solid-generic

Before writing any new code it requires a DRY check across modules/cores/lib, modules/cores/interfaces, and modules/cores/errors, extracting anything repeated 3+ times into a shared helper. Each of the 5 SOLID principles has its own detailed reference (single-responsibility.md through dependency-inversion.md), plus copy-paste-ready templates for modules, services, interfaces, validators, factories, errors, and tests.

SOLID Generic - TypeScript / Bun / Node.js

Agent Workflow (MANDATORY)

Before ANY implementation, spawn 3 agents in parallel, one Agent call each with a name:

1. fuse-ai-pilot:explore-codebase - Analyze project structure and existing patterns
2. fuse-ai-pilot:research-expert - Verify latest TypeScript/Bun docs via Context7
3. mcp__context7__query-docs - Check integration compatibility

After implementation, run fuse-ai-pilot:sniper for validation.

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DRY - Reuse Before Creating (MANDATORY)

Before writing ANY new code:

1. Grep the codebase for similar function names, patterns, or logic
2. Check shared locations: modules/cores/lib/, modules/cores/interfaces/, modules/cores/errors/
3. If similar code exists -> extend/reuse instead of duplicate
4. If code will be used by 2+ modules -> create in modules/cores/
5. Extract repeated logic (3+ occurrences) into shared helpers

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Absolute Rules (MANDATORY)

1. Files < 100 lines

• Split at 90 lines - Never exceed 100
• Modules < 80 lines
• Services < 60 lines
• Validators < 40 lines

2. Interfaces Separated (Modular MANDATORY)

modules/[feature]/src/interfaces/   # Feature types
  |- user.interface.ts
  \- service.interface.ts
modules/cores/interfaces/            # Shared types
  \- shared.interface.ts

NEVER put interfaces in implementation files. NEVER use flat src/ structure - always modules/.

3. JSDoc Mandatory

/**
 * Parse configuration from file path.
 *
 * @param filePath - Absolute path to config file
 * @returns Parsed configuration object
 * @throws ConfigError if file is invalid
 */
export function parseConfig(filePath: string): Config

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SOLID Principles (Detailed Guides)

#	Principle	Reference	Key Rule
S	Single Responsibility	single-responsibility.md	One file = one reason to change
O	Open/Closed	open-closed.md	Extend via composition, not modification
L	Liskov Substitution	liskov-substitution.md	Implementations honor interface contracts
I	Interface Segregation	interface-segregation.md	Many focused interfaces > one fat interface
D	Dependency Inversion	dependency-inversion.md	Depend on abstractions, inject dependencies

See solid-principles.md for overview and architecture-patterns.md for project structure.

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Code Templates

Template	Usage	Max Lines
module.md	TypeScript/Bun module	80
service.md	Service with DI	60
interface.md	TypeScript interfaces	-
validator.md	Zod validation schemas	40
factory.md	Factory pattern	60
error.md	Custom error classes	40
test.md	Bun test / Vitest	-

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Forbidden

• Files > 100 lines
• Interfaces in implementation files
• Business logic in entry points
• Missing JSDoc on exports
• any type
• Barrel exports (index.ts re-exports)
• Duplicating existing utility without Grep search first
• Copy-pasting logic blocks instead of extracting shared function
• Concrete dependencies without interface abstraction