fix: debounce watcher file change events

[k1LoW]

This pull request introduces a debouncing mechanism for file change events in the server, ensuring that rapid, repeated file changes are consolidated into a single notification. This prevents unnecessary duplicate events and improves system efficiency. The changes include new state fields, logic for debouncing, proper cleanup, and a unit test to verify the behavior.

Debouncing file change events:

• Added fileChangeDebounce and fileChangeTimers fields to the State struct, along with a default debounce duration constant (defaultFileChangeDebounce).
• Implemented the scheduleFileChanged method to debounce file change notifications, replacing direct calls to notifyFileChanged. This ensures only one notification is sent within the debounce window for each file. [1] [2] [3]
• Modified the State constructor and test setup to initialize the new debounce fields. [1] [2]

Resource cleanup:

• Updated CloseAllSubscribers to stop and remove timers from fileChangeTimers to avoid resource leaks.

Testing:

• Added a unit test TestScheduleFileChanged_DebouncesDuplicateEvents to verify that duplicate file change events are properly debounced and only a single notification is sent.

[Copilot]

Pull request overview

Introduces debouncing for filesystem change notifications in the Go server state to coalesce rapid repeated fsnotify events into a single file-changed SSE notification, reducing redundant client refreshes.

Changes:

• Added per-path debouncing state to State (fileChangeDebounce, fileChangeTimers) with a default debounce duration.
• Routed fsnotify write/create handling through scheduleFileChanged (debounced) and added timer cleanup in CloseAllSubscribers.
• Added a unit test verifying duplicate file-change events are debounced.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
internal/server/server.go	Adds debounced scheduling for file-changed notifications and cleans up per-file timers on shutdown.
internal/server/server_test.go	Initializes new debounce fields in test state and adds a debouncing behavior test.

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[github-actions]

Code Metrics Report

	main (54986b5)	#109 (55d8e17)	+/-
Coverage	52.2%	52.8%	+0.6%
Code to Test Ratio	1:0.5	1:0.5	-0.1
Test Execution Time	39s	36s	-3s

Details

  |                     | main (54986b5) | #109 (55d8e17) |  +/-  |
  |---------------------|----------------|----------------|-------|
+ | Coverage            |          52.2% |          52.8% | +0.6% |
  |   Files             |             37 |             37 |     0 |
  |   Lines             |           2900 |           2941 |   +41 |
+ |   Covered           |           1514 |           1555 |   +41 |
- | Code to Test Ratio  |          1:0.5 |          1:0.5 |  -0.1 |
  |   Code              |           4524 |           4570 |   +46 |
+ |   Test              |           2617 |           2619 |    +2 |
+ | Test Execution Time |            39s |            36s |   -3s |

Code coverage of files in pull request scope (72.4% → 73.4%)

Files	Coverage	+/-	Status
internal/server/server.go	73.4%	+1.0%	modified

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Reported by octocov

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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