378 lines
15 KiB
C#
378 lines
15 KiB
C#
using System.Text.Json;
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using MiaoJiZhang.Api.Contracts;
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using MiaoJiZhang.Domain.Enums;
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using MiaoJiZhang.Infrastructure.Persistence;
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using Microsoft.EntityFrameworkCore;
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namespace MiaoJiZhang.Api.Services;
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public sealed class BudgetRecommendationService(
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AppDbContext db,
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ILlmClient llm,
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ILogger<BudgetRecommendationService> logger)
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{
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private static readonly AgentToolDefinition AdjustBudgetTool = new(
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"adjust_budget_draft",
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"根据用户追加指令调整当前预算草稿。必须返回完整预算草稿，不能直接写入数据库。",
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JsonSerializer.Deserialize<JsonElement>(
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"""
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{
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"type": "object",
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"properties": {
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"suggestedTotal": {
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"type": "number",
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"minimum": 0
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},
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"items": {
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"type": "array",
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"maxItems": 50,
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"items": {
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"type": "object",
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"properties": {
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"categoryId": { "type": "integer" },
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"amount": { "type": "number", "minimum": 0 }
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},
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"required": ["categoryId", "amount"],
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"additionalProperties": false
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}
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},
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"summary": {
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"type": "string",
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"description": "一句话说明本次调整了什么"
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}
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},
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"required": ["suggestedTotal", "items", "summary"],
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"additionalProperties": false
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}
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"""));
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public async Task<BudgetRecommendationResponse> RefineAsync(
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long userId,
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long ledgerId,
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RefineBudgetRecommendationRequest request,
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CancellationToken ct)
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{
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if (!llm.IsEnabled)
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throw new InvalidOperationException("AI 预算调整尚未配置");
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var instruction = request.Instruction.Trim();
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if (instruction.Length == 0)
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throw new ArgumentException("请输入预算调整要求");
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if (instruction.Length > 500)
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throw new ArgumentException("单次调整要求不能超过 500 个字符");
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if (request.CurrentDraft.Items.Count > 50)
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throw new ArgumentException("预算分类数量过多");
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var contexts = await LoadCategoryContextsAsync(
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userId,
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ledgerId,
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request.Year,
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request.Month,
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ct);
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var (currentStart, currentEnd) =
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ChinaClock.MonthRangeUtc(request.Year, request.Month);
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var currentSpentTotal = await db.Transactions
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.Where(transaction =>
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transaction.UserId == userId &&
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transaction.LedgerId == ledgerId &&
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transaction.Type == TransactionType.Expense &&
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transaction.OccurredAt >= currentStart &&
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transaction.OccurredAt < currentEnd)
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.SumAsync(transaction => transaction.Amount, ct);
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if (contexts.Count == 0)
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throw new ArgumentException("没有可用于预算的支出分类");
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var currentItems = request.CurrentDraft.Items
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.Where(item => contexts.ContainsKey(item.CategoryId))
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.GroupBy(item => item.CategoryId)
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.ToDictionary(group => group.Key, group => Math.Max(0, group.Last().Amount));
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BudgetRecommendationResponse? validated = null;
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string? toolSummary = null;
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var response = await llm.RunAgentAsync(
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BuildSystemPrompt(request, contexts, currentItems, currentSpentTotal),
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instruction,
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[AdjustBudgetTool],
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(call, _) =>
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{
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if (call.Name != AdjustBudgetTool.Name)
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return Task.FromResult(JsonSerializer.Serialize(new
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{
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ok = false,
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error = "未知预算工具",
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}));
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try
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{
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validated = ValidateToolDraft(
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request,
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contexts,
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currentItems,
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currentSpentTotal,
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call.Arguments,
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out toolSummary);
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return Task.FromResult(JsonSerializer.Serialize(new
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{
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ok = true,
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draft = new
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{
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suggestedTotal = validated.SuggestedTotal,
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items = validated.Items.Select(item => new
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{
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categoryId = item.CategoryId,
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amount = item.SuggestedAmount,
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}),
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},
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warnings = validated.Warnings,
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}));
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}
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catch (Exception exception) when (
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exception is JsonException or ArgumentException)
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{
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return Task.FromResult(JsonSerializer.Serialize(new
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{
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ok = false,
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error = exception.Message,
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}));
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}
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},
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ct: ct);
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if (validated is null)
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{
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logger.LogWarning(
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"Budget refinement completed without tool call. user={UserId} ledger={LedgerId}",
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userId,
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ledgerId);
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throw new InvalidOperationException("AI 没有生成可用的预算调整草稿");
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}
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var summary = string.IsNullOrWhiteSpace(response.Text)
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? toolSummary ?? "已根据你的要求调整预算草稿"
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: response.Text.Trim();
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return validated with { AdjustmentSummary = summary };
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}
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private async Task<Dictionary<long, CategoryContext>> LoadCategoryContextsAsync(
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long userId,
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long ledgerId,
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int year,
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int month,
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CancellationToken ct)
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{
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var (currentStart, currentEnd) = ChinaClock.MonthRangeUtc(year, month);
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var historyStart = currentStart.AddMonths(-3);
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var categories = await db.Categories
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.Where(category =>
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!category.IsDeleted &&
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category.Type == TransactionType.Expense &&
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(category.UserId == null || category.UserId == userId))
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.Select(category => new
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{
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category.Id,
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category.Name,
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category.IconKey,
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category.ColorKey,
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})
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.ToListAsync(ct);
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var transactions = await db.Transactions
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.Where(transaction =>
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transaction.UserId == userId &&
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transaction.LedgerId == ledgerId &&
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transaction.Type == TransactionType.Expense &&
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transaction.OccurredAt >= historyStart &&
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transaction.OccurredAt < currentEnd)
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.Select(transaction => new
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{
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transaction.CategoryId,
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transaction.Amount,
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transaction.OccurredAt,
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})
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.ToListAsync(ct);
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return categories.ToDictionary(category => category.Id, category =>
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{
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var currentSpent = transactions
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.Where(transaction =>
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transaction.CategoryId == category.Id &&
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transaction.OccurredAt >= currentStart)
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.Sum(transaction => transaction.Amount);
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var history = Enumerable.Range(1, 3)
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.Select(offset =>
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{
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var start = currentStart.AddMonths(-offset);
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var end = start.AddMonths(1);
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return transactions
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.Where(transaction =>
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transaction.CategoryId == category.Id &&
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transaction.OccurredAt >= start &&
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transaction.OccurredAt < end)
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.Sum(transaction => transaction.Amount);
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})
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.Where(amount => amount > 0)
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.ToList();
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return new CategoryContext(
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category.Id,
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category.Name,
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category.IconKey,
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category.ColorKey,
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currentSpent,
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history.Count == 0 ? 0 : history.Average(),
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history.Count >= 3 ? "high" : history.Count > 0 ? "medium" : "low");
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});
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}
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private static string BuildSystemPrompt(
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RefineBudgetRecommendationRequest request,
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IReadOnlyDictionary<long, CategoryContext> contexts,
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IReadOnlyDictionary<long, decimal> currentItems,
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decimal currentSpentTotal)
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{
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var history = (request.History ?? [])
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.Where(turn => turn.Role is "user" or "assistant")
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.TakeLast(12)
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.Select(turn => new
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{
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role = turn.Role,
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content = turn.Content.Length <= 500
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? turn.Content
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: turn.Content[..500],
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});
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var payload = new
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{
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year = request.Year,
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month = request.Month,
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currentDraft = new
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{
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suggestedTotal = request.CurrentDraft.SuggestedTotal,
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items = currentItems.Select(item => new
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{
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categoryId = item.Key,
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amount = item.Value,
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}),
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},
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allowedCategories = contexts.Values.Select(context => new
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{
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categoryId = context.Id,
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name = context.Name,
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currentSpent = context.CurrentSpent,
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historicalAverage = context.HistoricalAverage,
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}),
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currentSpentTotal,
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recentConversation = history,
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};
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return """
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你是预算草稿调整 Agent。根据用户的最新指令和给定真实数据，必须调用 adjust_budget_draft。
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工具参数必须返回完整草稿；没有要求改变的分类保持不变。只能使用 allowedCategories 中的 categoryId。
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分类金额不得低于 currentSpent，总预算不得低于所有分类预算之和，也不得低于本月总支出。
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如果用户要求违反约束，给出最接近的有效草稿，并在 summary 中说明。
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工具成功后只回复一句简短、自然的调整说明，不要声称预算已经保存。
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财务上下文：
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""" + JsonSerializer.Serialize(payload);
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}
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internal static BudgetRecommendationResponse ValidateToolDraft(
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RefineBudgetRecommendationRequest request,
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IReadOnlyDictionary<long, CategoryContext> contexts,
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IReadOnlyDictionary<long, decimal> currentItems,
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decimal currentSpentTotal,
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string arguments,
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out string summary)
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{
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using var document = JsonDocument.Parse(arguments);
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var root = document.RootElement;
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if (!root.TryGetProperty("items", out var itemsNode) ||
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itemsNode.ValueKind != JsonValueKind.Array)
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throw new ArgumentException("AI 返回的预算分类无效");
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summary = root.TryGetProperty("summary", out var summaryNode)
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? summaryNode.GetString()?.Trim() ?? ""
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: "";
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var warnings = new List<string>();
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var proposed = new Dictionary<long, decimal>();
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foreach (var item in itemsNode.EnumerateArray())
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{
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if (!item.TryGetProperty("categoryId", out var categoryNode) ||
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!categoryNode.TryGetInt64(out var categoryId) ||
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!contexts.TryGetValue(categoryId, out var context))
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{
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warnings.Add("已忽略不存在或不可用的分类");
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continue;
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}
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if (!item.TryGetProperty("amount", out var amountNode) ||
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!amountNode.TryGetDecimal(out var amount))
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{
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warnings.Add($"“{context.Name}”金额无效，已保留原值");
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continue;
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}
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amount = Math.Max(0, decimal.Round(amount, 2));
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if (amount < context.CurrentSpent)
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{
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amount = context.CurrentSpent;
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warnings.Add($"“{context.Name}”不能低于已花 ¥{context.CurrentSpent:0.##}");
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}
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proposed[categoryId] = amount;
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}
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foreach (var current in currentItems)
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{
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if (!proposed.ContainsKey(current.Key))
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{
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proposed[current.Key] = current.Value;
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warnings.Add($"“{contexts[current.Key].Name}”未明确调整，已保留原值");
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}
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}
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if (proposed.Count == 0)
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throw new ArgumentException("AI 没有返回可用的分类预算");
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var requestedTotal =
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root.TryGetProperty("suggestedTotal", out var totalNode) &&
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totalNode.TryGetDecimal(out var parsedTotal)
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? Math.Max(0, decimal.Round(parsedTotal, 2))
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: Math.Max(0, request.CurrentDraft.SuggestedTotal);
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var categoryTotal = proposed.Values.Sum();
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var minimumTotal = Math.Max(categoryTotal, currentSpentTotal);
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if (requestedTotal < minimumTotal)
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{
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requestedTotal = minimumTotal;
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warnings.Add($"总预算不能低于分类合计或本月已花，已调整为 ¥{minimumTotal:0.##}");
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}
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var recommendationItems = proposed
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.Where(item => item.Value > 0)
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.Select(item =>
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{
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var context = contexts[item.Key];
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return new BudgetRecommendationItemDto(
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context.Id,
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context.Name,
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context.IconKey,
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item.Value,
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context.CurrentSpent,
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context.HistoricalAverage,
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context.Confidence,
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context.ColorKey);
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})
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.OrderByDescending(item => item.SuggestedAmount)
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.ToList();
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return new BudgetRecommendationResponse(
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request.Year,
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request.Month,
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requestedTotal,
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"预算草稿已调整，确认应用前不会写入正式预算。",
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recommendationItems,
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summary,
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warnings.Distinct().ToList());
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}
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internal sealed record CategoryContext(
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long Id,
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string Name,
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string IconKey,
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string ColorKey,
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decimal CurrentSpent,
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decimal HistoricalAverage,
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string Confidence);
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}
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