Fix notification delay by checking on editor change instead of only on interval

[Copilot]

Notifications for files not accessed in 24+ hours were delayed up to 60 seconds because checks only ran on a 1-minute interval timer.

Changes

• Trigger notification check immediately on editor change instead of waiting for interval timer
  • Made checkForReturningContext() public to call from updateUI()
  • Periodic check retained as fallback
• Add session-based deduplication to prevent showing the same notification multiple times
  • Track notified files in Set<string> cleared only on extension restart
• Ensure file access recorded exactly once per check using try-finally pattern
• Fix memory leak by disposing interval timer on deactivation

// Before: notification delayed until next interval tick
setInterval(() => {
  this.checkForReturningContext();
}, 60000);

// After: immediate check on editor change + interval fallback
const updateUI = () => {
  if (editor) {
    resurfacer.checkForReturningContext(); // Immediate
  }
};

The notification now appears instantly when opening a file after 24+ hours away, rather than after an unpredictable delay.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Notification Get Late</issue_title>
<issue_description>When i add this Extension So Notification Problem Are Face </issue_description>

<agent_instructions>disscuse with the issues</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@Yashrajsalunkhe can you give the details of it

• Fixes Notification Get Late #1

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