Rjf/amazing transit service

[robfitzgerald]

addresses time underflow bugs associated with scheduled transit traversal modeling leading to 1000-mile-radius transit isochrones.

[Copilot]

Pull request overview

Note

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This PR migrates the transit traversal implementation out of bambam into the bambam-gtfs crate while addressing time underflow/invalid-schedule edge cases in scheduled transit traversal.

Changes:

• Removed rust/bambam’s internal transit traversal module and switched registrations/imports to the bambam-gtfs implementation.
• Added/updated GTFS transit traversal logic to prevent negative/invalid time deltas (e.g., rejecting invalid departures, guarding “departure in the past”).
• Improved schedule ordering invariants and updated next-departure selection logic.

Reviewed changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
rust/bambam/src/model/traversal/transit/transit_ops.rs	Removed local transit ops (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/service.rs	Removed local service (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/schedule_loading_policy.rs	Removed local policy (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/schedule.rs	Removed local schedule types/tests (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/raw_schedule_row.rs	Removed local raw row type (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/query.rs	Removed local query type (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/model.rs	Removed local traversal model (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/mod.rs	Removed local transit module exports.
rust/bambam/src/model/traversal/transit/metadata.rs	Removed local GTFS metadata reader (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/engine.rs	Removed local engine (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/config.rs	Removed local config (migrated to bambam-gtfs).
rust/bambam/src/model/traversal/transit/builder.rs	Removed local traversal builder (registration now points to bambam-gtfs).
rust/bambam/src/model/traversal/mod.rs	Dropped pub mod transit; from bambam.
rust/bambam/src/model/builders.rs	Updated builder import to bambam_gtfs::...TransitTraversalBuilder.
rust/bambam/src/app/gtfs_config/run.rs	Updated config imports to use bambam-gtfs transit config/policy types.
rust/bambam/Cargo.toml	Added dependency on bambam-gtfs.
rust/bambam-gtfs/src/model/traversal/transit/transit_ops.rs	Updated time composition logic (duration build).
rust/bambam-gtfs/src/model/traversal/transit/schedule_loading_policy.rs	Added validation to reject departures with arrival before departure; added tests.
rust/bambam-gtfs/src/model/traversal/transit/schedule.rs	Tightened ordering (tie-breaker) and added invariant test.
rust/bambam-gtfs/src/model/traversal/transit/query.rs	Removed unused import; query remains for model building.
rust/bambam-gtfs/src/model/traversal/transit/model.rs	Refactored traversal into helper, added negative-wait guard, added tests.
rust/bambam-gtfs/src/model/traversal/transit/metadata.rs	Removed unused import.
rust/bambam-gtfs/src/model/traversal/transit/engine.rs	Changed next-departure selection to consider earliest arrival; pruned imports.
rust/bambam-gtfs/src/lib.rs	Exported model module.
rust/bambam-gtfs/Cargo.toml	Added missing dependencies for moved transit model code.

Comments suppressed due to low confidence (1)

rust/bambam-gtfs/src/model/traversal/transit/transit_ops.rs:1

• get_current_time is vulnerable to float edge cases: rounding can yield nanos == 1_000_000_000, and negative trip_time with fractional seconds can produce a negative remainder that gets cast to u32 (wraparound), causing Duration::new to fail or produce unintended values. Use a safer split/normalization that (a) rounds nanos, (b) clamps nanos into [0, 999_999_999] with carry into seconds, and (c) handles negative fractional seconds consistently; also remove the stray space before ; on line 22.

use std::collections::HashMap;

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