fix(bot): serialize autoplay replenish per guild, write redis on add

[LucasSantana-Dev]

Root Causes Fixed

Full analysis is in .claude/plans/autoplay-dedup-fix-2026-04-11.md.

1. Race condition (CRITICAL) — per-guild mutex

replenishQueue was called concurrently from playerStart, playerFinish, and playerSkip. Each call built its own local excludedUrls/excludedKeys sets at call time. If two calls overlapped by even a few milliseconds, both would see the same exclusion sets and independently select the same track.

Fix: Module-level replenishLocks: Map<string, Promise<void>>. Each replenishQueue call for a guild chains onto the previous call's promise, ensuring serialization.

2. Just-added tracks not in Redis for concurrent calls

Previously, autoplay tracks were only written to Redis history when they finished playing. The concurrent call from the next event would not find them in Redis exclusions.

Fix: addSelectedTracks now immediately writes each added track to Redis history (fire-and-forget void). The next replenish call (milliseconds later) finds them in Redis.

3. History lookback too short

Changed getTrackHistory(guild.id, 20) → getTrackHistory(guild.id, 50). Covers ~3h sessions.

Observability

• warnLog when Redis history is empty (potential Redis issue)
• debugLog with exclusion set sizes after build (visible in debug mode)

1905 tests, 0 failures.

Summary by CodeRabbit

• Improvements
  • Increased the historical track pool for autoplay selection from 20 to 50 entries, enhancing song variety and reducing repeat plays
  • Improved queue synchronization to prevent processing conflicts during concurrent operations

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Project	Deployment	Actions	Updated (UTC)
lucky	Ready	Preview, Comment	Apr 11, 2026 7:38pm

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

Test mocks extended with warnLog and trackHistoryService.addTrack stubs. Implementation refactors replenishQueue to a non-async synchronous wrapper enforcing per-guild serialization via in-memory Map-based mutex, delegates actual work to internal _replenishQueue, increases track history read size to 50, adds immediate history writes when selecting autoplay tracks, and expands exclusion-set construction to include title-only keys.

Changes

Cohort / File(s)	Summary
Test Mocks packages/bot/src/utils/music/queueManipulation.spec.ts	Extended Jest mocks to include warnLog: jest.fn() stub and trackHistoryService.addTrack mocked to return resolved promise.
Queue Replenishment Logic packages/bot/src/utils/music/queueManipulation.ts	Converted replenishQueue from async function to synchronous wrapper implementing per-guild mutex via Map<string, Promise<void>>, delegating to new internal _replenishQueue async function. Increased persistent history read size from 20 to 50. Added warning when history empty. Expanded exclusion-set construction to include YouTube video IDs and normalized title-only keys. Added immediate trackHistoryService.addTrackToHistory writes during selected track addition.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• fix(bot): harden autoplay responses and player error handling #230: Modifies same replenishQueue autoplay flow with async behavior and diagnostic logging enhancements.
• fix(bot): spotify-first, no duplicate play msg, soundcloud last #557: Updates same title-only deduplication and exclusion-key construction logic in queue manipulation.
• fix(bot): youtube video id dedup and pass finished track to replenish #562: Modifies YouTube video-ID-based exclusion deduplication and finishedTrack parameter handling in replenishQueue.

Suggested labels

bot, size/l

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title clearly and specifically summarizes the two main changes: implementing per-guild serialization for autoplay replenish operations and writing Redis history immediately on track addition.

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✨ 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/autoplay-mutex-and-dedup

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
92.6% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud