[bot-detection] Fix leak of background pre-warmer goroutine

[buixor]

reloads lead to a leak of dynamicModulePreWarmer (wasm runtime was shutdown, but not the associated go routine). Leads to increasing spam of this error in logs:

pre-warm of next epoch failed; first request after rotation will pay obfuscation cost

[github-actions]

@buixor: There are no 'kind' label on this PR. You need a 'kind' label to generate the release automatically.

• /kind feature
• /kind enhancement
• /kind refactoring
• /kind fix
• /kind chore
• /kind dependencies

Details

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[github-actions]

@buixor: There are no area labels on this PR. You can add as many areas as you see fit.

• /area agent
• /area local-api
• /area cscli
• /area appsec
• /area security
• /area configuration

Details

I am a bot created to help the crowdsecurity developers manage community feedback and contributions. You can check out my manifest file to understand my behavior and what I can do. If you want to use this for your project, you can check out the BirthdayResearch/oss-governance-bot repository.

[Copilot]

🟢 Ready to approve

The change cleanly addresses the reported goroutine leak with minimal surface area and adds a targeted regression test to prevent recurrence.

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Pull request overview

This PR fixes a goroutine leak in the AppSec challenge runtime where dynamicModulePreWarmer could keep ticking after a reload closed the underlying wazero runtime, resulting in repeated warning logs and accumulating background goroutines.

Changes:

• Run the dynamic-module pre-warmer under a Close()-owned cancellable context and cancel it during shutdown.
• Suppress the expected “runtime closed” instantiation error during shutdown by exiting the pre-warmer when its context is canceled.
• Add a regression test using go.uber.org/goleak to ensure the pre-warmer goroutine is not left behind after Close().

File summaries

File	Description
pkg/appsec/challenge/dynamic_module.go	Exits pre-warmer quietly on shutdown cancellation to avoid noisy warnings.
pkg/appsec/challenge/challenge.go	Introduces preWarmCancel, wires a cancelable pre-warmer context, cancels it in Close().
pkg/appsec/challenge/close_test.go	Adds goleak-based regression test ensuring Close() stops the pre-warmer goroutine.
go.mod	Adds go.uber.org/goleak as a direct dependency for the new test.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 0
• Review effort level: Lite

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[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.84%. Comparing base (380bb2e) to head (0ddd4e9).

Files with missing lines	Patch %	Lines
pkg/appsec/challenge/dynamic_module.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4589      +/-   ##
==========================================
- Coverage   64.36%   63.84%   -0.52%     
==========================================
  Files         499      516      +17     
  Lines       38544    39284     +740     
==========================================
+ Hits        24807    25079     +272     
- Misses      11413    11835     +422     
- Partials     2324     2370      +46     

Flag	Coverage Δ
bats	41.65% <0.00%> (-0.01%)	⬇️
unit-linux	40.56% <71.42%> (-0.02%)	⬇️
unit-windows	29.26% <71.42%> (?)

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[buixor]

/kind enhancement
/area appsec