Add recency, time-zone overlap, and work-context filters

[sajeetharan]

Problem

A mobile user found semantic queries such as "ml in europe" relevant, but could not narrow results by practical collaboration constraints: recent activity, working-hour overlap, or whether contributions are primarily solo/personal versus organization-owned work.

The current leaderboard filters only by country and top language. The current dataset also lacks explicit freshness, time-zone, and work-context fields, so this requires data pipeline and API support in addition to UI controls.

Proposed solution

Add composable discovery filters for:

• Recency: last meaningful GitHub activity within a selected window
• Time-zone overlap: minimum working-hour overlap relative to the viewer's selected time zone
• Work context: primarily personal/solo repositories, primarily organization-owned repositories, or mixed

Apply the filters consistently to semantic search, leaderboard results, and globe markers, with a compact mobile filter experience.

Acceptance criteria

• Define and document the source and meaning of lastActiveAt, time zone/UTC offset, and work-context classification
• Enrich the dataset and Cosmos DB schema/indexes with the required filterable fields
• Support recency windows such as 30 days, 90 days, 6 months, and 1 year
• Let users select a reference time zone and minimum overlap without requiring browser location permission
• Support Personal/solo, Organization, and Mixed work-context options
• Combine these filters with country, language, and semantic search queries
• Keep leaderboard, result count, and globe markers synchronized when filters change
• Make active filters clear and individually removable, including on mobile
• Provide honest Unknown states rather than guessing when source data is insufficient
• Add API and UI tests for individual filters, combined filters, unknown data, and empty results

Product and privacy notes

• Do not infer a user's actual working hours from commit timestamps. Use an explicit or location-derived time zone and a documented default availability window.
• Define "solo vs org" from repository ownership/context, not as a judgment about collaboration quality.
• Exclude private activity and expose only public source data.

Additional context

User feedback: "Would love filters for recency, time zone overlap, and solo vs org work."

Related: #24 (trending developers), #73 (agent-aware discovery filters).

[sajeetharan]

@pradipNP can you take a stab at it?

[pradipNP]

@pradipNP can you take a stab at it?

Thanks @sajeetharan,

Happy to take a look.

Since this touches the data pipeline, API layer, search, leaderboard, and globe filtering, I'd like to spend some time understanding the current implementation and put together an MVP plan before making changes.

I'll post a proposed implementation approach shortly.

[pradipNP]

Thanks @sajeetharan.

I've spent some time reviewing the implementation requirements. Since this touches the data pipeline, dataset enrichment, API layer, search, leaderboard, globe synchronization, and testing, I'd like to avoid blocking progress while I learn those parts of the codebase.

I'll continue contributing on smaller issues for now, but I'm happy to revisit this later if needed.