fix(insights): reduce activity aggregation overhead

[waleedlatif1]

Summary

• Aggregate workflow and chat activity separately before combining results, preserving exact member counts and duration averages.
• Add a concurrent covering index for activity queries and log when analytics fall back to the primary database.
• Format usage timestamps after aggregation and correct timezone bucketing for UTC ledger timestamps.

Type of Change

• Bug fix

Testing

82 focused tests passed, including PostgreSQL aggregation, timezone, scope, and pagination regressions. Verified the local app and benchmarked reads and writes with synthetic data. Type checks, lint, API validation, migration safety, and repository audits passed. Tested migration application and replay locally.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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Project	Deployment	Actions	Updated
docs	Ready	Preview	Sep 17, 2026 2:36am UTC

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge, with no outstanding correctness, security, or repository-rule issues identified.

Summary

This PR reduces analytics-query overhead while preserving aggregation accuracy and correct timezone behavior.

• Pre-aggregates workflow and chat activity separately before combining metrics.
• Formats usage timestamps after aggregation and applies the repository’s UTC timestamp contract during timezone bucketing.
• Adds focused PostgreSQL regression coverage to CI.
• Adds a replay-safe concurrent covering index and records its concurrent construction consistently in the Drizzle schema and snapshot.
• Logs when analytics reads fall back to the primary database.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  W[Workflow execution logs] --> WA[Aggregate workflow metrics]
  C[Copilot runs] --> CA[Aggregate chat metrics]
  WA --> U[Union aggregate rows]
  CA --> U
  U --> F[Combine counts and averages]
  F --> S[Activity summary and breakdown]
  L[Usage ledger timestamps] --> T[UTC-to-viewer timezone conversion]
  T --> B[Aggregate into calendar buckets]
  B --> O[Format bucket timestamps]

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[cubic-dev-ai]

All reported issues were addressed across 10 files

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[waleedlatif1]

@greptile

[waleedlatif1]

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[cubic-dev-ai]

@cubic-dev-ai review this PR

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[cubic-dev-ai]

No issues found across 10 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

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