Fix periodic check deadlock on incoming channel

[lestrrat]

Fixes #113

Decouple item dispatch from periodicCheck to break circular wait between c.outgoing and c.incoming.

[Copilot]

Pull request overview

This PR fixes the controller/worker circular wait reported in issue #113 by decoupling periodic refresh selection from dispatch, allowing the controller to keep draining c.incoming while dispatching work.

Changes:

• Refactors ctrlBackend.loop / periodicCheck so periodic checks return a dispatch queue that is drained while still servicing c.incoming.
• Removes the old sendWorker helper and moves “mark busy” into periodicCheck.
• Adds a regression test that reproduces the deadlock scenario and verifies Add() completes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
backend.go	Splits periodic check “select due work” from dispatch to avoid circular channel backpressure deadlock.
httprc_test.go	Adds a regression test for the periodic-check deadlock scenario described in issue #113.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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