Fix silent map-directive drop: use Channel(UNLIMITED) in HomeViewModel (#1904)

[bmander]

Fixes #1904.

Problem

HomeViewModel._mapDirectives was a Channel(capacity = 16) written with trySend. #1865 introduced this Channel (replacing a replay-0 SharedFlow) precisely so a directive emitted while HOME's collector is resubscribing would queue instead of vanish. But trySend fails silently once the bounded channel fills — 17+ directives queued while the user is on a pushed destination reproduces the very drop bug the Channel was introduced to fix, unlogged.

Fix

Switch to Channel(capacity = Channel.UNLIMITED). Directives are tiny and low-frequency, so an unbounded buffer never drops and costs nothing. trySend can then only fail on a closed channel (which this VM never does), so it stays a correct synchronous emit — the comments are updated to reflect that.

Test

Added a regression test that emits 40 directives (past the old bound of 16) with no collector subscribed, then subscribes and asserts all 40 are delivered in order. It fails under capacity = 16 and passes under UNLIMITED.

Verification

./gradlew :onebusaway-android:testObaGoogleDebugUnitTest --tests "org.onebusaway.android.ui.home.HomeViewModelTest" -PwarningsAsErrors=true → BUILD SUCCESSFUL, all tests green, no compiler warnings.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Ensured map actions are reliably queued when the map is not actively listening.
  • Prevented queued route-focus actions from being lost during bursts of activity.
  • Preserved the order of map directives for consistent results.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 7076a839-405a-4038-a26b-b5bf6c0e9c76

📥 Commits

Reviewing files that changed from the base of the PR and between 01c0970 and 702a559.

📒 Files selected for processing (2)

• onebusaway-android/src/main/java/org/onebusaway/android/ui/home/HomeViewModel.kt
• onebusaway-android/src/test/java/org/onebusaway/android/ui/home/HomeViewModelTest.kt

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📝 Walkthrough

Walkthrough

HomeViewModel now uses an unbounded channel for map directives, and a unit test verifies that directives emitted before collection are all retained and delivered in order.

Changes

Map directive delivery

Layer / File(s)	Summary
Unbounded directive queue and regression coverage onebusaway-android/src/main/java/org/onebusaway/android/ui/home/HomeViewModel.kt, onebusaway-android/src/test/java/org/onebusaway/android/ui/home/HomeViewModelTest.kt	_mapDirectives uses Channel.UNLIMITED, documentation reflects the updated trySend behavior, and a test verifies that 40 queued route directives are received in order.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fix: preventing silent map-directive drops by switching to an unlimited channel.
Linked Issues check	✅ Passed	The code switches _mapDirectives to Channel.UNLIMITED and adds a regression test, matching #1904’s requested fix.
Out of Scope Changes check	✅ Passed	Changes stay focused on HomeViewModel and its test, with only related comment updates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/1904-map-directives-unlimited-channel

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