2025-09-25 Engineering Team

[jpn--]

@ActivitySim/engineering

Agenda

• Check in on status of open PR's and tasks
• Testing of our official examples: against main, against the latest release, against older releases? And do we need or want a consistent usage of UV?

Task Status Summary

Mainline ActivitySim

• Estimation enhancements #917 - have at least partial review in #976, some changes needed
• Fix test #978 - UV with only-group needs to also include original dependencies.

Explicit Error Terms Visualization

• Viz filtering #10 - still marked as draft, still has active work

PopulationSim

• PopulationSim #192 - some fixes done, ready to merge?

SANDAG Example Model

• Settings Checker for Extensions #31 - @andkay reviewed comments, need to coordinate with @jpn-- to make sure tests are sufficient.
• Example model configs for telecommute_status model #30 - @i-am-sijia fixed the target pipeline file, thank you. Need short discussion on how we want to test and how we want to use UV.

[jpn--]

ActivitySim Engineering Team Meeting Notes

Meeting Overview

Agenda

• Post-conference check-in and travel experiences
• Review of open tasks and contract status
• Discussion of estimation enhancements pull request
• SANDAG model testing updates and UV workflow issues
• Release planning and version management
• Documentation updates
• Team membership changes

Participants

• Jeff Newman (@jpn--) - Driftless
• Joe Castiglione (@joecastiglione) - Zephyr
• Stefan Coe (@stefancoe) - PSRC
• David Hensle (@dhensle) - RSG
• Sijia Wang (@i-am-sijia) - WSP
• Andrew Kay (@andkay) - CS

Duration

45 minutes

Executive Summary

The team discussed post-conference updates and confirmed all contracts for phase 11B are in place. The main focus was resolving UV workflow issues in the SANDAG example model and deciding to merge the estimation enhancements pull request despite some remaining CDAP model improvements needed. A new ActivitySim release will be prepared with current enhancements, and the team addressed version synchronization between example models and the main codebase.

Meeting Notes

Contract Status Update

Joe Castiglione confirmed that all contracts and task orders for phase 11B have been executed and are backdated to September 1st, allowing all team members to proceed with billable work.

SANDAG Model Testing and UV Workflow

Sijia Wang reported updates to the SANDAG example model testing pipeline to address failures related to the telecommute status model. The issue arose because the example model was testing against the official ActivitySim 1.4 release rather than the main development branch.

Key technical changes made:

• Updated GitHub actions to test against the main branch instead of the latest release
• Modified the workflow to use virtual environment activation instead of uv run to ensure local development code is used rather than pulling from PyPI
• This prevents UV from automatically syncing to the official release specified in the project dependencies

The team discussed the need for consistent UV usage patterns and proper version management between example models and the main ActivitySim codebase.

Estimation Enhancements Pull Request

David Hensle advocated for merging the long-pending estimation enhancements pull request, noting extensive testing by both RSG and Transport for New South Wales. The enhancement has been successfully used in production environments with only minor issues discovered.

Jeff Newman mentioned feedback from John Gliebe regarding CDAP model improvements needed for estimation mode, but the team agreed to merge the current enhancements and address CDAP improvements in a future release. This aligns with the new approach of smaller, more frequent releases rather than waiting for complete feature sets.

Release Planning and Version Management

The team discussed the need for parallel versioning of ActivitySim and example models:

• Development versions should test against the main branch
• Released versions should be tagged together for consistency
• Users should have clear guidance on which example model version corresponds to which ActivitySim release
• This will provide a clear upgrade path for users moving between versions

Jeff Newman committed to:

• Merging the estimation enhancements
• Fixing the SANDAG model crash issue (related to memory profiling and pandas datetime handling)
• Creating a new ActivitySim release
• Continuing to support both GitHub and PyPI releases until UV workflow is fully established

Documentation Updates

Sijia Wang noted that the documentation still points to ActivitySim 1.3 rather than 1.4. Jeff Newman confirmed this is a known issue he's working to resolve through automated build scripts rather than manual fixes.

Team Membership Changes

The team discussed Joe Flood's transition from SANDAG to CS and how this affects engineering team participation. Joe Castiglione indicated that CS should determine internally how to handle team representation within their allocated budget. David Hensle suggested finding a replacement consortium member for the engineering team to maintain diverse agency perspectives.

Future Task Planning

Joe Castiglione mentioned a list of approximately 25 potential development tasks at varying levels of detail. The team agreed that the product community team should review and prioritize which items need more elaboration before consortium consideration.

Action Items

• Jeff Newman (@jpn--):

  • Merge estimation enhancements pull request
  • Merge Sijia's changes to SANDAG model testing
  • Fix SANDAG model crash issue related to memory profiling
  • Create new ActivitySim release
  • Resolve documentation version linking issue
  • Complete CDAP estimation mode improvements (issue #976)

• Joe Castiglione (@joecastiglione):

  • Work with product community team to review and prioritize the 25-item development task list
  • Determine which tasks need additional elaboration before consortium review

• Andrew Kay (@andkay) / CS:

  • Determine team representation arrangement for engineering meetings following Joe Flood's transition

• Engineering Team:

  • Develop consistent UV usage patterns and documentation as part of upcoming UV development task
  • Consider replacement consortium member for engineering team representation