fix: image counts are incorrectly calculated

[kmendell]

What This PR Implements

Related issue

Related Issue

Fixes # #1712

Changes Made

Testing Done

• Development environment started: ./scripts/development/dev.sh start
• Frontend verified at http://localhost:3000
• Backend verified at http://localhost:3552
• Manual testing completed (describe):
• No linting errors (e.g., just lint all)
• Backend tests pass: just test backend

Checklist

• This PR is not opened from my fork’s main branch

AI Tool Used (if applicable)

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I reviewed and edited all AI-generated output:
I ran all required tests and manually verified changes:

Additional Context

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Greptile Overview

Greptile Summary

Fixed incorrect image count calculations by replacing unreliable image.Containers field with proper container-to-image ID matching. The PR addresses two key issues:

• Image usage tracking: Now fetches all containers and builds a map of in-use image IDs, then checks each image against this map. Previously relied on image.Containers field which was producing incorrect counts (showing -1, 0, or 99 values).
• Update summary accuracy: GetUpdateSummary now filters counts to only live Docker images, preventing stale database records from inflating statistics.

The changes include comprehensive test coverage verifying the fixes work correctly, and integration tests to ensure the API counts align with the actual image data.

Confidence Score: 5/5

• This PR is safe to merge with no identified risks
• The changes are well-architected with proper error handling, comprehensive unit tests demonstrating the fix works correctly, and integration tests validating end-to-end behavior. The root cause is clearly addressed by replacing unreliable data with proper container-to-image ID matching
• No files require special attention

Important Files Changed

Filename	Overview
backend/internal/services/docker_client_service.go	Fixed image usage counting by checking container ImageIDs instead of unreliable image.Containers field
backend/internal/services/image_service.go	Refactored prune cleanup logic into smaller functions and added orphaned record cleanup
backend/internal/services/image_update_service.go	Fixed GetUpdateSummary to only count live Docker images, preventing stale data from inflating counts

_{Last reviewed commit: 19c5c57}

[kmendell]

• fix: image counts are incorrectly calculated #1760 👈 (View in Graphite)
• main

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[github-actions]

🔍 Deadcode Analysis

Found 3 unreachable functions in the backend.

View details

internal/services/auth_service.go:753:23: unreachable func: AuthService.GetAutoLoginConfig
internal/services/auth_service.go:787:23: unreachable func: AuthService.GetAutoLoginPassword
internal/utils/ws/hub.go:27:15: unreachable func: Hub.ClientCount

Only remove deadcode that you know is 100% no longer used.

Analysis from commit 5c31dc4

[getarcaneappbot]

Container images for this PR have been built successfully!

• Manager: ghcr.io/getarcaneapp/arcane:pr-1760
• Agent: ghcr.io/getarcaneapp/arcane-headless:pr-1760

Built from commit 593863e

[greptile-apps]

_{8 files reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

[kmendell]

@greptileai