merge: resolve conflicts — combine main's error handling with PR's subagent delegation

- session-stop.sh: keep check_jq guard + add pending-lessons archive
- track-code-change.sh: keep rate limiting + error handling, add pending-lessons
  queue + delegation output to sensei subagent
- track-command.sh: same pattern — pending-lessons + delegation output

Both sides rewrote the same logic differently: main improved error handling
(check_jq, log_error, json_escape), PR restructured output for subagent
pipeline (DOJ-2436). This merge keeps both improvements.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: lapc506

data/concept-tree.json

@@ -358,8 +358,36 @@
           "triggers": ["cache", "redis", "CDN", "load balancer"]
         }
       }
+    },
+    "debugging": {
+      "name": "Debugging",
+      "icon": "🐛",
+      "belt_requirement": "white",
+      "concepts": {
+        "error-reading": {
+          "name": "Error Reading",
+          "xp_to_master": 15,
+          "prerequisites": [],
+          "description": "Understanding error messages and stack traces",
+          "triggers": ["error", "Error:", "Traceback", "ENOENT", "stack trace"]
+        },
+        "debugging-mindset": {
+          "name": "Debugging Mindset",
+          "xp_to_master": 20,
+          "prerequisites": ["error-reading"],
+          "description": "Systematic approach to finding and fixing bugs",
+          "triggers": ["debug", "breakpoint", "console.log", "print("]
+        },
+        "common-errors": {
+          "name": "Common Errors",
+          "xp_to_master": 25,
+          "prerequisites": ["error-reading", "debugging-mindset"],
+          "description": "Recognizing and fixing common programming errors",
+          "triggers": ["TypeError", "ReferenceError", "SyntaxError", "undefined", "null"]
+        }
+      }
     }
   },
-  "total_concepts": 42,
+  "total_concepts": 45,
   "mastery_quiz_threshold": 3
 }

data/quiz-bank.json

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+# Cross-platform date utilities for CodeSensei
+# Supports: GNU date (Linux), BSD date (macOS), python3 fallback
+
+# Get today's date in YYYY-MM-DD format (UTC)
+date_today() {
+  date -u '+%Y-%m-%d' 2>/dev/null || python3 -c "from datetime import datetime; print(datetime.utcnow().strftime('%Y-%m-%d'))"
+}
+
+# Get yesterday's date in YYYY-MM-DD format (UTC)
+date_yesterday() {
+  # Try GNU date first
+  date -u -d 'yesterday' '+%Y-%m-%d' 2>/dev/null && return
+  # Try BSD date (macOS)
+  date -u -v-1d '+%Y-%m-%d' 2>/dev/null && return
+  # Python fallback
+  python3 -c "from datetime import datetime, timedelta; print((datetime.utcnow() - timedelta(days=1)).strftime('%Y-%m-%d'))" 2>/dev/null && return
+  # Last resort: empty string
+  echo ""
+}
+
+# Convert date string (YYYY-MM-DD) to epoch seconds
+date_to_epoch() {
+  local date_str="$1"
+  # Try GNU date
+  date -u -d "$date_str" '+%s' 2>/dev/null && return
+  # Try BSD date (macOS)
+  date -u -j -f '%Y-%m-%d %H:%M:%S' "${date_str} 00:00:00" '+%s' 2>/dev/null && return
+  # Python fallback
+  python3 -c "from datetime import datetime, timezone; print(int(datetime.strptime('$date_str', '%Y-%m-%d').replace(tzinfo=timezone.utc).timestamp()))" 2>/dev/null && return
+  echo "0"
+}
+
+# Get date N days ago in YYYY-MM-DD format (UTC)
+date_days_ago() {
+  local days="$1"
+  # Try GNU date
+  date -u -d "${days} days ago" '+%Y-%m-%d' 2>/dev/null && return
+  # Try BSD date (macOS)
+  date -u -v-${days}d '+%Y-%m-%d' 2>/dev/null && return
+  # Python fallback
+  python3 -c "from datetime import datetime, timedelta; print((datetime.utcnow() - timedelta(days=${days})).strftime('%Y-%m-%d'))" 2>/dev/null && return
+  echo ""
+}
+
+# Get current UTC timestamp in ISO format
+date_now_iso() {
+  date -u '+%Y-%m-%dT%H:%M:%SZ' 2>/dev/null || python3 -c "from datetime import datetime; print(datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%SZ'))"
+}

scripts/lib/date-compat.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+# CodeSensei — Shared Error Handling Library
+# Source this file in hook scripts for consistent error logging and JSON safety.
+#
+# Usage:
+#   source "$(dirname "$0")/lib/error-handling.sh"
+
+LOG_FILE="${HOME}/.code-sensei/error.log"
+MAX_LOG_LINES=1000
+
+# Log an error with timestamp and script name.
+# Usage: log_error "script-name" "message"
+log_error() {
+  local script_name="${1:-unknown}"
+  local message="$2"
+  local timestamp
+  timestamp=$(date -u '+%Y-%m-%dT%H:%M:%SZ' 2>/dev/null || date '+%Y-%m-%d')
+  mkdir -p "$(dirname "$LOG_FILE")"
+  printf '[%s] [%s] %s\n' "$timestamp" "$script_name" "$message" >> "$LOG_FILE"
+  # Cap log file to MAX_LOG_LINES
+  if [ -f "$LOG_FILE" ]; then
+    local line_count
+    line_count=$(wc -l < "$LOG_FILE" 2>/dev/null || echo 0)
+    if [ "$line_count" -gt "$MAX_LOG_LINES" ]; then
+      tail -n "$MAX_LOG_LINES" "$LOG_FILE" > "${LOG_FILE}.tmp" && mv "${LOG_FILE}.tmp" "$LOG_FILE"
+    fi
+  fi
+}
+
+# Safely escape a string for JSON interpolation.
+# Returns a JSON-encoded string including surrounding double quotes.
+# Usage: escaped=$(json_escape "$var")
+json_escape() {
+  local str="$1"
+  if command -v jq &>/dev/null; then
+    printf '%s' "$str" | jq -Rs '.'
+  else
+    # Basic fallback: escape backslashes, double quotes, and common control chars
+    printf '"%s"' "$(printf '%s' "$str" | sed 's/\\/\\\\/g; s/"/\\"/g')"
+  fi
+}
+
+# Check that jq is installed. Logs a one-time warning per session if missing.
+# Usage: check_jq "script-name" || exit 0
+check_jq() {
+  if ! command -v jq &>/dev/null; then
+    local warn_file="${HOME}/.code-sensei/.jq-warned"
+    if [ ! -f "$warn_file" ]; then
+      log_error "${1:-unknown}" "jq not installed — CodeSensei features limited. Install with: brew install jq"
+      touch "$warn_file"
+    fi
+    return 1
+  fi
+  return 0
+}