node --check desktop/renderer/app.js`, `npm run smoke:fallback`, and `npm run smoke:real-path`.
 - 2026-04-10: Started issue #346 to harden `desktop-smoke` result persistence after CI repeatedly failed with raw `ENOENT` on missing `result.json` in a planning-only PR. The slice is limited to `desktop/main.js`, `desktop/scripts/smoke.js`, and `.agents` continuity so smoke emits structured failures instead of crashing when Electron exits too early.
 - 2026-04-10: Added the desktop layout regression remediation block after reviewing the post-merge desktop state in real screenshots. Opened issues #342, #343, and #344 to target empty-pane collapse, stronger active-surface focus and context containment, and better runs-family density plus right-rail space budgeting without reopening core or `research_ui` scope.
-<<<<<<< HEAD
 - 2026-04-10: Added the Desktop architecture migration block after accepting the ADR direction for the new shell foundation. Opened issues #350, #354, #353, #355, #352, #359, #351, #357, #358, and #356 so the migration is tracked as real slices rather than dozens of micro-backlog items.
 - 2026-04-10: Started the desktop shared contracts foundation slice on branch `codex/desktop-shared-workspace-contract`. The goal is to establish the first real shared Desktop contract layer before opening the larger `desktop-typescript-base` slice, limited to workspace, runtime/snapshot, and smoke boundaries.
 - 2026-04-10: Completed the desktop shared contracts foundation slice. Added `desktop/shared` contracts for IPC channels, envelopes, workspace state, runtime state, snapshot status, and smoke results, and connected them back into `desktop/main.js`, `desktop/preload.js`, `desktop/renderer/app.js`, and `desktop/scripts/smoke.js` via narrow JSDoc typing only, without changing desktop behavior.
+- 2026-04-10: Started issue #354 on branch `codex/desktop-typescript-base`. This slice is limited to the real TypeScript base for `desktop/`: `tsconfig.json`, `types/global.d.ts`, package wiring, and only the minimum edits required in `main.js`, `preload.js`, and `renderer/app.js` so typecheck passes without changing desktop behavior.
+- 2026-04-10: Completed issue #354 TypeScript base real across Desktop. Added `desktop/tsconfig.json`, `desktop/types/global.d.ts`, and package wiring for `typecheck`, then applied only the minimum `@ts-check` and DOM/type narrowing changes in `desktop/main.js`, `desktop/preload.js`, and `desktop/renderer/app.js` so `npm run typecheck`, `node --check`, `npm run smoke:fallback`, and `npm run smoke:real-path` all pass without changing visible desktop behavior.
diff --git a/.agents/tasks/issue-354-typescript-base-across-desktop.md b/.agents/tasks/issue-354-typescript-base-across-desktop.md
index 234379e..2631eb0 100644
--- a/.agents/tasks/issue-354-typescript-base-across-desktop.md
+++ b/.agents/tasks/issue-354-typescript-base-across-desktop.md
@@ -1,15 +1,60 @@
 # Issue #354 — TypeScript Base Across Desktop
 
 ## Goal
-Establish the real TypeScript base for `desktop/` without changing runtime behavior.
+Establish the real TypeScript base for `desktop/` without changing runtime behavior or opening the renderer migration yet.
+
+---
+
+## Why this matters
+- turns `desktop/shared` into a first-class typed contract layer
+- prepares the modularization of `main.js` without spreading JS debt into more files first
+- keeps the migration sequence disciplined: contracts first, tooling second, architecture refactor third
+
+---
+
+## Scope
+
+### In scope
+- `desktop/tsconfig.json`
+- `desktop/types/global.d.ts`
+- `desktop/package.json`
+- minimal typecheck-driven edits in `desktop/main.js`, `desktop/preload.js`, and `desktop/renderer/app.js`
+- native consumption of `desktop/shared/ipc` and `desktop/shared/models`
+
+### Out of scope
+- modularizing `main.js`
+- React
+- Vite
+- `research_ui`
+- new shared models
+- functional behavior changes
+- visible UI changes
+
+---
+
+## Relevant files
+
+- `desktop/package.json`
+- `desktop/tsconfig.json`
+- `desktop/types/global.d.ts`
+- `desktop/main.js`
+- `desktop/preload.js`
+- `desktop/renderer/app.js`
+- `desktop/shared/`
+
+---
 
 ## Expected deliverable
-- `tsconfig.json`
-- `types/global.d.ts`
-- `typecheck`
-- native use of `desktop/shared`
+
+- TypeScript base configuration for the current Desktop shell
+- current Desktop entrypoints passing `typecheck` while staying in JS
+- no runtime behavior change
+
+---
 
 ## Done when
-- current Desktop JS entrypoints pass typecheck
-- smoke remains green
-- no functional change is introduced
+
+- `npm run typecheck` passes in `desktop/`
+- `node --check` passes for touched JS entrypoints
+- `smoke:fallback` and `smoke:real-path` stay green
+- `main.js`, `preload.js`, and `renderer/app.js` consume `desktop/shared` natively through the TS base
diff --git a/desktop/main.js b/desktop/main.js
index d29660e..66c09bc 100644
--- a/desktop/main.js
+++ b/desktop/main.js
@@ -1,3 +1,5 @@
+// @ts-check
+
 const { app, BrowserWindow, ipcMain, shell } = require("electron");
 const fs = require("fs");
 const fsp = require("fs/promises");
diff --git a/desktop/package-lock.json b/desktop/package-lock.json
index 777afc9..8756745 100644
--- a/desktop/package-lock.json
+++ b/desktop/package-lock.json
@@ -9,7 +9,9 @@
       "version": "0.1.0",
       "devDependencies": {
         "@modelcontextprotocol/sdk": "^1.20.0",
+        "@types/node": "^24.6.1",
         "electron": "^37.2.0",
+        "typescript": "^5.9.3",
         "zod": "^4.1.12"
       }
     },
@@ -146,13 +148,13 @@
       }
     },
     "node_modules/@types/node": {
-      "version": "22.19.15",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-22.19.15.tgz",
-      "integrity": "sha512-F0R/h2+dsy5wJAUe3tAU6oqa2qbWY5TpNfL/RGmo1y38hiyO1w3x2jPtt76wmuaJI4DQnOBu21cNXQ2STIUUWg==",
+      "version": "24.12.2",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-24.12.2.tgz",
+      "integrity": "sha512-A1sre26ke7HDIuY/M23nd9gfB+nrmhtYyMINbjI1zHJxYteKR6qSMX56FsmjMcDb3SMcjJg5BiRRgOCC/yBD0g==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "undici-types": "~6.21.0"
+        "undici-types": "~7.16.0"
       }
     },
     "node_modules/@types/responselike": {
@@ -583,6 +585,23 @@
         "node": ">= 12.20.55"
       }
     },
+    "node_modules/electron/node_modules/@types/node": {
+      "version": "22.19.17",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-22.19.17.tgz",
+      "integrity": "sha512-wGdMcf+vPYM6jikpS/qhg6WiqSV/OhG+jeeHT/KlVqxYfD40iYJf9/AE1uQxVWFvU7MipKRkRv8NSHiCGgPr8Q==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "undici-types": "~6.21.0"
+      }
+    },
+    "node_modules/electron/node_modules/undici-types": {
+      "version": "6.21.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.21.0.tgz",
+      "integrity": "sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/encodeurl": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/encodeurl/-/encodeurl-2.0.0.tgz",
@@ -1914,10 +1933,24 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/typescript": {
+      "version": "5.9.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
+      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
     "node_modules/undici-types": {
-      "version": "6.21.0",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.21.0.tgz",
-      "integrity": "sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ==",
+      "version": "7.16.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.16.0.tgz",
+      "integrity": "sha512-Zz+aZWSj8LE6zoxD+xrjh4VfkIG8Ya6LvYkZqtUQGJPZjYl53ypCaUwWqo7eI0x66KBGeRo+mlBEkMSeSZ38Nw==",
       "dev": true,
       "license": "MIT"
     },
diff --git a/desktop/package.json b/desktop/package.json
index b4d996c..fbf3b9c 100644
--- a/desktop/package.json
+++ b/desktop/package.json
@@ -7,6 +7,7 @@
   "scripts": {
     "start": "electron .",
     "dev": "electron .",
+    "typecheck": "tsc --project tsconfig.json --noEmit",
     "smoke": "npm run smoke:fallback",
     "smoke:fallback": "node scripts/smoke.js --mode=fallback",
     "smoke:real-path": "node scripts/smoke.js --mode=real-path",
@@ -14,7 +15,9 @@
   },
   "devDependencies": {
     "@modelcontextprotocol/sdk": "^1.20.0",
+    "@types/node": "^24.6.1",
     "electron": "^37.2.0",
+    "typescript": "^5.9.3",
     "zod": "^4.1.12"
   }
 }
diff --git a/desktop/preload.js b/desktop/preload.js
index 55ce161..c1a8ec2 100644
--- a/desktop/preload.js
+++ b/desktop/preload.js
@@ -1,3 +1,5 @@
+// @ts-check
+
 const { contextBridge, ipcRenderer } = require("electron");
 
 /** @typedef {import("./shared/models/workspace").WorkspaceState} WorkspaceState */
diff --git a/desktop/renderer/app.js b/desktop/renderer/app.js
index 2dee368..3f5fb8d 100644
--- a/desktop/renderer/app.js
+++ b/desktop/renderer/app.js
@@ -1,3 +1,5 @@
+// @ts-check
+
 import * as decisionStore from "./modules/decision-store.js";
 import {
   NAV_ACTION_BY_KIND,
@@ -41,6 +43,8 @@ import {
 /** @typedef {import("../shared/models/runtime").RuntimeStatus} RuntimeStatus */
 /** @typedef {import("../shared/models/runtime").RuntimeChipState} RuntimeChipState */
 /** @typedef {import("../shared/models/snapshot").SnapshotStatus} SnapshotStatus */
+/** @typedef {import("../shared/models/snapshot").SnapshotSource} SnapshotSource */
+/** @typedef {import("../shared/models/workspace").WorkspaceState} WorkspaceState */
 
 const CONFIG = {
   runsIndexPath: "/outputs/runs/runs_index.json",
@@ -70,7 +74,8 @@ const CONFIG = {
 let unsubscribeWorkspaceState = null;
 
 const state = {
-  workspace: { status: "starting", serverUrl: null, logs: [], error: null },
+  /** @type {WorkspaceState} */
+  workspace: { status: "starting", serverUrl: null, logs: [], error: null, source: null },
   snapshot: null,
   candidatesStore: defaultCandidatesStore(),
   candidatesLoaded: false,
@@ -124,52 +129,52 @@ const WORKBENCH_PRIORITY_KINDS = new Set([
 ]);
 
 const elements = {
-  runtimeSummary: document.getElementById("runtime-summary"),
-  runtimeMeta: document.getElementById("runtime-meta"),
-  runtimeAlert: document.getElementById("runtime-alert"),
-  runtimeRetry: document.getElementById("runtime-retry"),
-  runtimeChips: document.getElementById("runtime-chips"),
-  topbarEyebrow: document.getElementById("topbar-eyebrow"),
-  chatLog: document.getElementById("chat-log"),
-  chatForm: document.getElementById("chat-form"),
-  chatInput: document.getElementById("chat-input"),
-  chatStepbit: document.getElementById("chat-stepbit"),
-  chatAdapterStatus: document.getElementById("chat-adapter-status"),
-  tabsBar: document.getElementById("tabs-bar"),
-  tabContent: document.getElementById("tab-content"),
-  topbarTitle: document.getElementById("topbar-title"),
-  topbarSurfaceChip: document.getElementById("topbar-surface-chip"),
-  topbarRuntimeChip: document.getElementById("topbar-runtime-chip"),
-  topbarServerChip: document.getElementById("topbar-server-chip"),
-  paletteSearch: document.getElementById("palette-search"),
-  paletteInput: document.getElementById("palette-input"),
-  runCommand: document.getElementById("run-command"),
-  commandPaletteTrigger: document.getElementById("command-palette-trigger"),
-  openBrowserRuns: document.getElementById("open-browser-runs"),
-  paletteOverlay: document.getElementById("palette-overlay"),
-  closePalette: document.getElementById("close-palette"),
-  paletteResults: document.getElementById("palette-results"),
-  workflowLaunchForm: document.getElementById("workflow-launch-form"),
-  workflowLaunchCommand: document.getElementById("workflow-launch-command"),
-  workflowRunFields: document.getElementById("workflow-run-fields"),
-  workflowSweepFields: document.getElementById("workflow-sweep-fields"),
-  workflowLaunchTicker: document.getElementById("workflow-launch-ticker"),
-  workflowLaunchStart: document.getElementById("workflow-launch-start"),
-  workflowLaunchEnd: document.getElementById("workflow-launch-end"),
-  workflowLaunchInterval: document.getElementById("workflow-launch-interval"),
-  workflowLaunchCash: document.getElementById("workflow-launch-cash"),
-  workflowLaunchPaper: document.getElementById("workflow-launch-paper"),
-  workflowLaunchConfigPath: document.getElementById("workflow-launch-config-path"),
-  workflowLaunchOutDir: document.getElementById("workflow-launch-out-dir"),
-  workflowLaunchMeta: document.getElementById("workflow-launch-meta"),
-  workflowLaunchFeedback: document.getElementById("workflow-launch-feedback"),
-  workflowLaunchSubmit: document.getElementById("workflow-launch-submit"),
-  workflowJobsList: document.getElementById("workflow-jobs-list"),
-  workflowRunsMeta: document.getElementById("workflow-runs-meta"),
-  workflowRunsList: document.getElementById("workflow-runs-list"),
-  workflowOpenCompare: document.getElementById("workflow-open-compare"),
-  workflowClearSelection: document.getElementById("workflow-clear-selection"),
-  workspaceGrid: document.querySelector(".workspace-grid"),
+  runtimeSummary: /** @type {HTMLDivElement} */ (document.getElementById("runtime-summary")),
+  runtimeMeta: /** @type {HTMLDivElement} */ (document.getElementById("runtime-meta")),
+  runtimeAlert: /** @type {HTMLDivElement} */ (document.getElementById("runtime-alert")),
+  runtimeRetry: /** @type {HTMLButtonElement} */ (document.getElementById("runtime-retry")),
+  runtimeChips: /** @type {HTMLDivElement} */ (document.getElementById("runtime-chips")),
+  topbarEyebrow: /** @type {HTMLDivElement} */ (document.getElementById("topbar-eyebrow")),
+  chatLog: /** @type {HTMLDivElement} */ (document.getElementById("chat-log")),
+  chatForm: /** @type {HTMLFormElement} */ (document.getElementById("chat-form")),
+  chatInput: /** @type {HTMLTextAreaElement} */ (document.getElementById("chat-input")),
+  chatStepbit: /** @type {HTMLButtonElement} */ (document.getElementById("chat-stepbit")),
+  chatAdapterStatus: /** @type {HTMLDivElement} */ (document.getElementById("chat-adapter-status")),
+  tabsBar: /** @type {HTMLDivElement} */ (document.getElementById("tabs-bar")),
+  tabContent: /** @type {HTMLDivElement} */ (document.getElementById("tab-content")),
+  topbarTitle: /** @type {HTMLHeadingElement} */ (document.getElementById("topbar-title")),
+  topbarSurfaceChip: /** @type {HTMLDivElement} */ (document.getElementById("topbar-surface-chip")),
+  topbarRuntimeChip: /** @type {HTMLDivElement} */ (document.getElementById("topbar-runtime-chip")),
+  topbarServerChip: /** @type {HTMLDivElement} */ (document.getElementById("topbar-server-chip")),
+  paletteSearch: /** @type {HTMLInputElement} */ (document.getElementById("palette-search")),
+  paletteInput: /** @type {HTMLInputElement} */ (document.getElementById("palette-input")),
+  runCommand: /** @type {HTMLButtonElement} */ (document.getElementById("run-command")),
+  commandPaletteTrigger: /** @type {HTMLButtonElement} */ (document.getElementById("command-palette-trigger")),
+  openBrowserRuns: /** @type {HTMLButtonElement} */ (document.getElementById("open-browser-runs")),
+  paletteOverlay: /** @type {HTMLDivElement} */ (document.getElementById("palette-overlay")),
+  closePalette: /** @type {HTMLButtonElement} */ (document.getElementById("close-palette")),
+  paletteResults: /** @type {HTMLDivElement} */ (document.getElementById("palette-results")),
+  workflowLaunchForm: /** @type {HTMLFormElement} */ (document.getElementById("workflow-launch-form")),
+  workflowLaunchCommand: /** @type {HTMLSelectElement} */ (document.getElementById("workflow-launch-command")),
+  workflowRunFields: /** @type {HTMLDivElement} */ (document.getElementById("workflow-run-fields")),
+  workflowSweepFields: /** @type {HTMLDivElement} */ (document.getElementById("workflow-sweep-fields")),
+  workflowLaunchTicker: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-ticker")),
+  workflowLaunchStart: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-start")),
+  workflowLaunchEnd: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-end")),
+  workflowLaunchInterval: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-interval")),
+  workflowLaunchCash: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-cash")),
+  workflowLaunchPaper: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-paper")),
+  workflowLaunchConfigPath: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-config-path")),
+  workflowLaunchOutDir: /** @type {HTMLInputElement} */ (document.getElementById("workflow-launch-out-dir")),
+  workflowLaunchMeta: /** @type {HTMLDivElement} */ (document.getElementById("workflow-launch-meta")),
+  workflowLaunchFeedback: /** @type {HTMLDivElement} */ (document.getElementById("workflow-launch-feedback")),
+  workflowLaunchSubmit: /** @type {HTMLButtonElement} */ (document.getElementById("workflow-launch-submit")),
+  workflowJobsList: /** @type {HTMLDivElement} */ (document.getElementById("workflow-jobs-list")),
+  workflowRunsMeta: /** @type {HTMLDivElement} */ (document.getElementById("workflow-runs-meta")),
+  workflowRunsList: /** @type {HTMLDivElement} */ (document.getElementById("workflow-runs-list")),
+  workflowOpenCompare: /** @type {HTMLButtonElement} */ (document.getElementById("workflow-open-compare")),
+  workflowClearSelection: /** @type {HTMLButtonElement} */ (document.getElementById("workflow-clear-selection")),
+  workspaceGrid: /** @type {HTMLElement} */ (document.querySelector(".workspace-grid")),
 };
 
 const paletteActions = PALETTE_ACTION_SPECS.map((action) => ({
@@ -228,8 +233,9 @@ window.addEventListener("beforeunload", () => {
 
 function bindEvents() {
   document.querySelectorAll("[data-action]").forEach((button) => {
-    button.addEventListener("click", () => {
-      const action = button.dataset.action;
+    const actionButton = /** @type {HTMLElement} */ (button);
+    actionButton.addEventListener("click", () => {
+      const action = actionButton.dataset.action;
       if (action === "open-assistant") focusAssistant();
       if (action === "open-system") openSystemTab();
       if (action === "open-experiments") openExperimentsTab();
@@ -241,8 +247,9 @@ function bindEvents() {
     });
   });
   document.querySelectorAll("[data-prompt]").forEach((button) => {
-    button.addEventListener("click", () => {
-      const prompt = button.dataset.prompt || "";
+    const promptButton = /** @type {HTMLElement} */ (button);
+    promptButton.addEventListener("click", () => {
+      const prompt = promptButton.dataset.prompt || "";
       elements.chatInput.value = prompt;
       handleChatPrompt(prompt);
     });
@@ -408,18 +415,26 @@ async function refreshSnapshot() {
   }
 }
 
+/**
+ * @returns {Promise<{ runsRegistry: any, source: SnapshotSource, primaryError: Error | null }>}
+ */
 async function loadRunsRegistrySnapshot() {
+  /** @type {Error | null} */
   let primaryError = null;
   if (state.workspace.serverUrl) {
     try {
       const runsRegistry = await window.quantlabDesktop.requestJson(CONFIG.runsIndexPath);
-      return { runsRegistry, source: "api", primaryError: null };
+      /** @type {SnapshotSource} */
+      const source = "api";
+      return { runsRegistry, source, primaryError: null };
     } catch (error) {
-      primaryError = error;
+      primaryError = /** @type {Error} */ (error);
     }
   }
   const runsRegistry = await window.quantlabDesktop.readProjectJson(CONFIG.localRunsIndexPath);
-  return { runsRegistry, source: "local", primaryError };
+  /** @type {SnapshotSource} */
+  const source = "local";
+  return { runsRegistry, source, primaryError };
 }
 
 function renderAll() {
@@ -1001,9 +1016,9 @@ function renderTabs() {
   } else if (activeTab.kind === "candidates") {
     renderMarkupInto(elements.tabContent, renderCandidatesTab(activeTab));
   } else if (activeTab.kind === "paper") {
-    renderMarkupInto(elements.tabContent, renderPaperOpsTab(activeTab));
+    renderMarkupInto(elements.tabContent, renderPaperOpsTab());
   } else if (activeTab.kind === "system") {
-    renderMarkupInto(elements.tabContent, renderSystemTab(activeTab));
+    renderMarkupInto(elements.tabContent, renderSystemTab());
   } else if (activeTab.kind === "job") {
     renderMarkupInto(elements.tabContent, renderJobTab(activeTab));
   } else {
@@ -1054,8 +1069,9 @@ function renderPalette() {
     );
   }
   elements.paletteResults.querySelectorAll("[data-palette-action]").forEach((button) => {
-    button.addEventListener("click", () => {
-      const action = paletteActions.find((entry) => entry.id === button.dataset.paletteAction);
+    const paletteButton = /** @type {HTMLElement} */ (button);
+    paletteButton.addEventListener("click", () => {
+      const action = paletteActions.find((entry) => entry.id === paletteButton.dataset.paletteAction);
       if (!action) return;
       action.run();
       state.paletteOpen = false;
@@ -1270,16 +1286,18 @@ function renderRunsWorklist(runs) {
 
 function bindTabChromeEvents() {
   elements.tabsBar.querySelectorAll("[data-tab-id]").forEach((button) => {
-    button.addEventListener("click", () => {
-      state.activeTabId = button.dataset.tabId;
+    const tabButton = /** @type {HTMLElement} */ (button);
+    tabButton.addEventListener("click", () => {
+      state.activeTabId = tabButton.dataset.tabId;
       renderTabs();
       scheduleShellWorkspacePersist();
     });
   });
   elements.tabsBar.querySelectorAll("[data-close-tab]").forEach((button) => {
-    button.addEventListener("click", (event) => {
+    const closeButton = /** @type {HTMLElement} */ (button);
+    closeButton.addEventListener("click", (event) => {
       event.stopPropagation();
-      closeTab(button.dataset.closeTab);
+      closeTab(closeButton.dataset.closeTab);
     });
   });
 }
diff --git a/desktop/tsconfig.json b/desktop/tsconfig.json
new file mode 100644
index 0000000..acdf200
--- /dev/null
+++ b/desktop/tsconfig.json
@@ -0,0 +1,23 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "preserve",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022", "DOM"],
+    "allowJs": true,
+    "checkJs": false,
+    "noEmit": true,
+    "strict": false,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "types": ["node"]
+  },
+  "include": [
+    "main.js",
+    "preload.js",
+    "renderer/app.js",
+    "shared/**/*.ts",
+    "types/**/*.d.ts"
+  ]
+}
diff --git a/desktop/types/global.d.ts b/desktop/types/global.d.ts
new file mode 100644
index 0000000..a943b7c
--- /dev/null
+++ b/desktop/types/global.d.ts
@@ -0,0 +1,30 @@
+import type { WorkspaceState, WorkspaceStateListener } from "../shared/models/workspace";
+
+interface QuantlabDesktopBridge {
+  getWorkspaceState(): Promise<WorkspaceState>;
+  requestJson(relativePath: string): Promise<any>;
+  requestText(relativePath: string): Promise<string>;
+  getCandidatesStore(): Promise<any>;
+  saveCandidatesStore(store: any): Promise<any>;
+  getSweepDecisionStore(): Promise<any>;
+  saveSweepDecisionStore(store: any): Promise<any>;
+  getShellWorkspaceStore(): Promise<any>;
+  saveShellWorkspaceStore(store: any): Promise<any>;
+  listDirectory(targetPath: string, maxDepth?: number): Promise<any>;
+  readProjectText(targetPath: string): Promise<string>;
+  readProjectJson(targetPath: string): Promise<any>;
+  postJson(relativePath: string, payload: any): Promise<any>;
+  restartWorkspaceServer(): Promise<WorkspaceState>;
+  askStepbitChat(payload: any): Promise<any>;
+  openExternal(url: string): Promise<{ ok: true }>;
+  openPath(targetPath: string): Promise<{ ok: true }>;
+  onWorkspaceState(callback: WorkspaceStateListener): () => void;
+}
+
+declare global {
+  interface Window {
+    quantlabDesktop: QuantlabDesktopBridge;
+  }
+}
+
+export {};