feat: cursor paginated tree [ENG-2442]

[speaker-ender]

Ticket ENG-2442

Description Of Changes

UI update to use the new cursor based pagination for the monitor tree.
To be tested against changes in ENG-2440

Code Changes

• Creating new cursor pagination params
• Updating monitor tree to use new pagination params

Steps to Confirm

1. Visit a datastore monitor
2. Confirm that the tree pagination functions as expected without regressions

Pre-Merge Checklist

• Issue requirements met
• All CI pipelines succeeded
• CHANGELOG.md updated
  • Add a db-migration This indicates that a change includes a database migration label to the entry if your change includes a DB migration
  • Add a high-risk This issue suggests changes that have a high-probability of breaking existing code label to the entry if your change includes a high-risk change (i.e. potential for performance impact or unexpected regression) that should be flagged
  • Updates unreleased work already in Changelog, no new entry necessary
• UX feedback:
  • All UX related changes have been reviewed by a designer
  • No UX review needed
• Followup issues:
  • Followup issues created
  • No followup issues
• Database migrations:
  • Ensure that your downrev is up to date with the latest revision on main
  • Ensure that your downgrade() migration is correct and works
    • If a downgrade migration is not possible for this change, please call this out in the PR description!
  • No migrations
• Documentation:
  • Documentation complete, PR opened in fidesdocs
  • Documentation issue created in fidesdocs
  • If there are any new client scopes created as part of the pull request, remember to update public-facing documentation that references our scope registry
  • No documentation updates required

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Project	Deployment	Actions	Updated (UTC)
fides-plus-nightly	Ready	Preview, Comment	Feb 20, 2026 3:06pm

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
fides-privacy-center	Ignored		Feb 20, 2026 3:06pm

[greptile-apps]

Greptile Summary

This PR successfully migrates the monitor tree from offset-based to cursor-based pagination on the frontend, while also adding database indices to optimize tree queries on the backend.

Key changes:

• Frontend now uses cursor pagination (cursor_start/cursor_end) instead of page-based pagination (page/pageIndex) for the monitor tree
• Added two new database indices: ix_stagedresource_leaf_true_monitor_status_urn (partial index for leaf nodes) and ix_staged_resource_ancestor_anc_dist_desc (for ancestor queries)
• Migration includes smart conditional logic to defer index creation for large tables (>1M rows) to application startup
• Added async version of is_backfill_completed function with proper test coverage
• Reduced TREE_PAGE_SIZE from 20 to 10

Implementation quality:

• Proper race condition handling in MonitorTree.tsx using request sequence tracking
• Migration includes existence checks to avoid errors on downgrade
• Indices are properly registered in post_upgrade_index_creation.py for deferred creation
• Test coverage added for new async utility function

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The changes are well-structured with proper migration handling, test coverage, and backwards compatibility. The cursor pagination implementation follows established patterns, includes race condition handling, and has appropriate safeguards for large tables. No critical issues found.
• No files require special attention

Important Files Changed

Filename	Overview
clients/admin-ui/src/features/data-discovery-and-detection/action-center/action-center.slice.ts	Updated getMonitorTree query to use cursor pagination instead of page/size pagination
clients/admin-ui/src/features/data-discovery-and-detection/action-center/fields/MonitorTree.tsx	Refactored tree component to use cursor pagination with cursor_start/cursor_end instead of pageIndex, includes race condition handling
src/fides/api/models/detection_discovery/core.py	Added two new database indices: ix_stagedresource_leaf_true_monitor_status_urn and ix_staged_resource_ancestor_anc_dist_desc for query optimization
src/fides/api/alembic/migrations/versions/xx_2026_02_13_0100_29acbb0689de_add_is_leaf_is_true_index_to_.py	Migration conditionally creates indices based on table size (<1M rows), with proper downgrade handling and existence checks
src/fides/api/migrations/post_upgrade_index_creation.py	Updated to include new indices ix_stagedresource_leaf_true_monitor_status_urn and ix_staged_resource_ancestor_anc_dist_desc

_{Last reviewed commit: 87cf10c}

[greptile-apps]

_{12 files reviewed, no comments}

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[vcruces]

Looks great and worked perfectly for me!