Extend routing API to fetch and combine route-specific preferences with global preferences

[Copilot]

The /search endpoint previously only fetched global preferences. It now fetches and combines both global and route-specific preferences matching the exact origin/destination coordinates before sending to the AI agents service.

Service layer

• Added get_preferences_by_coordinates() to route_preference_service that filters by exact coordinate match with user isolation

API endpoint

• Updated /api/v1/routes/search to fetch three preference types in order:
  1. Request preferences (inline from request body)
  2. Global preferences (user's stored defaults)
  3. Route-specific preferences (matching exact coordinates)
• Combined list sent to AI agents service
• Graceful degradation on individual fetch failures

Example usage:

# User has global preference: "prefer eco-friendly routes"
# User has route-specific preference for (60.17, 24.94) → (60.21, 24.66): "avoid construction"
# Request includes: "prefer faster routes"

# All three are now combined and sent to AI agents:
preferences = [
    {"prompt": "prefer faster routes"},      # from request
    {"prompt": "prefer eco-friendly routes"}, # global
    {"prompt": "avoid construction"}          # route-specific
]

Testing

• 10 new tests covering coordinate matching, preference combinations, and failure scenarios

Original prompt

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This section details on the original issue you should resolve

<issue_title>Update the logic of the routing API fetching preferences</issue_title>
<issue_description>New preference fetching /search logic should:

• Get all the global preferences
• Get all the route-specific preferences with matching coordinates

Send combined preference list to ai_agents_service for processing as before.</issue_description>

<agent_instructions>Cover tests for this.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Update the logic of the routing API fetching preferences #54

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[zlendo1]

Lgtm