diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index b322f36..2c6709f 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -1,10 +1,10 @@
 name: Docker image
 
-# Publishes ghcr.io/<owner>/hexlode. Every merge to `main` updates the `main` tag. A release, the
-# `v1.2.3` tag Release Please starts this workflow for, publishes `latest`, `1.2.3` and `1.2`, then
-# calls the Dokploy deploy webhook, since Dokploy runs `latest`. Every image also gets a
-# `sha-<commit>` tag to roll back to. With the Sentry secret and variables set, the build uploads
-# source maps. See DEPLOY.md.
+# Publishes ghcr.io/<owner>/hexlode. Every merge to `main` updates the `main` tag and deploys
+# staging, which runs `main`. A release, the `v1.2.3` tag Release Please starts this workflow for,
+# publishes `latest`, `1.2.3` and `1.2` and deploys production, which runs `latest`. Every image also
+# gets a `sha-<commit>` tag to roll back to. With the Sentry secret and variables set, the build
+# uploads source maps. See DEPLOY.md.
 on:
   push:
     branches: [main]
@@ -139,22 +139,41 @@ jobs:
             while read -r tag; do echo "- \`$tag\`"; done <<< "$TAGS"
           } >> "$GITHUB_STEP_SUMMARY"
 
-  deploy:
-    name: deploy to Dokploy
+  # Each deploy calls its Dokploy application's webhook, and is skipped until that secret is set.
+  deploy-staging:
+    name: deploy staging
+    needs: image
+    if: github.ref == 'refs/heads/main'
+    runs-on: ubuntu-latest
+    environment: staging
+    steps:
+      - name: Call the staging deploy webhook
+        env:
+          WEBHOOK_URL: ${{ secrets.DOKPLOY_STAGING_WEBHOOK_URL }}
+        run: |
+          if [ -z "$WEBHOOK_URL" ]; then
+            echo "::notice::DOKPLOY_STAGING_WEBHOOK_URL is not set, so staging was not deployed."
+            exit 0
+          fi
+          curl -fsS --retry 3 --retry-all-errors -X POST "$WEBHOOK_URL"
+          echo
+          echo "Dokploy is deploying the main image to staging."
+
+  deploy-production:
+    name: deploy production
     needs: image
-    # Only releases deploy, and only once the webhook secret is set (see DEPLOY.md).
     if: startsWith(github.ref, 'refs/tags/v')
     runs-on: ubuntu-latest
     environment: production
     steps:
-      - name: Call the deploy webhook
+      - name: Call the production deploy webhook
         env:
-          DOKPLOY_WEBHOOK_URL: ${{ secrets.DOKPLOY_WEBHOOK_URL }}
+          WEBHOOK_URL: ${{ secrets.DOKPLOY_WEBHOOK_URL }}
         run: |
-          if [ -z "$DOKPLOY_WEBHOOK_URL" ]; then
-            echo "::notice::DOKPLOY_WEBHOOK_URL is not set, so Dokploy was not asked to deploy."
+          if [ -z "$WEBHOOK_URL" ]; then
+            echo "::notice::DOKPLOY_WEBHOOK_URL is not set, so production was not deployed."
             exit 0
           fi
-          curl -fsS --retry 3 --retry-all-errors -X POST "$DOKPLOY_WEBHOOK_URL"
+          curl -fsS --retry 3 --retry-all-errors -X POST "$WEBHOOK_URL"
           echo
-          echo "Dokploy is deploying the new image."
+          echo "Dokploy is deploying the release to production."
diff --git a/DEPLOY.md b/DEPLOY.md
index 2bc82c2..7bb5ceb 100644
--- a/DEPLOY.md
+++ b/DEPLOY.md
@@ -12,7 +12,7 @@ needs rebuilding to change a setting ([ADR 0008](./docs/adr/0008-one-image-confi
 | --- | --- |
 | `latest` | On every release. Production runs this tag. |
 | `1.2.3`, `1.2` | On every release: merging the Release Please pull request tags `v1.2.3`. |
-| `main` | On every merge to `main`, released or not. Use it to try unreleased changes. |
+| `main` | On every merge to `main`, released or not. Staging runs this tag. |
 | `sha-abc1234` | On every build. Use it to pin or roll back to one commit. |
 
 The container listens on port `3000`, runs as an unprivileged user, and answers `GET /api/health`
@@ -45,6 +45,7 @@ runs with analytics and error reports off.
 | `VITE_POSTHOG_KEY` | PostHog project key. Turns on cookieless analytics. |
 | `VITE_POSTHOG_HOST` | PostHog API host, for example `https://eu.i.posthog.com`. Defaults to the US host. |
 | `VITE_SENTRY_DSN` | Sentry DSN. Turns on error reports, logs and tracing in the browser and on the server. |
+| `HEXLODE_ENVIRONMENT` | `staging` on the staging application. Leave it unset in production, which reports as `production`. |
 | `PORT` | The port the server listens on. Defaults to `3000`; change the domain's port to match. |
 
 The `VITE_*` values are public: they reach every visitor's browser. Never put a secret in a
@@ -107,15 +108,38 @@ runs Node directly:
 
 Then click **Deploy**. Open `https://your-domain/api/health` to see the running version.
 
-## Deploying on every release
+## Staging and production
 
-Merging a pull request into `main` publishes the `main` image but deploys nothing. Merging the
-Release Please pull request makes a release: the `Docker image` workflow publishes `latest` and the
-version tags, then calls the application's Dokploy deploy webhook, and Dokploy pulls `latest` and
-redeploys. Copy the webhook from the application's
-**Deployments** tab in Dokploy and save it in GitHub (**Settings → Secrets and variables →
-Actions**) as the repository secret `DOKPLOY_WEBHOOK_URL`. Until it is set, the workflow publishes
-the image and skips the deploy.
+Hexlode runs as two Dokploy applications from the same image, with the same PostHog key and Sentry
+DSN:
+
+| | Staging | Production |
+| --- | --- | --- |
+| Image | `ghcr.io/pixelactstudio/hexlode:main` | `ghcr.io/pixelactstudio/hexlode:latest` |
+| Deploys when | a pull request is merged into `main` | the Release Please pull request is merged |
+| `HEXLODE_ENVIRONMENT` | `staging` | unset |
+| Webhook secret in GitHub | `DOKPLOY_STAGING_WEBHOOK_URL` | `DOKPLOY_WEBHOOK_URL` |
+
+So a merged change shows up on staging to test, and reaches production with the next release. Set
+up the staging application like production (steps 1 to 5 above) with the `main` image, its own
+domain with HTTPS, and `HEXLODE_ENVIRONMENT=staging`.
+
+Copy each application's webhook from its **Deployments** tab in Dokploy and save it in GitHub
+(**Settings → Secrets and variables → Actions**) as the repository secret in the table. Until a
+secret is set, the workflow publishes the image and skips that deploy.
+
+### Keeping staging out of the numbers
+
+Both applications report to the same Sentry and PostHog projects, labelled with their environment.
+
+- **Sentry** files every error, log and trace under the environment, `production` or `staging`.
+  Pick it with the environment selector at the top of Issues, Traces and Logs. Make alert rules
+  fire for the `production` environment only.
+- **PostHog** labels every event with an `environment` property. In **Project settings → Product
+  analytics → Filter out internal and test users**, add the filter `environment` **is not**
+  `staging`, add another for `development`, and turn on **Enable this filter on all new insights**.
+  Dashboards then count production only. To check events from staging, turn off **Filter out
+  internal and test users** on an insight.
 
 ## Readable Sentry stack traces
 
@@ -147,7 +171,7 @@ Set these up in Sentry itself:
 - **Uptime monitor** (**Insights → Uptime**): check `https://your-domain/api/health` so Sentry
   alerts you when the site is down.
 - **Alerts** (**Alerts → Create alert**): for example, email on every new issue, or when errors in
-  an hour pass a number.
+  an hour pass a number. Set their environment to `production`, so testing on staging stays quiet.
 
 ## Rolling back
 
diff --git a/docs/adr/0005-cookieless-explicit-analytics.md b/docs/adr/0005-cookieless-explicit-analytics.md
index 7d9dfc2..b46b42b 100644
--- a/docs/adr/0005-cookieless-explicit-analytics.md
+++ b/docs/adr/0005-cookieless-explicit-analytics.md
@@ -17,6 +17,10 @@ They carry the product signal autocapture cannot: tools, pipeline shapes, node t
 counts, timings and error codes. Events never contain file names, paths, pixels, image metadata or
 text the user types.
 
+Every event carries the app version and an `environment` property, `production` or `staging`, from
+`HEXLODE_ENVIRONMENT`. Staging reports to the same project, since the free plan has one, and
+PostHog's test account filter keeps it out of dashboards.
+
 ## Considered options
 
 - **Explicit events only** (the first version). Private, but the web analytics dashboard stayed
diff --git a/implementation.md b/implementation.md
index 940e2a6..c2387e8 100644
--- a/implementation.md
+++ b/implementation.md
@@ -152,7 +152,8 @@ removed.
   browser tests in three engines; coverage; the build with a smoke test of the server; and the
   Docker image with a smoke test of the container, its health check, runtime settings and an ARM
   build. CodeQL, `pnpm audit`, dependency review and PR titles run in their own workflows. A push
-  to `main` only publishes the `main` image, since the pull request already ran the checks;
+  to `main` only publishes the `main` image and deploys staging, since the pull request already
+  ran the checks;
   CodeQL, the audit and the scale test also run on a schedule.
 - Release Please keeps a release pull request open on `main` from the Conventional Commits merged
   there; merging it tags the version, writes the changelog, publishes `latest` and the version tags, and
@@ -181,8 +182,11 @@ removed.
 ## Deployment
 
 The app runs as one Docker container that serves the Nitro build. The `Docker image` workflow
-publishes `ghcr.io/pixelactstudio/hexlode` for x86 and ARM: `main` on every merge to `main`, and
-`latest` on every release, after which it calls the Dokploy deploy webhook on the maintainer's VPS. Dokploy pulls the image, sets its environment and
+publishes `ghcr.io/pixelactstudio/hexlode` for x86 and ARM: `main` on every merge to `main`, which
+deploys the staging application, and `latest` on every release, which deploys production. Each
+deploy calls that application's Dokploy webhook on the maintainer's VPS. Staging sets
+`HEXLODE_ENVIRONMENT=staging`, so Sentry files its reports under `staging` and PostHog's test
+account filter keeps its events out of production dashboards. Dokploy pulls the image, sets its environment and
 handles the domain and HTTPS ([ADR 0008](./docs/adr/0008-one-image-configured-at-runtime.md)).
 `/api/health` answers the container health check that Dokploy's zero-downtime updates wait for.
 A future cloud mode adds a Postgres service on the same VPS, reached through `DATABASE_URL`.
diff --git a/instrument.server.mjs b/instrument.server.mjs
index d18cf1e..d149be0 100644
--- a/instrument.server.mjs
+++ b/instrument.server.mjs
@@ -6,7 +6,12 @@ if (sentryDsn) {
   Sentry.init({
     dsn: sentryDsn,
     release: process.env.HEXLODE_VERSION,
-    environment: process.env.NODE_ENV === 'production' ? 'production' : 'development',
+    // Matches the environment src/features/usage/validators.ts hands the browser.
+    environment: /^[a-z][a-z0-9-]{0,31}$/.test(process.env.HEXLODE_ENVIRONMENT ?? '')
+      ? process.env.HEXLODE_ENVIRONMENT
+      : process.env.NODE_ENV === 'production'
+        ? 'production'
+        : 'development',
     sendDefaultPii: false,
     dataCollection: {
       userInfo: false,
diff --git a/src/env.ts b/src/env.ts
index 6753c83..75098c2 100644
--- a/src/env.ts
+++ b/src/env.ts
@@ -15,6 +15,7 @@ export const env = createEnv({
     SENTRY_ORG: z.string().min(1).optional(),
     SENTRY_PROJECT: z.string().min(1).optional(),
     HEXLODE_VERSION: z.string().min(1).optional(),
+    HEXLODE_ENVIRONMENT: z.string().min(1).optional(),
   },
   clientPrefix: 'VITE_',
   client: {
diff --git a/src/features/usage/__tests__/public-config.test.ts b/src/features/usage/__tests__/public-config.test.ts
index bbbd3b0..3a58235 100644
--- a/src/features/usage/__tests__/public-config.test.ts
+++ b/src/features/usage/__tests__/public-config.test.ts
@@ -10,6 +10,7 @@ describe('public config', () => {
         VITE_POSTHOG_HOST: 'https://eu.i.posthog.com',
         VITE_SENTRY_DSN: 'https://key@o1.ingest.sentry.io/2',
         HEXLODE_VERSION: '1.4.0',
+        HEXLODE_ENVIRONMENT: 'staging',
         DATABASE_URL: 'postgresql://secret@db/hexlode',
       }),
     ).toEqual({
@@ -17,9 +18,21 @@ describe('public config', () => {
       posthogHost: 'https://eu.i.posthog.com',
       sentryDsn: 'https://key@o1.ingest.sentry.io/2',
       appVersion: '1.4.0',
+      environment: 'staging',
     })
   })
 
+  // Staging runs the same image with HEXLODE_ENVIRONMENT=staging; production leaves it unset.
+  it('names the environment production in a production server unless told otherwise', () => {
+    expect(parsePublicConfig({ NODE_ENV: 'production' }).environment).toBe('production')
+    expect(parsePublicConfig({ NODE_ENV: 'development' }).environment).toBe('development')
+    expect(parsePublicConfig({}).environment).toBe('development')
+    expect(
+      parsePublicConfig({ NODE_ENV: 'production', HEXLODE_ENVIRONMENT: 'Staging area!' })
+        .environment,
+    ).toBe('production')
+  })
+
   it('leaves out settings that are empty or not valid', () => {
     expect(
       parsePublicConfig({
@@ -27,7 +40,7 @@ describe('public config', () => {
         VITE_POSTHOG_HOST: 'not a url',
         VITE_SENTRY_DSN: '',
       }),
-    ).toEqual({})
+    ).toEqual({ environment: 'development' })
   })
 
   // The page carries the config so the browser can start Sentry before it hydrates.
@@ -36,6 +49,7 @@ describe('public config', () => {
       posthogKey: 'phc_live',
       sentryDsn: 'https://key@o1.ingest.sentry.io/2',
       appVersion: '1.4.0',
+      environment: 'staging',
     }
     expect(parsePublicConfigJson(JSON.stringify({ ...config, extra: 'x' }))).toEqual(config)
     expect(parsePublicConfigJson(JSON.stringify({ sentryDsn: 'not a url' }))).toEqual({})
diff --git a/src/features/usage/__tests__/start.test.ts b/src/features/usage/__tests__/start.test.ts
index 69ebf8d..a20b61d 100644
--- a/src/features/usage/__tests__/start.test.ts
+++ b/src/features/usage/__tests__/start.test.ts
@@ -32,11 +32,13 @@ describe('starting analytics and error reports', () => {
     await startErrorReporting({
       sentryDsn: 'https://key@o1.ingest.sentry.io/2',
       appVersion: '1.4.0',
+      environment: 'staging',
     })
     expect(init).toHaveBeenCalledWith(
       expect.objectContaining({
         dsn: 'https://key@o1.ingest.sentry.io/2',
         release: '1.4.0',
+        environment: 'staging',
         sendDefaultPii: false,
         enableLogs: true,
         tracesSampleRate: expect.any(Number),
diff --git a/src/features/usage/__tests__/usage.test.ts b/src/features/usage/__tests__/usage.test.ts
index f6a6b2e..83c873e 100644
--- a/src/features/usage/__tests__/usage.test.ts
+++ b/src/features/usage/__tests__/usage.test.ts
@@ -55,10 +55,15 @@ describe('analytics', () => {
     })
   })
 
-  it('labels every event with the app version', () => {
+  it('labels every event with the app version and environment', () => {
     const posthog = fakePostHog()
-    createAnalytics({ key: 'phc_test', appVersion: '1.4.0', posthog: posthog.client })
-    expect(posthog.registered).toEqual([{ app_version: '1.4.0' }])
+    createAnalytics({
+      key: 'phc_test',
+      appVersion: '1.4.0',
+      environment: 'staging',
+      posthog: posthog.client,
+    })
+    expect(posthog.registered).toEqual([{ app_version: '1.4.0', environment: 'staging' }])
   })
 
   // PostHog hashes the IP into the daily cookieless ID and drops cookieless events without one.
diff --git a/src/features/usage/constants.ts b/src/features/usage/constants.ts
index 474341f..ac96235 100644
--- a/src/features/usage/constants.ts
+++ b/src/features/usage/constants.ts
@@ -4,6 +4,9 @@ export const PUBLIC_CONFIG_META = 'hexlode-config'
 /** PostHog's recommended defaults as of this date, as its TanStack Start guide sets them. */
 export const POSTHOG_DEFAULTS = '2026-05-30'
 
+/** An environment name such as `staging`: lowercase letters, digits and dashes. */
+export const ENVIRONMENT_PATTERN = /^[a-z][a-z0-9-]{0,31}$/
+
 export const DEFAULT_POSTHOG_HOST = 'https://us.i.posthog.com'
 
 /**
diff --git a/src/features/usage/error-reports.ts b/src/features/usage/error-reports.ts
index 3744618..1f5d97d 100644
--- a/src/features/usage/error-reports.ts
+++ b/src/features/usage/error-reports.ts
@@ -33,7 +33,7 @@ export async function startErrorReporting(config: PublicConfig) {
   Sentry.init({
     dsn,
     release: config.appVersion,
-    environment: import.meta.env?.PROD ? 'production' : 'development',
+    environment: config.environment ?? (import.meta.env?.PROD ? 'production' : 'development'),
     sendDefaultPii: false,
     enableLogs: true,
     tracesSampleRate: TRACES_SAMPLE_RATE,
diff --git a/src/features/usage/public-config.ts b/src/features/usage/public-config.ts
index a5fe9b2..0f3c706 100644
--- a/src/features/usage/public-config.ts
+++ b/src/features/usage/public-config.ts
@@ -12,5 +12,7 @@ export const getPublicConfig = createServerFn({ method: 'GET' }).handler(() =>
     VITE_POSTHOG_HOST: process.env.VITE_POSTHOG_HOST || import.meta.env.VITE_POSTHOG_HOST,
     VITE_SENTRY_DSN: process.env.VITE_SENTRY_DSN || import.meta.env.VITE_SENTRY_DSN,
     HEXLODE_VERSION: process.env.HEXLODE_VERSION,
+    HEXLODE_ENVIRONMENT: process.env.HEXLODE_ENVIRONMENT,
+    NODE_ENV: process.env.NODE_ENV,
   }),
 )
diff --git a/src/features/usage/types.ts b/src/features/usage/types.ts
index 7b5b0f4..26627e5 100644
--- a/src/features/usage/types.ts
+++ b/src/features/usage/types.ts
@@ -9,4 +9,9 @@ export interface PublicConfig {
   sentryDsn?: string
   /** The running image's version, from `HEXLODE_VERSION`. Labels events and error reports. */
   appVersion?: string
+  /**
+   * `production`, `staging` or `development`, from `HEXLODE_ENVIRONMENT`. Sentry files reports under
+   * it and PostHog labels events with it, so staging stays out of production numbers.
+   */
+  environment?: string
 }
diff --git a/src/features/usage/usage.ts b/src/features/usage/usage.ts
index 3a74344..0929ad7 100644
--- a/src/features/usage/usage.ts
+++ b/src/features/usage/usage.ts
@@ -32,14 +32,18 @@ export interface AnalyticsOptions {
   key?: string
   host?: string
   appVersion?: string
+  environment?: string
   posthog: PostHogLike
 }
 
-export function createAnalytics({ key, host, appVersion, posthog }: AnalyticsOptions) {
+export function createAnalytics({ key, host, appVersion, environment, posthog }: AnalyticsOptions) {
   const enabled = Boolean(key)
   if (key) {
     posthog.init(key, { ...POSTHOG_OPTIONS, api_host: host || DEFAULT_POSTHOG_HOST })
-    if (appVersion) posthog.register({ app_version: appVersion })
+    // PostHog's test account filter hides every environment but production from dashboards.
+    const labels = { app_version: appVersion, environment }
+    const defined = Object.fromEntries(Object.entries(labels).filter(([, value]) => value))
+    if (Object.keys(defined).length > 0) posthog.register(defined)
   }
   return {
     track<E extends AnalyticsEventName>(event: E, properties: EventProperties<E>) {
@@ -73,6 +77,7 @@ export function startAnalytics(config: PublicConfig) {
           key,
           host: config.posthogHost,
           appVersion: config.appVersion,
+          environment: config.environment,
           posthog: posthog as unknown as PostHogLike,
         })
       } catch {
diff --git a/src/features/usage/validators.ts b/src/features/usage/validators.ts
index ed79216..a5d0c70 100644
--- a/src/features/usage/validators.ts
+++ b/src/features/usage/validators.ts
@@ -1,9 +1,11 @@
 import { z } from 'zod'
 
+import { ENVIRONMENT_PATTERN } from '#/features/usage/constants'
 import type { PublicConfig } from '#/features/usage/types'
 
 const optionalText = z.string().trim().min(1).optional().catch(undefined)
 const optionalUrl = z.url().optional().catch(undefined)
+const optionalEnvironment = z.string().regex(ENVIRONMENT_PATTERN).optional().catch(undefined)
 
 function withoutEmpty(config: PublicConfig): PublicConfig {
   return Object.fromEntries(
@@ -18,6 +20,9 @@ export function parsePublicConfig(env: Record<string, string | undefined>): Publ
     posthogHost: optionalUrl.parse(env.VITE_POSTHOG_HOST),
     sentryDsn: optionalUrl.parse(env.VITE_SENTRY_DSN),
     appVersion: optionalText.parse(env.HEXLODE_VERSION),
+    environment:
+      optionalEnvironment.parse(env.HEXLODE_ENVIRONMENT) ??
+      (env.NODE_ENV === 'production' ? 'production' : 'development'),
   })
 }
 
@@ -26,6 +31,7 @@ const publicConfigSchema = z.object({
   posthogHost: optionalUrl,
   sentryDsn: optionalUrl,
   appVersion: optionalText,
+  environment: optionalEnvironment,
 })
 
 /** Reads the settings the server wrote into the page. Anything malformed is left out. */