Detect repository stack (SDK install)

Before installing anything, you must understand the project. Identify what the project is built with and whether LaunchDarkly is already present.

This skill is nested under LaunchDarkly SDK Install (onboarding); the parent Step 1 is detect. Next: Generate integration plan unless the decision tree sends you elsewhere.

1. Language and framework

Look for the indicator files below (and related root layout), then read the relevant manifests to infer language and framework.

Look for these files to identify the stack:

File	Language/Framework
package.json	JavaScript/TypeScript (check for React, Next.js, Vue, Angular, Express, React Native, Electron, etc.)
requirements.txt, pyproject.toml, Pipfile, setup.py	Python (check for Django, Flask, FastAPI)
go.mod	Go (check for Gin, Echo, Fiber, Chi)
pom.xml, build.gradle, build.gradle.kts	Java/Kotlin (check for Spring, Quarkus, Android)
Gemfile	Ruby (check for Rails, Sinatra)
*.csproj, *.sln, *.fsproj	.NET/C# (check for ASP.NET, MAUI, Xamarin, WPF, UWP)
composer.json	PHP (check for Laravel, Symfony)
Cargo.toml	Rust (check for Actix, Axum, Rocket)
pubspec.yaml	Flutter/Dart
Package.swift, Podfile, *.xcodeproj	Swift/iOS
AndroidManifest.xml	Android (also check build.gradle for com.android)
rebar.config, mix.exs	Erlang/Elixir
CMakeLists.txt, Makefile (with C/C++ patterns)	C/C++ (check for #include patterns)
*.cabal, stack.yaml	Haskell
*.lua, rockspec	Lua
manifest, *.brs	Roku (BrightScript)
wrangler.toml	Cloudflare Workers (edge SDK)
vercel.json with edge functions	Vercel Edge (edge SDK)

Read the dependency file to identify the specific framework. For package.json, check both dependencies and devDependencies.

If you cannot identify the language or framework:

D5 -- BLOCKING: Call your structured question tool now.

• question: "I couldn't detect the project's language or framework. Which SDK would you like to use?"
• options: Present the available SDKs from SDK recipes as selectable options.
• STOP. Do not write the question as text. Do not continue until the user selects an option.

2. Package manager

Identify how the project installs dependencies:

Indicator	Package Manager
package-lock.json	npm
yarn.lock	yarn
pnpm-lock.yaml	pnpm
bun.lockb	bun
Pipfile.lock	pipenv
poetry.lock	poetry
go.sum	go modules
Gemfile.lock	bundler

Use the detected package manager for all install commands. If multiple lock files exist, prefer the one that was most recently modified.

3. Monorepo layout

Some repositories host multiple packages or services. Look for these indicators:

File / pattern	Tool or layout
pnpm-workspace.yaml	pnpm workspaces
lerna.json	Lerna
nx.json	Nx
turbo.json	Turborepo
rush.json	Rush
packages/ directory with multiple package.json files	Generic monorepo

When any of these apply, do not assume the repo root is the integration target:

D5 -- BLOCKING: Call your structured question tool now.

• question: "This is a monorepo. Which package, app, or service should I integrate LaunchDarkly into?"
• options: List the discovered packages/apps as selectable options.
• STOP. Do not write the question as text. Do not continue until the user selects an option.

Then run the rest of this detect step -- language, package manager, entrypoint, and SDK search -- in that target directory (and its subtree), not only at the root.

4. Application entrypoint

Find the main file where the application starts. In a monorepo, apply the patterns below within the chosen package after section 3 Monorepo layout. Common patterns:

• Node.js (server): Check package.json "main" field, or look for index.js, server.js, app.js, src/index.ts
• NestJS: Look for src/main.ts or src/main.js
• Python: Look for app.py, main.py, manage.py, wsgi.py, or the [tool.poetry.scripts] section
• Go: Look for main.go or cmd/*/main.go
• Java: Search for public static void main or @SpringBootApplication
• Ruby: Look for config.ru, config/application.rb
• React/Vue/Angular: Look for src/index.tsx, src/main.tsx, src/App.tsx, src/main.ts
• Next.js: App Router -- app/layout.tsx or app/layout.js (root layout). Pages Router -- pages/_app.tsx or pages/_app.js
• React Native: Look for App.tsx, App.js, index.js (with AppRegistry.registerComponent)
• Electron: Check package.json "main"; common paths include main.js or src/main.ts
• JavaScript (browser): Look for index.html, src/index.js, or bundler entry in webpack.config.js / vite.config.ts
• Flutter: Look for lib/main.dart
• Swift/iOS: Look for AppDelegate.swift, SceneDelegate.swift, or @main struct
• Android: Look for MainActivity.java or MainActivity.kt

5a. Classify workspace confidence

After sections 1-4, classify the workspace into one of three states before continuing. This classification determines how the rest of the flow proceeds.

State	Meaning	Criteria
Clear app	A runnable application was found	Language/framework detected, a real entrypoint exists, dependency manifest is present with application dependencies
Unclear / weak evidence	Something is present but it does not clearly represent a runnable app	Stray or minimal package.json (e.g. only devDependencies, no scripts), isolated config/manifest files, theme or config-only folders, token/fixture JSON, lockfiles without corresponding source, or multiple conflicting indicators with no dominant app structure
No app found	No recognizable application structure was detected	No dependency manifests, no entrypoints, no source files matching known patterns, or the workspace is empty / contains only documentation

Weak evidence must not be treated as confirmation. Examples of weak evidence:

• A package.json with no scripts section and no application source files
• A lone requirements.txt in a directory of data files or notebooks
• Config, theme, or fixture directories with manifests that do not represent a runnable service
• Monorepo roots where the real apps live in subdirectories but none was selected

Branching by state:

• Clear app → continue to section 6 (Existing LaunchDarkly SDK) and then SDK confirmation.

• Unclear / weak evidence:

D5-UNCLEAR -- BLOCKING: Call your structured question tool now.

• question: "I found some project files, but I'm not confident I've identified the right application to integrate. Can you point me to the correct app folder?"
• context: Briefly describe what you found and why it's ambiguous (e.g., "There's a package.json at the root, but it has no start script and no application source files").
• options:
  • Present any candidate folders you detected as selectable options
  • "It's somewhere else -- I'll tell you the path"
  • "There is no app yet -- help me create a demo"
• STOP. Do not make code changes, install packages, or generate an integration plan until the user confirms the target. Do not continue until the user selects an option.

After the user points to the correct folder, re-run detection (sections 1-4) scoped to that folder.

• No app found:

Tell the user clearly: "I didn't find a runnable application in this workspace." Then offer two paths:

D5-NOAPP -- BLOCKING: Call your structured question tool now.

• question: "I didn't find a runnable application in this workspace. How would you like to proceed?"
• options:
  • "Point me to the right folder -- the app is somewhere else"
  • "Create a minimal demo app so I can try LaunchDarkly"
• STOP. Do not continue until the user selects an option.

If the user chooses "point me to the right folder," re-run detection scoped to the path they provide. If they choose "create a demo app," create a minimal runnable app in a new subfolder (e.g. launchdarkly-demo/) using the simplest stack you can scaffold (Node.js + Express or a static HTML page are good defaults), then continue detection from that subfolder.

Do not declare onboarding complete unless the app target has been confirmed and the app can actually run.

6. Existing LaunchDarkly SDK

Search the codebase for existing LaunchDarkly usage:

Search for: launchdarkly, ldclient, ld-client, LDClient, @launchdarkly, launchdarkly-

Check:

• Is the SDK already in the dependency file?
• Is there initialization code?
• Is it properly configured or partially set up?
• Are there already feature flag evaluations?

SDK confirmation

After detecting the stack, confirm the SDK choice with the user:

• If one SDK is clearly the right fit: Present your recommendation and get confirmation:

D5 -- BLOCKING: Call your structured question tool now.

• question: "Based on what I found, I recommend the [SDK name] SDK. Does that look right?"

• options:

  • "Yes, proceed with that SDK" -> continue to plan
  • "No, I want a different one" -> let user specify

• STOP. Do not write the question as text. Do not continue until the user selects an option.

• If multiple SDKs could apply (e.g., a Next.js project with both server and client components):

  • If the user already asked for both (e.g. "frontend and backend," "server + browser," "API and SPA"): Treat that as a dual-SDK scope. Proceed to Generate integration plan with both SDKs in scope -- do not plan or implement only one and assume the other is "covered."
  • If scope is unclear:

D5 -- BLOCKING: Call your structured question tool now.

• question: "This project has both server-side and client-side surfaces. Which do you want to integrate?"
• options:
  • "Server-side only"
  • "Client-side only"
  • "Both server-side and client-side"
• STOP. Do not write the question as text. Do not continue until the user selects an option.

If they choose both, the plan must include two concrete integrations (see plan: Dual SDK integrations).

• If you cannot determine the right SDK: Present the available options from the SDK recipes as selectable options in your question tool and use the same blocking pattern above.

Decision tree

After detection and confirmation:

• No app found or unclear --> Already handled by D5-NOAPP / D5-UNCLEAR in section 5a. Do not proceed to plan until the user confirms a real app target.
• SDK already installed and initialized --> Skip to Create first feature flag (parent Step 6)
• SDK installed but not initialized --> Skip to Apply code changes (just add init code)
• SDK not present --> Continue to Generate integration plan
• Multiple targets detected (e.g., frontend + backend) --> If the user wants both SDKs (confirmed via D5 above), continue to Generate integration plan with dual-SDK scope (two packages, two entrypoints). If they want one surface only, plan for that single SDK.
• Language not detected --> Already handled by the D5 blocking question in section 1.

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Upon completion (normal path): Generate integration plan