Stirling-PDF/AGENTS.md

AGENTS.md

This file provides guidance to AI Agents when working with code in this repository.

Common Development Commands

Build and Test

• Build project: ./gradlew clean build
• Run locally: ./gradlew bootRun
• Full test suite: ./test.sh (builds all Docker variants and runs comprehensive tests)
• Code formatting: ./gradlew spotlessApply (runs automatically before compilation)

Docker Development

• Build ultra-lite: docker build -t stirlingtools/stirling-pdf:latest-ultra-lite -f ./Dockerfile.ultra-lite .
• Build standard: docker build -t stirlingtools/stirling-pdf:latest -f ./Dockerfile .
• Build fat version: docker build -t stirlingtools/stirling-pdf:latest-fat -f ./Dockerfile.fat .
• Example compose files: Located in exampleYmlFiles/ directory

Security Mode Development

Set DOCKER_ENABLE_SECURITY=true environment variable to enable security features during development. This is required for testing the full version locally.

Python Development

Development for the AI engine happens in the engine/ folder. The frontend calls the Python via Java as a proxy.

• Follow the engine-specific guidance in engine/AGENTS.md for Python architecture, code style, and AI usage.
• Use Makefile commands for Python work:
  • From engine/: make check to lint, type-check, test, etc. and make fix to fix easily fixable linting and formatting issues.
• The project structure is defined in engine/pyproject.toml. Any new dependencies should be listed there, followed by running make install.

Frontend Development

• Frontend dev server: cd frontend && npm run dev (requires backend on localhost:8080)
• Tech Stack: Vite + React + TypeScript + Mantine UI + TailwindCSS
• Proxy Configuration: Vite proxies /api/* calls to backend (localhost:8080)
• Build Process: DO NOT run build scripts manually - builds are handled by CI/CD pipelines
• Package Installation: DO NOT run npm install commands - package management handled separately
• Deployment Options:
  • Desktop App: npm run tauri-build (native desktop application)
  • Web Server: npm run build then serve dist/ folder
  • Development: npm run tauri-dev for desktop dev mode

Environment Variables

• All VITE_* variables must be declared in the appropriate example file:
  • frontend/config/.env.example — core, proprietary, and shared vars
  • frontend/config/.env.saas.example — SaaS-only vars
  • frontend/config/.env.desktop.example — desktop (Tauri)-only vars
• Never use || 'hardcoded-fallback' inline — put defaults in the example files
• npm run prep / prep:saas / prep:desktop auto-create the env files from examples on first run, and error if any required keys are missing
• These prep scripts run automatically at the start of all dev*, build*, and tauri* commands
• See frontend/README.md#environment-variables for full documentation

Import Paths - CRITICAL

ALWAYS use @app/* for imports. Do not use @core/* or @proprietary/* unless explicitly wrapping/extending a lower layer implementation.

For a broader explanation of the frontend layering and override architecture, see frontend/DeveloperGuide.md.

// ✅ CORRECT - Use @app/* for all imports
import { AppLayout } from "@app/components/AppLayout";
import { useFileContext } from "@app/contexts/FileContext";
import { FileContext } from "@app/contexts/FileContext";

// ❌ WRONG - Do not use @core/* or @proprietary/* in normal code
import { AppLayout } from "@core/components/AppLayout";
import { useFileContext } from "@proprietary/contexts/FileContext";

Only use explicit aliases when:

• Building layer-specific override that wraps a lower layer's component
• Example: import { AppProviders as CoreAppProviders } from "@core/components/AppProviders" when creating proprietary/AppProviders.tsx that extends the core version

The @app/* alias automatically resolves to the correct layer based on build target (core/proprietary/desktop) and handles the fallback cascade.

Component Override Pattern (Stub/Shadow)

Use this pattern for desktop-specific or proprietary-specific features WITHOUT runtime checks or conditionals.

How it works:

1. Core defines stub component (returns null or no-op)
2. Desktop/proprietary overrides with same path/name
3. Core imports via @app/* - higher layer "shadows" core in those builds
4. No @ts-ignore, no isTauri() checks, no runtime conditionals!

Example - Desktop-specific footer:

// core/components/rightRail/RightRailFooterExtensions.tsx (stub)
interface RightRailFooterExtensionsProps {
  className?: string;
}

export function RightRailFooterExtensions(_props: RightRailFooterExtensionsProps) {
  return null; // Stub - does nothing in web builds
}

// desktop/components/rightRail/RightRailFooterExtensions.tsx (real implementation)
import { Box } from '@mantine/core';
import { BackendHealthIndicator } from '@app/components/BackendHealthIndicator';

interface RightRailFooterExtensionsProps {
  className?: string;
}

export function RightRailFooterExtensions({ className }: RightRailFooterExtensionsProps) {
  return (
    <Box className={className}>
      <BackendHealthIndicator />
    </Box>
  );
}

// core/components/shared/RightRail.tsx (usage - works in ALL builds)
import { RightRailFooterExtensions } from '@app/components/rightRail/RightRailFooterExtensions';

export function RightRail() {
  return (
    <div>
      {/* In web builds: renders nothing (stub returns null) */}
      {/* In desktop builds: renders BackendHealthIndicator */}
      <RightRailFooterExtensions className="right-rail-footer" />
    </div>
  );
}

Build resolution:

• Core build: @app/* → core/* → Gets stub (returns null)
• Desktop build: @app/* → desktop/* → Gets real implementation (shadows core)

Benefits:

• No runtime checks or feature flags
• Type-safe across all builds
• Clean, readable code
• Build-time optimization (dead code elimination)

Multi-Tool Workflow Architecture

Frontend designed for stateful document processing:

• Users upload PDFs once, then chain tools (split → merge → compress → view)
• File state and processing results persist across tool switches
• No file reloading between tools - performance critical for large PDFs (up to 100GB+)

FileContext - Central State Management

Location: frontend/src/core/contexts/FileContext.tsx

• Active files: Currently loaded PDFs and their variants
• Tool navigation: Current mode (viewer/pageEditor/fileEditor/toolName)
• Memory management: PDF document cleanup, blob URL lifecycle, Web Worker management
• IndexedDB persistence: File storage with thumbnail caching
• Preview system: Tools can preview results (e.g., Split → Viewer → back to Split) without context pollution

Critical: All file operations go through FileContext. Don't bypass with direct file handling.

Processing Services

• enhancedPDFProcessingService: Background PDF parsing and manipulation
• thumbnailGenerationService: Web Worker-based with main-thread fallback
• fileStorage: IndexedDB with LRU cache management

Memory Management Strategy

Why manual cleanup exists: Large PDFs (up to 100GB+) through multiple tools accumulate:

• PDF.js documents that need explicit .destroy() calls
• Blob URLs from tool outputs that need revocation
• Web Workers that need termination Without cleanup: browser crashes with memory leaks.

Tool Development

Architecture: Modular hook-based system with clear separation of concerns:

• useToolOperation (frontend/src/core/hooks/tools/shared/useToolOperation.ts): Main orchestrator hook

  • Coordinates all tool operations with consistent interface
  • Integrates with FileContext for operation tracking
  • Handles validation, error handling, and UI state management

• Supporting Hooks:

  • useToolState: UI state management (loading, progress, error, files)
  • useToolApiCalls: HTTP requests and file processing
  • useToolResources: Blob URLs, thumbnails, ZIP downloads

• Utilities:

  • toolErrorHandler: Standardized error extraction and i18n support
  • toolResponseProcessor: API response handling (single/zip/custom)
  • toolOperationTracker: FileContext integration utilities

Three Tool Patterns:

Pattern 1: Single-File Tools (Individual processing)

• Backend processes one file per API call
• Set multiFileEndpoint: false
• Examples: Compress, Rotate

return useToolOperation({
  operationType: 'compress',
  endpoint: '/api/v1/misc/compress-pdf',
  buildFormData: (params, file: File) => { /* single file */ },
  multiFileEndpoint: false,
});

Pattern 2: Multi-File Tools (Batch processing)

• Backend accepts MultipartFile[] arrays in single API call
• Set multiFileEndpoint: true
• Examples: Split, Merge, Overlay

return useToolOperation({
  operationType: 'split',
  endpoint: '/api/v1/general/split-pages',
  buildFormData: (params, files: File[]) => { /* all files */ },
  multiFileEndpoint: true,
  filePrefix: 'split_',
});

Pattern 3: Complex Tools (Custom processing)

• Tools with complex routing logic or non-standard processing
• Provide customProcessor for full control
• Examples: Convert, OCR

return useToolOperation({
  operationType: 'convert',
  customProcessor: async (params, files) => { /* custom logic */ },
});

Benefits:

• No Timeouts: Operations run until completion (supports 100GB+ files)
• Consistent: All tools follow same pattern and interface
• Maintainable: Single responsibility hooks, easy to test and modify
• i18n Ready: Built-in internationalization support
• Type Safe: Full TypeScript support with generic interfaces
• Memory Safe: Automatic resource cleanup and blob URL management

Architecture Overview

Project Structure

• Backend: Spring Boot application
• Frontend: React-based SPA in /frontend directory
  • File Storage: IndexedDB for client-side file persistence and thumbnails
  • Internationalization: JSON-based translations (converted from backend .properties)
• PDF Processing: PDFBox for core PDF operations, LibreOffice for conversions, PDF.js for client-side rendering
• Security: Spring Security with optional authentication (controlled by DOCKER_ENABLE_SECURITY)
• Configuration: YAML-based configuration with environment variable overrides

Controller Architecture

• API Controllers (src/main/java/.../controller/api/): REST endpoints for PDF operations
  • Organized by function: converters, security, misc, pipeline
  • Follow pattern: @RestController + @RequestMapping("/api/v1/...")

Key Components

• SPDFApplication.java: Main application class with desktop UI and browser launching logic
• ConfigInitializer: Handles runtime configuration and settings files
• Pipeline System: Automated PDF processing workflows via PipelineController
• Security Layer: Authentication, authorization, and user management (when enabled)

Frontend Directory Structure

The frontend is organized with a clear separation of concerns:

• frontend/src/core/: Main application code (shared, production-ready components)

  • core/components/: React components organized by feature
    • core/components/tools/: Individual PDF tool implementations
    • core/components/viewer/: PDF viewer components
    • core/components/pageEditor/: Page manipulation UI
    • core/components/tooltips/: Help tooltips for tools
    • core/components/shared/: Reusable UI components
  • core/contexts/: React Context providers
    • FileContext.tsx: Central file state management
    • file/: File reducer and selectors
    • toolWorkflow/: Tool workflow state
  • core/hooks/: Custom React hooks
    • hooks/tools/: Tool-specific operation hooks (one directory per tool)
    • hooks/tools/shared/: Shared hook utilities (useToolOperation, etc.)
  • core/constants/: Application constants and configuration
  • core/data/: Static data (tool taxonomy, etc.)
  • core/services/: Business logic services (PDF processing, storage, etc.)

• frontend/src/desktop/: Desktop-specific (Tauri) code

• frontend/src/proprietary/: Proprietary/licensed features

• frontend/src-tauri/: Tauri (Rust) native desktop application code

• frontend/public/: Static assets served directly

  • public/locales/: Translation JSON files

Component Architecture

• Static Assets: CSS, JS, and resources in src/main/resources/static/ (legacy) + frontend/public/ (modern)
• Internationalization:
  • Backend: messages_*.properties files
  • Frontend: JSON files in frontend/public/locales/ (converted from .properties)
  • Conversion Script: scripts/convert_properties_to_json.py

Configuration Modes

• Ultra-lite: Basic PDF operations only
• Standard: Full feature set
• Fat: Pre-downloaded dependencies for air-gapped environments
• Security Mode: Adds authentication, user management, and enterprise features

Testing Strategy

• Integration Tests: Cucumber tests in testing/cucumber/
• Docker Testing: test.sh validates all Docker variants
• Manual Testing: No unit tests currently - relies on UI and API testing

Development Workflow

1. Local Development:
   • Backend: ./gradlew bootRun (runs on localhost:8080)
   • Frontend: cd frontend && npm run dev (runs on localhost:5173, proxies to backend)
2. Docker Testing: Use ./test.sh before submitting PRs
3. Code Style: Spotless enforces Google Java Format automatically
4. Translations:
   • Backend: Use helper scripts in /scripts for multi-language updates
   • Frontend: Update JSON files in frontend/public/locales/ or use conversion script
5. Documentation: API docs auto-generated and available at /swagger-ui/index.html

Frontend Architecture Status

• Core Status: React SPA architecture complete with multi-tool workflow support
• State Management: FileContext handles all file operations and tool navigation
• File Processing: Production-ready with memory management for large PDF workflows (up to 100GB+)
• Tool Integration: Modular hook architecture with useToolOperation orchestrator
  • Individual hooks: useToolState, useToolApiCalls, useToolResources
  • Utilities: toolErrorHandler, toolResponseProcessor, toolOperationTracker
  • Pattern: Each tool creates focused operation hook, UI consumes state/actions
• Preview System: Tool results can be previewed without polluting file context (Split tool example)
• Performance: Web Worker thumbnails, IndexedDB persistence, background processing

Translation Rules

• CRITICAL: Always update translations in en-GB only, never en-US
• Translation files are located in frontend/public/locales/

Important Notes

• Java Version: Minimum JDK 21, supports and recommends JDK 25
• Lombok: Used extensively - ensure IDE plugin is installed
• File Persistence:
  • Backend: Designed to be stateless - files are processed in memory/temp locations only
  • Frontend: Uses IndexedDB for client-side file storage and caching (with thumbnails)
• Security: When DOCKER_ENABLE_SECURITY=false, security-related classes are excluded from compilation
• Import Paths: ALWAYS use @app/* for imports - never use @core/* or @proprietary/* unless explicitly wrapping/extending a lower layer
• FileContext: All file operations MUST go through FileContext - never bypass with direct File handling
• Memory Management: Manual cleanup required for PDF.js documents and blob URLs - don't remove cleanup code
• Tool Development: New tools should follow useToolOperation hook pattern (see useCompressOperation.ts)
• Performance Target: Must handle PDFs up to 100GB+ without browser crashes
• Preview System: Tools can preview results without polluting main file context (see Split tool implementation)
• Adding Tools: See ADDING_TOOLS.md for complete guide to creating new PDF tools

Communication Style

• Be direct and to the point
• No apologies or conversational filler
• Answer questions directly without preamble
• Explain reasoning concisely when asked
• Avoid unnecessary elaboration

Decision Making

• Ask clarifying questions before making assumptions
• Stop and ask when uncertain about project-specific details
• Confirm approach before making structural changes
• Request guidance on preferences (cross-platform vs specific tools, etc.)
• Verify understanding of requirements before proceeding