Pipeline Overview

How nestjs-doctor works from CLI invocation to final output.

Flow

CLI Entry

src/cli/index.ts

Load Config

src/core/config-loader.ts

Detect Project

src/core/project-detector.ts

Collect Files

src/core/file-collector.ts

Parse AST

src/engine/ast-parser.ts

Build Module Graph

src/engine/module-graph.ts

Resolve Providers

src/engine/type-resolver.ts

Run Rules

src/engine/rule-runner.ts

Filter Diagnostics

src/core/filter-diagnostics.ts

Calculate Score

src/scorer/index.ts

Output

src/cli/output/

Directory Map

Directory	Responsibility
`src/cli/`	CLI flags, entry point, output formatters
`src/core/`	Config loading, file collection, project detection, diagnostic filtering
`src/engine/`	AST parsing, module graph, provider resolution, rule execution
`src/rules/`	All 40 rules organized by category (`security/`, `correctness/`, `architecture/`, `performance/`)
`src/scorer/`	Score calculation, severity weights, score labels
`src/types/`	Shared type definitions (`Diagnostic`, `Config`, `Result`, errors)

Steps

The pipeline has 10 stages. In a monorepo, stages 2-9 run once per sub-project.

#	Stage	Source	Scope
1	Config Loading	`src/core/config-loader.ts`	Once
2	Project Detection	`src/core/project-detector.ts`	Per project
3	File Collection	`src/core/file-collector.ts`	Per project
4	AST Parsing	`src/engine/ast-parser.ts`	Per project
5	Module Graph	`src/engine/module-graph.ts`	Per project
6	Provider Resolution	`src/engine/type-resolver.ts`	Per project
7	Rule Execution	`src/engine/rule-runner.ts`	Per project
8	Diagnostic Filtering	`src/core/filter-diagnostics.ts`	Per project
9	Scoring	`src/scorer/index.ts`	Per project + combined
10	Output	`src/cli/output/`	Once

Orchestrator

The scan() and scanMonorepo() functions in src/core/scanner.ts wire these stages together. The CLI calls one of these, and the Node.js API (diagnose(), diagnoseMonorepo()) wraps them with path validation.

Parallel Execution

The pipeline exploits concurrency where stages are independent:

Single-project mode: custom rule resolution and file collection run concurrently (Promise.all), and project detection runs in parallel with rule execution.
Monorepo mode: file collection for all sub-projects runs in parallel, and then each sub-project's full analysis (AST parsing through scoring) runs concurrently via Promise.all.

HTML Report

Run npx nestjs-doctor . --report to generate an interactive HTML report. The output is a self-contained nestjs-doctor-report.html file that auto-opens in your browser. It includes four tabs: summary, diagnostics, an interactive module graph (nodes, directed edges, circular dependency highlighting), and a custom rule lab.