2025-10-23 Engineering Team

[joecastiglione]

@ActivitySim/engineering

Agenda

• Updates on 11B tasks

  • Consolidated Error Definitions (CS) -- ActivitySim#1000. Seems mostly done?
  • Trace files consistent hash (CS)
  • UV Support (WSP + All)
  • Clean up loggging (CS) -- ActivitySim#1004 Looks done?
  • Consistent Alternatives File Formatting (RSG)
  • Trip Scheduling Choice Reproducible Random (RSG) -- ActivitySim#1005
  • Fix Shadow Price Zones Reopening (RSG)
  • Global Option to Skip Households on Fail (WSP)
  • Example SANDAG Model Update (WSP) -- sandag-abm3-example#37 needs review from SANDAG and @jpn--
  • SANDAG Sharrow Performance Optimization (DL)

• Code Formatting

  • We are using an old version of Black (22), which leads to accidents
  • Let's move to Ruff

• Other Topics

  • EET Next Steps, RSG scoping progress?
  • Fix for explicit chunk merged.

[jpn--]

ActivitySim Engineering Meeting Notes

Meeting Overview

Agenda

Discussion of Task 11B progress, including trip scheduling choice implementation, test infrastructure improvements, code formatting updates, and UV installation documentation.

Participants

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

Duration

63 minutes

Executive Summary

The engineering team discussed progress on Task 11B deliverables, with significant focus on testing infrastructure and maintenance policies. RSG completed work on trip scheduling choice with reproducible random numbers, including a new unit test. The team decided to recommend retiring an removing unmaintained example models from the repository while ensuring proper unit tests exist for all unique components. Additional topics covered included transitioning from Black to Ruff for code formatting and updating UV installation documentation based on agency feedback.

Meeting Notes

Trip Scheduling Choice Implementation (RSG)

RSG completed the trip scheduling choice work with reproducible random numbers. The ARC test that was previously disabled has been turned back on and is now passing. The implementation includes a new unit test specifically for the trip scheduling choice component. The team confirmed that ARC's production model does use this trip scheduling component, making this work relevant to consortium members.

Testing Infrastructure and Example Models

The team had an extensive discussion about testing philosophy and maintenance of example models in the repository. Several legacy prototype models (ARC, MWCOG, SEMCOG) remain in the repository but have diverged, sometimes significantly, from agencies' production implementations. These models are contributing to maintenance overhead without providing value.

The team decided to adopt a new testing approach that includes maintaining only two canonical example models (MTC and SANDAG) for integration testing, creating unit tests for individual components rather than maintaining multiple full example models, retiring legacy prototype models that are no longer actively maintained by their respective agencies.

The settings checker identified issues with the prototype ARC example using legacy configuration structures. Rather than supporting multiple configuration approaches indefinitely, the team agreed to deprecate legacy methods and provide migration support to consortium members still using deprecated features.

Stefan Coe suggested creating a linked list of agency implementations on the ActivitySim documentation homepage, allowing agencies to reference each other's work without maintaining outdated examples in the main repository.

Code Formatting Transition

Jeff Newman proposed transitioning from Black (2022 version) to Ruff for code formatting. Ruff is faster, more up-to-date, and can also provide linting capabilities. The team agreed to this transition with configuration to auto-fix formatting issues similar to Black's behavior. Limited linting rules will be enabled initially to catch obvious issues without overwhelming the codebase with warnings.

UV Installation Documentation

Sijia Wang provided an update on UV installation outreach efforts. Three agencies (SANDAG, PSRC, SEMCOG) have successfully adopted UV. Documentation improvements were identified including guidance for global installation across multiple users on the same machine, integration with OpenM++, and clarification of use cases for "uv add activitysim" versus "uv sync."

The team agreed to update documentation first before conducting a second round of agency outreach, allowing more agencies to benefit from improved guidance.

SANDAG Example Model Update

WSP's work to update the SANDAG example model to match SANDAG's production model is substantially complete for the non-Sharrow version and awaits SANDAG review. The Sharrow version compatibility work remains pending. A few minor bugs were identified in the production model during this process.

Action Items

• Jeff Newman (@jpn--): Review and merge RSG's trip scheduling choice pull request; create pull request to transition from Black to Ruff for code formatting with appropriate configuration; complete Sharrow version compatibility for SANDAG example model
• David Hensle (@dhensle): Turn off ARC test in the trip scheduling choice pull request and flag for review; prepare park and ride discussion topic for next week's meeting
• Jeff Newman (@jpn--): Create separate pull request to remove ARC example model from consortium repository
• Sijia Wang (@i-am-sijia): Draft documentation updates for UV installation including global installation guidance and use case clarifications for team review
• ** Jeff Newman (@jpn--)*: Draft document testing philosophy and policies in ActivitySim documentation; create inventory of components requiring unit tests; develop plan to retire remaining legacy prototype models
• Product/Community Team: Review and approve decision to retire non-canonical example models before implementation
• SANDAG (@bhargavasana or designee): Review WSP's pull request updating SANDAG example model to production model consistency, and decide whether SANDAG should adopt fixes implemented for the consortium back into the SANDAG production model
• Jeff Newman (@jpn--): Review CS pull requests from Joe Flood for error definition consolidation and logging cleanup