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955//! Tool loop detection for the agent execution loop.
//!
//! Tracks tool calls within a single agent loop execution using SHA-256
//! hashes of `(tool_name, serialized_params)`. Detects when the agent is
//! stuck calling the same tool repeatedly and provides graduated responses:
//! warn, block, or circuit-break the entire loop.
//!
//! Enhanced features beyond basic hash-counting:
//! - **Outcome-aware detection**: tracks result hashes so identical call+result
//! pairs escalate faster than just repeated calls.
//! - **Ping-pong detection**: identifies A-B-A-B or A-B-C-A-B-C alternating
//! patterns that evade single-hash counting.
//! - **Poll tool handling**: relaxed thresholds for tools expected to be called
//! repeatedly (e.g. `shell_exec` status checks).
//! - **Backoff suggestions**: recommends increasing wait times for polling.
//! - **Warning bucket**: prevents spam by upgrading to Block after repeated
//! warnings for the same call.
//! - **Statistics snapshot**: exposes internal state for debugging and API.
use serde::Serialize;
use sha2::{Digest, Sha256};
use std::collections::{HashMap, HashSet};
/// Tools that are expected to be polled repeatedly.
const POLL_TOOLS: &[&str] = &[
"shell_exec", // checking command output
];
/// Maximum recent call history size for ping-pong detection.
const HISTORY_SIZE: usize = 30;
/// Backoff schedule in milliseconds for polling tools.
const BACKOFF_SCHEDULE_MS: &[u64] = &[5000, 10000, 30000, 60000];
/// Configuration for the loop guard.
#[derive(Debug, Clone)]
pub struct LoopGuardConfig {
/// Number of identical calls before a warning is appended.
pub warn_threshold: u32,
/// Number of identical calls before the call is blocked.
pub block_threshold: u32,
/// Total tool calls across all tools before circuit-breaking.
pub global_circuit_breaker: u32,
/// Multiplier for poll tool thresholds (poll tools get thresholds * this).
pub poll_multiplier: u32,
/// Number of identical outcome pairs before a warning.
pub outcome_warn_threshold: u32,
/// Number of identical outcome pairs before the next call is auto-blocked.
pub outcome_block_threshold: u32,
/// Minimum repeats of a ping-pong pattern before blocking.
pub ping_pong_min_repeats: u32,
/// Max warnings per unique tool call hash before upgrading to Block.
pub max_warnings_per_call: u32,
}
impl Default for LoopGuardConfig {
fn default() -> Self {
Self {
warn_threshold: 3,
block_threshold: 5,
global_circuit_breaker: 30,
poll_multiplier: 3,
outcome_warn_threshold: 2,
outcome_block_threshold: 3,
ping_pong_min_repeats: 3,
max_warnings_per_call: 3,
}
}
}
/// Verdict from the loop guard on whether a tool call should proceed.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum LoopGuardVerdict {
/// Proceed normally.
Allow,
/// Proceed, but append a warning to the tool result.
Warn(String),
/// Block this specific tool call (skip execution).
Block(String),
/// Circuit-break the entire agent loop.
CircuitBreak(String),
}
/// Snapshot of the loop guard state (for debugging/API).
#[derive(Debug, Clone, Serialize)]
pub struct LoopGuardStats {
/// Total tool calls made in this loop execution.
pub total_calls: u32,
/// Number of unique (tool_name + params) combinations seen.
pub unique_calls: u32,
/// Number of calls that were blocked.
pub blocked_calls: u32,
/// Whether a ping-pong pattern has been detected.
pub ping_pong_detected: bool,
/// The tool name that has been repeated the most (if any).
pub most_repeated_tool: Option<String>,
/// The count of the most repeated tool call.
pub most_repeated_count: u32,
}
/// Tracks tool calls within a single agent loop to detect loops.
pub struct LoopGuard {
config: LoopGuardConfig,
/// Count of identical (tool_name + params) calls, keyed by SHA-256 hex hash.
call_counts: HashMap<String, u32>,
/// Total tool calls in this loop execution.
total_calls: u32,
/// Count of identical (tool_call_hash + result_hash) pairs.
outcome_counts: HashMap<String, u32>,
/// Call hashes that are blocked due to repeated identical outcomes.
blocked_outcomes: HashSet<String>,
/// Recent tool call hashes (ring buffer of last HISTORY_SIZE).
recent_calls: Vec<String>,
/// Warnings already emitted (to prevent spam). Key = call hash, value = count emitted.
warnings_emitted: HashMap<String, u32>,
/// Tracks poll counts per command hash for backoff suggestions.
poll_counts: HashMap<String, u32>,
/// Total calls that were blocked.
blocked_calls: u32,
/// Map from call hash to tool name (for stats reporting).
hash_to_tool: HashMap<String, String>,
}
impl LoopGuard {
/// Create a new loop guard with the given configuration.
pub fn new(config: LoopGuardConfig) -> Self {
Self {
config,
call_counts: HashMap::new(),
total_calls: 0,
outcome_counts: HashMap::new(),
blocked_outcomes: HashSet::new(),
recent_calls: Vec::with_capacity(HISTORY_SIZE),
warnings_emitted: HashMap::new(),
poll_counts: HashMap::new(),
blocked_calls: 0,
hash_to_tool: HashMap::new(),
}
}
/// Check whether a tool call should proceed.
///
/// Returns a verdict indicating whether to allow, warn, block, or
/// circuit-break. The caller should act on the verdict before executing
/// the tool.
pub fn check(&mut self, tool_name: &str, params: &serde_json::Value) -> LoopGuardVerdict {
self.total_calls += 1;
// Global circuit breaker
if self.total_calls > self.config.global_circuit_breaker {
self.blocked_calls += 1;
return LoopGuardVerdict::CircuitBreak(format!(
"Circuit breaker: exceeded {} total tool calls in this loop. \
The agent appears to be stuck.",
self.config.global_circuit_breaker
));
}
let hash = Self::compute_hash(tool_name, params);
self.hash_to_tool
.entry(hash.clone())
.or_insert_with(|| tool_name.to_string());
// Track recent calls for ping-pong detection
if self.recent_calls.len() >= HISTORY_SIZE {
self.recent_calls.remove(0);
}
self.recent_calls.push(hash.clone());
// Check if this call hash was blocked by outcome detection
if self.blocked_outcomes.contains(&hash) {
self.blocked_calls += 1;
return LoopGuardVerdict::Block(format!(
"Blocked: tool '{}' is returning identical results repeatedly. \
The current approach is not working — try something different.",
tool_name
));
}
let count = self.call_counts.entry(hash.clone()).or_insert(0);
*count += 1;
let count_val = *count;
// Determine effective thresholds (poll tools get relaxed thresholds)
let is_poll = Self::is_poll_call(tool_name, params);
let multiplier = if is_poll {
self.config.poll_multiplier
} else {
1
};
let effective_warn = self.config.warn_threshold * multiplier;
let effective_block = self.config.block_threshold * multiplier;
// Check per-hash thresholds
if count_val >= effective_block {
self.blocked_calls += 1;
return LoopGuardVerdict::Block(format!(
"Blocked: tool '{}' called {} times with identical parameters. \
Try a different approach or different parameters.",
tool_name, count_val
));
}
if count_val >= effective_warn {
// Warning bucket: check if we've already warned too many times
let warning_count = self.warnings_emitted.entry(hash.clone()).or_insert(0);
*warning_count += 1;
if *warning_count > self.config.max_warnings_per_call {
// Upgrade to block after too many warnings
self.blocked_calls += 1;
return LoopGuardVerdict::Block(format!(
"Blocked: tool '{}' called {} times with identical parameters \
(warnings exhausted). Try a different approach.",
tool_name, count_val
));
}
return LoopGuardVerdict::Warn(format!(
"Warning: tool '{}' has been called {} times with identical parameters. \
Consider a different approach.",
tool_name, count_val
));
}
// Ping-pong detection (runs even if individual hash counts are low)
if let Some(ping_pong_msg) = self.detect_ping_pong() {
// Count how many full pattern repeats we have
let repeats = self.count_ping_pong_repeats();
if repeats >= self.config.ping_pong_min_repeats {
self.blocked_calls += 1;
return LoopGuardVerdict::Block(ping_pong_msg);
}
// Below min_repeats, just warn
let warning_count = self
.warnings_emitted
.entry(format!("pingpong_{}", hash))
.or_insert(0);
*warning_count += 1;
if *warning_count <= self.config.max_warnings_per_call {
return LoopGuardVerdict::Warn(ping_pong_msg);
}
}
LoopGuardVerdict::Allow
}
/// Record the outcome of a tool call. Call this AFTER tool execution.
///
/// Hashes `(tool_name | params_json | result_truncated)` and tracks how
/// many times an identical call produces an identical result. Returns a
/// warning string if outcome repetition is detected.
pub fn record_outcome(
&mut self,
tool_name: &str,
params: &serde_json::Value,
result: &str,
) -> Option<String> {
let outcome_hash = Self::compute_outcome_hash(tool_name, params, result);
let call_hash = Self::compute_hash(tool_name, params);
let count = self.outcome_counts.entry(outcome_hash).or_insert(0);
*count += 1;
let count_val = *count;
if count_val >= self.config.outcome_block_threshold {
// Mark the call hash so the NEXT check() auto-blocks it
self.blocked_outcomes.insert(call_hash);
return Some(format!(
"Tool '{}' is returning identical results — the approach isn't working.",
tool_name
));
}
if count_val >= self.config.outcome_warn_threshold {
return Some(format!(
"Tool '{}' is returning identical results — the approach isn't working.",
tool_name
));
}
None
}
/// Get the suggested backoff delay (in milliseconds) for a polling tool call.
///
/// Returns `None` if this is not a poll call. Returns `Some(ms)` with a
/// suggested delay from the backoff schedule, capping at the last entry.
pub fn get_poll_backoff(&mut self, tool_name: &str, params: &serde_json::Value) -> Option<u64> {
if !Self::is_poll_call(tool_name, params) {
return None;
}
let hash = Self::compute_hash(tool_name, params);
let count = self.poll_counts.entry(hash).or_insert(0);
*count += 1;
// count is 1-indexed; backoff starts on the second call
if *count <= 1 {
return None;
}
let idx = (*count as usize).saturating_sub(2);
let delay = BACKOFF_SCHEDULE_MS
.get(idx)
.copied()
.unwrap_or(*BACKOFF_SCHEDULE_MS.last().unwrap_or(&60000));
Some(delay)
}
/// Get a snapshot of current loop guard statistics.
pub fn stats(&self) -> LoopGuardStats {
let unique_calls = self.call_counts.len() as u32;
// Find the most repeated tool call
let mut most_repeated_tool: Option<String> = None;
let mut most_repeated_count: u32 = 0;
for (hash, &count) in &self.call_counts {
if count > most_repeated_count {
most_repeated_count = count;
most_repeated_tool = self.hash_to_tool.get(hash).cloned();
}
}
LoopGuardStats {
total_calls: self.total_calls,
unique_calls,
blocked_calls: self.blocked_calls,
ping_pong_detected: self.detect_ping_pong_pure(),
most_repeated_tool,
most_repeated_count,
}
}
/// Check if a tool call looks like a polling operation.
///
/// Poll tools (like `shell_exec` for status checks) are expected to be
/// called repeatedly and get relaxed loop detection thresholds.
fn is_poll_call(tool_name: &str, params: &serde_json::Value) -> bool {
// Known poll tools with short commands that look like status checks
if POLL_TOOLS.contains(&tool_name) {
if let Some(cmd) = params.get("command").and_then(|v| v.as_str()) {
let cmd_lower = cmd.to_lowercase();
// Short commands that explicitly check status/wait/poll
if cmd.len() < 50
&& (cmd_lower.contains("status")
|| cmd_lower.contains("poll")
|| cmd_lower.contains("wait")
|| cmd_lower.contains("watch")
|| cmd_lower.contains("tail")
|| cmd_lower.contains("ps ")
|| cmd_lower.contains("jobs")
|| cmd_lower.contains("pgrep")
|| cmd_lower.contains("docker ps")
|| cmd_lower.contains("kubectl get"))
{
return true;
}
}
}
// Generic poll detection via params keywords
let params_str = serde_json::to_string(params)
.unwrap_or_default()
.to_lowercase();
params_str.contains("status") || params_str.contains("poll") || params_str.contains("wait")
}
/// Detect ping-pong patterns (A-B-A-B or A-B-C-A-B-C) in recent call history.
///
/// Checks if the last 6+ calls form a repeating pattern of length 2 or 3.
/// Returns a warning message if a pattern is detected, `None` otherwise.
fn detect_ping_pong(&self) -> Option<String> {
self.detect_ping_pong_impl()
}
/// Pure version for stats (no &mut self needed, just reads state).
fn detect_ping_pong_pure(&self) -> bool {
self.detect_ping_pong_impl().is_some()
}
/// Shared ping-pong detection implementation.
fn detect_ping_pong_impl(&self) -> Option<String> {
let len = self.recent_calls.len();
// Check for pattern of length 2 (A-B-A-B-A-B)
// Need at least 6 entries for 3 repeats of length 2
if len >= 6 {
let tail = &self.recent_calls[len - 6..];
let a = &tail[0];
let b = &tail[1];
if a != b && tail[2] == *a && tail[3] == *b && tail[4] == *a && tail[5] == *b {
let tool_a = self
.hash_to_tool
.get(a)
.cloned()
.unwrap_or_else(|| "unknown".to_string());
let tool_b = self
.hash_to_tool
.get(b)
.cloned()
.unwrap_or_else(|| "unknown".to_string());
return Some(format!(
"Ping-pong detected: tools '{}' and '{}' are alternating \
repeatedly. Break the cycle by trying a different approach.",
tool_a, tool_b
));
}
}
// Check for pattern of length 3 (A-B-C-A-B-C-A-B-C)
// Need at least 9 entries for 3 repeats of length 3
if len >= 9 {
let tail = &self.recent_calls[len - 9..];
let a = &tail[0];
let b = &tail[1];
let c = &tail[2];
// Ensure they're not all the same (that's just repetition, not ping-pong)
if !(a == b && b == c)
&& tail[3] == *a
&& tail[4] == *b
&& tail[5] == *c
&& tail[6] == *a
&& tail[7] == *b
&& tail[8] == *c
{
let tool_a = self
.hash_to_tool
.get(a)
.cloned()
.unwrap_or_else(|| "unknown".to_string());
let tool_b = self
.hash_to_tool
.get(b)
.cloned()
.unwrap_or_else(|| "unknown".to_string());
let tool_c = self
.hash_to_tool
.get(c)
.cloned()
.unwrap_or_else(|| "unknown".to_string());
return Some(format!(
"Ping-pong detected: tools '{}', '{}', '{}' are cycling \
repeatedly. Break the cycle by trying a different approach.",
tool_a, tool_b, tool_c
));
}
}
None
}
/// Count how many full repeats of the detected ping-pong pattern exist
/// in the recent call history.
fn count_ping_pong_repeats(&self) -> u32 {
let len = self.recent_calls.len();
// Check pattern of length 2
if len >= 4 {
let a = &self.recent_calls[len - 2];
let b = &self.recent_calls[len - 1];
if a != b {
let mut repeats: u32 = 0;
let mut i = len;
while i >= 2 {
i -= 2;
if self.recent_calls[i] == *a && self.recent_calls[i + 1] == *b {
repeats += 1;
} else {
break;
}
}
if repeats >= 2 {
return repeats;
}
}
}
// Check pattern of length 3
if len >= 6 {
let a = &self.recent_calls[len - 3];
let b = &self.recent_calls[len - 2];
let c = &self.recent_calls[len - 1];
if !(a == b && b == c) {
let mut repeats: u32 = 0;
let mut i = len;
while i >= 3 {
i -= 3;
if self.recent_calls[i] == *a
&& self.recent_calls[i + 1] == *b
&& self.recent_calls[i + 2] == *c
{
repeats += 1;
} else {
break;
}
}
if repeats >= 2 {
return repeats;
}
}
}
0
}
/// Compute a SHA-256 hash of the tool name and parameters.
fn compute_hash(tool_name: &str, params: &serde_json::Value) -> String {
let mut hasher = Sha256::new();
hasher.update(tool_name.as_bytes());
hasher.update(b"|");
// Serialize params deterministically (serde_json sorts object keys)
let params_str = serde_json::to_string(params).unwrap_or_default();
hasher.update(params_str.as_bytes());
hex::encode(hasher.finalize())
}
/// Compute a SHA-256 hash of the tool name, parameters, AND result.
///
/// Result is truncated to 1000 chars to avoid hashing huge outputs
/// while still catching identical short results.
fn compute_outcome_hash(tool_name: &str, params: &serde_json::Value, result: &str) -> String {
let mut hasher = Sha256::new();
hasher.update(tool_name.as_bytes());
hasher.update(b"|");
let params_str = serde_json::to_string(params).unwrap_or_default();
hasher.update(params_str.as_bytes());
hasher.update(b"|");
let truncated = if result.len() > 1000 {
&result[..1000]
} else {
result
};
hasher.update(truncated.as_bytes());
hex::encode(hasher.finalize())
}
}
#[cfg(test)]
mod tests {
use super::*;
// ========================================================================
// Existing tests (preserved unchanged)
// ========================================================================
#[test]
fn allow_below_threshold() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params = serde_json::json!({"query": "test"});
let v = guard.check("web_search", ¶ms);
assert_eq!(v, LoopGuardVerdict::Allow);
let v = guard.check("web_search", ¶ms);
assert_eq!(v, LoopGuardVerdict::Allow);
}
#[test]
fn warn_at_threshold() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params = serde_json::json!({"path": "/etc/passwd"});
// Calls 1, 2 = Allow
guard.check("file_read", ¶ms);
guard.check("file_read", ¶ms);
// Call 3 = Warn (warn_threshold = 3)
let v = guard.check("file_read", ¶ms);
assert!(matches!(v, LoopGuardVerdict::Warn(_)));
}
#[test]
fn block_at_threshold() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params = serde_json::json!({"command": "ls"});
for _ in 0..4 {
guard.check("shell_exec", ¶ms);
}
// Call 5 = Block (block_threshold = 5)
let v = guard.check("shell_exec", ¶ms);
assert!(matches!(v, LoopGuardVerdict::Block(_)));
}
#[test]
fn different_params_no_collision() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
for i in 0..10 {
let params = serde_json::json!({"query": format!("query_{}", i)});
let v = guard.check("web_search", ¶ms);
assert_eq!(v, LoopGuardVerdict::Allow);
}
}
#[test]
fn global_circuit_breaker() {
let config = LoopGuardConfig {
warn_threshold: 100,
block_threshold: 100,
global_circuit_breaker: 5,
..Default::default()
};
let mut guard = LoopGuard::new(config);
for i in 0..5 {
let params = serde_json::json!({"n": i});
let v = guard.check("tool", ¶ms);
assert_eq!(v, LoopGuardVerdict::Allow);
}
// Call 6 triggers circuit breaker (> 5)
let v = guard.check("tool", &serde_json::json!({"n": 5}));
assert!(matches!(v, LoopGuardVerdict::CircuitBreak(_)));
}
#[test]
fn default_config() {
let config = LoopGuardConfig::default();
assert_eq!(config.warn_threshold, 3);
assert_eq!(config.block_threshold, 5);
assert_eq!(config.global_circuit_breaker, 30);
}
// ========================================================================
// New tests — Outcome-Aware Detection
// ========================================================================
#[test]
fn test_outcome_aware_warning() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params = serde_json::json!({"query": "weather"});
let result = "sunny 72F";
// First outcome: no warning
let w = guard.record_outcome("web_search", ¶ms, result);
assert!(w.is_none());
// Second identical outcome: warning (outcome_warn_threshold = 2)
let w = guard.record_outcome("web_search", ¶ms, result);
assert!(w.is_some());
assert!(w.unwrap().contains("identical results"));
}
#[test]
fn test_outcome_aware_blocks_next_call() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params = serde_json::json!({"query": "weather"});
let result = "sunny 72F";
// Record 3 identical outcomes (outcome_block_threshold = 3)
guard.record_outcome("web_search", ¶ms, result);
guard.record_outcome("web_search", ¶ms, result);
let w = guard.record_outcome("web_search", ¶ms, result);
assert!(w.is_some());
// The NEXT check() for this call hash should auto-block
let v = guard.check("web_search", ¶ms);
assert!(matches!(v, LoopGuardVerdict::Block(_)));
if let LoopGuardVerdict::Block(msg) = v {
assert!(msg.contains("identical results"));
}
}
// ========================================================================
// New tests — Ping-Pong Detection
// ========================================================================
#[test]
fn test_ping_pong_ab_detection() {
let mut guard = LoopGuard::new(LoopGuardConfig {
// Set thresholds high so individual hash counting doesn't interfere
warn_threshold: 100,
block_threshold: 100,
ping_pong_min_repeats: 3,
..Default::default()
});
let params_a = serde_json::json!({"file": "a.txt"});
let params_b = serde_json::json!({"file": "b.txt"});
// A-B-A-B-A-B = 3 repeats of (A,B)
guard.check("file_read", ¶ms_a);
guard.check("file_write", ¶ms_b);
guard.check("file_read", ¶ms_a);
guard.check("file_write", ¶ms_b);
guard.check("file_read", ¶ms_a);
let v = guard.check("file_write", ¶ms_b);
// Should detect ping-pong and block (3 full repeats)
assert!(
matches!(v, LoopGuardVerdict::Block(ref msg) if msg.contains("Ping-pong"))
|| matches!(v, LoopGuardVerdict::Warn(ref msg) if msg.contains("Ping-pong")),
"Expected ping-pong detection, got: {:?}",
v
);
}
#[test]
fn test_ping_pong_abc_detection() {
let mut guard = LoopGuard::new(LoopGuardConfig {
warn_threshold: 100,
block_threshold: 100,
ping_pong_min_repeats: 3,
..Default::default()
});
let params_a = serde_json::json!({"a": 1});
let params_b = serde_json::json!({"b": 2});
let params_c = serde_json::json!({"c": 3});
// A-B-C-A-B-C-A-B-C = 3 repeats of (A,B,C)
for _ in 0..3 {
guard.check("tool_a", ¶ms_a);
guard.check("tool_b", ¶ms_b);
guard.check("tool_c", ¶ms_c);
}
// The pattern should be detected by the 9th call
let stats = guard.stats();
assert!(stats.ping_pong_detected);
}
#[test]
fn test_no_false_ping_pong() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
// Various different calls — no pattern
for i in 0..10 {
let params = serde_json::json!({"n": i});
guard.check("tool", ¶ms);
}
let stats = guard.stats();
assert!(!stats.ping_pong_detected);
}
// ========================================================================
// New tests — Poll Tool Handling
// ========================================================================
#[test]
fn test_poll_tool_relaxed_thresholds() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
// shell_exec with short status-check command = poll call
// Default thresholds: warn=3, block=5, poll_multiplier=3
// Effective for poll: warn=9, block=15
let params = serde_json::json!({"command": "docker ps --status running"});
// Calls 1..8 should all be Allow (below warn=9)
for _ in 0..8 {
let v = guard.check("shell_exec", ¶ms);
assert_eq!(
v,
LoopGuardVerdict::Allow,
"Poll tool should have relaxed thresholds"
);
}
// Call 9 should be Warn
let v = guard.check("shell_exec", ¶ms);
assert!(
matches!(v, LoopGuardVerdict::Warn(_)),
"Expected warn at poll threshold, got: {:?}",
v
);
}
#[test]
fn test_is_poll_call_detection() {
// shell_exec with short status-check command
assert!(LoopGuard::is_poll_call(
"shell_exec",
&serde_json::json!({"command": "docker ps --status"})
));
// shell_exec with short tail command
assert!(LoopGuard::is_poll_call(
"shell_exec",
&serde_json::json!({"command": "tail -f /var/log/app.log"})
));
// shell_exec with short command but NO poll keywords — NOT a poll
assert!(!LoopGuard::is_poll_call(
"shell_exec",
&serde_json::json!({"command": "echo hi"})
));
// shell_exec with long command — NOT a poll
assert!(!LoopGuard::is_poll_call(
"shell_exec",
&serde_json::json!({"command": "this is a very long command that definitely exceeds fifty characters in length"})
));
// Non-poll tool with no poll keywords
assert!(!LoopGuard::is_poll_call(
"file_read",
&serde_json::json!({"path": "/etc/hosts"})
));
// Generic poll detection via params containing "status"
assert!(LoopGuard::is_poll_call(
"some_tool",
&serde_json::json!({"check": "status"})
));
// Generic poll detection via params containing "poll"
assert!(LoopGuard::is_poll_call(
"api_call",
&serde_json::json!({"action": "poll_results"})
));
// Generic poll detection via params containing "wait"
assert!(LoopGuard::is_poll_call(
"queue",
&serde_json::json!({"mode": "wait_for_completion"})
));
}
// ========================================================================
// New tests — Backoff Schedule
// ========================================================================
#[test]
fn test_poll_backoff_schedule() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params = serde_json::json!({"command": "kubectl get pods --status"});
// First call: no backoff
let b = guard.get_poll_backoff("shell_exec", ¶ms);
assert_eq!(b, None);
// Second call: 5000ms
let b = guard.get_poll_backoff("shell_exec", ¶ms);
assert_eq!(b, Some(5000));
// Third call: 10000ms
let b = guard.get_poll_backoff("shell_exec", ¶ms);
assert_eq!(b, Some(10000));
// Fourth call: 30000ms
let b = guard.get_poll_backoff("shell_exec", ¶ms);
assert_eq!(b, Some(30000));
// Fifth call: 60000ms
let b = guard.get_poll_backoff("shell_exec", ¶ms);
assert_eq!(b, Some(60000));
// Sixth call: caps at 60000ms
let b = guard.get_poll_backoff("shell_exec", ¶ms);
assert_eq!(b, Some(60000));
// Non-poll tool: no backoff
let non_poll = serde_json::json!({"path": "/etc/hosts"});
let b = guard.get_poll_backoff("file_read", &non_poll);
assert_eq!(b, None);
}
// ========================================================================
// New tests — Warning Bucket
// ========================================================================
#[test]
fn test_warning_bucket_limits() {
let mut guard = LoopGuard::new(LoopGuardConfig {
warn_threshold: 2,
block_threshold: 100, // set very high so only warning bucket triggers block
max_warnings_per_call: 2,
..Default::default()
});
let params = serde_json::json!({"x": 1});
// Call 1: Allow
let v = guard.check("tool", ¶ms);
assert_eq!(v, LoopGuardVerdict::Allow);
// Call 2: Warn (hits warn_threshold=2), warning_count = 1
let v = guard.check("tool", ¶ms);
assert!(matches!(v, LoopGuardVerdict::Warn(_)));
// Call 3: Warn again, warning_count = 2
let v = guard.check("tool", ¶ms);
assert!(matches!(v, LoopGuardVerdict::Warn(_)));
// Call 4: warning_count would be 3, exceeds max_warnings_per_call=2 -> Block
let v = guard.check("tool", ¶ms);
assert!(
matches!(v, LoopGuardVerdict::Block(_)),
"Expected block after warning limit, got: {:?}",
v
);
}
#[test]
fn test_warning_upgrade_to_block() {
let mut guard = LoopGuard::new(LoopGuardConfig {
warn_threshold: 1,
block_threshold: 100,
max_warnings_per_call: 1,
..Default::default()
});
let params = serde_json::json!({"y": 2});
// Call 1: Warn (warn_threshold=1), warning_count = 1
let v = guard.check("tool", ¶ms);
assert!(matches!(v, LoopGuardVerdict::Warn(_)));
// Call 2: warning_count would be 2, exceeds max_warnings_per_call=1 -> Block
let v = guard.check("tool", ¶ms);
assert!(
matches!(v, LoopGuardVerdict::Block(ref msg) if msg.contains("warnings exhausted")),
"Expected block with 'warnings exhausted', got: {:?}",
v
);
}
// ========================================================================
// New tests — Statistics Snapshot
// ========================================================================
#[test]
fn test_stats_snapshot() {
let mut guard = LoopGuard::new(LoopGuardConfig::default());
let params_a = serde_json::json!({"a": 1});
let params_b = serde_json::json!({"b": 2});
// 3 calls to tool_a, 1 to tool_b
guard.check("tool_a", ¶ms_a);
guard.check("tool_a", ¶ms_a);
guard.check("tool_a", ¶ms_a);
guard.check("tool_b", ¶ms_b);
let stats = guard.stats();
assert_eq!(stats.total_calls, 4);
assert_eq!(stats.unique_calls, 2);
assert_eq!(stats.most_repeated_tool, Some("tool_a".to_string()));
assert_eq!(stats.most_repeated_count, 3);
assert!(!stats.ping_pong_detected);
}
// ========================================================================
// New tests — History Ring Buffer
// ========================================================================
#[test]
fn test_history_ring_buffer_limit() {
let config = LoopGuardConfig {
warn_threshold: 100,
block_threshold: 100,
global_circuit_breaker: 200,
..Default::default()
};
let mut guard = LoopGuard::new(config);
// Push 50 unique calls (exceeds HISTORY_SIZE of 30)
for i in 0..50 {
let params = serde_json::json!({"n": i});
guard.check("tool", ¶ms);
}
// Internal ring buffer should be capped at HISTORY_SIZE
assert_eq!(guard.recent_calls.len(), HISTORY_SIZE);
// Stats should reflect all 50 calls
let stats = guard.stats();
assert_eq!(stats.total_calls, 50);
assert_eq!(stats.unique_calls, 50);
}
}