AnchorCli/ContextCompactionService.cs

using Microsoft.Extensions.AI;
using Spectre.Console;
using AnchorCli.OpenRouter;

namespace AnchorCli;

/// <summary>
/// Handles context compaction when the conversation approaches token limits.
/// </summary>
internal sealed class ContextCompactionService
{
    private readonly ContextCompactor _compactor;
    private readonly List<ChatMessage> _history;
    private readonly TokenTracker _tokenTracker;

    public ContextCompactionService(
        ContextCompactor compactor,
        List<ChatMessage> history,
        TokenTracker tokenTracker)
    {
        _compactor = compactor;
        _history = history;
        _tokenTracker = tokenTracker;
    }

    /// <summary>
    /// Checks if compaction is needed and performs it if so.
    /// Returns true if compaction was performed.
    /// </summary>
    public async Task<bool> TryCompactAsync()
    {
        if (!_tokenTracker.ShouldCompact())
        {
            return false;
        }

        var pct = _tokenTracker.ContextUsagePercent;
        AnsiConsole.MarkupLine(
            $"[yellow]⚠ Context at {pct:F0}% — compacting conversation history...[/]");

        bool compacted = await AnsiConsole.Status()
            .Spinner(Spinner.Known.BouncingBar)
            .SpinnerStyle(Style.Parse("yellow"))
            .StartAsync("Compacting context...", async ctx =>
                await _compactor.TryCompactAsync(_history, default));

        if (compacted)
        {
            AnsiConsole.MarkupLine(
                $"[green]✓ Context compacted ({_history.Count} messages remaining)[/]");
        }
        else
        {
            AnsiConsole.MarkupLine(
                "[dim grey]  (compaction skipped — not enough history to compress)[/]");
        }

        AnsiConsole.WriteLine();
        return compacted;
    }
}