ambi 0.2.2

A flexible, multi-backend, customizable AI agent framework, entirely based on Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

// src/agent/core/context.rs

use crate::types::message::Message;
use serde::{Deserialize, Serialize};
use std::sync::Arc;

#[derive(Serialize, Deserialize, Default)]
pub struct ChatHistory {
    messages: Vec<(Arc<Message>, usize)>,
    cached_text_len: usize,
    total_tokens: usize,
}

impl ChatHistory {
    pub fn new() -> Self {
        Self {
            messages: Vec::new(),
            cached_text_len: 0,
            total_tokens: 0,
        }
    }

    pub fn push(&mut self, msg: Message, exact_tokens: usize) {
        self.total_tokens += exact_tokens;
        self.messages.push((Arc::new(msg), exact_tokens));
    }

    pub fn all(&self) -> &[(Arc<Message>, usize)] {
        &self.messages
    }

    pub fn clear(&mut self) {
        self.messages.clear();
        self.cached_text_len = 0;
        self.total_tokens = 0;
    }

    pub fn len(&self) -> usize {
        self.messages.len()
    }

    pub fn is_empty(&self) -> bool {
        self.messages.is_empty()
    }

    pub fn truncate(&mut self, len: usize) {
        if len < self.messages.len() {
            self.messages.truncate(len);
            self.recalculate_len();
        }
    }

    pub fn estimate_tokens(&self) -> usize {
        if self.total_tokens > 0 {
            self.total_tokens
        } else {
            self.cached_text_len / 4
        }
    }

    fn recalculate_len(&mut self) {
        self.cached_text_len = self.messages.iter().map(|m| m.0.text_len()).sum();
        self.total_tokens = self.messages.iter().map(|(_, t)| *t).sum();
    }

    pub fn evict_old_messages(
        &mut self,
        initial_keep: usize,
        recent_keep: usize,
        max_safe_tokens: usize,
        prompt_overhead: usize,
    ) -> Vec<Arc<Message>> {
        let total = self.messages.len();
        let total_tokens = self.estimate_tokens();

        if total <= initial_keep + recent_keep
            && (total_tokens + prompt_overhead) <= max_safe_tokens
        {
            return Vec::new();
        }

        let mut safe_cut_idx = total.saturating_sub(recent_keep).max(initial_keep);

        let mut remaining_len: usize = self.messages[safe_cut_idx..]
            .iter()
            .map(|m| m.0.text_len())
            .sum();

        while safe_cut_idx < total {
            if (remaining_len / 4 + prompt_overhead) <= max_safe_tokens {
                break;
            }
            remaining_len = remaining_len.saturating_sub(self.messages[safe_cut_idx].0.text_len());
            safe_cut_idx += 1;
        }

        while safe_cut_idx < total && safe_cut_idx > initial_keep {
            if matches!(&*self.messages[safe_cut_idx].0, Message::User { .. }) {
                break;
            }
            safe_cut_idx += 1;
        }

        if safe_cut_idx >= total {
            safe_cut_idx = total.saturating_sub(1).max(initial_keep);
        }

        let evicted = self
            .messages
            .drain(initial_keep..safe_cut_idx)
            .map(|(m, _)| m)
            .collect::<Vec<_>>();

        if initial_keep > 0
            && self.messages.len() > initial_keep
            && matches!(&*self.messages[initial_keep - 1].0, Message::User { .. })
            && matches!(&*self.messages[initial_keep].0, Message::User { .. })
        {
            self.messages.insert(
                initial_keep,
                (
                    Arc::new(Message::Assistant {
                        content: "[...History Truncated...]".to_string(),
                        tool_calls: vec![],
                    }),
                    0,
                ),
            );
        }

        self.recalculate_len();

        evicted
    }
}