[PROTOTYPE] web interference detection

[madblex]

Asana Task/Github Issue: https://app.asana.com/1/137249556945/project/1206054067224240/task/1211804981097440

Description

This PR builds a prototype for the WebInterferenceDetection system:

• the service with the detection logic
• the associated WebInterferenceDetection content feature prototype + example usages
• working integration in the BrokerProtection content feature

Goals

• Keep all interference detection logic in one place (services/web-interference-detection/) to avoid duplication across features while maintaining flexibility for future detector types.
• All detectors use common utilities from detection-utils.js (selector checking, visibility detection, pattern matching) to maximise code reuse and consistency.
• The service architecture intentionally avoids over-constraining detector implementations. We will revisit this based on what patterns emerge.
• Unsure about this: Each interference type has an independent configuration with observeDOMChanges flag controlling whether continuous monitoring is enabled per-detector.

Caveats

Current implementation creates new observers for each detect() call when observeDOMChanges: true. Multiple detections may create redundant observers. Future iterations should consider observer pooling/reuse, debouncing detection calls, or centralised DOM observation.

Testing Steps

n/a

Checklist

Please tick all that apply:

• [ ] I have tested this change locally
• [ ] I have tested this change locally in all supported browsers
• [ ] This change will be visible to users
• [ ] I have added automated tests that cover this change
• [ ] I have ensured the change is gated by config
• [ ] This change was covered by a ship review
• [ ] This change was covered by a tech design
• [ ] Any dependent config has been merged

---

[!NOTE] Introduces a config-driven Web Interference Detection service (bot/fraud/YouTube ads) with messaging APIs, a new feature entry point, and BrokerProtection integration.

• Services:
  • injected/src/services/web-interference-detection/: New detection service with detectors bot-detection, fraud-detection, youtube-ads-detection, shared utils (detection-utils, result-factory), default config, and type definitions.
  • detector-service.js: Orchestrates detections per request and optional continuous monitoring via callbacks.
• Features:
  • features/web-interference-detection.js: New content feature enabling on-demand detection (detectInterference) and continuous monitoring (startInterferenceMonitoring), emitting interferenceDetected/interferenceChanged.
  • features/broker-protection.js: Integrates detection via createWebInterferenceService, adds detectInterference handler and emits interferenceDetected/interferenceDetectionError.
• Utilities:
  • error-utils.js: Adds safeCall helper.
• Config/Types:
  • default-config.js: Default interference configuration (bot, fraud, YouTube ads).
  • types/*.js: API and detection type definitions.

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[github-actions[bot]]

Temporary Branch Update

The temporary branch has been updated with the latest changes. Below are the details:

• Branch Name: pr-releases/pr-2048
• Commit Hash: a0b8a36c5acbbeb38af7582f64d96734741e4745
• Last Updated: November 6, 2025 at 4:43:00 PM UTC
• Install Command: npm i github:duckduckgo/content-scope-scripts#a0b8a36c5acbbeb38af7582f64d96734741e4745

Please use the above install command to update to the latest version.

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[Beta] Generated file diff

Time updated: Thu, 06 Nov 2025 16:43:18 GMT

Android

    - android/autofillImport.js

• android/brokerProtection.js

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Apple

    - apple/contentScopeIsolated.js

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Integration

    - integration/contentScope.js

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Windows

    - windows/contentScope.js

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