lash_sansio/
session.rs

1use crate::{AttachmentRef, ToolCallRecord};
2
3#[derive(Clone, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
4pub struct ExecImage {
5    pub mime: String,
6    #[serde(default, skip_serializing_if = "Option::is_none")]
7    pub reference: Option<AttachmentRef>,
8    #[serde(default, skip_serializing_if = "Vec::is_empty")]
9    pub data: Vec<u8>,
10    pub label: String,
11    #[serde(default, skip_serializing_if = "Option::is_none")]
12    pub width: Option<u32>,
13    #[serde(default, skip_serializing_if = "Option::is_none")]
14    pub height: Option<u32>,
15}
16
17#[derive(Clone, Debug, Default, serde::Serialize, serde::Deserialize, PartialEq, Eq)]
18pub struct TextProjectionMetadata {
19    pub truncated: bool,
20    pub original_chars: usize,
21    pub projected_chars: usize,
22    pub original_lines: usize,
23    pub projected_lines: usize,
24    pub limit: usize,
25    pub limit_mode: String,
26    pub max_lines: usize,
27}
28
29#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
30pub struct ExecResponse {
31    pub observations: Vec<String>,
32    pub observation_truncation: Vec<TextProjectionMetadata>,
33    pub tool_calls: Vec<ToolCallRecord>,
34    pub images: Vec<ExecImage>,
35    pub printed_images: Vec<AttachmentRef>,
36    pub error: Option<String>,
37    pub duration_ms: u64,
38    /// When the surrounding session uses protocol-specific finish behavior,
39    /// this carries the protocol's terminal value. The dispatch loop uses it
40    /// as the terminal result of the session. `None` for chat-style sessions
41    /// and for typed sessions whose step continued without finishing.
42    pub terminal_finish: Option<serde_json::Value>,
43}
44
45/// Exact prompt-usage snapshot from the most recent completed LLM call.
46#[derive(Clone, Debug, Default, serde::Serialize, serde::Deserialize, PartialEq, Eq)]
47pub struct PromptUsage {
48    pub prompt_context_tokens: usize,
49    pub input_tokens: usize,
50    pub cached_input_tokens: usize,
51    #[serde(default)]
52    pub context_budget_tokens: usize,
53}
54
55/// Pure multi-turn session state for hosts that want lash behavior without the runtime.
56#[derive(Clone, Debug, Default, serde::Serialize, serde::Deserialize)]
57pub struct SansIoSessionState {
58    pub session_id: String,
59    #[serde(default)]
60    pub messages: Vec<crate::Message>,
61    #[serde(default)]
62    pub protocol_iteration: usize,
63    #[serde(default)]
64    pub token_usage: crate::TokenUsage,
65    #[serde(default, skip_serializing_if = "Option::is_none")]
66    pub last_prompt_usage: Option<PromptUsage>,
67    #[serde(default, skip_serializing_if = "Option::is_none")]
68    pub protocol_state: Option<serde_json::Value>,
69}
70
71#[derive(Clone, Debug, Default)]
72pub struct CompletedTurn {
73    pub messages: Vec<crate::Message>,
74    pub tool_calls: Vec<ToolCallRecord>,
75    pub protocol_iteration: usize,
76    pub token_usage: crate::TokenUsage,
77    pub last_prompt_usage: Option<PromptUsage>,
78    pub protocol_state: Option<serde_json::Value>,
79}
80
81pub fn apply_completed_turn(
82    mut state: SansIoSessionState,
83    turn: CompletedTurn,
84) -> SansIoSessionState {
85    state.messages = turn.messages;
86    state.protocol_iteration = turn.protocol_iteration;
87    state.token_usage = turn.token_usage;
88    state.last_prompt_usage = turn.last_prompt_usage;
89    state.protocol_state = turn.protocol_state;
90    state
91}
92
93#[cfg(test)]
94mod tests {
95    use super::*;
96
97    #[test]
98    fn completed_turn_replaces_projected_session_state() {
99        let state = SansIoSessionState {
100            session_id: "session".to_string(),
101            protocol_iteration: 1,
102            ..SansIoSessionState::default()
103        };
104        let reduced = apply_completed_turn(
105            state,
106            CompletedTurn {
107                protocol_iteration: 4,
108                token_usage: crate::TokenUsage {
109                    input_tokens: 10,
110                    output_tokens: 3,
111                    cached_input_tokens: 1,
112                    reasoning_tokens: 2,
113                },
114                last_prompt_usage: Some(PromptUsage {
115                    prompt_context_tokens: 7,
116                    input_tokens: 6,
117                    cached_input_tokens: 1,
118                    context_budget_tokens: 100,
119                }),
120                ..CompletedTurn::default()
121            },
122        );
123
124        assert_eq!(reduced.protocol_iteration, 4);
125        assert_eq!(reduced.token_usage.input_tokens, 10);
126        assert_eq!(
127            reduced
128                .last_prompt_usage
129                .expect("prompt usage present")
130                .prompt_context_tokens,
131            7
132        );
133    }
134}
lash_sansio/session.rs

lash_sansio/
session.rs
