1. 1//! Shared "current turn" boundary used by adapters that must decide which
2. 2//! messages are still part of the turn in progress (thinking blocks kept
3. 3//! verbatim, since the provider may require replay) versus a closed prior
4. 4//! turn (thinking stripped, since no provider needs it across turns).
5. 5
6. 6use crate::types::{ContentBlock, Message, Role};
7. 7
8. 8/// Index of the first message belonging to the current turn: the last user
9. 9/// message that carries a `Text` block and no `ToolResult` block. A
10. 10/// `ToolResult`-only user message is a mid-turn continuation, not a new
11. 11/// directive, so it does not start a new "current turn". When no such
12. 12/// message exists, the whole history is treated as current (index 0) —
13. 13/// the safe default, since it never strips a signature the provider needs.
14. 14pub fn current_turn_boundary(messages: &[Message]) -> usize {
15. 15 messages
16. 16 .iter()
17. 17 .enumerate()
18. 18 .rev()
19. 19 .find(|(_, m)| {
20. 20 m.role == Role::User
21. 21 && m.content
22. 22 .iter()
23. 23 .any(|b| matches!(b, ContentBlock::Text { .. }))
24. 24 && !m
25. 25 .content
26. 26 .iter()
27. 27 .any(|b| matches!(b, ContentBlock::ToolResult { .. }))
28. 28 })
29. 29 .map(|(i, _)| i)
30. 30 .unwrap_or(0)
31. 31}
32. 32
33. 33/// A copy of `m` with every `Thinking` block removed.
34. 34pub fn strip_thinking(m: &Message) -> Message {
35. 35 Message {
36. 36 role: m.role,
37. 37 content: m
38. 38 .content
39. 39 .iter()
40. 40 .filter(|b| !matches!(b, ContentBlock::Thinking { .. }))
41. 41 .cloned()
42. 42 .collect(),
43. 43 }
44. 44}
45. 45
46. 46#[cfg(test)]
47. 47mod tests {
48. 48 use super::*;
49. 49 use crate::types::ContentBlock;
50. 50
51. 51 #[test]
52. 52 fn boundary_is_the_last_fresh_directive() {
53. 53 let messages = vec![
54. 54 Message::user_text("first question"),
55. 55 Message::assistant(vec![ContentBlock::text("answer 1")]),
56. 56 Message::user_text("second question"),
57. 57 Message::assistant(vec![ContentBlock::ToolUse {
58. 58 id: "t1".into(),
59. 59 name: "search".into(),
60. 60 input: serde_json::json!({}),
61. 61 }]),
62. 62 Message {
63. 63 role: Role::User,
64. 64 content: vec![ContentBlock::tool_result("t1", "result")],
65. 65 },
66. 66 ];
67. 67 assert_eq!(current_turn_boundary(&messages), 2);
68. 68 }
69. 69
70. 70 #[test]
71. 71 fn no_fresh_directive_defaults_to_the_whole_history() {
72. 72 let messages = vec![Message {
73. 73 role: Role::User,
74. 74 content: vec![ContentBlock::tool_result("t1", "result")],
75. 75 }];
76. 76 assert_eq!(current_turn_boundary(&messages), 0);
77. 77 }
78. 78
79. 79 #[test]
80. 80 fn strip_thinking_removes_only_thinking_blocks() {
81. 81 let m = Message::assistant(vec![
82. 82 ContentBlock::Thinking {
83. 83 text: "hmm".into(),
84. 84 signature: Some("sig".into()),
85. 85 },
86. 86 ContentBlock::text("visible"),
87. 87 ]);
88. 88 let stripped = strip_thinking(&m);
89. 89 assert_eq!(stripped.content, vec![ContentBlock::text("visible")]);
90. 90 }
91. 91}
92. 92