Add config drift comparison tool for YAML merge

[npeham]

Summary

Adds a new "Compare & merge" feature to the configuration panel that allows users to paste a librechat.yaml file and compare it against the values currently configured in LibreChat. The tool identifies:

• Conflicts: Fields with differing values between the pasted YAML and LibreChat's current config (must be resolved before merging)
• Drift: Configured values missing from the pasted YAML (automatically folded into the merge)
• In-sync values: Fields that match between both sources

When no conflicts exist, users receive a single merged YAML ready to save, combining their pasted config with all currently configured values.

Change Type

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Implementation Details

New Components & Routes

• ConfigDiffPage (src/components/configuration/ConfigDiffPage.tsx): Main UI component with two-column layout (input YAML on left, results on right)
  • Handles file upload and manual YAML pasting
  • Displays conflicts, additions, and merged result
  • Copy-to-clipboard for merged YAML
• Route: /configuration/diff with permission checks matching the main configuration page

Core Logic

• computeConfigDrift() (src/utils/drift.ts): Compares pasted config against configured values, identifies conflicts/additions, and produces merged result
• buildConfiguredValues() (src/utils/drift.ts): Aggregates currently configured values from file config and database overrides
• parseConfigYamlFn() (src/server/config.ts): Server function that parses and validates pasted YAML, returning literal parsed values (not AppService-expanded) for accurate comparison

Types

• New src/types/drift.ts with interfaces for conflicts, additions, and drift results

UI Integration

• Added "Compare & merge" link in the configuration page header
• New localization strings for the drift comparison feature

Testing

• Unit tests for computeConfigDrift() and buildConfiguredValues() covering:
  • Identifying additions (configured paths missing from pasted YAML)
  • Detecting conflicts (differing values)
  • Treating deeply equal objects/arrays as in-sync
  • Sorting results by path
  • Merging with proper precedence (DB overrides > file config)

Testing

Run unit tests:

bun test src/utils/drift.test.ts

Manual testing:

1. Navigate to Configuration → Compare & merge
2. Paste a valid librechat.yaml or upload a file
3. Click "Compare" to see drift analysis
4. Verify conflicts are displayed when values differ
5. Verify merged YAML is generated when no conflicts exist
6. Test copy-to-clipboard functionality

Checklist

• Code adheres to project style guidelines (single-word naming, DRY, type safety)
• Self-reviewed code for correctness and clarity
• Complex logic documented with JSDoc
• No new warnings or TypeScript errors
• Unit tests added and passing
• Follows import conventions (barrel imports, type namespace)
• Proper permission checks aligned with configuration page

https://claude.ai/code/session_01NPqLTVpwriTqEc91NkjSsz