Replace SCAN-based outbox delete with reverse index in Redis store

[andrewwormald]

Problem

DeleteOutboxEvent uses SCAN to iterate all outbox keys, then runs a Lua script doing LRANGE 0 -1 on each. This is O(workflows * events) — it won't scale.

Why

The code itself had a TODO acknowledging this. As workflows and events grow, delete latency grows linearly and blocks the outbox consumer.

Fix

Add a reverse index (outbox-event-id -> outbox-key) written atomically in the store Lua script. DeleteOutboxEvent now does a single GET + targeted LREM.

🤖 Generated with Claude Code

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 26ae3299-6c73-466c-9b79-e5207172508d

📥 Commits

Reviewing files that changed from the base of the PR and between f4d926f and 8946426.

📒 Files selected for processing (2)

• adapters/wredis/store.go
• adapters/wredis/store_test.go

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/redis-delete-outbox-reverse-index

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube Cloud