diff --git a/CLAUDE.md b/CLAUDE.md
index 7560f96..418161e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -36,7 +36,7 @@ The system uses a modular architecture with reusable components in the `lib/` di
    - Supports both flat JSON format and Claude CLI format (`result`, `sessionId`, `metadata`)
    - Extracts structured fields: status, exit_signal, work_type, files_modified
    - **Session management**: `store_session_id()`, `get_last_session_id()`, `should_resume_session()`
-   - Automatic session persistence to `.session_id` file with 24-hour expiration
+   - Automatic session persistence to `.claude_session_id` file with 24-hour expiration
    - Detects test-only loops and stuck error patterns
    - Two-stage error filtering to eliminate false positives
    - Multi-line error matching for accurate stuck loop detection
@@ -314,7 +314,7 @@ bats tests/unit/test_cli_parsing.bats
   - `get_last_session_id()` - Retrieves stored session ID
   - `should_resume_session()` - Checks session validity (24-hour expiration)
 - Added `get_epoch_seconds()` to date_utils.sh for cross-platform epoch time
-- Auto-persists sessionId to `.session_id` file during response analysis
+- Auto-persists sessionId to `.claude_session_id` file during response analysis
 - Added 16 new tests covering Claude CLI format and session management
 - Test count: 239 (up from 223)
 
diff --git a/lib/response_analyzer.sh b/lib/response_analyzer.sh
index c3c138c..107326d 100644
--- a/lib/response_analyzer.sh
+++ b/lib/response_analyzer.sh
@@ -72,7 +72,6 @@ parse_json_response() {
 
     # Detect JSON format by checking for Claude CLI fields
     local has_result_field=$(jq -r 'has("result")' "$output_file" 2>/dev/null)
-    local has_session_id_field=$(jq -r 'has("sessionId")' "$output_file" 2>/dev/null)
 
     # Extract fields - support both flat format and Claude CLI format
     # Priority: Claude CLI fields first, then flat format fields
@@ -94,6 +93,10 @@ parse_json_response() {
     local files_modified=$(jq -r '.metadata.files_changed // .files_modified // 0' "$output_file" 2>/dev/null)
 
     # Error count: from flat format OR derived from metadata.has_errors
+    # Note: When only has_errors=true is present (without explicit error_count),
+    # we set error_count=1 as a minimum. This is defensive programming since
+    # the stuck detection threshold is >5 errors, so 1 error won't trigger it.
+    # Actual error count may be higher, but precise count isn't critical for our logic.
     local error_count=$(jq -r '.error_count // 0' "$output_file" 2>/dev/null)
     local has_errors=$(jq -r '.metadata.has_errors // false' "$output_file" 2>/dev/null)
     if [[ "$has_errors" == "true" && "$error_count" == "0" ]]; then
@@ -232,9 +235,10 @@ analyze_response() {
             local json_confidence=$(jq -r '.confidence' .json_parse_result 2>/dev/null || echo "0")
             local session_id=$(jq -r '.session_id' .json_parse_result 2>/dev/null || echo "")
 
-            # Persist session ID if present
+            # Persist session ID if present (for session continuity across loop iterations)
             if [[ -n "$session_id" && "$session_id" != "null" ]]; then
                 store_session_id "$session_id"
+                [[ "${VERBOSE_PROGRESS:-}" == "true" ]] && echo "DEBUG: Persisted session ID: $session_id" >&2
             fi
 
             # JSON parsing provides high confidence
@@ -567,8 +571,8 @@ detect_stuck_loop() {
 # SESSION MANAGEMENT FUNCTIONS
 # =============================================================================
 
-# Session file location
-SESSION_FILE=".session_id"
+# Session file location - standardized across ralph_loop.sh and response_analyzer.sh
+SESSION_FILE=".claude_session_id"
 # Session expiration time in seconds (24 hours)
 SESSION_EXPIRATION_SECONDS=86400
 
@@ -628,16 +632,24 @@ should_resume_session() {
     local session_time
 
     # Parse ISO timestamp to epoch - try multiple formats for cross-platform compatibility
+    # Strip milliseconds if present (e.g., 2026-01-09T10:30:00.123+00:00 → 2026-01-09T10:30:00+00:00)
+    local clean_timestamp="${timestamp}"
+    if [[ "$timestamp" =~ \.[0-9]+[+-Z] ]]; then
+        clean_timestamp=$(echo "$timestamp" | sed 's/\.[0-9]*\([+-Z]\)/\1/')
+    fi
+
     if command -v gdate &>/dev/null; then
         # macOS with coreutils
-        session_time=$(gdate -d "$timestamp" +%s 2>/dev/null)
+        session_time=$(gdate -d "$clean_timestamp" +%s 2>/dev/null)
     elif date --version 2>&1 | grep -q GNU; then
         # GNU date (Linux)
-        session_time=$(date -d "$timestamp" +%s 2>/dev/null)
+        session_time=$(date -d "$clean_timestamp" +%s 2>/dev/null)
     else
         # BSD date (macOS without coreutils) - try parsing ISO format
-        # Format: 2026-01-09T10:30:00+00:00 or similar
-        session_time=$(date -j -f "%Y-%m-%dT%H:%M:%S" "${timestamp%[+-]*}" +%s 2>/dev/null)
+        # Format: 2026-01-09T10:30:00+00:00 or 2026-01-09T10:30:00Z
+        # Strip timezone suffix for BSD date parsing
+        local date_only="${clean_timestamp%[+-Z]*}"
+        session_time=$(date -j -f "%Y-%m-%dT%H:%M:%S" "$date_only" +%s 2>/dev/null)
     fi
 
     # If we couldn't parse the timestamp, consider session expired
diff --git a/tests/unit/test_json_parsing.bats b/tests/unit/test_json_parsing.bats
index e304bb4..e29c94e 100644
--- a/tests/unit/test_json_parsing.bats
+++ b/tests/unit/test_json_parsing.bats
@@ -657,7 +657,7 @@ EOF
     assert_equal "$output_format" "json"
 }
 
-@test "analyze_response persists sessionId to .session_id file" {
+@test "analyze_response persists sessionId to .claude_session_id file" {
     local output_file="$LOG_DIR/test_output.log"
 
     cat > "$output_file" << 'EOF'
@@ -670,9 +670,9 @@ EOF
     analyze_response "$output_file" 1
 
     # Session ID should be persisted for continuity
-    [[ -f ".session_id" ]] || skip "Session persistence not yet implemented"
+    [[ -f ".claude_session_id" ]] || skip "Session persistence not yet implemented"
 
-    local stored_session=$(cat .session_id)
+    local stored_session=$(cat .claude_session_id)
     [[ "$stored_session" == *"session-persist-test-123"* ]]
 }
 
@@ -683,15 +683,15 @@ EOF
 @test "store_session_id writes session to file with timestamp" {
     run store_session_id "session-test-abc"
 
-    [[ -f ".session_id" ]] || skip "store_session_id not yet implemented"
+    [[ -f ".claude_session_id" ]] || skip "store_session_id not yet implemented"
 
-    local content=$(cat .session_id)
+    local content=$(cat .claude_session_id)
     [[ "$content" == *"session-test-abc"* ]]
 }
 
 @test "get_last_session_id retrieves stored session" {
     # First store a session
-    echo '{"session_id": "session-retrieve-test", "timestamp": "2026-01-09T10:00:00Z"}' > .session_id
+    echo '{"session_id": "session-retrieve-test", "timestamp": "2026-01-09T10:00:00Z"}' > .claude_session_id
 
     run get_last_session_id
 
@@ -699,7 +699,7 @@ EOF
 }
 
 @test "get_last_session_id returns empty when no session file" {
-    rm -f .session_id
+    rm -f .claude_session_id
 
     run get_last_session_id
 
@@ -711,7 +711,7 @@ EOF
 @test "should_resume_session returns true for recent session" {
     # Store a recent session (simulated as current timestamp)
     local now=$(date +%s)
-    echo "{\"session_id\": \"session-recent\", \"timestamp\": \"$(date -Iseconds)\"}" > .session_id
+    echo "{\"session_id\": \"session-recent\", \"timestamp\": \"$(date -Iseconds)\"}" > .claude_session_id
 
     run should_resume_session
 
@@ -721,7 +721,7 @@ EOF
 
 @test "should_resume_session returns false for old session" {
     # Store an old session (24+ hours ago)
-    echo '{"session_id": "session-old", "timestamp": "2020-01-01T00:00:00Z"}' > .session_id
+    echo '{"session_id": "session-old", "timestamp": "2020-01-01T00:00:00Z"}' > .claude_session_id
 
     run should_resume_session
 
@@ -730,7 +730,7 @@ EOF
 }
 
 @test "should_resume_session returns false when no session file" {
-    rm -f .session_id
+    rm -f .claude_session_id
 
     run should_resume_session