fix(circuit-breaker): fix detect_stuck_loop function and add tests

Addresses additional CodeRabbit findings in lib/response_analyzer.sh:

CRITICAL (line 267):
- Fixed detect_stuck_loop() to use two-stage filtering
- Was using naive grep -i "error\|failed" pattern
- Now filters JSON fields before extracting errors
- Pattern aligned with analyze_response() for consistency

DEAD CODE (line 18):
- Removed unused STUCK_INDICATORS array
- Array was defined but never referenced in code
- Reduces maintenance burden per coding guidelines

TEST COVERAGE:
- Added comprehensive test suite for detect_stuck_loop()
- New file: tests/test_stuck_loop_detection.sh
- 7 test scenarios validating:
  * JSON fields don't trigger false stuck detection
  * Actual repeated errors are correctly detected
  * Type annotations are properly excluded
  * Function returns appropriate exit codes

Test results:
✓ Error detection tests: 13/13 passing
✓ Stuck loop tests: 7/7 passing
✓ Total: 20/20 tests passing

This ensures both error detection functions (analyze_response and
detect_stuck_loop) use identical filtering logic, preventing circuit
breaker false positives across all code paths.

Addresses CodeRabbit review comments:
- Outside diff range comment: line 267 (Critical)
- Outside diff range comment: line 18 (Dead code)
- Outside diff range comment: lines 254-286 (Test coverage)

lib/response_analyzer.sh

@@ -15,7 +15,6 @@ NC='\033[0m'
 # Analysis configuration
 COMPLETION_KEYWORDS=("done" "complete" "finished" "all tasks complete" "project complete" "ready for review")
 TEST_ONLY_PATTERNS=("npm test" "bats" "pytest" "jest" "cargo test" "go test" "running tests")
-STUCK_INDICATORS=("error" "failed" "cannot" "unable to" "blocked")
 NO_WORK_PATTERNS=("nothing to do" "no changes" "already implemented" "up to date")
 
 # Analyze Claude Code response and extract signals
@@ -263,8 +262,12 @@ detect_stuck_loop() {
         return 1  # Not enough history
     fi
 
-    # Extract key errors from current output
+    # Extract key errors from current output using two-stage filtering
-    local current_errors=$(grep -i "error\|failed" "$current_output" 2>/dev/null | sort | uniq)
+    # Stage 1: Filter out JSON field patterns to avoid false positives
+    # Stage 2: Extract actual error messages
+    local current_errors=$(grep -v '"[^"]*error[^"]*":' "$current_output" 2>/dev/null | \
+                          grep -E '(^Error:|^ERROR:|^error:|\]: error|Link: error|Error occurred|failed with error|[Ee]xception|Fatal|FATAL)' 2>/dev/null | \
+                          sort | uniq)
 
     if [[ -z "$current_errors" ]]; then
         return 1  # No errors

tests/test_stuck_loop_detection.sh

@@ -0,0 +1,200 @@
+#!/bin/bash
+# Test script for detect_stuck_loop function
+# Validates that the stuck loop detection uses two-stage filtering
+# to avoid false positives from JSON fields
+#
+# TEST STRATEGY:
+# The detect_stuck_loop function extracts errors from current output and checks
+# if the same errors appear in the last 3 historical outputs. This test validates:
+#
+# 1. Two-stage filtering is applied (same as analyze_response)
+# 2. JSON field names don't cause false stuck loop detection
+# 3. Actual repeated errors are correctly detected
+# 4. Function returns appropriate exit codes
+
+set -e
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+# Test counter
+TESTS_PASSED=0
+TESTS_FAILED=0
+
+# Create temporary directory for test files
+TEST_DIR=$(mktemp -d)
+HISTORY_DIR="$TEST_DIR/logs"
+mkdir -p "$HISTORY_DIR"
+trap 'rm -rf "$TEST_DIR"' EXIT
+
+# Source the response_analyzer.sh to get access to detect_stuck_loop function
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../lib/response_analyzer.sh"
+
+# Helper function to run tests
+run_test() {
+    local test_name="$1"
+    local expected_result="$2"  # 0 = stuck detected, 1 = not stuck
+
+    echo -e "\n${YELLOW}Running test: $test_name${NC}"
+
+    # Call detect_stuck_loop function
+    local result=1
+    if detect_stuck_loop "$TEST_DIR/current_output.log" "$HISTORY_DIR"; then
+        result=0
+    else
+        result=1
+    fi
+
+    # Check result
+    if [[ $result -eq $expected_result ]]; then
+        echo -e "${GREEN}✓ PASS${NC} - Expected exit code: $expected_result, Got: $result"
+        TESTS_PASSED=$((TESTS_PASSED + 1))
+    else
+        echo -e "${RED}✗ FAIL${NC} - Expected exit code: $expected_result, Got: $result"
+        echo "Current output:"
+        cat "$TEST_DIR/current_output.log"
+        echo "History files:"
+        ls -la "$HISTORY_DIR"
+        TESTS_FAILED=$((TESTS_FAILED + 1))
+    fi
+}
+
+echo "========================================"
+echo "Stuck Loop Detection Test Suite"
+echo "========================================"
+
+# Test 1: No history - should return not stuck (exit code 1)
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+Error: Build failed
+EOF
+# Empty history directory
+rm -f "$HISTORY_DIR"/*
+run_test "No history available" 1
+
+# Create history directory again for next tests
+mkdir -p "$HISTORY_DIR"
+
+# Test 2: JSON with "is_error": false should NOT trigger stuck detection
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+{
+  "is_error": false,
+  "error_count": 0,
+  "status": "success"
+}
+EOF
+# Create 3 history files with same JSON
+for i in 1 2 3; do
+    cat > "$HISTORY_DIR/claude_output_00${i}.log" << 'EOF'
+{
+  "is_error": false,
+  "error_count": 0,
+  "status": "success"
+}
+EOF
+done
+run_test "JSON fields should not trigger stuck detection" 1
+
+# Test 3: Actual repeated errors should trigger stuck detection
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+Build started
+Error: Failed to compile src/main.ts
+Type error on line 42
+EOF
+# Create 3 history files with same error
+for i in 1 2 3; do
+    sleep 0.1  # Ensure different timestamps
+    cat > "$HISTORY_DIR/claude_output_00${i}.log" << 'EOF'
+Build started
+Error: Failed to compile src/main.ts
+Type error on line 42
+EOF
+done
+run_test "Repeated actual errors trigger stuck detection" 0
+
+# Test 4: Different errors should NOT trigger stuck detection
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+Error: Database connection failed
+EOF
+# Create history with different errors
+sleep 0.1
+cat > "$HISTORY_DIR/claude_output_001.log" << 'EOF'
+Error: File not found
+EOF
+sleep 0.1
+cat > "$HISTORY_DIR/claude_output_002.log" << 'EOF'
+Error: Permission denied
+EOF
+sleep 0.1
+cat > "$HISTORY_DIR/claude_output_003.log" << 'EOF'
+Error: Network timeout
+EOF
+run_test "Different errors should not trigger stuck detection" 1
+
+# Test 5: No errors in current output should return not stuck
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+Build successful
+All tests passed
+Deployment complete
+EOF
+# History doesn't matter if current has no errors
+run_test "No errors in current output" 1
+
+# Test 6: Mixed JSON + real error - only real error should be extracted
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+{
+  "is_error": false,
+  "status": "processing"
+}
+Error: Compilation failed
+EOF
+# Create history with same real error (JSON part varies)
+for i in 1 2 3; do
+    sleep 0.1
+    cat > "$HISTORY_DIR/claude_output_00${i}.log" << 'EOF'
+{
+  "is_error": false,
+  "status": "different"
+}
+Error: Compilation failed
+EOF
+done
+run_test "Mixed JSON and error - only error matters" 0
+
+# Test 7: Type annotations should not trigger stuck detection
+cat > "$TEST_DIR/current_output.log" << 'EOF'
+diff --git a/src/error.ts b/src/error.ts
++export class ErrorHandler {
++  handleError(error: Error) {
++    console.log(error);
+EOF
+# Create history with similar code diffs
+for i in 1 2 3; do
+    sleep 0.1
+    cat > "$HISTORY_DIR/claude_output_00${i}.log" << 'EOF'
+diff --git a/src/error.ts b/src/error.ts
++export class ErrorHandler {
++  handleError(error: Error) {
++    console.log(error);
+EOF
+done
+run_test "Type annotations should not trigger stuck detection" 1
+
+# Print summary
+echo ""
+echo "========================================"
+echo "Test Summary"
+echo "========================================"
+echo -e "${GREEN}Passed: $TESTS_PASSED${NC}"
+echo -e "${RED}Failed: $TESTS_FAILED${NC}"
+echo "========================================"
+
+if [[ $TESTS_FAILED -gt 0 ]]; then
+    exit 1
+else
+    echo -e "${GREEN}All tests passed!${NC}"
+    exit 0
+fi