g3/crates/g3-core/tests/test_context_thinning.rs

use g3_core::ContextWindow;
use g3_providers::{Message, MessageRole};

#[test]
fn test_thinning_thresholds() {
    let mut context = ContextWindow::new(10000);
    
    // At 0%, should not thin
    assert!(!context.should_thin());
    
    // Simulate reaching 50% usage
    context.used_tokens = 5000;
    assert!(context.should_thin());
    
    // After thinning at 50%, should not thin again until next threshold
    context.last_thinning_percentage = 50;
    assert!(!context.should_thin());
    
    // At 60%, should thin again
    context.used_tokens = 6000;
    assert!(context.should_thin());
    
    // After thinning at 60%, should not thin
    context.last_thinning_percentage = 60;
    assert!(!context.should_thin());
    
    // At 70%, should thin
    context.used_tokens = 7000;
    assert!(context.should_thin());
    
    // At 80%, should thin
    context.last_thinning_percentage = 70;
    context.used_tokens = 8000;
    assert!(context.should_thin());
    
    // After 80%, should not thin (compaction takes over)
    context.last_thinning_percentage = 80;
    context.used_tokens = 8500;
    assert!(!context.should_thin());
}

#[test]
fn test_thin_context_basic() {
    let mut context = ContextWindow::new(10000);
    
    // Add some messages to the first third
    for i in 0..9 {
        if i % 2 == 0 {
            context.add_message(Message {
                role: MessageRole::Assistant,
                content: format!("Assistant message {}", i),
            });
        } else {
            // Add tool results with varying sizes
            let content = if i == 1 {
                // Large tool result (> 1000 chars)
                format!("Tool result: {}", "x".repeat(1500))
            } else if i == 3 {
                // Another large tool result
                format!("Tool result: {}", "y".repeat(2000))
            } else {
                // Small tool result (< 1000 chars)
                format!("Tool result: small result {}", i)
            };
            
            context.add_message(Message {
                role: MessageRole::User,
                content,
            });
        }
    }
    
    // Trigger thinning at 50%
    context.used_tokens = 5000;
    let summary = context.thin_context();
    
    println!("Thinning summary: {}", summary);
    
    // Should have thinned at least 1 large tool result in the first third
    assert!(summary.contains("1 tool result"), "Summary was: {}", summary);
    assert!(summary.contains("50%"));
    
    // Check that the large tool results were replaced
    let first_third_end = context.conversation_history.len() / 3;
    for i in 0..first_third_end {
        if let Some(msg) = context.conversation_history.get(i) {
            if matches!(msg.role, MessageRole::User) && msg.content.starts_with("Tool result:") {
                if msg.content.len() > 1000 {
                    panic!("Found un-thinned large tool result at index {}", i);
                }
            }
        }
    }
}

#[test]
fn test_thin_context_no_large_results() {
    let mut context = ContextWindow::new(10000);
    
    // Add only small messages
    for i in 0..9 {
        context.add_message(Message {
            role: MessageRole::User,
            content: format!("Tool result: small {}", i),
        });
    }
    
    context.used_tokens = 5000;
    let summary = context.thin_context();
    
    // Should report no large results found
    assert!(summary.contains("no large tool results found"));
}

#[test]
fn test_thin_context_only_affects_first_third() {
    let mut context = ContextWindow::new(10000);
    
    // Add 12 messages (first third = 4 messages)
    for i in 0..12 {
        let content = if i % 2 == 1 {
            // All odd indices are large tool results
            format!("Tool result: {}", "x".repeat(1500))
        } else {
            format!("Assistant message {}", i)
        };
        
        let role = if i % 2 == 1 {
            MessageRole::User
        } else {
            MessageRole::Assistant
        };
        
        context.add_message(Message { role, content });
    }
    
    context.used_tokens = 5000;
    let summary = context.thin_context();
    
    // First third is 4 messages (indices 0-3), so only indices 1 and 3 should be thinned
    // That's 2 tool results
    assert!(summary.contains("2 tool results"));
    
    // Check that messages after the first third are NOT thinned
    let first_third_end = context.conversation_history.len() / 3;
    for i in first_third_end..context.conversation_history.len() {
        if let Some(msg) = context.conversation_history.get(i) {
            if matches!(msg.role, MessageRole::User) && msg.content.starts_with("Tool result:") {
                // These should still be large (not thinned)
                if i % 2 == 1 {
                    assert!(msg.content.len() > 1000, 
                        "Message at index {} should not have been thinned", i);
                }
            }
        }
    }
}