diff --git a/.changeset/calm-metrics-retry.md b/.changeset/calm-metrics-retry.md
new file mode 100644
index 0000000..402685a
--- /dev/null
+++ b/.changeset/calm-metrics-retry.md
@@ -0,0 +1,5 @@
+---
+'@logdash/node': patch
+---
+
+fix: retry only the metric that failed, so a failed request no longer re-applies `mutateMetric` changes that already went through
diff --git a/.changeset/config.json b/.changeset/config.json
index d5e9940..9bdce4c 100644
--- a/.changeset/config.json
+++ b/.changeset/config.json
@@ -1,11 +1,11 @@
 {
-  "$schema": "https://unpkg.com/@changesets/config@3.0.5/schema.json",
-  "changelog": "@changesets/cli/changelog",
-  "commit": false,
-  "fixed": [],
-  "linked": [],
-  "access": "public",
-  "baseBranch": "main",
-  "updateInternalDependencies": "patch",
-  "ignore": []
+	"$schema": "https://unpkg.com/@changesets/config@3.0.5/schema.json",
+	"changelog": "@changesets/cli/changelog",
+	"commit": false,
+	"fixed": [],
+	"linked": [],
+	"access": "public",
+	"baseBranch": "main",
+	"updateInternalDependencies": "patch",
+	"ignore": []
 }
diff --git a/.changeset/tidy-apps-wave.md b/.changeset/tidy-apps-wave.md
new file mode 100644
index 0000000..8c6117d
--- /dev/null
+++ b/.changeset/tidy-apps-wave.md
@@ -0,0 +1,5 @@
+---
+'@logdash/node': minor
+---
+
+feat: add `app` option that names the app sending each log and metric
diff --git a/.prettierrc b/.prettierrc
index ed1c0bc..1ba6ef0 100644
--- a/.prettierrc
+++ b/.prettierrc
@@ -1,12 +1,12 @@
 {
-  "useTabs": true,
-  "singleQuote": true,
-  "trailingComma": "all",
-  "printWidth": 80,
-  "semi": true,
-  "proseWrap": "preserve",
-  "endOfLine": "lf",
-  "tabWidth": 4,
-  "arrowParens": "always",
-  "htmlWhitespaceSensitivity": "ignore"
+	"useTabs": true,
+	"singleQuote": true,
+	"trailingComma": "all",
+	"printWidth": 80,
+	"semi": true,
+	"proseWrap": "preserve",
+	"endOfLine": "lf",
+	"tabWidth": 4,
+	"arrowParens": "always",
+	"htmlWhitespaceSensitivity": "ignore"
 }
diff --git a/README.md b/README.md
index 5f4a1ed..996e45f 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,24 @@ authLogdash.info('User logged in');
 authLogdash.error('Authentication failed');
 ```
 
+## Apps
+
+A domain has one domain key, shared by all of its apps, for example a desktop app, an API and a landing page.
+Set `app` to name this app, so the dashboard can filter logs and metrics by app.
+Logdash creates the app when its first log or metric arrives.
+
+```typescript
+const logdash = new Logdash('<your-domain-key>', { app: 'desktop' });
+
+logdash.info('Window opened');
+
+// Namespaced instances keep the app
+const sidebarLogdash = logdash.withNamespace('sidebar');
+sidebarLogdash.info('Sidebar collapsed');
+```
+
+Older service keys ignore `app`.
+
 ## Metrics
 
 ```typescript
@@ -70,6 +88,7 @@ new Logdash(apiKey?, options?)
 | `apiKey`          | no       | -                        | Api key used to authorize against logdash servers. If you don't provide one, logs will be logged into local console only |
 | `options.host`    | no       | `https://api.logdash.io` | Custom API host, useful with self-hosted instances                                                                       |
 | `options.verbose` | no       | `false`                  | Useful for debugging purposes                                                                                            |
+| `options.app`     | no       | -                        | Name of the app that sends the logs and metrics, for example `desktop` or `api`. See [Apps](#apps)                       |
 
 ## License
 
diff --git a/package.json b/package.json
index 6ff47ef..a6a3109 100644
--- a/package.json
+++ b/package.json
@@ -1,50 +1,50 @@
 {
-  "name": "@logdash/node",
-  "version": "1.0.2",
-  "private": false,
-  "description": "How solo founders keep their SaaS apps healthy.",
-  "scripts": {
-    "build": "tsc -p tsconfig.lib.json",
-    "test": "vitest run",
-    "test:watch": "vitest",
-    "release": "pnpm build && changeset publish",
-    "changeset": "changeset",
-    "version-packages": "changeset version"
-  },
-  "author": "Logdash Team <logdash.contact@gmail.com>",
-  "license": "MIT",
-  "repository": {
-    "type": "git",
-    "url": "git+https://github.com/logdash-io/node-sdk.git"
-  },
-  "homepage": "https://github.com/logdash-io/node-sdk",
-  "devDependencies": {
-    "@changesets/cli": "^2.29.8",
-    "@swc/core": "^1.15.6",
-    "@types/node": "^25.0.3",
-    "prettier": "^3.7.4",
-    "typescript": "5.9.3",
-    "vitest": "^4.0.16"
-  },
-  "bugs": {
-    "url": "https://github.com/logdash-io/node-sdk/issues"
-  },
-  "packageManager": "pnpm@9.0.0",
-  "engines": {
-    "node": ">=18"
-  },
-  "type": "module",
-  "main": "./dist/index.js",
-  "module": "./dist/index.js",
-  "types": "./dist/index.d.ts",
-  "keywords": [
-    "observability",
-    "monitoring",
-    "logging",
-    "tracing",
-    "metrics"
-  ],
-  "dependencies": {
-    "chalk": "^5.6.2"
-  }
+	"name": "@logdash/node",
+	"version": "1.0.2",
+	"private": false,
+	"description": "How solo founders keep their SaaS apps healthy.",
+	"scripts": {
+		"build": "tsc -p tsconfig.lib.json",
+		"test": "vitest run",
+		"test:watch": "vitest",
+		"release": "pnpm build && changeset publish",
+		"changeset": "changeset",
+		"version-packages": "changeset version"
+	},
+	"author": "Logdash Team <logdash.contact@gmail.com>",
+	"license": "MIT",
+	"repository": {
+		"type": "git",
+		"url": "git+https://github.com/logdash-io/node-sdk.git"
+	},
+	"homepage": "https://github.com/logdash-io/node-sdk",
+	"devDependencies": {
+		"@changesets/cli": "^2.29.8",
+		"@swc/core": "^1.15.6",
+		"@types/node": "^25.0.3",
+		"prettier": "^3.7.4",
+		"typescript": "5.9.3",
+		"vitest": "^4.0.16"
+	},
+	"bugs": {
+		"url": "https://github.com/logdash-io/node-sdk/issues"
+	},
+	"packageManager": "pnpm@9.0.0",
+	"engines": {
+		"node": ">=18"
+	},
+	"type": "module",
+	"main": "./dist/index.js",
+	"module": "./dist/index.js",
+	"types": "./dist/index.d.ts",
+	"keywords": [
+		"observability",
+		"monitoring",
+		"logging",
+		"tracing",
+		"metrics"
+	],
+	"dependencies": {
+		"chalk": "^5.6.2"
+	}
 }
diff --git a/src/Logdash.ts b/src/Logdash.ts
index bd5ae4d..b38206e 100644
--- a/src/Logdash.ts
+++ b/src/Logdash.ts
@@ -11,6 +11,7 @@ import { LogLevel, LOG_LEVEL_COLORS } from './types/LogLevel.js';
 export interface LogdashOptions {
 	host?: string;
 	verbose?: boolean;
+	app?: string;
 }
 
 interface LogdashCore {
@@ -18,6 +19,7 @@ interface LogdashCore {
 	metricQueue: RequestQueue<MetricPayload> | null;
 	sequenceNumber: number;
 	verbose: boolean;
+	app?: string;
 }
 
 export class Logdash {
@@ -49,11 +51,16 @@ export class Logdash {
 					logQueue: new RequestQueue((logs) =>
 						transport.sendLogs(logs),
 					),
-					metricQueue: new RequestQueue((metrics) =>
-						transport.sendMetrics(metrics),
+					// Each metric is its own request, so it is its own batch:
+					// a retry must not re-apply metrics that already went through
+					metricQueue: new RequestQueue(
+						(metrics) => transport.sendMetrics(metrics),
+						{ batchSize: 1 },
 					),
 					sequenceNumber: 0,
 					verbose,
+					// An empty app means no app: leave it out of payloads
+					app: options?.app || undefined,
 				};
 			} else {
 				internalLogger.warn('No API key provided, using local mode.');
@@ -124,6 +131,7 @@ export class Logdash {
 			value,
 			operation: 'set',
 			namespace: this.namespace,
+			app: this.core.app,
 		});
 	}
 
@@ -141,6 +149,7 @@ export class Logdash {
 			value: delta,
 			operation: 'change',
 			namespace: this.namespace,
+			app: this.core.app,
 		});
 	}
 
@@ -184,6 +193,7 @@ export class Logdash {
 			createdAt: now.toISOString(),
 			sequenceNumber: this.core.sequenceNumber++,
 			namespace: this.namespace,
+			app: this.core.app,
 		});
 	}
 
diff --git a/src/__tests__/Logdash.test.ts b/src/__tests__/Logdash.test.ts
index d972d37..b99392c 100644
--- a/src/__tests__/Logdash.test.ts
+++ b/src/__tests__/Logdash.test.ts
@@ -2,12 +2,21 @@ import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 import { Logdash } from '../Logdash.js';
 
 describe('Logdash', () => {
+	let mockFetch: ReturnType<typeof vi.fn>;
+
 	beforeEach(() => {
 		vi.spyOn(console, 'log').mockImplementation(() => {});
+		mockFetch = vi.fn().mockResolvedValue({
+			ok: true,
+			status: 200,
+			statusText: 'OK',
+		});
+		vi.stubGlobal('fetch', mockFetch);
 	});
 
 	afterEach(() => {
 		vi.restoreAllMocks();
+		vi.unstubAllGlobals();
 	});
 
 	describe('constructor', () => {
@@ -169,4 +178,100 @@ describe('Logdash', () => {
 			logdash.destroy();
 		});
 	});
+
+	describe('metric retries', () => {
+		afterEach(() => {
+			vi.useRealTimers();
+		});
+
+		it('re-sends only the metric that failed', async () => {
+			vi.useFakeTimers();
+			mockFetch.mockImplementation(async (_url, init) =>
+				JSON.parse(init.body).name === 'failing'
+					? { ok: false, status: 500, statusText: 'Server Error' }
+					: { ok: true, status: 200, statusText: 'OK' },
+			);
+			const logdash = new Logdash('test-key');
+			logdash.mutateMetric('requests', 1);
+			logdash.mutateMetric('failing', 1);
+
+			const flushed = logdash.flush();
+			await vi.advanceTimersByTimeAsync(10_000);
+			await flushed;
+			logdash.destroy();
+
+			const sent = mockFetch.mock.calls.map(
+				([, init]) => JSON.parse(init.body).name,
+			);
+			expect(sent.filter((name) => name === 'requests')).toHaveLength(1);
+			expect(sent.filter((name) => name === 'failing')).toHaveLength(3);
+		});
+	});
+
+	describe('app', () => {
+		// Sends a log and a metric from the root and from a namespaced
+		// instance, and returns the request bodies they produced
+		async function send(logdash: Logdash) {
+			const auth = logdash.withNamespace('auth');
+			logdash.info('root log');
+			logdash.setMetric('users', 1);
+			auth.info('auth log');
+			auth.mutateMetric('logins', 1);
+			await logdash.flush();
+			logdash.destroy();
+
+			const bodies = (path: string) =>
+				mockFetch.mock.calls
+					.filter(([url]) => url.endsWith(path))
+					.map(([, init]) => JSON.parse(init.body));
+
+			return {
+				logs: bodies('/logs/batch').flatMap((body) => body.logs),
+				metrics: bodies('/metrics'),
+			};
+		}
+
+		it('adds app to every log and metric', async () => {
+			const { logs, metrics } = await send(
+				new Logdash('test-key', { app: 'desktop' }),
+			);
+
+			expect(logs).toEqual([
+				expect.objectContaining({
+					message: 'root log',
+					app: 'desktop',
+				}),
+				expect.objectContaining({
+					message: 'auth log',
+					namespace: 'auth',
+					app: 'desktop',
+				}),
+			]);
+			expect(metrics).toEqual([
+				{ name: 'users', value: 1, operation: 'set', app: 'desktop' },
+				{
+					name: 'logins',
+					value: 1,
+					operation: 'change',
+					namespace: 'auth',
+					app: 'desktop',
+				},
+			]);
+		});
+
+		it.each([undefined, ''])(
+			'leaves app out of every log and metric when app is %j',
+			async (app) => {
+				const { logs, metrics } = await send(
+					new Logdash('test-key', { app }),
+				);
+
+				expect(logs).toHaveLength(2);
+				expect(metrics).toHaveLength(2);
+				for (const payload of [...logs, ...metrics]) {
+					expect(payload).not.toHaveProperty('app');
+				}
+			},
+		);
+	});
 });
diff --git a/src/transport/HttpTransport.ts b/src/transport/HttpTransport.ts
index aab2217..240b2ed 100644
--- a/src/transport/HttpTransport.ts
+++ b/src/transport/HttpTransport.ts
@@ -64,6 +64,7 @@ export interface LogPayload {
 	createdAt: string;
 	sequenceNumber: number;
 	namespace?: string;
+	app?: string;
 }
 
 export interface MetricPayload {
@@ -71,4 +72,5 @@ export interface MetricPayload {
 	value: number;
 	operation: 'set' | 'change';
 	namespace?: string;
+	app?: string;
 }
diff --git a/tsconfig.json b/tsconfig.json
index 0b40889..964fe0f 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,20 +1,20 @@
 {
-    "files": [],
-    "include": [],
-    "references": [
-        {
-            "path": "./tsconfig.lib.json"
-        }
-    ],
-    "compilerOptions": {
-        "rootDir": ".",
-        "forceConsistentCasingInFileNames": true,
-        "strict": false,
-        "noImplicitOverride": true,
-        "noPropertyAccessFromIndexSignature": true,
-        "noImplicitReturns": true,
-        "noFallthroughCasesInSwitch": true,
-        "experimentalDecorators": true,
-        "emitDecoratorMetadata": true,
-    },
+	"files": [],
+	"include": [],
+	"references": [
+		{
+			"path": "./tsconfig.lib.json"
+		}
+	],
+	"compilerOptions": {
+		"rootDir": ".",
+		"forceConsistentCasingInFileNames": true,
+		"strict": false,
+		"noImplicitOverride": true,
+		"noPropertyAccessFromIndexSignature": true,
+		"noImplicitReturns": true,
+		"noFallthroughCasesInSwitch": true,
+		"experimentalDecorators": true,
+		"emitDecoratorMetadata": true
+	}
 }
diff --git a/tsconfig.lib.json b/tsconfig.lib.json
index 2d9d1e7..39e9a9a 100644
--- a/tsconfig.lib.json
+++ b/tsconfig.lib.json
@@ -1,29 +1,24 @@
 {
-  "extends": "./tsconfig.json",
-  "compilerOptions": {
-    "esModuleInterop": true,
-    "skipLibCheck": true,
-    "target": "ES2020",
-    "allowJs": true,
-    "resolveJsonModule": true,
-    "moduleDetection": "force",
-    "isolatedModules": true,
-    "strict": false,
-    "noUncheckedIndexedAccess": true,
-    "noImplicitOverride": true,
-    "module": "NodeNext",
-    "moduleResolution": "NodeNext",
-    "outDir": "dist",
-    "rootDir": "src",
-    "sourceMap": true,
-    "declaration": true,
-    "declarationMap": true
-  },
-  "exclude": [
-    "src/**/*.spec.ts",
-    "node_modules/**/*"
-  ],
-  "include": [
-    "src/**/*.ts"
-  ]
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"esModuleInterop": true,
+		"skipLibCheck": true,
+		"target": "ES2020",
+		"allowJs": true,
+		"resolveJsonModule": true,
+		"moduleDetection": "force",
+		"isolatedModules": true,
+		"strict": false,
+		"noUncheckedIndexedAccess": true,
+		"noImplicitOverride": true,
+		"module": "NodeNext",
+		"moduleResolution": "NodeNext",
+		"outDir": "dist",
+		"rootDir": "src",
+		"sourceMap": true,
+		"declaration": true,
+		"declarationMap": true
+	},
+	"exclude": ["src/**/*.spec.ts", "node_modules/**/*"],
+	"include": ["src/**/*.ts"]
 }