loop-guardrail 0.1.0

Repetitive execution loop detector for AI agents.
Documentation 
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use loop_guardrail::{
    canonical_tool_args, ToolCallGuardrailConfig, ToolCallGuardrailController,
    ToolCallSignature, append_toolguard_guidance, toolguard_synthetic_result,
};
use serde_json::json;

#[test]
fn test_canonical_args_sorting() {
    let val1 = json!({"b": 2, "a": 1});
    let val2 = json!({"a": 1, "b": 2});
    assert_eq!(canonical_tool_args(&val1), canonical_tool_args(&val2));
    assert_eq!(canonical_tool_args(&val1), "{\"a\":1,\"b\":2}");

    // Test deep key sorting recursively
    let deep_val1 = json!({"x": {"y": 2, "z": 1}, "a": 5});
    let deep_val2 = json!({"a": 5, "x": {"z": 1, "y": 2}});
    assert_eq!(canonical_tool_args(&deep_val1), canonical_tool_args(&deep_val2));
}

#[test]
fn test_signature_hashing() {
    let sig1 = ToolCallSignature::from_call("test", Some(&json!({"x": 1})));
    let sig2 = ToolCallSignature::from_call("test", Some(&json!({"x": 1})));
    let sig3 = ToolCallSignature::from_call("test", Some(&json!({"x": 2})));

    assert_eq!(sig1.args_hash, sig2.args_hash);
    assert_ne!(sig1.args_hash, sig3.args_hash);
}

#[test]
fn test_failure_counting_and_warnings() {
    let config = ToolCallGuardrailConfig {
        hard_stop_enabled: true,
        warnings_enabled: true,
        exact_failure_warn_after: 2,
        exact_failure_block_after: 3,
        ..Default::default()
    };
    let mut ctrl = ToolCallGuardrailController::new(Some(config));

    // First call: before_call allows
    let dec1 = ctrl.before_call("terminal", Some(&json!({"cmd": "ls"})));
    assert!(dec1.allows_execution());

    // Fails once
    let dec_after1 = ctrl.after_call("terminal", Some(&json!({"cmd": "ls"})), Some("Error: cmd not found"), Some(true));
    assert_eq!(dec_after1.action, "allow");

    // Second call
    let dec2 = ctrl.before_call("terminal", Some(&json!({"cmd": "ls"})));
    assert!(dec2.allows_execution());

    // Fails second time -> warns
    let dec_after2 = ctrl.after_call("terminal", Some(&json!({"cmd": "ls"})), Some("Error: cmd not found"), Some(true));
    assert_eq!(dec_after2.action, "warn");

    // Third call
    let dec3 = ctrl.before_call("terminal", Some(&json!({"cmd": "ls"})));
    assert!(dec3.allows_execution());

    // Fails third time
    let _dec_after3 = ctrl.after_call("terminal", Some(&json!({"cmd": "ls"})), Some("Error: cmd not found"), Some(true));

    // Fourth call -> blocked!
    let dec4 = ctrl.before_call("terminal", Some(&json!({"cmd": "ls"})));
    assert_eq!(dec4.action, "block");
    assert!(dec4.should_halt());
}

#[test]
fn test_no_progress_tracking() {
    let config = ToolCallGuardrailConfig {
        hard_stop_enabled: true,
        warnings_enabled: true,
        no_progress_warn_after: 2,
        no_progress_block_after: 3,
        ..Default::default()
    };
    let mut ctrl = ToolCallGuardrailController::new(Some(config));

    // First call: read file
    let args = json!({"path": "file.txt"});
    let dec1 = ctrl.before_call("read_file", Some(&args));
    assert!(dec1.allows_execution());

    let dec_after1 = ctrl.after_call("read_file", Some(&args), Some("hello"), Some(false));
    assert_eq!(dec_after1.action, "allow");

    // Second call: read file returning same content -> warns
    let dec_after2 = ctrl.after_call("read_file", Some(&args), Some("hello"), Some(false));
    assert_eq!(dec_after2.action, "warn");

    // Third call: read file returning same content again
    let _dec_after3 = ctrl.after_call("read_file", Some(&args), Some("hello"), Some(false));

    // Fourth call: blocked in before_call
    let dec4 = ctrl.before_call("read_file", Some(&args));
    assert_eq!(dec4.action, "block");
}

#[test]
fn test_guidance_formatting() {
    let mut ctrl = ToolCallGuardrailController::new(None);
    let args = json!({"cmd": "ls"});
    let _dec = ctrl.after_call("terminal", Some(&args), Some("Error"), Some(true)); // exact_count = 1
    let dec2 = ctrl.after_call("terminal", Some(&args), Some("Error"), Some(true)); // exact_count = 2 -> warns

    assert_eq!(dec2.action, "warn");

    let result_guided = append_toolguard_guidance("Error output", &dec2);
    assert!(result_guided.contains("[Tool loop warning:"));
    assert!(result_guided.contains("count=2"));

    let synth = toolguard_synthetic_result(&dec2);
    assert!(synth.contains("\"error\":"));
}

#[test]
fn test_scale_guardrail_performance() {
    let mut ctrl = ToolCallGuardrailController::new(None);
    let start = std::time::Instant::now();
    for i in 0..10000 {
        let tool_name = if i % 2 == 0 { "web_search" } else { "read_file" };
        let args = json!({"query": format!("term_{}", i)});
        let _ = ctrl.before_call(tool_name, Some(&args));
        let failed = i % 2 != 0;
        let _ = ctrl.after_call(
            tool_name,
            Some(&args),
            Some(if failed { "Error" } else { "result" }),
            Some(failed),
        );
    }
    let duration = start.elapsed();
    assert!(duration < std::time::Duration::from_secs(1));
}