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[fix] deduplicate hook handler invocations when installed in multiple scopes #58
Description
Activity
- added a commit that references this issue
on Apr 9, 2026 I would like to work on this. I am investigating a runtime, cross-process deduplication guard keyed by Claude session/tool invocation IDs so duplicate scope handlers replay the same policy decision without duplicating evaluation, activity, or telemetry. I will include concurrency coverage and run the full CONTRIBUTING.md gate before opening a PR.
When hooks are installed in multiple Claude Code scopes (user + project + local), Claude Code spawns one handler process per scope for every tool call. Each process receives the identical stdin payload and independently writes a duplicate dashboard entry, fires duplicate PostHog telemetry, and adds ~2x latency. The install-time warning detects this but there was no runtime guard.
Symptoms:
Dashboard shows 2× or 3× entries per tool call
totalEvents / denyCount stats inflated by scope count
Double latency per tool call