diff --git a/packages/types/src/vscode-extension-host.ts b/packages/types/src/vscode-extension-host.ts
index 63d5be87a8..2111a6d081 100644
--- a/packages/types/src/vscode-extension-host.ts
+++ b/packages/types/src/vscode-extension-host.ts
@@ -103,6 +103,7 @@ export interface ExtensionMessage {
 		| "rules"
 		| "fileContent"
 		| "rooHistoryImportProgress"
+		| "diagnosticsRequest"
 	text?: string
 	/** For fileContent: { path, content, error? } */
 	fileContent?: { path: string; content: string | null; error?: string }
@@ -150,6 +151,7 @@ export interface ExtensionMessage {
 	// eslint-disable-next-line @typescript-eslint/no-explicit-any
 	values?: Record<string, any>
 	requestId?: string
+	diagnostics?: WebviewDiagnosticsSnapshot
 	promptText?: string
 	results?:
 		| { path: string; type: "file" | "folder"; label?: string }[]
@@ -438,6 +440,40 @@ export type ClineAskResponse = "yesButtonClicked" | "noButtonClicked" | "message
 
 export type AudioType = "notification" | "celebration" | "progress_loop"
 
+export interface WebviewDiagnosticsSnapshot {
+	capturedAt: string
+	didHydrateState?: boolean
+	documentReadyState?: "loading" | "interactive" | "complete"
+	documentVisibilityState?: "hidden" | "visible" | "prerender"
+	activeView?: string
+	rootMounted?: boolean
+	rootChildCount?: number
+	lastReceivedStateSequence?: number
+	lastAppliedStateSequence?: number
+	staleStateRejectionCount?: number
+	unknownMessageUpdateCount?: number
+	currentTaskId?: string
+	chatMessageCount?: number
+	historyItemCount?: number
+	todoCount?: number
+	viewport?: { width: number; height: number; devicePixelRatio: number }
+	theme?: {
+		kind?: number
+		identifier?: string
+		bodyForeground?: string
+		bodyBackground?: string
+		rootForeground?: string
+		rootBackground?: string
+		variables?: Record<string, string>
+	}
+	error?: {
+		name?: string
+		message?: string
+		fingerprint?: string
+		stackLocations?: string[]
+	}
+}
+
 export interface UpdateTodoListPayload {
 	// eslint-disable-next-line @typescript-eslint/no-explicit-any
 	todos: any[]
@@ -632,6 +668,7 @@ export interface WebviewMessage {
 		| "deleteRule"
 		| "openRuleFile"
 		| "openRulesDirectory"
+		| "diagnosticsResponse"
 	text?: string
 	taskId?: string
 	editedMessageContent?: string
@@ -678,6 +715,7 @@ export interface WebviewMessage {
 	/** Target mode slugs for updateSkillModes */
 	newSkillModeSlugs?: string[] // For updateSkillModes (new mode restrictions)
 	requestId?: string
+	diagnostics?: WebviewDiagnosticsSnapshot
 	ids?: string[]
 	terminalOperation?: "continue" | "abort"
 	messageTs?: number
diff --git a/packages/types/src/vscode.ts b/packages/types/src/vscode.ts
index fd4e31116d..d70bec5845 100644
--- a/packages/types/src/vscode.ts
+++ b/packages/types/src/vscode.ts
@@ -48,6 +48,7 @@ export const commandIds = [
 	"toggleAutoApprove",
 
 	"showRipgrepDiagnostic",
+	"createDiagnosticsReport",
 ] as const
 
 export type CommandId = (typeof commandIds)[number]
diff --git a/src/activate/__tests__/registerCommands.spec.ts b/src/activate/__tests__/registerCommands.spec.ts
index 67a2b935ec..b5cbcad73f 100644
--- a/src/activate/__tests__/registerCommands.spec.ts
+++ b/src/activate/__tests__/registerCommands.spec.ts
@@ -93,6 +93,10 @@ vi.mock("../../services/ripgrep/diagnostic", () => ({
 	registerRipgrepDiagnosticCommand: vi.fn().mockReturnValue({ dispose: vi.fn() }),
 }))
 
+vi.mock("../../services/diagnostics", () => ({
+	createDiagnosticsReport: vi.fn().mockResolvedValue(undefined),
+}))
+
 describe("getVisibleProviderOrLog", () => {
 	let mockOutputChannel: vscode.OutputChannel
 
@@ -192,6 +196,21 @@ describe("registerCommands handlers", () => {
 		expect(mockContext.subscriptions).toContain(disposable)
 	})
 
+	it("creates diagnostics from all provider instances without requiring a visible provider", async () => {
+		const { createDiagnosticsReport } = await import("../../services/diagnostics")
+		const providers = [{}, {}]
+		;(ClineProvider.getAllInstances as Mock).mockReturnValue(providers)
+		;(ClineProvider.getVisibleInstance as Mock).mockReturnValue(undefined)
+
+		await handlers["zoo-code.createDiagnosticsReport"]()
+
+		expect(createDiagnosticsReport).toHaveBeenCalledWith({
+			context: mockContext,
+			outputChannel: mockOutputChannel,
+			providers,
+		})
+	})
+
 	it("settingsButtonClicked posts both settingsButtonClicked and didBecomeVisible actions", () => {
 		handlers["zoo-code.settingsButtonClicked"]()
 
diff --git a/src/activate/registerCommands.ts b/src/activate/registerCommands.ts
index 692aabfd68..d4be15110e 100644
--- a/src/activate/registerCommands.ts
+++ b/src/activate/registerCommands.ts
@@ -14,6 +14,7 @@ import { CodeIndexManager } from "../services/code-index/manager"
 import { importSettingsWithFeedback } from "../core/config/importExport"
 import { MdmService } from "../services/mdm/MdmService"
 import { registerRipgrepDiagnosticCommand } from "../services/ripgrep/diagnostic"
+import { createDiagnosticsReport } from "../services/diagnostics"
 import { t } from "../i18n"
 
 /**
@@ -173,6 +174,12 @@ const getCommandsMap = ({
 			filePath,
 		)
 	},
+	createDiagnosticsReport: () =>
+		createDiagnosticsReport({
+			context,
+			outputChannel,
+			providers: ClineProvider.getAllInstances(),
+		}),
 	focusInput: async () => {
 		try {
 			await focusPanel(tabPanel, sidebarPanel)
diff --git a/src/core/webview/ClineProvider.ts b/src/core/webview/ClineProvider.ts
index 573cf92a5b..0aa5366c23 100644
--- a/src/core/webview/ClineProvider.ts
+++ b/src/core/webview/ClineProvider.ts
@@ -36,6 +36,7 @@ import {
 	type ToolUsage,
 	type ExtensionMessage,
 	type ExtensionState,
+	type WebviewDiagnosticsSnapshot,
 	type MarketplaceInstalledMetadata,
 	RooCodeEventName,
 	requestyDefaultModelId,
@@ -85,6 +86,11 @@ import { CodeIndexManager } from "../../services/code-index/manager"
 import type { IndexProgressUpdate } from "../../services/code-index/interfaces/manager"
 import { MdmService } from "../../services/mdm/MdmService"
 import { SkillsManager } from "../../services/skills/SkillsManager"
+import {
+	DiagnosticsRecorder,
+	DiagnosticsRequestBroker,
+	type DiagnosticsProviderSourceSnapshot,
+} from "../../services/diagnostics"
 
 import { fileExistsAtPath } from "../../utils/fs"
 import { setTtsEnabled, setTtsSpeed } from "../../utils/tts"
@@ -189,6 +195,8 @@ export class ClineProvider
 	private taskEventListeners: WeakMap<Task, Array<() => void>> = new WeakMap()
 	private currentWorkspacePath: string | undefined
 	private _disposed = false
+	private readonly diagnosticsRecorder = new DiagnosticsRecorder(200)
+	private readonly diagnosticsRequestBroker = new DiagnosticsRequestBroker()
 	private readonly rateLimitClock: RateLimitClock = createRateLimitClock()
 
 	private recentTasksCache?: string[]
@@ -291,6 +299,7 @@ export class ClineProvider
 		)
 
 		ClineProvider.activeInstances.add(this)
+		this.diagnosticsRecorder.record({ boundary: "provider", phase: "success", type: "created" })
 
 		this.mdmService = mdmService
 		void this.updateGlobalState("codebaseIndexModels", EMBEDDING_MODEL_PROFILES)
@@ -447,6 +456,8 @@ export class ClineProvider
 	 * Initialize the TaskHistoryStore and migrate from globalState if needed.
 	 */
 	private async initializeTaskHistoryStore(): Promise<void> {
+		const startedAt = Date.now()
+		this.diagnosticsRecorder.record({ boundary: "task-history", phase: "start", type: "initialize" })
 		try {
 			await this.taskHistoryStore.initialize()
 
@@ -467,7 +478,19 @@ export class ClineProvider
 			}
 
 			this.taskHistoryStoreInitialized = true
+			this.diagnosticsRecorder.record({
+				boundary: "task-history",
+				phase: "success",
+				type: "initialize",
+				elapsedMs: Date.now() - startedAt,
+			})
 		} catch (error) {
+			this.diagnosticsRecorder.record({
+				boundary: "task-history",
+				phase: "failure",
+				type: "initialize",
+				elapsedMs: Date.now() - startedAt,
+			})
 			this.log(`[initializeTaskHistoryStore] Error: ${error instanceof Error ? error.message : String(error)}`)
 		}
 	}
@@ -746,6 +769,7 @@ export class ClineProvider
 		}
 
 		this._disposed = true
+		this.diagnosticsRecorder.record({ boundary: "provider", phase: "start", type: "dispose" })
 		this.log("Disposing ClineProvider...")
 
 		// Reject any tasks still waiting for a scheduler permit so they don't
@@ -800,6 +824,7 @@ export class ClineProvider
 		this.flushGlobalStateWriteThrough()
 		this.log("Disposed all disposables")
 		ClineProvider.activeInstances.delete(this)
+		this.diagnosticsRequestBroker.dispose()
 
 		// Clean up any event listeners attached to this provider
 		this.removeAllListeners()
@@ -922,6 +947,11 @@ export class ClineProvider
 	async resolveWebviewView(webviewView: vscode.WebviewView | vscode.WebviewPanel) {
 		this.view = webviewView
 		const inTabMode = "onDidChangeViewState" in webviewView
+		this.diagnosticsRecorder.record({
+			boundary: "provider",
+			phase: "success",
+			type: "view-resolved",
+		})
 
 		if (inTabMode) {
 			setPanel(webviewView, "tab")
@@ -998,6 +1028,11 @@ export class ClineProvider
 			// WebviewView and WebviewPanel have all the same properties except
 			// for this visibility listener panel.
 			const viewStateDisposable = webviewView.onDidChangeViewState(() => {
+				this.diagnosticsRecorder.record({
+					boundary: "provider",
+					phase: "success",
+					type: this.view?.visible ? "view-visible" : "view-hidden",
+				})
 				if (this.view?.visible) {
 					void this.postMessageToWebview({ type: "action", action: "didBecomeVisible" })
 				} else {
@@ -1009,6 +1044,11 @@ export class ClineProvider
 		} else if ("onDidChangeVisibility" in webviewView) {
 			// sidebar
 			const visibilityDisposable = webviewView.onDidChangeVisibility(() => {
+				this.diagnosticsRecorder.record({
+					boundary: "provider",
+					phase: "success",
+					type: this.view?.visible ? "view-visible" : "view-hidden",
+				})
 				if (this.view?.visible) {
 					void this.postMessageToWebview({ type: "action", action: "didBecomeVisible" })
 				} else {
@@ -1354,17 +1394,80 @@ export class ClineProvider
 	}
 
 	public async postMessageToWebview(message: ExtensionMessage) {
+		const startedAt = Date.now()
+		const taskId = this.getCurrentTask()?.taskId
+		this.diagnosticsRecorder.record({
+			boundary: "webview-out",
+			phase: "start",
+			type: message.type,
+			action: message.action,
+			stateSequence: message.type === "state" ? message.state?.clineMessagesSeq : undefined,
+			taskId,
+		})
 		if (this._disposed) {
+			this.diagnosticsRecorder.record({
+				boundary: "webview-out",
+				phase: "failure",
+				type: message.type,
+				action: message.action,
+				elapsedMs: Date.now() - startedAt,
+				taskId,
+			})
 			return
 		}
 
 		try {
-			await this.view?.webview.postMessage(message)
+			const delivered = await this.view?.webview.postMessage(message)
+			this.diagnosticsRecorder.record({
+				boundary: "webview-out",
+				phase: delivered ? "success" : "failure",
+				type: message.type,
+				action: message.action,
+				elapsedMs: Date.now() - startedAt,
+				stateSequence: message.type === "state" ? message.state?.clineMessagesSeq : undefined,
+				taskId,
+			})
 		} catch {
+			this.diagnosticsRecorder.record({
+				boundary: "webview-out",
+				phase: "failure",
+				type: message.type,
+				action: message.action,
+				elapsedMs: Date.now() - startedAt,
+				taskId,
+			})
 			// View disposed, drop message silently
 		}
 	}
 
+	public getDiagnosticsSnapshot(): DiagnosticsProviderSourceSnapshot {
+		const currentTask = this.getCurrentTask()
+		const events = this.diagnosticsRecorder.snapshot(100)
+		return {
+			renderContext: this.renderContext,
+			disposed: this._disposed,
+			viewPresent: Boolean(this.view),
+			visible: this.view?.visible === true,
+			launched: this.isViewLaunched,
+			taskHistoryInitialized: this.taskHistoryStoreInitialized,
+			taskCount: this.taskRegistry.length,
+			currentTaskId: currentTask?.taskId,
+			currentMessageCount: currentTask?.clineMessages.length ?? 0,
+			currentTodoCount: currentTask?.todoList?.length ?? 0,
+			history: this.taskHistoryStore.getAll(),
+			events: events.events,
+			eventsTruncated: events.truncated,
+		}
+	}
+
+	public requestWebviewDiagnostics(timeoutMs = 1_000): Promise<WebviewDiagnosticsSnapshot | undefined> {
+		if (this._disposed || !this.view) return Promise.resolve(undefined)
+		return this.diagnosticsRequestBroker.request(
+			(requestId) => this.postMessageToWebview({ type: "diagnosticsRequest", requestId }),
+			timeoutMs,
+		)
+	}
+
 	private async getHMRHtmlContent(webview: vscode.Webview): Promise<string> {
 		let localPort = "5173"
 
@@ -1553,8 +1656,31 @@ export class ClineProvider
 	 * @param webview A reference to the extension webview
 	 */
 	private setWebviewMessageListener(webview: vscode.Webview) {
-		const onReceiveMessage = async (message: WebviewMessage) =>
-			webviewMessageHandler(this, message, this.marketplaceManager)
+		const onReceiveMessage = async (message: WebviewMessage) => {
+			const startedAt = Date.now()
+			this.diagnosticsRecorder.record({ boundary: "webview-in", phase: "start", type: message.type })
+			try {
+				if (message.type === "diagnosticsResponse" && message.requestId) {
+					this.diagnosticsRequestBroker.resolve(message.requestId, message.diagnostics)
+				} else {
+					await webviewMessageHandler(this, message, this.marketplaceManager)
+				}
+				this.diagnosticsRecorder.record({
+					boundary: "webview-in",
+					phase: "success",
+					type: message.type,
+					elapsedMs: Date.now() - startedAt,
+				})
+			} catch (error) {
+				this.diagnosticsRecorder.record({
+					boundary: "webview-in",
+					phase: "failure",
+					type: message.type,
+					elapsedMs: Date.now() - startedAt,
+				})
+				throw error
+			}
+		}
 
 		const messageDisposable = webview.onDidReceiveMessage(onReceiveMessage)
 		this.webviewDisposables.push(messageDisposable)
@@ -2144,13 +2270,39 @@ export class ClineProvider
 	}
 
 	async showTaskWithId(id: string) {
-		if (id !== this.getCurrentTask()?.taskId) {
-			// Non-current task.
-			const { historyItem } = await this.getTaskWithId(id)
-			await this.createTaskWithHistoryItem(historyItem) // Clears existing task.
-		}
+		const startedAt = Date.now()
+		this.diagnosticsRecorder.record({
+			boundary: "task-navigation",
+			phase: "start",
+			type: "show-task",
+			taskId: id,
+		})
+		try {
+			if (id !== this.getCurrentTask()?.taskId) {
+				// Non-current task.
+				const { historyItem } = await this.getTaskWithId(id)
+				await this.createTaskWithHistoryItem(historyItem) // Clears existing task.
+			}
 
-		await this.postMessageToWebview({ type: "action", action: "chatButtonClicked" })
+			await this.postMessageToWebview({ type: "action", action: "chatButtonClicked" })
+			this.diagnosticsRecorder.record({
+				boundary: "task-navigation",
+				phase: "success",
+				type: "show-task",
+				taskId: id,
+				elapsedMs: Date.now() - startedAt,
+				messageCount: this.getCurrentTask()?.clineMessages.length ?? 0,
+			})
+		} catch (error) {
+			this.diagnosticsRecorder.record({
+				boundary: "task-navigation",
+				phase: "failure",
+				type: "show-task",
+				taskId: id,
+				elapsedMs: Date.now() - startedAt,
+			})
+			throw error
+		}
 	}
 
 	async exportTaskWithId(id: string) {
diff --git a/src/package.json b/src/package.json
index f272137dc2..997fc27973 100644
--- a/src/package.json
+++ b/src/package.json
@@ -165,6 +165,11 @@
 				"title": "%command.showRipgrepDiagnostic.title%",
 				"category": "%configuration.title%"
 			},
+			{
+				"command": "zoo-code.createDiagnosticsReport",
+				"title": "%command.createDiagnosticsReport.title%",
+				"category": "%configuration.title%"
+			},
 			{
 				"command": "zoo-code.toggleAutoApprove",
 				"title": "%command.toggleAutoApprove.title%",
diff --git a/src/package.nls.ca.json b/src/package.nls.ca.json
index 6ddaf181b4..416e638920 100644
--- a/src/package.nls.ca.json
+++ b/src/package.nls.ca.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Explicar Aquesta Ordre",
 	"command.acceptInput.title": "Acceptar Entrada/Suggeriment",
 	"command.showRipgrepDiagnostic.title": "Mostra el diagnòstic de Ripgrep",
+	"command.createDiagnosticsReport.title": "Crea un informe de diagnòstic",
 	"command.toggleAutoApprove.title": "Alternar Auto-Aprovació",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.de.json b/src/package.nls.de.json
index 4c8eccb293..63984345ea 100644
--- a/src/package.nls.de.json
+++ b/src/package.nls.de.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Diesen Befehl Erklären",
 	"command.acceptInput.title": "Eingabe/Vorschlag Akzeptieren",
 	"command.showRipgrepDiagnostic.title": "Ripgrep-Diagnose anzeigen",
+	"command.createDiagnosticsReport.title": "Diagnosebericht erstellen",
 	"command.toggleAutoApprove.title": "Auto-Genehmigung Umschalten",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.es.json b/src/package.nls.es.json
index 11a705880b..e678db39e9 100644
--- a/src/package.nls.es.json
+++ b/src/package.nls.es.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Explicar Este Comando",
 	"command.acceptInput.title": "Aceptar Entrada/Sugerencia",
 	"command.showRipgrepDiagnostic.title": "Mostrar diagnóstico de Ripgrep",
+	"command.createDiagnosticsReport.title": "Crear informe de diagnóstico",
 	"command.toggleAutoApprove.title": "Alternar Auto-Aprobación",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.fr.json b/src/package.nls.fr.json
index 573350bc9a..9e42ed6f09 100644
--- a/src/package.nls.fr.json
+++ b/src/package.nls.fr.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Expliquer cette Commande",
 	"command.acceptInput.title": "Accepter l'Entrée/Suggestion",
 	"command.showRipgrepDiagnostic.title": "Afficher le diagnostic Ripgrep",
+	"command.createDiagnosticsReport.title": "Créer un rapport de diagnostic",
 	"command.toggleAutoApprove.title": "Basculer Auto-Approbation",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.hi.json b/src/package.nls.hi.json
index 8135af2ab3..aadd22c94d 100644
--- a/src/package.nls.hi.json
+++ b/src/package.nls.hi.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "यह कमांड समझाएं",
 	"command.acceptInput.title": "इनपुट/सुझाव स्वीकारें",
 	"command.showRipgrepDiagnostic.title": "Ripgrep डायग्नोस्टिक दिखाएं",
+	"command.createDiagnosticsReport.title": "डायग्नोस्टिक रिपोर्ट बनाएं",
 	"command.toggleAutoApprove.title": "ऑटो-अनुमोदन टॉगल करें",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.id.json b/src/package.nls.id.json
index c5740ad00b..8163935f63 100644
--- a/src/package.nls.id.json
+++ b/src/package.nls.id.json
@@ -24,6 +24,7 @@
 	"command.terminal.explainCommand.title": "Jelaskan Perintah Ini",
 	"command.acceptInput.title": "Terima Input/Saran",
 	"command.showRipgrepDiagnostic.title": "Tampilkan Diagnostik Ripgrep",
+	"command.createDiagnosticsReport.title": "Buat Laporan Diagnostik",
 	"command.toggleAutoApprove.title": "Alihkan Persetujuan Otomatis",
 	"configuration.title": "Zoo Code",
 	"commands.allowedCommands.description": "Perintah yang dapat dijalankan secara otomatis ketika 'Selalu setujui operasi eksekusi' diaktifkan",
diff --git a/src/package.nls.it.json b/src/package.nls.it.json
index ebf2167a99..bea17811a8 100644
--- a/src/package.nls.it.json
+++ b/src/package.nls.it.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Spiega Questo Comando",
 	"command.acceptInput.title": "Accetta Input/Suggerimento",
 	"command.showRipgrepDiagnostic.title": "Mostra diagnostica Ripgrep",
+	"command.createDiagnosticsReport.title": "Crea rapporto di diagnostica",
 	"command.toggleAutoApprove.title": "Attiva/Disattiva Auto-Approvazione",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.ja.json b/src/package.nls.ja.json
index f9daa4bb93..e84ff292c1 100644
--- a/src/package.nls.ja.json
+++ b/src/package.nls.ja.json
@@ -24,6 +24,7 @@
 	"command.terminal.explainCommand.title": "このコマンドを説明",
 	"command.acceptInput.title": "入力/提案を承認",
 	"command.showRipgrepDiagnostic.title": "Ripgrep 診断を表示",
+	"command.createDiagnosticsReport.title": "診断レポートを作成",
 	"command.toggleAutoApprove.title": "自動承認を切替",
 	"configuration.title": "Zoo Code",
 	"commands.allowedCommands.description": "'常に実行操作を承認する'が有効な場合に自動実行できるコマンド",
diff --git a/src/package.nls.json b/src/package.nls.json
index 4fac644eab..a83dc68354 100644
--- a/src/package.nls.json
+++ b/src/package.nls.json
@@ -24,6 +24,7 @@
 	"command.terminal.explainCommand.title": "Explain This Command",
 	"command.acceptInput.title": "Accept Input/Suggestion",
 	"command.showRipgrepDiagnostic.title": "Show Ripgrep Diagnostic",
+	"command.createDiagnosticsReport.title": "Create Diagnostics Report",
 	"command.toggleAutoApprove.title": "Toggle Auto-Approve",
 	"configuration.title": "Zoo Code",
 	"commands.allowedCommands.description": "Commands that can be auto-executed when 'Always approve execute operations' is enabled",
diff --git a/src/package.nls.ko.json b/src/package.nls.ko.json
index a743902280..2b8a486b06 100644
--- a/src/package.nls.ko.json
+++ b/src/package.nls.ko.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "이 명령어 설명",
 	"command.acceptInput.title": "입력/제안 수락",
 	"command.showRipgrepDiagnostic.title": "Ripgrep 진단 표시",
+	"command.createDiagnosticsReport.title": "진단 보고서 만들기",
 	"command.toggleAutoApprove.title": "자동 승인 전환",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.nl.json b/src/package.nls.nl.json
index 72bc15f89a..f7f38ad189 100644
--- a/src/package.nls.nl.json
+++ b/src/package.nls.nl.json
@@ -24,6 +24,7 @@
 	"command.terminal.explainCommand.title": "Leg Dit Commando Uit",
 	"command.acceptInput.title": "Invoer/Suggestie Accepteren",
 	"command.showRipgrepDiagnostic.title": "Ripgrep-diagnose weergeven",
+	"command.createDiagnosticsReport.title": "Diagnoserapport maken",
 	"command.toggleAutoApprove.title": "Auto-Goedkeuring Schakelen",
 	"configuration.title": "Zoo Code",
 	"commands.allowedCommands.description": "Commando's die automatisch kunnen worden uitgevoerd wanneer 'Altijd goedkeuren uitvoerbewerkingen' is ingeschakeld",
diff --git a/src/package.nls.pl.json b/src/package.nls.pl.json
index 92fb97778b..1c3f17a322 100644
--- a/src/package.nls.pl.json
+++ b/src/package.nls.pl.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Wyjaśnij tę Komendę",
 	"command.acceptInput.title": "Akceptuj Wprowadzanie/Sugestię",
 	"command.showRipgrepDiagnostic.title": "Pokaż diagnostykę Ripgrep",
+	"command.createDiagnosticsReport.title": "Utwórz raport diagnostyczny",
 	"command.toggleAutoApprove.title": "Przełącz Auto-Zatwierdzanie",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.pt-BR.json b/src/package.nls.pt-BR.json
index 872af10e80..68a414a75e 100644
--- a/src/package.nls.pt-BR.json
+++ b/src/package.nls.pt-BR.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Explicar Este Comando",
 	"command.acceptInput.title": "Aceitar Entrada/Sugestão",
 	"command.showRipgrepDiagnostic.title": "Mostrar diagnóstico do Ripgrep",
+	"command.createDiagnosticsReport.title": "Criar relatório de diagnóstico",
 	"command.toggleAutoApprove.title": "Alternar Auto-Aprovação",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.ru.json b/src/package.nls.ru.json
index cb38655945..fbfa84d8c5 100644
--- a/src/package.nls.ru.json
+++ b/src/package.nls.ru.json
@@ -24,6 +24,7 @@
 	"command.terminal.explainCommand.title": "Объяснить эту команду",
 	"command.acceptInput.title": "Принять ввод/предложение",
 	"command.showRipgrepDiagnostic.title": "Показать диагностику Ripgrep",
+	"command.createDiagnosticsReport.title": "Создать диагностический отчёт",
 	"command.toggleAutoApprove.title": "Переключить Авто-Подтверждение",
 	"configuration.title": "Zoo Code",
 	"commands.allowedCommands.description": "Команды, которые могут быть автоматически выполнены, когда включена опция 'Всегда подтверждать операции выполнения'",
diff --git a/src/package.nls.tr.json b/src/package.nls.tr.json
index 7d995723ce..f1a02aa58b 100644
--- a/src/package.nls.tr.json
+++ b/src/package.nls.tr.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Bu Komutu Açıkla",
 	"command.acceptInput.title": "Girişi/Öneriyi Kabul Et",
 	"command.showRipgrepDiagnostic.title": "Ripgrep Tanılamasını Göster",
+	"command.createDiagnosticsReport.title": "Tanılama Raporu Oluştur",
 	"command.toggleAutoApprove.title": "Otomatik Onayı Değiştir",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.vi.json b/src/package.nls.vi.json
index b50e4db508..c8a30026e9 100644
--- a/src/package.nls.vi.json
+++ b/src/package.nls.vi.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "Giải Thích Lệnh Này",
 	"command.acceptInput.title": "Chấp Nhận Đầu Vào/Gợi Ý",
 	"command.showRipgrepDiagnostic.title": "Hiển thị chẩn đoán Ripgrep",
+	"command.createDiagnosticsReport.title": "Tạo báo cáo chẩn đoán",
 	"command.toggleAutoApprove.title": "Bật/Tắt Tự Động Phê Duyệt",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.zh-CN.json b/src/package.nls.zh-CN.json
index 0686d03a14..e8ad29c6fd 100644
--- a/src/package.nls.zh-CN.json
+++ b/src/package.nls.zh-CN.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "解释此命令",
 	"command.acceptInput.title": "接受输入/建议",
 	"command.showRipgrepDiagnostic.title": "显示 Ripgrep 诊断",
+	"command.createDiagnosticsReport.title": "创建诊断报告",
 	"command.toggleAutoApprove.title": "切换自动批准",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/package.nls.zh-TW.json b/src/package.nls.zh-TW.json
index 8005e0de7f..dafa11fb81 100644
--- a/src/package.nls.zh-TW.json
+++ b/src/package.nls.zh-TW.json
@@ -15,6 +15,7 @@
 	"command.terminal.explainCommand.title": "解釋此命令",
 	"command.acceptInput.title": "接受輸入/建議",
 	"command.showRipgrepDiagnostic.title": "顯示 Ripgrep 診斷",
+	"command.createDiagnosticsReport.title": "建立診斷報告",
 	"command.toggleAutoApprove.title": "切換自動批准",
 	"views.activitybar.title": "Zoo Code",
 	"views.contextMenu.label": "Zoo Code",
diff --git a/src/services/diagnostics/__tests__/command.spec.ts b/src/services/diagnostics/__tests__/command.spec.ts
new file mode 100644
index 0000000000..626209a255
--- /dev/null
+++ b/src/services/diagnostics/__tests__/command.spec.ts
@@ -0,0 +1,96 @@
+const mocks = vi.hoisted(() => ({
+	writeFile: vi.fn(),
+	buildDiagnosticsReport: vi.fn(),
+	getStorageBasePath: vi.fn(),
+	openTextDocument: vi.fn(),
+	showTextDocument: vi.fn(),
+	writeText: vi.fn(),
+	showInformationMessage: vi.fn(),
+	showWarningMessage: vi.fn(),
+	showErrorMessage: vi.fn(),
+}))
+
+vi.mock("fs/promises", () => ({ writeFile: mocks.writeFile }))
+vi.mock("../../../utils/storage", () => ({ getStorageBasePath: mocks.getStorageBasePath }))
+vi.mock("../report", () => ({ buildDiagnosticsReport: mocks.buildDiagnosticsReport }))
+vi.mock("vscode", () => ({
+	version: "1.100.0",
+	UIKind: { Desktop: 1, Web: 2 },
+	ColorThemeKind: { Light: 1, Dark: 2, HighContrast: 3, HighContrastLight: 4 },
+	env: {
+		appName: "Visual Studio Code",
+		uiKind: 1,
+		language: "en",
+		remoteName: undefined,
+		clipboard: { writeText: mocks.writeText },
+	},
+	workspace: {
+		workspaceFolders: [],
+		getConfiguration: vi.fn(() => ({ get: vi.fn(() => "") })),
+		openTextDocument: mocks.openTextDocument,
+	},
+	window: {
+		activeColorTheme: { kind: 2 },
+		showTextDocument: mocks.showTextDocument,
+		showInformationMessage: mocks.showInformationMessage,
+		showWarningMessage: mocks.showWarningMessage,
+		showErrorMessage: mocks.showErrorMessage,
+	},
+}))
+
+import type * as vscode from "vscode"
+
+import { createDiagnosticsReport } from "../command"
+
+describe("createDiagnosticsReport", () => {
+	const outputChannel = { appendLine: vi.fn() } as Pick<vscode.OutputChannel, "appendLine"> as vscode.OutputChannel
+	const context = {
+		globalStorageUri: { fsPath: "/private/storage/path" },
+	} as Pick<vscode.ExtensionContext, "globalStorageUri"> as vscode.ExtensionContext
+
+	beforeEach(() => {
+		vi.clearAllMocks()
+		mocks.getStorageBasePath.mockResolvedValue("/private/storage/path")
+		mocks.buildDiagnosticsReport.mockResolvedValue({ schemaVersion: 1, privacy: { uploaded: false } })
+		mocks.writeFile.mockResolvedValue(undefined)
+		mocks.openTextDocument.mockResolvedValue({})
+		mocks.showTextDocument.mockResolvedValue(undefined)
+		mocks.writeText.mockResolvedValue(undefined)
+	})
+
+	it("writes valid JSON to temp, opens it, and copies the same JSON without a provider", async () => {
+		await createDiagnosticsReport({ context, outputChannel, providers: [] })
+
+		expect(mocks.buildDiagnosticsReport).toHaveBeenCalledWith(expect.objectContaining({ providers: [] }))
+		expect(mocks.writeFile).toHaveBeenCalledWith(
+			expect.stringMatching(/zoo-code-diagnostics-\d+-[a-f0-9]{8}\.json$/),
+			expect.any(String),
+			"utf8",
+		)
+		const json = mocks.writeFile.mock.calls[0][1]
+		expect(() => JSON.parse(json)).not.toThrow()
+		expect(mocks.writeText).toHaveBeenCalledWith(json)
+		expect(mocks.openTextDocument).toHaveBeenCalledWith(mocks.writeFile.mock.calls[0][0])
+		expect(mocks.showInformationMessage).toHaveBeenCalledWith(expect.stringContaining("No data was uploaded"))
+	})
+
+	it("reports only a sanitized failure category", async () => {
+		mocks.writeFile.mockRejectedValue(new Error("secret path /Users/person/report.json"))
+
+		await createDiagnosticsReport({ context, outputChannel, providers: [] })
+
+		expect(outputChannel.appendLine).toHaveBeenCalledWith("[createDiagnosticsReport] failed: Error")
+		expect(outputChannel.appendLine).not.toHaveBeenCalledWith(expect.stringContaining("/Users/person"))
+		expect(mocks.showErrorMessage).toHaveBeenCalledWith("Zoo Code could not create the diagnostics report.")
+	})
+
+	it("still copies the report when opening the document fails", async () => {
+		mocks.openTextDocument.mockRejectedValue(new Error("editor unavailable"))
+
+		await createDiagnosticsReport({ context, outputChannel, providers: [] })
+
+		expect(mocks.writeText).toHaveBeenCalledTimes(1)
+		expect(outputChannel.appendLine).toHaveBeenCalledWith("[createDiagnosticsReport] open failed")
+		expect(mocks.showWarningMessage).toHaveBeenCalledWith(expect.stringContaining("could not open or copy"))
+	})
+})
diff --git a/src/services/diagnostics/__tests__/persistence.spec.ts b/src/services/diagnostics/__tests__/persistence.spec.ts
new file mode 100644
index 0000000000..2ce9575f46
--- /dev/null
+++ b/src/services/diagnostics/__tests__/persistence.spec.ts
@@ -0,0 +1,139 @@
+import * as fs from "fs/promises"
+import * as os from "os"
+import * as path from "path"
+
+import type { HistoryItem } from "@roo-code/types"
+
+import { collectPersistenceDiagnostics } from "../persistence"
+
+describe("collectPersistenceDiagnostics", () => {
+	let storagePath: string
+
+	beforeEach(async () => {
+		storagePath = await fs.mkdtemp(path.join(os.tmpdir(), "zoo-diagnostics-test-"))
+	})
+
+	afterEach(async () => {
+		await fs.rm(storagePath, { recursive: true, force: true })
+	})
+
+	it("inspects task files structurally without returning content", async () => {
+		const history: HistoryItem[] = [
+			{
+				id: "raw-parent-id",
+				number: 1,
+				ts: 10,
+				task: "PRIVATE TASK TITLE",
+				tokensIn: 1,
+				tokensOut: 1,
+				totalCost: 0,
+				status: "delegated",
+				childIds: ["raw-child-id"],
+				awaitingChildId: "raw-child-id",
+			},
+			{
+				id: "raw-child-id",
+				parentTaskId: "raw-parent-id",
+				number: 2,
+				ts: 20,
+				task: "SECRET CHILD TITLE",
+				tokensIn: 2,
+				tokensOut: 2,
+				totalCost: 0,
+				status: "active",
+			},
+		]
+		const tasksPath = path.join(storagePath, "tasks")
+		await fs.mkdir(path.join(tasksPath, "raw-child-id"), { recursive: true })
+		await fs.writeFile(path.join(tasksPath, "_index.json"), JSON.stringify({ version: 1, entries: history }))
+		await fs.writeFile(path.join(tasksPath, "raw-child-id", "history_item.json"), JSON.stringify(history[1]))
+		await fs.writeFile(
+			path.join(tasksPath, "raw-child-id", "ui_messages.json"),
+			JSON.stringify([
+				{ ts: 100, text: "PRIVATE PROMPT" },
+				{ ts: 200, text: "PRIVATE RESPONSE" },
+			]),
+		)
+
+		const result = await collectPersistenceDiagnostics({
+			storagePath,
+			history,
+			currentTaskIds: ["raw-child-id"],
+			pseudonymize: (value) => `hashed-${value === "raw-child-id" ? "child" : "parent"}`,
+		})
+
+		expect(result.index).toMatchObject({ parseStatus: "valid", version: 1, entryCount: 2 })
+		expect(result.tasks.find((task) => task.id === "hashed-child")?.uiMessages).toMatchObject({
+			parseStatus: "valid",
+			messageCount: 2,
+			firstTimestamp: 100,
+			lastTimestamp: 200,
+		})
+		const serialized = JSON.stringify(result)
+		expect(serialized).not.toContain("PRIVATE")
+		expect(serialized).not.toContain("raw-child-id")
+	})
+
+	it("reports corrupt and missing files without throwing", async () => {
+		const history: HistoryItem[] = [
+			{
+				id: "task-1",
+				number: 1,
+				ts: 10,
+				task: "not reported",
+				tokensIn: 0,
+				tokensOut: 0,
+				totalCost: 0,
+			},
+		]
+		const taskPath = path.join(storagePath, "tasks", "task-1")
+		await fs.mkdir(taskPath, { recursive: true })
+		await fs.writeFile(path.join(taskPath, "ui_messages.json"), "not json")
+
+		const result = await collectPersistenceDiagnostics({
+			storagePath,
+			history,
+			currentTaskIds: ["task-1"],
+			pseudonymize: () => "task-hash",
+		})
+
+		expect(result.index.exists).toBe(false)
+		expect(result.tasks[0].historyItem.exists).toBe(false)
+		expect(result.tasks[0].uiMessages.parseStatus).toBe("invalid")
+	})
+
+	it("reports cycles in parent relationships", async () => {
+		const history: HistoryItem[] = [
+			{
+				id: "task-1",
+				parentTaskId: "task-2",
+				number: 1,
+				ts: 10,
+				task: "not reported",
+				tokensIn: 0,
+				tokensOut: 0,
+				totalCost: 0,
+			},
+			{
+				id: "task-2",
+				parentTaskId: "task-1",
+				number: 2,
+				ts: 20,
+				task: "not reported",
+				tokensIn: 0,
+				tokensOut: 0,
+				totalCost: 0,
+			},
+		]
+
+		const result = await collectPersistenceDiagnostics({
+			storagePath,
+			history,
+			currentTaskIds: ["task-1"],
+			pseudonymize: (value) => `hashed-${value}`,
+		})
+
+		expect(result.tasks).toHaveLength(2)
+		expect(result.tasks.every((task) => task.integrityFindings.includes("parentCycle"))).toBe(true)
+	})
+})
diff --git a/src/services/diagnostics/__tests__/recorder.spec.ts b/src/services/diagnostics/__tests__/recorder.spec.ts
new file mode 100644
index 0000000000..731b744617
--- /dev/null
+++ b/src/services/diagnostics/__tests__/recorder.spec.ts
@@ -0,0 +1,15 @@
+import { DiagnosticsRecorder } from "../recorder"
+
+describe("DiagnosticsRecorder", () => {
+	it("keeps a bounded structural trail without payload fields", () => {
+		const recorder = new DiagnosticsRecorder(3)
+		for (let index = 0; index < 5; index++) {
+			recorder.record({ boundary: "webview-out", phase: "success", type: `message-${index}` })
+		}
+
+		const snapshot = recorder.snapshot(2)
+		expect(snapshot.truncated).toBe(true)
+		expect(snapshot.events.map((event) => event.type)).toEqual(["message-3", "message-4"])
+		expect(JSON.stringify(snapshot)).not.toContain("payload")
+	})
+})
diff --git a/src/services/diagnostics/__tests__/report.spec.ts b/src/services/diagnostics/__tests__/report.spec.ts
new file mode 100644
index 0000000000..085d82b582
--- /dev/null
+++ b/src/services/diagnostics/__tests__/report.spec.ts
@@ -0,0 +1,163 @@
+import * as fs from "fs/promises"
+import * as os from "os"
+import * as path from "path"
+
+import type { DiagnosticsProviderSource } from "../types"
+import { buildDiagnosticsReport } from "../report"
+
+describe("buildDiagnosticsReport", () => {
+	it("produces bounded, pseudonymized, privacy-safe valid JSON", async () => {
+		const storagePath = await fs.mkdtemp(path.join(os.tmpdir(), "zoo-report-test-"))
+		const provider: DiagnosticsProviderSource = {
+			getDiagnosticsSnapshot: () => ({
+				renderContext: "sidebar",
+				disposed: false,
+				viewPresent: true,
+				visible: false,
+				launched: true,
+				taskHistoryInitialized: true,
+				taskCount: 1,
+				currentTaskId: "raw-task-id",
+				currentMessageCount: 4,
+				currentTodoCount: 2,
+				history: [
+					{
+						id: "raw-task-id",
+						number: 1,
+						ts: 1,
+						task: "TOP SECRET PROMPT",
+						tokensIn: 0,
+						tokensOut: 0,
+						totalCost: 0,
+					},
+					{
+						id: "failed-navigation-target",
+						number: 2,
+						ts: 2,
+						task: "ANOTHER SECRET PROMPT",
+						tokensIn: 0,
+						tokensOut: 0,
+						totalCost: 0,
+					},
+				],
+				events: [
+					...Array.from({ length: 99 }, (_, index) => ({
+						timestamp: new Date(index).toISOString(),
+						boundary: "webview-out" as const,
+						phase: "success" as const,
+						type: "state",
+						taskId: "raw-task-id",
+					})),
+					{
+						timestamp: new Date(100).toISOString(),
+						boundary: "task-navigation" as const,
+						phase: "failure" as const,
+						type: "show-task",
+						taskId: "failed-navigation-target",
+					},
+				],
+				eventsTruncated: true,
+			}),
+			requestWebviewDiagnostics: async () => ({
+				capturedAt: new Date(0).toISOString(),
+				didHydrateState: true,
+				activeView: "chat",
+				currentTaskId: "raw-task-id",
+				chatMessageCount: 4,
+				theme: {
+					bodyBackground: "#fff",
+					variables: {
+						"--vscode-editor-background": "#fff",
+						"--private-secret": "API_KEY_SECRET",
+					},
+				},
+				error: {
+					message: "user@example.com /Users/person/private.ts",
+					fingerprint: "error-123",
+					stackLocations: ["webview-ui/src/App.tsx:1", "/Users/person/private.ts:2"],
+				},
+			}),
+		}
+
+		try {
+			const report = await buildDiagnosticsReport({
+				providers: [provider],
+				storagePath,
+				version: "1.2.3",
+				releaseChannel: "stable",
+				environment: {
+					vscodeVersion: "1.100.0",
+					appName: "Visual Studio Code",
+					uiKind: "desktop",
+					platform: "linux",
+					architecture: "x64",
+					locale: "en",
+					remote: false,
+					workspaceFolderCount: 1,
+					customStorageConfigured: false,
+					colorThemeKind: "dark",
+				},
+			})
+			const serialized = JSON.stringify(report)
+			expect(() => JSON.parse(serialized)).not.toThrow()
+			expect(report.providers[0].events).toHaveLength(100)
+			expect(report.providers[0].currentTask).toMatch(/^task-[a-f0-9]{12}$/)
+			expect(report.providers[0].webviewResponse).toBe("received")
+			expect(report.persistence.tasks).toHaveLength(2)
+			expect(report.providers[0].webview).toMatchObject({
+				didHydrateState: true,
+				currentTask: report.providers[0].currentTask,
+			})
+			expect(serialized).not.toContain("raw-task-id")
+			expect(serialized).not.toContain("failed-navigation-target")
+			expect(serialized).not.toContain("TOP SECRET")
+			expect(serialized).not.toContain("API_KEY_SECRET")
+			expect(serialized).not.toContain("user@example.com")
+			expect(serialized).not.toContain("/Users/person")
+			expect(serialized).not.toContain("webview-ui/src/App.tsx")
+			expect(report.privacy).toMatchObject({ conversationContentIncluded: false, uploaded: false })
+		} finally {
+			await fs.rm(storagePath, { recursive: true, force: true })
+		}
+	})
+
+	it("marks a nonresponsive webview unavailable", async () => {
+		const provider: DiagnosticsProviderSource = {
+			getDiagnosticsSnapshot: () => ({
+				renderContext: "editor",
+				disposed: false,
+				viewPresent: false,
+				visible: false,
+				launched: false,
+				taskHistoryInitialized: false,
+				taskCount: 0,
+				currentMessageCount: 0,
+				currentTodoCount: 0,
+				history: [],
+				events: [],
+				eventsTruncated: false,
+			}),
+			requestWebviewDiagnostics: async () => undefined,
+		}
+		const report = await buildDiagnosticsReport({
+			providers: [provider],
+			storagePath: os.tmpdir(),
+			version: "1",
+			releaseChannel: "stable",
+			environment: {
+				vscodeVersion: "1",
+				appName: "Code",
+				uiKind: "desktop",
+				platform: "linux",
+				architecture: "x64",
+				locale: "en",
+				remote: false,
+				workspaceFolderCount: 0,
+				customStorageConfigured: false,
+				colorThemeKind: "dark",
+			},
+		})
+
+		expect(report.providers[0].webviewResponse).toBe("unavailable")
+	})
+})
diff --git a/src/services/diagnostics/__tests__/requestBroker.spec.ts b/src/services/diagnostics/__tests__/requestBroker.spec.ts
new file mode 100644
index 0000000000..67fe1018af
--- /dev/null
+++ b/src/services/diagnostics/__tests__/requestBroker.spec.ts
@@ -0,0 +1,27 @@
+import { DiagnosticsRequestBroker } from "../requestBroker"
+
+describe("DiagnosticsRequestBroker", () => {
+	it("correlates a live webview response", async () => {
+		const broker = new DiagnosticsRequestBroker()
+		let requestId = ""
+		const response = broker.request(async (id) => {
+			requestId = id
+		}, 100)
+
+		expect(requestId).not.toBe("")
+		expect(broker.resolve(requestId, { capturedAt: "2026-01-01T00:00:00.000Z", activeView: "chat" })).toBe(true)
+		await expect(response).resolves.toMatchObject({ activeView: "chat" })
+	})
+
+	it("returns unavailable after the response timeout", async () => {
+		vi.useFakeTimers()
+		try {
+			const broker = new DiagnosticsRequestBroker()
+			const response = broker.request(async () => {}, 1_000)
+			await vi.advanceTimersByTimeAsync(1_000)
+			await expect(response).resolves.toBeUndefined()
+		} finally {
+			vi.useRealTimers()
+		}
+	})
+})
diff --git a/src/services/diagnostics/command.ts b/src/services/diagnostics/command.ts
new file mode 100644
index 0000000000..3821869d5b
--- /dev/null
+++ b/src/services/diagnostics/command.ts
@@ -0,0 +1,86 @@
+import * as fs from "fs/promises"
+import * as os from "os"
+import * as path from "path"
+import { randomBytes } from "crypto"
+import * as vscode from "vscode"
+
+import { Package } from "../../shared/package"
+import { getStorageBasePath } from "../../utils/storage"
+import { buildDiagnosticsReport } from "./report"
+import type { DiagnosticsProviderSource } from "./types"
+
+export async function createDiagnosticsReport(options: {
+	context: vscode.ExtensionContext
+	outputChannel: vscode.OutputChannel
+	providers: DiagnosticsProviderSource[]
+}): Promise<void> {
+	try {
+		const colorThemeKind = (() => {
+			switch (vscode.window.activeColorTheme.kind) {
+				case vscode.ColorThemeKind.Light:
+					return "light" as const
+				case vscode.ColorThemeKind.Dark:
+					return "dark" as const
+				case vscode.ColorThemeKind.HighContrast:
+					return "highContrast" as const
+				case vscode.ColorThemeKind.HighContrastLight:
+					return "highContrastLight" as const
+				default:
+					return "unknown" as const
+			}
+		})()
+		const storagePath = await getStorageBasePath(options.context.globalStorageUri.fsPath)
+		const report = await buildDiagnosticsReport({
+			providers: options.providers,
+			storagePath,
+			version: Package.version,
+			releaseChannel: Package.releaseChannel,
+			environment: {
+				vscodeVersion: vscode.version,
+				appName: vscode.env.appName,
+				uiKind:
+					vscode.env.uiKind === vscode.UIKind.Desktop
+						? "desktop"
+						: vscode.env.uiKind === vscode.UIKind.Web
+							? "web"
+							: "unknown",
+				platform: process.platform,
+				architecture: process.arch,
+				locale: vscode.env.language,
+				remote: Boolean(vscode.env.remoteName),
+				workspaceFolderCount: vscode.workspace.workspaceFolders?.length ?? 0,
+				customStorageConfigured: Boolean(
+					vscode.workspace.getConfiguration(Package.name).get<string>("customStoragePath", ""),
+				),
+				colorThemeKind,
+			},
+		})
+		const json = JSON.stringify(report, null, 2)
+		const fileName = `zoo-code-diagnostics-${Date.now()}-${randomBytes(4).toString("hex")}.json`
+		const filePath = path.join(os.tmpdir(), fileName)
+		await fs.writeFile(filePath, json, "utf8")
+		const [openResult, copyResult] = await Promise.allSettled([
+			vscode.workspace
+				.openTextDocument(filePath)
+				.then((document) => vscode.window.showTextDocument(document, { preview: true })),
+			vscode.env.clipboard.writeText(json),
+		])
+		if (openResult.status === "fulfilled" && copyResult.status === "fulfilled") {
+			await vscode.window.showInformationMessage(
+				"Zoo Code: redacted diagnostics copied and opened for review. No data was uploaded.",
+			)
+		} else {
+			if (openResult.status === "rejected")
+				options.outputChannel.appendLine("[createDiagnosticsReport] open failed")
+			if (copyResult.status === "rejected")
+				options.outputChannel.appendLine("[createDiagnosticsReport] copy failed")
+			await vscode.window.showWarningMessage(
+				"Zoo Code created the diagnostics report, but could not open or copy every result. No data was uploaded.",
+			)
+		}
+	} catch (error) {
+		const category = error instanceof Error ? error.name : "UnknownError"
+		options.outputChannel.appendLine(`[createDiagnosticsReport] failed: ${category}`)
+		await vscode.window.showErrorMessage("Zoo Code could not create the diagnostics report.")
+	}
+}
diff --git a/src/services/diagnostics/index.ts b/src/services/diagnostics/index.ts
new file mode 100644
index 0000000000..4be6430873
--- /dev/null
+++ b/src/services/diagnostics/index.ts
@@ -0,0 +1,9 @@
+export { createDiagnosticsReport } from "./command"
+export { DiagnosticsRecorder } from "./recorder"
+export { DiagnosticsRequestBroker } from "./requestBroker"
+export type {
+	DiagnosticsProviderSource,
+	DiagnosticsProviderSourceSnapshot,
+	DiagnosticsReportV1,
+	DiagnosticsStructuralEvent,
+} from "./types"
diff --git a/src/services/diagnostics/persistence.ts b/src/services/diagnostics/persistence.ts
new file mode 100644
index 0000000000..33d5d9d6be
--- /dev/null
+++ b/src/services/diagnostics/persistence.ts
@@ -0,0 +1,182 @@
+import * as fs from "fs/promises"
+import * as path from "path"
+
+import type { HistoryItem } from "@roo-code/types"
+
+import { GlobalFileNames } from "../../shared/globalFileNames"
+import type { DiagnosticsFileInspection, DiagnosticsPersistenceReport } from "./types"
+
+const MAX_TASKS = 10
+const MAX_INSPECTION_BYTES = 25 * 1024 * 1024
+const FILE_TIMEOUT_MS = 500
+
+function withTimeout<T>(operation: Promise<T>, timeoutMs: number): Promise<T> {
+	return new Promise<T>((resolve, reject) => {
+		const timeout = setTimeout(() => reject(new Error("timeout")), timeoutMs)
+		void operation.then(
+			(value) => {
+				clearTimeout(timeout)
+				resolve(value)
+			},
+			(error) => {
+				clearTimeout(timeout)
+				reject(error)
+			},
+		)
+	})
+}
+
+function getShape(value: unknown): DiagnosticsFileInspection["topLevelShape"] {
+	if (Array.isArray(value)) return "array"
+	if (value !== null && typeof value === "object") return "object"
+	return "other"
+}
+
+async function inspectJson(filePath: string): Promise<{ inspection: DiagnosticsFileInspection; value?: unknown }> {
+	try {
+		const stat = await withTimeout(fs.stat(filePath), FILE_TIMEOUT_MS)
+		if (stat.size > MAX_INSPECTION_BYTES) {
+			return { inspection: { exists: true, size: stat.size, parseStatus: "tooLargeToInspect" } }
+		}
+		const raw = await withTimeout(fs.readFile(filePath, "utf8"), FILE_TIMEOUT_MS)
+		try {
+			const value: unknown = JSON.parse(raw)
+			return {
+				inspection: { exists: true, size: stat.size, parseStatus: "valid", topLevelShape: getShape(value) },
+				value,
+			}
+		} catch {
+			return { inspection: { exists: true, size: stat.size, parseStatus: "invalid" } }
+		}
+	} catch (error) {
+		if (typeof error === "object" && error !== null && "code" in error && error.code === "ENOENT") {
+			return { inspection: { exists: false } }
+		}
+		return { inspection: { exists: false, parseStatus: "unavailable" } }
+	}
+}
+
+function isHistoryItem(value: unknown): value is HistoryItem {
+	return value !== null && typeof value === "object" && "id" in value && typeof value.id === "string"
+}
+
+function isSafeTaskId(value: string): boolean {
+	return /^[A-Za-z0-9_-]{1,128}$/.test(value)
+}
+
+function hasParentCycle(item: HistoryItem, byId: Map<string, HistoryItem>): boolean {
+	const visited = new Set<string>()
+	let current: HistoryItem | undefined = item
+	while (current) {
+		if (visited.has(current.id)) return true
+		visited.add(current.id)
+		current = current.parentTaskId ? byId.get(current.parentTaskId) : undefined
+	}
+	return false
+}
+
+function selectRelevant(history: HistoryItem[], currentIds: string[]): HistoryItem[] {
+	const byId = new Map(history.map((item) => [item.id, item]))
+	const selected = new Set<string>()
+	const queue = [...currentIds]
+	if (queue.length === 0 && history[0]) queue.push(history[0].id)
+
+	while (queue.length > 0 && selected.size < MAX_TASKS) {
+		const id = queue.shift()
+		if (!id || selected.has(id)) continue
+		selected.add(id)
+		const item = byId.get(id)
+		if (!item) continue
+		for (const related of [item.rootTaskId, item.parentTaskId, item.awaitingChildId, ...(item.childIds ?? [])]) {
+			if (related && !selected.has(related)) queue.push(related)
+		}
+	}
+
+	return Array.from(selected, (id) => byId.get(id)).filter(
+		(item): item is HistoryItem => item !== undefined && isSafeTaskId(item.id),
+	)
+}
+
+export async function collectPersistenceDiagnostics(options: {
+	storagePath: string
+	history: HistoryItem[]
+	currentTaskIds: string[]
+	pseudonymize: (value: string) => string
+}): Promise<DiagnosticsPersistenceReport> {
+	const { storagePath, history, currentTaskIds, pseudonymize } = options
+	const tasksPath = path.join(storagePath, "tasks")
+	const relevant = selectRelevant(history, currentTaskIds)
+	const relevantIds = new Set(relevant.map((item) => item.id))
+	const byId = new Map(history.map((item) => [item.id, item]))
+	const indexResult = await inspectJson(path.join(tasksPath, GlobalFileNames.historyIndex))
+
+	let indexEntries: unknown[] | undefined
+	let indexVersion: number | undefined
+	if (indexResult.value !== null && typeof indexResult.value === "object" && !Array.isArray(indexResult.value)) {
+		const value = indexResult.value as Record<string, unknown>
+		indexVersion = typeof value.version === "number" ? value.version : undefined
+		indexEntries = Array.isArray(value.entries) ? value.entries : undefined
+	}
+	const indexIds = new Set(indexEntries?.filter(isHistoryItem).map((item) => item.id) ?? [])
+
+	const tasks = await Promise.all(
+		relevant.map(async (item) => {
+			const taskPath = path.join(tasksPath, item.id)
+			const [historyItemResult, uiMessagesResult] = await Promise.all([
+				inspectJson(path.join(taskPath, GlobalFileNames.historyItem)),
+				inspectJson(path.join(taskPath, GlobalFileNames.uiMessages)),
+			])
+			const messages = Array.isArray(uiMessagesResult.value) ? uiMessagesResult.value : undefined
+			const timestamps = (messages ?? [])
+				.map((message) =>
+					message !== null && typeof message === "object" && "ts" in message && typeof message.ts === "number"
+						? message.ts
+						: undefined,
+				)
+				.filter((timestamp): timestamp is number => timestamp !== undefined)
+			const findings: string[] = []
+			for (const related of [
+				item.rootTaskId,
+				item.parentTaskId,
+				item.awaitingChildId,
+				...(item.childIds ?? []),
+			]) {
+				if (related && !byId.has(related)) findings.push("missingReferencedTask")
+			}
+			if (item.awaitingChildId && item.status !== "delegated") findings.push("awaitingChildStatusMismatch")
+			if (item.parentTaskId && !byId.get(item.parentTaskId)?.childIds?.includes(item.id)) {
+				findings.push("parentChildMismatch")
+			}
+			if (hasParentCycle(item, byId)) findings.push("parentCycle")
+
+			return {
+				id: pseudonymize(item.id),
+				rootTask: item.rootTaskId ? pseudonymize(item.rootTaskId) : undefined,
+				parentTask: item.parentTaskId ? pseudonymize(item.parentTaskId) : undefined,
+				children: (item.childIds ?? []).slice(0, MAX_TASKS).map(pseudonymize),
+				status: item.status,
+				number: item.number,
+				historyItem: historyItemResult.inspection,
+				uiMessages: {
+					...uiMessagesResult.inspection,
+					messageCount: messages?.length,
+					firstTimestamp: timestamps[0],
+					lastTimestamp: timestamps.at(-1),
+				},
+				integrityFindings: Array.from(new Set(findings)),
+			}
+		}),
+	)
+
+	return {
+		cacheEntryCount: history.length,
+		index: {
+			...indexResult.inspection,
+			version: indexVersion,
+			entryCount: indexEntries?.length,
+			relevantEntriesPresent: Array.from(relevantIds).filter((id) => indexIds.has(id)).length,
+			cacheCountMatches: indexEntries ? indexEntries.length === history.length : undefined,
+		},
+		tasks,
+	}
+}
diff --git a/src/services/diagnostics/recorder.ts b/src/services/diagnostics/recorder.ts
new file mode 100644
index 0000000000..6193cadf6b
--- /dev/null
+++ b/src/services/diagnostics/recorder.ts
@@ -0,0 +1,24 @@
+import type { DiagnosticsStructuralEvent } from "./types"
+
+export class DiagnosticsRecorder {
+	private readonly events: DiagnosticsStructuralEvent[] = []
+	private totalEventCount = 0
+
+	constructor(private readonly capacity = 200) {}
+
+	record(event: Omit<DiagnosticsStructuralEvent, "timestamp"> & { timestamp?: string }): void {
+		this.totalEventCount++
+		this.events.push({ ...event, timestamp: event.timestamp ?? new Date().toISOString() })
+		if (this.events.length > this.capacity) {
+			this.events.splice(0, this.events.length - this.capacity)
+		}
+	}
+
+	snapshot(limit = 100): { events: DiagnosticsStructuralEvent[]; truncated: boolean } {
+		const boundedLimit = Math.max(0, Math.min(limit, this.capacity))
+		return {
+			events: this.events.slice(-boundedLimit),
+			truncated: this.totalEventCount > boundedLimit,
+		}
+	}
+}
diff --git a/src/services/diagnostics/report.ts b/src/services/diagnostics/report.ts
new file mode 100644
index 0000000000..e69bdfa788
--- /dev/null
+++ b/src/services/diagnostics/report.ts
@@ -0,0 +1,222 @@
+import { createHash, randomBytes } from "crypto"
+
+import type { HistoryItem, WebviewDiagnosticsSnapshot } from "@roo-code/types"
+
+import { collectPersistenceDiagnostics } from "./persistence"
+import type {
+	DiagnosticsProviderReport,
+	DiagnosticsProviderSource,
+	DiagnosticsProviderSourceSnapshot,
+	DiagnosticsReportV1,
+} from "./types"
+
+const WEBVIEW_TIMEOUT_MS = 1_000
+const MAX_STRING_LENGTH = 120
+const ALLOWED_THEME_VARIABLES = new Set([
+	"--vscode-foreground",
+	"--vscode-editor-background",
+	"--vscode-editor-foreground",
+	"--vscode-sideBar-background",
+	"--vscode-sideBar-foreground",
+])
+
+function withTimeout<T>(operation: Promise<T>, timeoutMs: number): Promise<T | undefined> {
+	return new Promise((resolve) => {
+		const timeout = setTimeout(() => resolve(undefined), timeoutMs)
+		void operation.then(
+			(value) => {
+				clearTimeout(timeout)
+				resolve(value)
+			},
+			() => {
+				clearTimeout(timeout)
+				resolve(undefined)
+			},
+		)
+	})
+}
+
+function safeToken(value: unknown, maxLength = MAX_STRING_LENGTH): string | undefined {
+	if (typeof value !== "string") return undefined
+	const trimmed = value.slice(0, maxLength)
+	return /^[\w .#(),%:/-]*$/.test(trimmed) && !trimmed.includes("://") ? trimmed : undefined
+}
+
+function safeCount(value: unknown): number | undefined {
+	return typeof value === "number" && Number.isFinite(value) && value >= 0 ? value : undefined
+}
+
+export function sanitizeWebviewDiagnostics(
+	snapshot: WebviewDiagnosticsSnapshot,
+	pseudonymize: (value: string) => string,
+): Record<string, unknown> {
+	const variables = Object.fromEntries(
+		Object.entries(snapshot.theme?.variables ?? {})
+			.filter(([key]) => ALLOWED_THEME_VARIABLES.has(key))
+			.map(([key, value]) => [key, safeToken(value, 64)])
+			.filter((entry): entry is [string, string] => entry[1] !== undefined),
+	)
+	return {
+		capturedAt: safeToken(snapshot.capturedAt),
+		didHydrateState: typeof snapshot.didHydrateState === "boolean" ? snapshot.didHydrateState : undefined,
+		documentReadyState: safeToken(snapshot.documentReadyState),
+		documentVisibilityState: safeToken(snapshot.documentVisibilityState),
+		activeView: safeToken(snapshot.activeView, 40),
+		rootMounted: typeof snapshot.rootMounted === "boolean" ? snapshot.rootMounted : undefined,
+		rootChildCount: safeCount(snapshot.rootChildCount),
+		lastReceivedStateSequence: safeCount(snapshot.lastReceivedStateSequence),
+		lastAppliedStateSequence: safeCount(snapshot.lastAppliedStateSequence),
+		staleStateRejectionCount: safeCount(snapshot.staleStateRejectionCount),
+		unknownMessageUpdateCount: safeCount(snapshot.unknownMessageUpdateCount),
+		currentTask: snapshot.currentTaskId ? pseudonymize(snapshot.currentTaskId) : undefined,
+		chatMessageCount: safeCount(snapshot.chatMessageCount),
+		historyItemCount: safeCount(snapshot.historyItemCount),
+		todoCount: safeCount(snapshot.todoCount),
+		viewport: snapshot.viewport
+			? {
+					width: safeCount(snapshot.viewport.width),
+					height: safeCount(snapshot.viewport.height),
+					devicePixelRatio: safeCount(snapshot.viewport.devicePixelRatio),
+				}
+			: undefined,
+		theme: snapshot.theme
+			? {
+					kind: safeCount(snapshot.theme.kind),
+					identifier: safeToken(snapshot.theme.identifier, 80),
+					bodyForeground: safeToken(snapshot.theme.bodyForeground, 64),
+					bodyBackground: safeToken(snapshot.theme.bodyBackground, 64),
+					rootForeground: safeToken(snapshot.theme.rootForeground, 64),
+					rootBackground: safeToken(snapshot.theme.rootBackground, 64),
+					variables,
+				}
+			: undefined,
+		error: snapshot.error
+			? {
+					name: safeToken(snapshot.error.name, 40),
+					fingerprint: safeToken(snapshot.error.fingerprint, 128),
+				}
+			: undefined,
+	}
+}
+
+function mergeHistory(snapshots: DiagnosticsProviderSourceSnapshot[]): HistoryItem[] {
+	const byId = new Map<string, HistoryItem>()
+	for (const snapshot of snapshots) {
+		for (const item of snapshot.history) byId.set(item.id, item)
+	}
+	return Array.from(byId.values()).sort((a, b) => b.ts - a.ts)
+}
+
+export async function buildDiagnosticsReport(options: {
+	providers: DiagnosticsProviderSource[]
+	storagePath: string
+	version: string
+	releaseChannel: string
+	environment: DiagnosticsReportV1["environment"]
+}): Promise<DiagnosticsReportV1> {
+	const salt = randomBytes(32)
+	const pseudonymize = (value: string) =>
+		`task-${createHash("sha256").update(salt).update(value).digest("hex").slice(0, 12)}`
+	const collectionErrors: string[] = []
+	const snapshots = options.providers.map((provider, index) => {
+		try {
+			return provider.getDiagnosticsSnapshot()
+		} catch {
+			collectionErrors.push(`provider-${index + 1}:snapshot-failed`)
+			return {
+				renderContext: "sidebar" as const,
+				disposed: false,
+				viewPresent: false,
+				visible: false,
+				launched: false,
+				taskHistoryInitialized: false,
+				taskCount: 0,
+				currentMessageCount: 0,
+				currentTodoCount: 0,
+				history: [],
+				events: [],
+				eventsTruncated: false,
+			}
+		}
+	})
+
+	const providerReports: DiagnosticsProviderReport[] = await Promise.all(
+		options.providers.map(async (provider, index) => {
+			const snapshot = snapshots[index]
+			const webview = await withTimeout(
+				provider.requestWebviewDiagnostics(WEBVIEW_TIMEOUT_MS),
+				WEBVIEW_TIMEOUT_MS + 100,
+			)
+			if (!webview && snapshot.viewPresent) collectionErrors.push(`provider-${index + 1}:webview-unavailable`)
+			return {
+				instance: index + 1,
+				renderContext: snapshot.renderContext,
+				disposed: snapshot.disposed,
+				viewPresent: snapshot.viewPresent,
+				visible: snapshot.visible,
+				launched: snapshot.launched,
+				taskHistoryInitialized: snapshot.taskHistoryInitialized,
+				taskCount: snapshot.taskCount,
+				currentTask: snapshot.currentTaskId ? pseudonymize(snapshot.currentTaskId) : undefined,
+				currentMessageCount: snapshot.currentMessageCount,
+				currentTodoCount: snapshot.currentTodoCount,
+				events: snapshot.events.slice(-100).map((event) => ({
+					timestamp: safeToken(event.timestamp, 40) ?? "invalid",
+					boundary: event.boundary,
+					phase: event.phase,
+					type: safeToken(event.type, 80),
+					action: safeToken(event.action, 80),
+					elapsedMs: safeCount(event.elapsedMs),
+					stateSequence: safeCount(event.stateSequence),
+					messageCount: safeCount(event.messageCount),
+					task: event.taskId ? pseudonymize(event.taskId) : undefined,
+				})),
+				eventsTruncated: snapshot.eventsTruncated || snapshot.events.length > 100,
+				webviewResponse: webview ? "received" : "unavailable",
+				webview: webview ? sanitizeWebviewDiagnostics(webview, pseudonymize) : undefined,
+			}
+		}),
+	)
+
+	let persistence: DiagnosticsReportV1["persistence"]
+	try {
+		persistence = await collectPersistenceDiagnostics({
+			storagePath: options.storagePath,
+			history: mergeHistory(snapshots),
+			currentTaskIds: snapshots.flatMap((snapshot) => [
+				...(snapshot.currentTaskId ? [snapshot.currentTaskId] : []),
+				...snapshot.events
+					.filter((event) => event.boundary === "task-navigation" && event.taskId)
+					.map((event) => event.taskId!),
+			]),
+			pseudonymize,
+		})
+	} catch {
+		collectionErrors.push("persistence:collection-failed")
+		persistence = { cacheEntryCount: 0, index: { exists: false, parseStatus: "unavailable" }, tasks: [] }
+	}
+
+	return {
+		schemaVersion: 1,
+		capturedAt: new Date().toISOString(),
+		privacy: {
+			conversationContentIncluded: false,
+			uploaded: false,
+			excluded: [
+				"conversation content",
+				"task titles and tool payloads",
+				"API history and settings values",
+				"secrets, tokens, and identity",
+				"machine identifiers and hostnames",
+				"workspace paths and repository details",
+				"raw task and workspace identifiers",
+				"raw logs",
+			],
+		},
+		extension: { version: options.version, releaseChannel: options.releaseChannel },
+		environment: options.environment,
+		providers: providerReports,
+		persistence,
+		collectionErrors,
+	}
+}
diff --git a/src/services/diagnostics/requestBroker.ts b/src/services/diagnostics/requestBroker.ts
new file mode 100644
index 0000000000..e03ecf574f
--- /dev/null
+++ b/src/services/diagnostics/requestBroker.ts
@@ -0,0 +1,46 @@
+import { randomUUID } from "crypto"
+
+import type { WebviewDiagnosticsSnapshot } from "@roo-code/types"
+
+export class DiagnosticsRequestBroker {
+	private readonly pending = new Map<
+		string,
+		{ resolve: (snapshot: WebviewDiagnosticsSnapshot | undefined) => void; timeout: ReturnType<typeof setTimeout> }
+	>()
+
+	request(
+		send: (requestId: string) => Promise<void>,
+		timeoutMs: number,
+	): Promise<WebviewDiagnosticsSnapshot | undefined> {
+		const requestId = randomUUID()
+		return new Promise((resolve) => {
+			const timeout = setTimeout(() => {
+				this.pending.delete(requestId)
+				resolve(undefined)
+			}, timeoutMs)
+			this.pending.set(requestId, { resolve, timeout })
+			void send(requestId).catch(() => {
+				clearTimeout(timeout)
+				this.pending.delete(requestId)
+				resolve(undefined)
+			})
+		})
+	}
+
+	resolve(requestId: string, snapshot: WebviewDiagnosticsSnapshot | undefined): boolean {
+		const pending = this.pending.get(requestId)
+		if (!pending) return false
+		clearTimeout(pending.timeout)
+		this.pending.delete(requestId)
+		pending.resolve(snapshot)
+		return true
+	}
+
+	dispose(): void {
+		for (const pending of this.pending.values()) {
+			clearTimeout(pending.timeout)
+			pending.resolve(undefined)
+		}
+		this.pending.clear()
+	}
+}
diff --git a/src/services/diagnostics/types.ts b/src/services/diagnostics/types.ts
new file mode 100644
index 0000000000..48a91d2d14
--- /dev/null
+++ b/src/services/diagnostics/types.ts
@@ -0,0 +1,115 @@
+import type { HistoryItem, WebviewDiagnosticsSnapshot } from "@roo-code/types"
+
+export type DiagnosticsEventPhase = "start" | "success" | "failure"
+
+export interface DiagnosticsStructuralEvent {
+	timestamp: string
+	boundary: "provider" | "webview-in" | "webview-out" | "task-history" | "task-navigation"
+	phase: DiagnosticsEventPhase
+	type?: string
+	action?: string
+	elapsedMs?: number
+	stateSequence?: number
+	taskId?: string
+	messageCount?: number
+}
+
+export interface DiagnosticsProviderSourceSnapshot {
+	renderContext: "sidebar" | "editor"
+	disposed: boolean
+	viewPresent: boolean
+	visible: boolean
+	launched: boolean
+	taskHistoryInitialized: boolean
+	taskCount: number
+	currentTaskId?: string
+	currentMessageCount: number
+	currentTodoCount: number
+	history: HistoryItem[]
+	events: DiagnosticsStructuralEvent[]
+	eventsTruncated: boolean
+}
+
+export interface DiagnosticsProviderSource {
+	getDiagnosticsSnapshot(): DiagnosticsProviderSourceSnapshot
+	requestWebviewDiagnostics(timeoutMs?: number): Promise<WebviewDiagnosticsSnapshot | undefined>
+}
+
+export interface DiagnosticsReportV1 {
+	schemaVersion: 1
+	capturedAt: string
+	privacy: {
+		conversationContentIncluded: false
+		uploaded: false
+		excluded: string[]
+	}
+	extension: {
+		version: string
+		releaseChannel: string
+	}
+	environment: {
+		vscodeVersion: string
+		appName: string
+		uiKind: "desktop" | "web" | "unknown"
+		platform: string
+		architecture: string
+		locale: string
+		remote: boolean
+		workspaceFolderCount: number
+		customStorageConfigured: boolean
+		colorThemeKind: "light" | "dark" | "highContrast" | "highContrastLight" | "unknown"
+	}
+	providers: DiagnosticsProviderReport[]
+	persistence: DiagnosticsPersistenceReport
+	collectionErrors: string[]
+}
+
+export interface DiagnosticsProviderReport {
+	instance: number
+	renderContext: "sidebar" | "editor"
+	disposed: boolean
+	viewPresent: boolean
+	visible: boolean
+	launched: boolean
+	taskHistoryInitialized: boolean
+	taskCount: number
+	currentTask?: string
+	currentMessageCount: number
+	currentTodoCount: number
+	events: Array<Omit<DiagnosticsStructuralEvent, "taskId"> & { task?: string }>
+	eventsTruncated: boolean
+	webviewResponse: "received" | "unavailable"
+	webview?: Record<string, unknown>
+}
+
+export interface DiagnosticsFileInspection {
+	exists: boolean
+	size?: number
+	parseStatus?: "valid" | "invalid" | "tooLargeToInspect" | "unavailable"
+	topLevelShape?: "array" | "object" | "other"
+}
+
+export interface DiagnosticsPersistenceReport {
+	cacheEntryCount: number
+	index: DiagnosticsFileInspection & {
+		version?: number
+		entryCount?: number
+		relevantEntriesPresent?: number
+		cacheCountMatches?: boolean
+	}
+	tasks: Array<{
+		id: string
+		rootTask?: string
+		parentTask?: string
+		children: string[]
+		status?: HistoryItem["status"]
+		number?: number
+		historyItem: DiagnosticsFileInspection
+		uiMessages: DiagnosticsFileInspection & {
+			messageCount?: number
+			firstTimestamp?: number
+			lastTimestamp?: number
+		}
+		integrityFindings: string[]
+	}>
+}
diff --git a/webview-ui/src/App.tsx b/webview-ui/src/App.tsx
index 0521499dbb..4cc7d9a3d0 100644
--- a/webview-ui/src/App.tsx
+++ b/webview-ui/src/App.tsx
@@ -22,6 +22,7 @@ import ErrorBoundary from "./components/ErrorBoundary"
 import { useAddNonInteractiveClickListener } from "./components/ui/hooks/useNonInteractiveClick"
 import { TooltipProvider } from "./components/ui/tooltip"
 import { STANDARD_TOOLTIP_DELAY } from "./components/ui/standard-tooltip"
+import { recordDiagnosticsActiveTab } from "./utils/diagnostics"
 
 type Tab = "settings" | "history" | "chat" | "marketplace"
 
@@ -164,6 +165,8 @@ const App = () => {
 
 	useEvent("message", onMessage)
 
+	useEffect(() => recordDiagnosticsActiveTab(tab), [tab])
+
 	useEffect(() => {
 		if (shouldShowAnnouncement && tab === "chat") {
 			setShowAnnouncement(true)
diff --git a/webview-ui/src/components/ErrorBoundary.tsx b/webview-ui/src/components/ErrorBoundary.tsx
index 51500570d0..3f3ecdc901 100644
--- a/webview-ui/src/components/ErrorBoundary.tsx
+++ b/webview-ui/src/components/ErrorBoundary.tsx
@@ -3,6 +3,7 @@ import { telemetryClient } from "@src/utils/TelemetryClient"
 import { withTranslation, WithTranslation } from "react-i18next"
 import { enhanceErrorWithSourceMaps } from "@src/utils/sourceMapUtils"
 import { EXTERNAL_LINKS } from "@src/constants/externalLinks"
+import { recordDiagnosticsError } from "@src/utils/diagnostics"
 
 type ErrorProps = {
 	children: React.ReactNode
@@ -21,6 +22,7 @@ class ErrorBoundary extends Component<ErrorProps, ErrorState> {
 	}
 
 	static getDerivedStateFromError(error: unknown) {
+		recordDiagnosticsError("errorBoundary", error)
 		let errorMessage = ""
 
 		if (error instanceof Error) {
diff --git a/webview-ui/src/context/ExtensionStateContext.tsx b/webview-ui/src/context/ExtensionStateContext.tsx
index d0d4e37afa..62004818b2 100644
--- a/webview-ui/src/context/ExtensionStateContext.tsx
+++ b/webview-ui/src/context/ExtensionStateContext.tsx
@@ -1,4 +1,4 @@
-import React, { createContext, useCallback, useEffect, useState } from "react"
+import React, { createContext, useCallback, useEffect, useRef, useState } from "react"
 
 import {
 	type ProviderSettings,
@@ -32,6 +32,12 @@ import { experimentDefault } from "@roo/experiments"
 
 import { vscode } from "@src/utils/vscode"
 import { convertTextMateToHljs } from "@src/utils/textMateToHljs"
+import {
+	recordDiagnosticsHydration,
+	recordDiagnosticsExtensionState,
+	recordDiagnosticsStateSequence,
+	recordDiagnosticsUnknownMessageUpdate,
+} from "@src/utils/diagnostics"
 
 export interface ExtensionStateContextType extends ExtensionState {
 	historyPreviewCollapsed?: boolean // Add the new state property
@@ -272,6 +278,17 @@ export const ExtensionStateContextProvider: React.FC<{ children: React.ReactNode
 		includeCurrentCost: true,
 		lockApiConfigAcrossModes: false,
 	})
+	const stateRef = useRef(state)
+	stateRef.current = state
+
+	useEffect(() => {
+		recordDiagnosticsExtensionState({
+			currentTaskId: state.currentTaskId,
+			chatMessageCount: state.clineMessages.length,
+			historyItemCount: state.taskHistory.length,
+			todoCount: state.currentTaskTodos?.length ?? 0,
+		})
+	}, [state.currentTaskId, state.clineMessages.length, state.taskHistory.length, state.currentTaskTodos?.length])
 
 	const [didHydrateState, setDidHydrateState] = useState(false)
 	const [showWelcome, setShowWelcome] = useState(false)
@@ -316,9 +333,11 @@ export const ExtensionStateContextProvider: React.FC<{ children: React.ReactNode
 			switch (message.type) {
 				case "state": {
 					const newState = message.state ?? {}
+					recordDiagnosticsStateSequence(newState.clineMessagesSeq, newState.clineMessages !== undefined)
 					setState((prevState) => mergeExtensionState(prevState, newState))
 					setShowWelcome(!checkExistKey(newState.apiConfiguration, newState.zooCodeIsAuthenticated))
 					setDidHydrateState(true)
+					recordDiagnosticsHydration(true)
 					// Update alwaysAllowFollowupQuestions if present in state message
 					if ((newState as any).alwaysAllowFollowupQuestions !== undefined) {
 						setAlwaysAllowFollowupQuestions((newState as any).alwaysAllowFollowupQuestions)
@@ -380,6 +399,9 @@ export const ExtensionStateContextProvider: React.FC<{ children: React.ReactNode
 				}
 				case "messageUpdated": {
 					const clineMessage = message.clineMessage!
+					if (!stateRef.current.clineMessages.some((existing) => existing.ts === clineMessage.ts)) {
+						recordDiagnosticsUnknownMessageUpdate()
+					}
 					setState((prevState) => {
 						// worth noting it will never be possible for a more up-to-date message to be sent here or in normal messages post since the presentAssistantContent function uses lock
 						const lastIndex = findLastIndex(prevState.clineMessages, (msg) => msg.ts === clineMessage.ts)
diff --git a/webview-ui/src/index.tsx b/webview-ui/src/index.tsx
index 4793c0272a..fd43c8b332 100644
--- a/webview-ui/src/index.tsx
+++ b/webview-ui/src/index.tsx
@@ -6,6 +6,9 @@ import App from "./App"
 import "../node_modules/@vscode/codicons/dist/codicon.css"
 
 import { getHighlighter } from "./utils/highlighter"
+import { installWebviewDiagnostics } from "./utils/diagnostics"
+
+installWebviewDiagnostics()
 
 // Initialize Shiki early to hide initialization latency (async)
 getHighlighter().catch((error: Error) => console.error("Failed to initialize Shiki highlighter:", error))
diff --git a/webview-ui/src/utils/__tests__/diagnostics.spec.ts b/webview-ui/src/utils/__tests__/diagnostics.spec.ts
new file mode 100644
index 0000000000..4471555973
--- /dev/null
+++ b/webview-ui/src/utils/__tests__/diagnostics.spec.ts
@@ -0,0 +1,109 @@
+import {
+	createWebviewDiagnosticsSnapshot,
+	installWebviewDiagnostics,
+	recordDiagnosticsActiveTab,
+	recordDiagnosticsError,
+	recordDiagnosticsExtensionState,
+	recordDiagnosticsHydration,
+	recordDiagnosticsStateSequence,
+	recordDiagnosticsUnknownMessageUpdate,
+} from "../diagnostics"
+import { vscode } from "../vscode"
+
+vi.mock("../vscode", () => ({
+	vscode: {
+		postMessage: vi.fn(),
+	},
+}))
+
+describe("webview diagnostics", () => {
+	beforeAll(() => {
+		const root = document.createElement("div")
+		root.id = "root"
+		root.append(document.createElement("div"))
+		document.body.append(root)
+		document.documentElement.style.setProperty("--vscode-foreground", "#eeeeee")
+		document.documentElement.style.color = "rgb(238, 238, 238)"
+		document.documentElement.style.backgroundColor = "rgb(30, 30, 30)"
+	})
+
+	afterAll(() => {
+		document.getElementById("root")?.remove()
+		document.documentElement.removeAttribute("style")
+	})
+
+	it("collects a bounded structural snapshot without error paths", () => {
+		recordDiagnosticsHydration(true)
+		recordDiagnosticsActiveTab("settings")
+		recordDiagnosticsExtensionState({
+			currentTaskId: "task-123",
+			chatMessageCount: 4,
+			historyItemCount: 7,
+			todoCount: 2,
+		})
+
+		recordDiagnosticsStateSequence(25, true)
+		recordDiagnosticsStateSequence(24, true)
+
+		for (let update = 0; update < 12; update += 1) {
+			recordDiagnosticsUnknownMessageUpdate()
+		}
+
+		recordDiagnosticsError(
+			"windowError",
+			new Error("Secret content at /Users/example/private/file.ts and C:\\Users\\example\\secret.ts"),
+		)
+
+		const snapshot = createWebviewDiagnosticsSnapshot()
+
+		expect(snapshot.didHydrateState).toBe(true)
+		expect(snapshot.activeView).toBe("settings")
+		expect(snapshot).toMatchObject({
+			currentTaskId: "task-123",
+			chatMessageCount: 4,
+			historyItemCount: 7,
+			todoCount: 2,
+		})
+		expect(snapshot.lastReceivedStateSequence).toBe(24)
+		expect(snapshot.lastAppliedStateSequence).toBe(25)
+		expect(snapshot.staleStateRejectionCount).toBe(1)
+		expect(snapshot.unknownMessageUpdateCount).toBe(12)
+		expect(snapshot).toMatchObject({ rootMounted: true, rootChildCount: 1 })
+		expect(snapshot.theme).toMatchObject({
+			rootForeground: "rgb(238, 238, 238)",
+			rootBackground: "rgb(30, 30, 30)",
+		})
+		expect(snapshot.theme?.variables?.["--vscode-foreground"]).toBe("#eeeeee")
+		expect(snapshot.error).toMatchObject({ name: "Error", fingerprint: expect.stringMatching(/^fnv1a-/) })
+		expect(snapshot.error).not.toHaveProperty("message")
+		expect(snapshot.error).not.toHaveProperty("stackLocations")
+	})
+
+	it("responds only to valid diagnostics requests and contains posting failures", () => {
+		installWebviewDiagnostics()
+
+		window.dispatchEvent(new MessageEvent("message", { data: { type: "other", requestId: "ignored" } }))
+		expect(vscode.postMessage).not.toHaveBeenCalled()
+
+		window.dispatchEvent(
+			new MessageEvent("message", { data: { type: "diagnosticsRequest", requestId: "request-1" } }),
+		)
+
+		expect(vscode.postMessage).toHaveBeenCalledWith(
+			expect.objectContaining({
+				type: "diagnosticsResponse",
+				requestId: "request-1",
+				diagnostics: expect.objectContaining({ activeView: "settings" }),
+			}),
+		)
+
+		vi.mocked(vscode.postMessage).mockImplementationOnce(() => {
+			throw new Error("disconnected")
+		})
+		expect(() => {
+			window.dispatchEvent(
+				new MessageEvent("message", { data: { type: "diagnosticsRequest", requestId: "request-2" } }),
+			)
+		}).not.toThrow()
+	})
+})
diff --git a/webview-ui/src/utils/diagnostics.ts b/webview-ui/src/utils/diagnostics.ts
new file mode 100644
index 0000000000..eb56db9dfc
--- /dev/null
+++ b/webview-ui/src/utils/diagnostics.ts
@@ -0,0 +1,242 @@
+import type { WebviewDiagnosticsSnapshot } from "@roo-code/types"
+
+import { vscode } from "./vscode"
+
+const VSCODE_CSS_VARIABLES = [
+	"--vscode-foreground",
+	"--vscode-editor-background",
+	"--vscode-editor-foreground",
+	"--vscode-sideBar-background",
+	"--vscode-sideBar-foreground",
+] as const
+
+type DiagnosticsErrorSource = "errorBoundary" | "windowError" | "unhandledRejection"
+type DiagnosticsSnapshot = WebviewDiagnosticsSnapshot & { didHydrateState: boolean }
+
+const diagnosticsState = {
+	didHydrateState: false,
+	lastReceivedStateSequence: undefined as number | undefined,
+	lastAppliedStateSequence: undefined as number | undefined,
+	staleStateRejectionCount: 0,
+	unknownMessageUpdateCount: 0,
+	activeView: undefined as string | undefined,
+	currentTaskId: undefined as string | undefined,
+	chatMessageCount: 0,
+	historyItemCount: 0,
+	todoCount: 0,
+	error: undefined as WebviewDiagnosticsSnapshot["error"],
+}
+
+const fingerprint = (value: string): string => {
+	let hash = 2166136261
+	for (let index = 0; index < value.length; index += 1) {
+		hash ^= value.charCodeAt(index)
+		hash = Math.imul(hash, 16777619)
+	}
+	return `fnv1a-${(hash >>> 0).toString(16).padStart(8, "0")}`
+}
+
+const getErrorName = (error: unknown): string => {
+	if (!(error instanceof Error)) {
+		return "UnknownError"
+	}
+
+	const name = error.name.replace(/[^A-Za-z0-9_.-]/g, "").slice(0, 40)
+	return name || "Error"
+}
+
+const getErrorFingerprintSource = (source: DiagnosticsErrorSource, error: unknown): string => {
+	if (error instanceof Error) {
+		const message = error.message.slice(0, 1_000).replace(/(?:[A-Za-z]:\\|\\\\|\/)\S+/g, "[path]")
+		return `${source}:${error.name}:${message}`
+	}
+	return `${source}:${typeof error}`
+}
+
+export const recordDiagnosticsHydration = (didHydrateState: boolean) => {
+	diagnosticsState.didHydrateState = didHydrateState
+}
+
+export const recordDiagnosticsExtensionState = (state: {
+	currentTaskId?: string
+	chatMessageCount: number
+	historyItemCount: number
+	todoCount: number
+}) => {
+	diagnosticsState.currentTaskId = state.currentTaskId
+	diagnosticsState.chatMessageCount = state.chatMessageCount
+	diagnosticsState.historyItemCount = state.historyItemCount
+	diagnosticsState.todoCount = state.todoCount
+}
+
+export const recordDiagnosticsStateSequence = (sequence: unknown, hasMessages: boolean) => {
+	if (typeof sequence !== "number" || !Number.isSafeInteger(sequence) || sequence < 0) {
+		return
+	}
+
+	diagnosticsState.lastReceivedStateSequence = sequence
+	if (!hasMessages) {
+		return
+	}
+
+	if (
+		diagnosticsState.lastAppliedStateSequence !== undefined &&
+		sequence <= diagnosticsState.lastAppliedStateSequence
+	) {
+		diagnosticsState.staleStateRejectionCount = Math.min(
+			diagnosticsState.staleStateRejectionCount + 1,
+			Number.MAX_SAFE_INTEGER,
+		)
+		return
+	}
+
+	diagnosticsState.lastAppliedStateSequence = sequence
+}
+
+export const recordDiagnosticsUnknownMessageUpdate = () => {
+	diagnosticsState.unknownMessageUpdateCount = Math.min(
+		diagnosticsState.unknownMessageUpdateCount + 1,
+		Number.MAX_SAFE_INTEGER,
+	)
+}
+
+export const recordDiagnosticsActiveTab = (activeView: string) => {
+	diagnosticsState.activeView = activeView
+}
+
+export const recordDiagnosticsError = (source: DiagnosticsErrorSource, error: unknown) => {
+	try {
+		diagnosticsState.error = {
+			name: getErrorName(error),
+			fingerprint: fingerprint(getErrorFingerprintSource(source, error)),
+		}
+	} catch {
+		diagnosticsState.error = {
+			name: "UnknownError",
+			fingerprint: fingerprint(`${source}:unavailable`),
+		}
+	}
+}
+
+const readDocumentSnapshot = (): Pick<
+	WebviewDiagnosticsSnapshot,
+	"documentReadyState" | "documentVisibilityState" | "rootMounted" | "rootChildCount"
+> => {
+	if (typeof document === "undefined") {
+		return {}
+	}
+
+	try {
+		const root = document.getElementById("root")
+		return {
+			documentReadyState: document.readyState,
+			documentVisibilityState: document.visibilityState,
+			rootMounted: root?.hasChildNodes() ?? false,
+			rootChildCount: root?.childElementCount ?? 0,
+		}
+	} catch {
+		return {}
+	}
+}
+
+const readViewportSnapshot = (): WebviewDiagnosticsSnapshot["viewport"] => {
+	if (typeof window === "undefined") {
+		return undefined
+	}
+
+	const { innerWidth, innerHeight, devicePixelRatio } = window
+	if (![innerWidth, innerHeight, devicePixelRatio].every(Number.isFinite)) {
+		return undefined
+	}
+
+	return { width: innerWidth, height: innerHeight, devicePixelRatio }
+}
+
+const readThemeSnapshot = (): WebviewDiagnosticsSnapshot["theme"] => {
+	if (typeof window === "undefined" || typeof document === "undefined") {
+		return undefined
+	}
+
+	try {
+		const bodyStyle = window.getComputedStyle(document.body)
+		const rootStyle = window.getComputedStyle(document.documentElement)
+		const variables = Object.fromEntries(
+			VSCODE_CSS_VARIABLES.map((name) => [name, rootStyle.getPropertyValue(name).trim()]).filter(
+				(entry) => entry[1] !== "",
+			),
+		)
+
+		return {
+			bodyForeground: bodyStyle.color || undefined,
+			bodyBackground: bodyStyle.backgroundColor || undefined,
+			rootForeground: rootStyle.color || undefined,
+			rootBackground: rootStyle.backgroundColor || undefined,
+			variables,
+		}
+	} catch {
+		return undefined
+	}
+}
+
+export const createWebviewDiagnosticsSnapshot = (): DiagnosticsSnapshot => ({
+	capturedAt: new Date().toISOString(),
+	didHydrateState: diagnosticsState.didHydrateState,
+	...readDocumentSnapshot(),
+	activeView: diagnosticsState.activeView,
+	lastReceivedStateSequence: diagnosticsState.lastReceivedStateSequence,
+	lastAppliedStateSequence: diagnosticsState.lastAppliedStateSequence,
+	staleStateRejectionCount: diagnosticsState.staleStateRejectionCount,
+	unknownMessageUpdateCount: diagnosticsState.unknownMessageUpdateCount,
+	currentTaskId: diagnosticsState.currentTaskId,
+	chatMessageCount: diagnosticsState.chatMessageCount,
+	historyItemCount: diagnosticsState.historyItemCount,
+	todoCount: diagnosticsState.todoCount,
+	viewport: readViewportSnapshot(),
+	theme: readThemeSnapshot(),
+	error: diagnosticsState.error ? { ...diagnosticsState.error } : undefined,
+})
+
+const isDiagnosticsRequest = (value: unknown): value is { type: "diagnosticsRequest"; requestId: string } => {
+	if (typeof value !== "object" || value === null) {
+		return false
+	}
+
+	const message = value as Record<string, unknown>
+	return (
+		message.type === "diagnosticsRequest" && typeof message.requestId === "string" && message.requestId.length > 0
+	)
+}
+
+let installedWindow: Window | undefined
+
+export const installWebviewDiagnostics = () => {
+	if (typeof window === "undefined" || installedWindow === window) {
+		return
+	}
+
+	installedWindow = window
+
+	window.addEventListener("message", (event) => {
+		if (!isDiagnosticsRequest(event.data)) {
+			return
+		}
+
+		try {
+			vscode.postMessage({
+				type: "diagnosticsResponse",
+				requestId: event.data.requestId,
+				diagnostics: createWebviewDiagnosticsSnapshot(),
+			})
+		} catch {
+			// Diagnostics must never destabilize an already unhealthy webview.
+		}
+	})
+
+	window.addEventListener("error", (event) => {
+		recordDiagnosticsError("windowError", event.error ?? event.message)
+	})
+
+	window.addEventListener("unhandledrejection", (event) => {
+		recordDiagnosticsError("unhandledRejection", event.reason)
+	})
+}