Refactor Enemy Processing Pipeline

[candour]

I have refactored the core enemy processing pipeline in MainViewModel.kt to improve both performance and code simplicity.

Key improvements include:

• Unified Pipeline: Combined disparate logic for transients (held enemies, expired effects) and enemy movement into a single handleEnemyPipeline method, reducing redundant iterations over the enemy list.
• Batch State Updates: Introduced an EngineUpdateBatch mechanism to collect health losses, gold changes, and hex modifications. These are now applied to the GameState in a single batch, significantly reducing the overhead of immutable state copying.
• Optimized Grab/Hold Mechanics: Replaced an O(N_tiles) search for held enemies with an efficient lookup map based on heldEnemyId, improving engine performance during ticks with many active stalls.
• Improved Consistency: Addressed edge cases where released enemies would wait a frame before moving, and ensured that stall-based puddle tracking remains accurate even on permanently wet tiles.

A record of this architectural refactor has been added to fixes.md under REF-012.

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PR created automatically by Jules for task 8137139885773267720 started by @candour

Summary by CodeRabbit

• Refactor
  • Improved game loop efficiency through consolidated enemy and board state processing.
  • Enhanced consistency of enemy movement, status effects, and buff interactions.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 1041f4bf-012e-49bc-9d7d-4a0860c2f926

📥 Commits

Reviewing files that changed from the base of the PR and between 1560232 and 62ce7a1.

📒 Files selected for processing (1)

• fixes.md

📝 Walkthrough

Walkthrough

Consolidated MainViewModel.kt enemy-tick processing by introducing EngineUpdateBatch to batch health loss and hex mutations, refactoring updateGame to use a new unified handleEnemyPipeline instead of separate transient and movement helpers, and removing the old updateTransientState method. Updated fixes.md to document the refactor.

Changes

Enemy Processing Pipeline Consolidation

Layer / File(s)	Summary
EngineUpdateBatch data structure app/src/main/java/com/messark/hawker/MainViewModel.kt	New private EngineUpdateBatch container collects per-tick enemy processing results: total health loss and hex state updates map.
updateGame pipeline reorganization app/src/main/java/com/messark/hawker/MainViewModel.kt	updateGame refactored to compute expired transients inline, call handleEnemyPipeline with EngineUpdateBatch, apply batched health loss and hex mutations back to GameState; old updateTransientState helper removed.
handleEnemyPipeline implementation app/src/main/java/com/messark/hawker/MainViewModel.kt	New consolidated pipeline replaces prior multi-function approach; handles held/enqueued enemy release, special behavior state transitions, Tiger Mom buffing, puddle slow with stall tracking, path-based movement and health loss, Tiger Mom buff action application.
Refactor documentation fixes.md	Added REF-012 entry documenting enemy processing pipeline consolidation, batch optimization, and held-enemy tracking improvements.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• candour/towerpower#164: Overlapping refactor of MainViewModel's per-tick enemy processing pipeline and batched hex/stall update logic.
• candour/towerpower#153: Both modify updateGame enemy-tick processing with puddle slow and special wet-hex behavior via behavior-based EnemyDefinition API.
• candour/towerpower#125: Both refactor enemy movement logic including puddle slows and Tiger Mom buff targeting; this PR consolidates those flows into handleEnemyPipeline.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Refactor Enemy Processing Pipeline' directly and accurately summarizes the main change: consolidation of enemy processing logic into a unified pipeline with optimized batching and held-enemy tracking.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

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• Create PR with unit tests
• Commit unit tests in branch refactor-enemy-pipeline-8137139885773267720

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[github-actions]

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Actionable comments posted: 1

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 52517a9e-bcca-4ea0-882b-a824ac75e173

📥 Commits

Reviewing files that changed from the base of the PR and between bfe5c7f and 1560232.

📒 Files selected for processing (2)

• app/src/main/java/com/messark/hawker/MainViewModel.kt
• fixes.md

[candour]

Align REF-012 date/status with actual merge timeline.

Line 47 currently logs REF-012 as 2026-07-10 and Resolved, but this PR is still open (created on May 18, 2026). Please use the actual pr creation date.

[google-labs-jules]

Align REF-012 date/status with actual merge timeline.

Line 47 currently logs REF-012 as 2026-07-10 and Resolved, but this PR is still open (created on May 18, 2026). Please use the actual pr creation date.

Acknowledged. I've updated the date for REF-012 to 2026-05-18 and changed the status to 'In Progress' to align with the PR timeline.

[github-actions]

Build Successful! 🚀

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[candour]

@coderabbitai resolve

[coderabbitai]

✅ Actions performed

Comments resolved and changes approved.