Agent-Skills.md

Agent Skills: Sentry Browser SDK

Full Sentry SDK setup for browser JavaScript. Use when asked to "add Sentry to a website", "install @sentry/browser", or configure error monitoring, tracing, session replay, or logging for vanilla JavaScript, jQuery, static sites, or WordPress.

UncategorizedID: nikolovlazar/dotfiles/sentry-browser-sdk

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nikolovlazar/dotfiles
nikolovlazar
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.agents/skills/sentry-browser-sdk/SKILL.md

Skill Metadata

Name
sentry-browser-sdk
Description
Full Sentry SDK setup for browser JavaScript. Use when asked to "add Sentry to a website", "install @sentry/browser", or configure error monitoring, tracing, session replay, or logging for vanilla JavaScript, jQuery, static sites, or WordPress.

All Skills > SDK Setup > Browser SDK

Sentry Browser SDK

Opinionated wizard that scans your project and guides you through complete Sentry setup for browser JavaScript — vanilla JS, jQuery, static sites, WordPress, and any JS project without a framework-specific SDK.

Invoke This Skill When

  • User asks to "add Sentry to a website" or set up Sentry for plain JavaScript
  • User wants to install @sentry/browser or configure the Loader Script
  • User has a WordPress, Shopify, Squarespace, or static HTML site
  • User wants error monitoring, tracing, session replay, or logging without a framework
  • No framework-specific SDK applies

Note: SDK versions and APIs below reflect @sentry/browser ≥10.0.0. Always verify against docs.sentry.io/platforms/javascript/ before implementing.

Phase 1: Detect

CRITICAL — Check for frameworks first. Framework-specific SDKs provide significantly better coverage and must be recommended before proceeding with @sentry/browser.

Step 1A: Framework Detection (Redirect If Found)

# Check for React
cat package.json 2>/dev/null | grep -E '"react"'

# Check for Next.js
cat package.json 2>/dev/null | grep '"next"'

# Check for Vue
cat package.json 2>/dev/null | grep '"vue"'

# Check for Angular
cat package.json 2>/dev/null | grep '"@angular/core"'

# Check for Svelte / SvelteKit
cat package.json 2>/dev/null | grep -E '"svelte"|"@sveltejs/kit"'

# Check for Remix
cat package.json 2>/dev/null | grep -E '"@remix-run/react"|"@remix-run/node"'

# Check for Nuxt
cat package.json 2>/dev/null | grep '"nuxt"'

# Check for Astro
cat package.json 2>/dev/null | grep '"astro"'

# Check for Ember
cat package.json 2>/dev/null | grep '"ember-source"'

# Check for Node.js server frameworks (wrong SDK entirely)
cat package.json 2>/dev/null | grep -E '"express"|"fastify"|"@nestjs/core"|"koa"'

If a framework is detected, stop and redirect:

| Framework detected | Redirect to | |-------------------|-------------| | next | Load sentry-nextjs-sdk skill — do not proceed here | | react (without Next.js) | Load sentry-react-sdk skill — do not proceed here | | vue | Suggest @sentry/vue — see docs.sentry.io/platforms/javascript/guides/vue/ | | @angular/core | Suggest @sentry/angular — see docs.sentry.io/platforms/javascript/guides/angular/ | | @sveltejs/kit | Load sentry-svelte-sdk skill — do not proceed here | | svelte (SPA, no kit) | Suggest @sentry/svelte — see docs.sentry.io/platforms/javascript/guides/svelte/ | | @remix-run | Suggest @sentry/remix — see docs.sentry.io/platforms/javascript/guides/remix/ | | nuxt | Suggest @sentry/nuxt — see docs.sentry.io/platforms/javascript/guides/nuxt/ | | astro | Suggest @sentry/astro — see docs.sentry.io/platforms/javascript/guides/astro/ | | ember-source | Suggest @sentry/ember — see docs.sentry.io/platforms/javascript/guides/ember/ | | express / fastify / @nestjs/core | This is a Node.js server — load sentry-node-sdk or sentry-nestjs-sdk skill |

Why redirect matters: Framework SDKs add router-aware transactions, error boundaries, component tracking, and often SSR coverage. Using @sentry/browser directly in a React or Next.js app loses all of that.

Only continue with @sentry/browser if no framework is detected.

Step 1B: Installation Method Detection

# Check if there's a package.json at all (bundler environment)
ls package.json 2>/dev/null

# Check package manager
ls package-lock.json yarn.lock pnpm-lock.yaml bun.lockb 2>/dev/null

# Check build tool
ls vite.config.ts vite.config.js webpack.config.js rollup.config.js esbuild.config.js 2>/dev/null
cat package.json 2>/dev/null | grep -E '"vite"|"webpack"|"rollup"|"esbuild"'

# Check for CMS or static site indicators
ls wp-config.php wp-content/ 2>/dev/null   # WordPress
ls _config.yml _config.yaml 2>/dev/null    # Jekyll
ls config.toml 2>/dev/null                 # Hugo
ls .eleventy.js 2>/dev/null                # Eleventy

# Check for existing Sentry
cat package.json 2>/dev/null | grep '"@sentry/'
grep -r "sentry-cdn.com\|js.sentry-cdn.com" . --include="*.html" -l 2>/dev/null | head -3

What to determine:

| Question | Impact | |----------|--------| | package.json exists + bundler? | → Path A: npm install | | WordPress, Shopify, static HTML, no npm? | → Path B: Loader Script | | Script tags only, no Loader Script access? | → Path C: CDN bundle | | Already has @sentry/browser? | Skip install, go straight to feature config | | Build tool is Vite / webpack / Rollup / esbuild? | Source maps plugin to configure |

Phase 2: Recommend

Present a recommendation based on what you found. Lead with a concrete proposal, don't ask open-ended questions.

Recommended (core coverage):

  • ✅ Error Monitoring — always; captures unhandled errors and promise rejections
  • ✅ Tracing — recommended for any interactive site; tracks page load and user interactions
  • ✅ Session Replay — recommended for user-facing apps; records sessions around errors

Optional (enhanced observability):

  • ⚡ User Feedback — capture reports directly from users after errors
  • ⚡ Logging — structured logs via Sentry.logger.*; requires npm or CDN logs bundle (not available via Loader Script)
  • ⚡ Profiling — JS Self-Profiling API; beta, Chromium-only, requires Document-Policy: js-profiling response header

Feature recommendation logic:

| Feature | Recommend when... | |---------|------------------| | Error Monitoring | Always — non-negotiable baseline | | Tracing | Always for interactive pages — page load + navigation spans are high-value | | Session Replay | User-facing app, support flows, or checkout pages | | User Feedback | Support-focused app; want in-app bug reports with screenshots | | Logging | Structured log search or log-to-trace correlation needed; npm path only | | Profiling | Performance-critical, Chromium-only app; Document-Policy: js-profiling header required |

Installation path recommendation:

| Scenario | Recommended path | |----------|-----------------| | Project has package.json + bundler | Path A (npm) — full features, source maps, tree-shaking | | WordPress, Shopify, Squarespace, static HTML | Path B (Loader Script) — zero build tooling, always up to date | | Static HTML without Loader Script access | Path C (CDN bundle) — manual <script> tag |

Propose: "I recommend setting up Error Monitoring + Tracing + Session Replay using Path A (npm). Want me to also add Logging or User Feedback?"

Phase 3: Guide

Path A: npm / yarn / pnpm (Recommended — Bundler Projects)

Install

npm install @sentry/browser --save
# or
yarn add @sentry/browser
# or
pnpm add @sentry/browser

Create src/instrument.ts

Sentry must initialize before any other code runs. Put Sentry.init() in a dedicated sidecar file:

import * as Sentry from "@sentry/browser";

Sentry.init({
  dsn: import.meta.env.VITE_SENTRY_DSN, // Adjust per build tool (see table below)
  environment: import.meta.env.MODE,
  release: import.meta.env.VITE_APP_VERSION, // inject at build time

  sendDefaultPii: true,

  integrations: [
    Sentry.browserTracingIntegration(),
    Sentry.replayIntegration({
      maskAllText: true,
      blockAllMedia: true,
    }),
  ],

  // Tracing
  tracesSampleRate: 1.0, // lower to 0.1–0.2 in production
  tracePropagationTargets: ["localhost", /^https:\/\/yourapi\.io/],

  // Session Replay
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,

  enableLogs: true,
});

DSN environment variable by build tool:

| Build Tool | Variable Name | Access in code | |------------|--------------|----------------| | Vite | VITE_SENTRY_DSN | import.meta.env.VITE_SENTRY_DSN | | Custom webpack | SENTRY_DSN | process.env.SENTRY_DSN | | esbuild | SENTRY_DSN | process.env.SENTRY_DSN | | Rollup | SENTRY_DSN | process.env.SENTRY_DSN |

Entry Point Setup

Import instrument.ts as the very first import in your entry file:

// src/main.ts or src/index.ts
import "./instrument";  // ← MUST be first

// ... rest of your app

Source Maps Setup (Strongly Recommended)

Without source maps, stack traces show minified code. Set up the build plugin to upload source maps automatically:

No dedicated browser wizard: There is no npx @sentry/wizard -i browser flag. The closest is npx @sentry/wizard@latest -i sourcemaps which configures source map upload only for an already-initialized SDK.

Vite (vite.config.ts):

import { defineConfig } from "vite";
import { sentryVitePlugin } from "@sentry/vite-plugin";

export default defineConfig({
  build: { sourcemap: "hidden" },
  plugins: [
    // sentryVitePlugin MUST be last
    sentryVitePlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
});

webpack (webpack.config.js):

const { sentryWebpackPlugin } = require("@sentry/webpack-plugin");

module.exports = {
  devtool: "hidden-source-map",
  plugins: [
    sentryWebpackPlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
};

Rollup (rollup.config.js):

import { sentryRollupPlugin } from "@sentry/rollup-plugin";

export default {
  output: { sourcemap: "hidden" },
  plugins: [
    sentryRollupPlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
};

esbuild (build.js):

const { sentryEsbuildPlugin } = require("@sentry/esbuild-plugin");

require("esbuild").build({
  entryPoints: ["src/index.ts"],
  bundle: true,
  sourcemap: "hidden",
  plugins: [
    sentryEsbuildPlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
});

⚠️ esbuild plugin does not fully support splitting: true. Use sentry-cli instead if code splitting is enabled.

Using sentry-cli (any toolchain / CI):

# After your build step:
npx @sentry/cli sourcemaps inject ./dist
npx @sentry/cli sourcemaps upload ./dist

Add .env for auth (never commit):

SENTRY_AUTH_TOKEN=sntrys_...
SENTRY_ORG=my-org-slug
SENTRY_PROJECT=my-project-slug

Path B: Loader Script (WordPress, Static Sites, Shopify, Squarespace)

Best for: Sites without a build system. The Loader Script is a single <script> tag that lazily loads the full SDK, always stays up to date via Sentry's CDN, and buffers errors before the SDK loads.

Get the Loader Script: Sentry UI → Settings → Projects → (your project) → SDK Setup → Loader Script

Copy the generated tag and place it as the first script on every page:

<!DOCTYPE html>
<html>
  <head>
    <!-- Configure BEFORE the loader tag -->
    <script>
      window.sentryOnLoad = function () {
        Sentry.init({
          // DSN is already configured in the loader URL
          tracesSampleRate: 1.0,
          replaysSessionSampleRate: 0.1,
          replaysOnErrorSampleRate: 1.0,
        });
      };
    </script>

    <!-- Loader Script FIRST — before all other scripts -->
    <script
      src="https://js.sentry-cdn.com/YOUR_PUBLIC_KEY.min.js"
      crossorigin="anonymous"
    ></script>
  </head>
  ...
</html>

Loader loading modes:

| Mode | How | When SDK loads | |------|-----|---------------| | Lazy (default) | Nothing extra | On first error or manual Sentry call | | Eager | Add data-lazy="no" to <script> | After all page scripts finish | | Manual | Call Sentry.forceLoad() | Whenever you call it |

Safe to call before SDK loads (buffered):

  • Sentry.captureException()
  • Sentry.captureMessage()
  • Sentry.captureEvent()
  • Sentry.addBreadcrumb()
  • Sentry.withScope()

For other methods, use Sentry.onLoad():

<script>
  window.Sentry && Sentry.onLoad(function () {
    Sentry.setUser({ id: "123" });
  });
</script>

Set release via global (optional):

<script>
  window.SENTRY_RELEASE = { id: "my-app@1.0.0" };
</script>

Loader Script limitations:

  • ❌ No Sentry.logger.* (logging) — npm path only
  • ❌ No framework-specific features (React ErrorBoundary, Vue Router tracking, etc.)
  • ❌ Tracing headers only added to fetch calls made after SDK loads
  • ❌ Version changes take a few minutes to propagate via CDN cache
  • ⚠️ Use defer (not async) on all other scripts when using the loader

CSP requirements:

script-src: https://browser.sentry-cdn.com https://js.sentry-cdn.com
connect-src: *.sentry.io

Path C: CDN Bundles (Manual Script Tags)

Best for: Pages that can't use the Loader Script but need synchronous loading.

Pick the bundle that matches your feature needs and place it before all other scripts:

Errors only (minimal footprint):

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.min.js"
  integrity="sha384-L/HYBH2QCeLyXhcZ0hPTxWMnyMJburPJyVoBmRk4OoilqrOWq5kU4PNTLFYrCYPr"
  crossorigin="anonymous"
></script>

Errors + Tracing:

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.min.js"
  integrity="sha384-DIqcfVcfIewrWiNWfVZcGWExO5v673hkkC5ixJnmAprAfJajpUDEAL35QgkOB5gw"
  crossorigin="anonymous"
></script>

Errors + Session Replay:

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.replay.min.js"
  integrity="sha384-sbojwIJFpv9duIzsI9FRm87g7pB15s4QwJS1m1xMSOdV1CF3pwgrPPEu38Em7M9+"
  crossorigin="anonymous"
></script>

Errors + Tracing + Replay (recommended full setup):

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.replay.min.js"
  integrity="sha384-oo2U4zsTxaHSPXJEnXtaQPeS4Z/qbTqoBL9xFgGxvjJHKQjIrB+VRlu97/iXBtzw"
  crossorigin="anonymous"
></script>

Errors + Tracing + Replay + User Feedback:

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.replay.feedback.min.js"
  integrity="sha384-SmHU39Qs9cua0KLtq3A6gis1/cqM1nZ6fnGzlvWAPiwhBDO5SmwFQV65BBpJnB3n"
  crossorigin="anonymous"
></script>

Full bundle (all features):

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.replay.feedback.logs.metrics.min.js"
  integrity="sha384-gOjSzRxwpXpy0FlT6lg/AVhagqrsUrOWUO7jm6TJwuZ9YVHtYK0MBA2hW2FGrIGl"
  crossorigin="anonymous"
></script>

CDN bundle variants summary:

| Bundle | Features | When to use | |--------|----------|-------------| | bundle.min.js | Errors only | Absolute minimum footprint | | bundle.tracing.min.js | + Tracing | Performance monitoring | | bundle.replay.min.js | + Replay | Session recording | | bundle.tracing.replay.min.js | + Tracing + Replay | Full observability | | bundle.tracing.replay.feedback.min.js | + User Feedback | + in-app feedback widget | | bundle.logs.metrics.min.js | + Logs + Metrics | Structured logs (CDN) | | bundle.tracing.replay.feedback.logs.metrics.min.js | Everything | Max coverage |

Initialize after the script tag:

<script>
  Sentry.init({
    dsn: "https://YOUR_KEY@o0.ingest.sentry.io/YOUR_PROJECT",
    environment: "production",
    release: "my-app@1.0.0",
    integrations: [
      Sentry.browserTracingIntegration(),
      Sentry.replayIntegration({
        maskAllText: true,
        blockAllMedia: true,
      }),
    ],
    tracesSampleRate: 1.0,
    tracePropagationTargets: ["localhost", /^https:\/\/yourapi\.io/],
    replaysSessionSampleRate: 0.1,
    replaysOnErrorSampleRate: 1.0,
  });
</script>

CDN CSP requirements:

script-src: https://browser.sentry-cdn.com https://js.sentry-cdn.com
connect-src: *.sentry.io

For Each Agreed Feature

Walk through features one at a time. Load the reference file, follow its steps, verify before moving on:

| Feature | Reference | Load when... | |---------|-----------|-------------| | Error Monitoring | ${SKILL_ROOT}/references/error-monitoring.md | Always (baseline) | | Tracing | ${SKILL_ROOT}/references/tracing.md | Page load / API call tracing | | Session Replay | ${SKILL_ROOT}/references/session-replay.md | User-facing app | | Logging | ${SKILL_ROOT}/references/logging.md | Structured log search; npm or CDN logs bundle (not Loader Script) | | Profiling | ${SKILL_ROOT}/references/profiling.md | Performance-critical, Chromium-only | | User Feedback | ${SKILL_ROOT}/references/user-feedback.md | Capture user reports after errors |

For each feature: Read ${SKILL_ROOT}/references/<feature>.md, follow steps exactly, verify it works.

Configuration Reference

Key Sentry.init() Options

| Option | Type | Default | Notes | |--------|------|---------|-------| | dsn | string | — | Required. SDK disabled when empty | | environment | string | "production" | e.g., "staging", "development" | | release | string | — | e.g., "my-app@1.0.0" or git SHA — links errors to releases | | sendDefaultPii | boolean | false | Includes IP addresses and request headers | | tracesSampleRate | number | — | 0–1; 1.0 in dev, 0.1–0.2 in prod | | tracesSampler | function | — | Per-transaction sampling; overrides rate | | tracePropagationTargets | (string\|RegExp)[] | same-origin | Outgoing URLs that receive distributed tracing headers | | replaysSessionSampleRate | number | — | Fraction of all sessions recorded | | replaysOnErrorSampleRate | number | — | Fraction of error sessions recorded | | enableLogs | boolean | false | Enable Sentry.logger.* API (npm or CDN logs bundle; not Loader Script) | | attachStackTrace | boolean | false | Stack traces on captureMessage() calls | | maxBreadcrumbs | number | 100 | Breadcrumbs stored per event | | debug | boolean | false | Verbose SDK output to console | | tunnel | string | — | Proxy URL to bypass ad blockers | | ignoreErrors | (string\|RegExp)[] | [] | Drop errors matching these patterns | | denyUrls | (string\|RegExp)[] | [] | Drop errors from scripts at these URLs | | allowUrls | (string\|RegExp)[] | [] | Only capture errors from these script URLs | | spotlight | boolean\|string | false | Forward events to Spotlight local dev overlay |

Browser-Specific Options

| Option | Type | Default | Notes | |--------|------|---------|-------| | cdnBaseUrl | string | — | Base URL for lazy-loading integrations | | skipBrowserExtensionCheck | boolean | false | Skip check for browser extension context |

window.SENTRY_RELEASE Global (CDN / Loader Path)

Set the release version before the SDK loads:

<script>
  window.SENTRY_RELEASE = { id: "my-app@1.0.0" };
</script>

Verification

Trigger test events to confirm Sentry is receiving data:

npm / CDN path:

<!-- Add temporarily to your page -->
<button onclick="throw new Error('Sentry Browser Test Error')">
  Test Error
</button>

Performance verification (npm path):

import * as Sentry from "@sentry/browser";

Sentry.startSpan({ name: "Test Span", op: "test" }, () => {
  // your operation
});

Manual capture:

Sentry.captureException(new Error("Manual test"));
Sentry.captureMessage("Manual test message", "info");

Check the Sentry dashboard:

  • Issues → error appears within seconds
  • Traces → page load transaction visible
  • Replays → session recording visible after page interaction
  • Logs → structured log entries if logging enabled (npm or CDN logs bundle)

Set debug: true in Sentry.init() and check the browser console if nothing appears.

Phase 4: Cross-Link

After completing browser setup, check for a companion backend missing Sentry coverage:

ls ../backend ../server ../api ../go ../python 2>/dev/null
cat ../go.mod 2>/dev/null | head -3
cat ../requirements.txt ../pyproject.toml 2>/dev/null | head -3
cat ../Gemfile 2>/dev/null | head -3
cat ../pom.xml 2>/dev/null | grep '<artifactId>' | head -3
cat ../composer.json 2>/dev/null | head -3

If a backend exists without Sentry configured, suggest the matching skill:

| Backend detected | Suggest skill | |-----------------|--------------| | Go (go.mod) | sentry-go-sdk | | Python (requirements.txt, pyproject.toml) | sentry-python-sdk | | Ruby (Gemfile) | sentry-ruby-sdk | | PHP (composer.json) | sentry-php-sdk | | .NET (*.csproj, *.sln) | sentry-dotnet-sdk | | Java (pom.xml, build.gradle) | See docs.sentry.io/platforms/java/ | | Node.js (Express, Fastify) | sentry-node-sdk | | NestJS (@nestjs/core) | sentry-nestjs-sdk |

Troubleshooting

| Issue | Solution | |-------|----------| | Events not appearing | Set debug: true, check DSN, open browser console for SDK errors | | Source maps not working | Build in production mode (npm run build); verify SENTRY_AUTH_TOKEN is set | | Minified stack traces | Source maps not uploading — check build plugin config; run npx @sentry/wizard@latest -i sourcemaps | | CDN bundle not found | Check version number in URL; see browser.sentry-cdn.com for latest | | SRI integrity error | Hash mismatch — re-copy the full <script> tag including integrity attribute from this skill | | Loader Script not firing | Verify it's the first <script> on the page; check for CSP errors in console | | Tracing not working with Loader | Fetch calls before SDK loads won't be traced — wrap early calls in Sentry.onLoad() | | sentryOnLoad not called | Must define window.sentryOnLoad before the loader <script> tag | | Logging not available | Sentry.logger.* requires npm or a CDN bundle with .logs. in its name — not supported via Loader Script | | Profiling not working | Verify Document-Policy: js-profiling header on document responses; Chromium-only | | Ad blockers dropping events | Set tunnel: "/sentry-tunnel" and add a server-side relay endpoint | | Session replay not recording | Confirm replayIntegration() is in init; check replaysSessionSampleRate > 0 | | Replay CSP errors | Add worker-src 'self' blob: and child-src 'self' blob: to your CSP | | tracePropagationTargets not matching | Check regex escaping; default is same-origin only | | Events blocked by browser extension | Add denyUrls: [/chrome-extension:\/\//] to filter extension errors | | High event volume | Lower sampleRate (errors) and tracesSampleRate from 1.0 in production | | Source maps uploaded after deploy | Source maps must be uploaded before errors occur — integrate into CI/CD | | esbuild splitting conflict | sentryEsbuildPlugin doesn't support splitting: true — use sentry-cli instead |