diff --git a/agents/sensei.md b/agents/sensei.md
index 36bfbb8..8c80501 100644
--- a/agents/sensei.md
+++ b/agents/sensei.md
@@ -22,6 +22,21 @@ You live inside Claude Code and your mission is to teach people programming whil
 - **Concise** — you teach in small bites. One concept at a time. Never walls of text
 - **Fun** — learning should feel like leveling up in a game, not reading a textbook
 
+## When Invoked via Delegation (Pending Lessons)
+
+If you are invoked by the main Claude instance via the Task tool after a hook delegation, read the pending lessons queue at `~/.code-sensei/pending-lessons/`. Each `.json` file contains a structured teaching moment:
+
+```json
+{"timestamp":"...","type":"micro-lesson|inline-insight|command-hint","tech":"react","file":"src/App.jsx","belt":"white","firstEncounter":true}
+```
+
+Process the most recent entry (or batch if multiple are pending). Produce the appropriate teaching content based on the `type`:
+- **micro-lesson**: First-time encounter — explain what the technology/concept is and why it matters (2-3 sentences)
+- **inline-insight**: Already-seen technology — brief explanation of what this specific change/command does (1-2 sentences)
+- **command-hint**: Unknown command type — explain only if educational, skip if trivial
+
+Always read the user's profile (`~/.code-sensei/profile.json`) to calibrate your belt-level language.
+
 ## The Dojo Way (Teaching Philosophy)
 
 1. **Learn by DOING** — you never explain something the user hasn't encountered. You explain what just happened in THEIR project
diff --git a/commands/recap.md b/commands/recap.md
index c5b8b33..4ffa602 100644
--- a/commands/recap.md
+++ b/commands/recap.md
@@ -10,10 +10,16 @@ You are CodeSensei 🥋 by Dojo Coding. The user wants a summary of what they le
 
 1. Read the user's profile from `~/.code-sensei/profile.json`
 
-2. Analyze the current session:
+2. Drain pending lessons from `~/.code-sensei/pending-lessons/`:
+   - Read all `.json` files in the directory
+   - Each file contains a structured teaching moment: `{"timestamp","type","tech/concept","file/command","belt","firstEncounter"}`
+   - Use these to build a complete picture of what was learned this session
+   - After processing, you may reference these lessons in the recap
+
+3. Analyze the current session:
    - What files were created or modified?
    - What technologies/tools were used?
-   - What concepts were encountered?
+   - What concepts were encountered (from profile + pending lessons)?
    - How many quizzes were taken and results?
    - What was the user trying to build?
 
diff --git a/scripts/session-stop.sh b/scripts/session-stop.sh
index 2c217c2..1b31107 100644
--- a/scripts/session-stop.sh
+++ b/scripts/session-stop.sh
@@ -63,6 +63,23 @@ if [ "$SESSION_CONCEPTS" -gt 0 ]; then
   echo "You encountered $SESSION_CONCEPTS new concepts this session! Use /code-sensei:recap next time for a full summary."
 fi
 
+# Archive pending lessons from this session (DOJ-2436)
+PENDING_DIR="${PROFILE_DIR}/pending-lessons"
+ARCHIVE_DIR="${PROFILE_DIR}/lessons-archive"
+if [ -d "$PENDING_DIR" ] && [ "$(ls -A "$PENDING_DIR" 2>/dev/null)" ]; then
+  mkdir -p "$ARCHIVE_DIR"
+  ARCHIVE_FILE="${ARCHIVE_DIR}/${TODAY}.jsonl"
+  # Concatenate all pending lesson files into the daily archive
+  for f in "$PENDING_DIR"/*.json; do
+    [ -f "$f" ] && cat "$f" >> "$ARCHIVE_FILE"
+  done
+  # Clear the pending queue
+  rm -f "$PENDING_DIR"/*.json
+
+  # Cap archive size: keep only last 30 days of archives (~1MB)
+  find "$ARCHIVE_DIR" -name "*.jsonl" -type f | sort | head -n -30 | xargs -r rm -f
+fi
+
 rm -f "$SESSION_STATE"
 rm -f "$PROFILE_DIR/.jq-warned"
 
diff --git a/scripts/track-code-change.sh b/scripts/track-code-change.sh
index e649cb3..3a973a7 100644
--- a/scripts/track-code-change.sh
+++ b/scripts/track-code-change.sh
@@ -167,12 +167,30 @@ if [ $? -ne 0 ]; then
   BELT="white"
 fi
 
+# --- Pending lessons queue (durable, per-lesson file to avoid append races) --- (DOJ-2436)
+PENDING_DIR="${PROFILE_DIR}/pending-lessons"
+mkdir -p "$PENDING_DIR"
+
 if [ "$IS_FIRST_EVER" = "true" ]; then
-  CONTEXT="🥋 CodeSensei micro-lesson trigger: The user just encountered '$TECH' for the FIRST TIME (file: $FILE_PATH). Their belt level is '$BELT'. Provide a brief 2-sentence explanation of what $TECH is and why it matters for their project. Adapt language to their belt level. Keep it concise and non-intrusive -- weave it naturally into your response, don't stop everything for a lecture."
+  LESSON_TYPE="micro-lesson"
 else
-  CONTEXT="🥋 CodeSensei inline insight: Claude just used '$TOOL_NAME' on '$FILE_PATH' ($TECH). The user's belt level is '$BELT'. Provide a brief 1-2 sentence explanation of what this change does and why, adapted to their belt level. Keep it natural and non-intrusive -- weave it into your response as a quick teaching moment."
+  LESSON_TYPE="inline-insight"
 fi
 
+# Write one JSON file per lesson (atomic, no race conditions)
+LESSON_ID="${TIMESTAMP}-$(printf '%05d' $$)"
+LESSON_FILE="${PENDING_DIR}/${LESSON_ID}.json"
+SAFE_FILE_PATH_LESSON=$(printf '%s' "$FILE_PATH" | sed 's/\\/\\\\/g; s/"/\\"/g')
+SAFE_TOOL_NAME_LESSON=$(printf '%s' "$TOOL_NAME" | sed 's/\\/\\\\/g; s/"/\\"/g')
+if ! printf '{"timestamp":"%s","type":"%s","tech":"%s","file":"%s","tool":"%s","belt":"%s","firstEncounter":%s}\n' \
+  "$TIMESTAMP" "$LESSON_TYPE" "$TECH" "$SAFE_FILE_PATH_LESSON" "$SAFE_TOOL_NAME_LESSON" "$BELT" "$IS_FIRST_EVER" > "$LESSON_FILE"
+then
+  log_error "$SCRIPT_NAME" "Failed to write pending lesson: $LESSON_FILE"
+fi
+
+# --- Delegation hint: delegate teaching to sensei subagent --- (DOJ-2436)
+CONTEXT="CodeSensei: New teaching moment detected ($TECH, $FILE_PATH). If the user is not in the middle of a complex task, use the Task tool to invoke the 'sensei' agent. Pass it the latest pending lesson from ~/.code-sensei/pending-lessons/."
+
 ESCAPED_CONTEXT=$(json_escape "$CONTEXT")
 printf '{"hookSpecificOutput":{"hookEventName":"PostToolUse","additionalContext":%s}}\n' "$ESCAPED_CONTEXT"
 
diff --git a/scripts/track-command.sh b/scripts/track-command.sh
index d89ad60..96c2313 100644
--- a/scripts/track-command.sh
+++ b/scripts/track-command.sh
@@ -234,16 +234,37 @@ if [ $? -ne 0 ]; then
   BELT="white"
 fi
 
-if [ "$ERROR_IS_FIRST_EVER" = "true" ] && [ -n "$ERROR_CONCEPT" ]; then
-  CONTEXT="🥋 CodeSensei micro-lesson trigger: The user just encountered '$ERROR_CONCEPT' for the FIRST TIME while reading command output ($SAFE_CMD). Their belt level is '$BELT'. Provide a brief 2-sentence explanation of how to read this kind of error and why it matters. Adapt language to their belt level. Keep it supportive and practical."
+# --- Pending lessons queue (durable, per-lesson file to avoid append races) --- (DOJ-2436)
+PENDING_DIR="${PROFILE_DIR}/pending-lessons"
+mkdir -p "$PENDING_DIR"
+
+if [ "$IS_FIRST_EVER" = "true" ] && [ -n "$CONCEPT" ]; then
+  LESSON_TYPE="micro-lesson"
+elif [ "$ERROR_IS_FIRST_EVER" = "true" ] && [ -n "$ERROR_CONCEPT" ]; then
+  LESSON_TYPE="micro-lesson"
+elif [ -n "$CONCEPT" ]; then
+  LESSON_TYPE="inline-insight"
 elif [ -n "$ERROR_CONCEPT" ]; then
-  CONTEXT="🥋 CodeSensei inline insight: An error appeared in the command output ($SAFE_CMD). The user's belt level is '$BELT'. This is a great moment to teach '$ERROR_CONCEPT' -- briefly explain how to read and interpret this type of error in 1-2 sentences, adapted to their belt level. Keep it supportive and practical."
-elif [ "$IS_FIRST_EVER" = "true" ]; then
-  CONTEXT="🥋 CodeSensei micro-lesson trigger: The user just encountered '$CONCEPT' for the FIRST TIME (command: $SAFE_CMD). Their belt level is '$BELT'. Provide a brief 2-sentence explanation of what $CONCEPT means and why it matters. Adapt language to their belt level. Keep it concise and non-intrusive."
+  LESSON_TYPE="inline-insight"
 else
-  CONTEXT="🥋 CodeSensei inline insight: Claude just ran a '$CONCEPT' command ($SAFE_CMD). The user's belt level is '$BELT'. Provide a brief 1-sentence explanation of what this command does, adapted to their belt level. Keep it natural and non-intrusive."
+  LESSON_TYPE="command-hint"
 fi
 
+# Write one JSON file per lesson (atomic, no race conditions)
+LESSON_ID="${TIMESTAMP}-$(printf '%05d' $$)"
+LESSON_FILE="${PENDING_DIR}/${LESSON_ID}.json"
+DISPLAY_TOPIC="${ERROR_CONCEPT:-${CONCEPT:-shell command}}"
+SAFE_DISPLAY_TOPIC=$(printf '%s' "$DISPLAY_TOPIC" | sed 's/\\/\\\\/g; s/"/\\"/g')
+if ! printf '{"timestamp":"%s","type":"%s","concept":"%s","command":"%s","belt":"%s","firstEncounter":%s}\n' \
+  "$TIMESTAMP" "$LESSON_TYPE" "$SAFE_DISPLAY_TOPIC" "$SAFE_CMD" "$BELT" \
+  "$([ "$IS_FIRST_EVER" = "true" ] || [ "$ERROR_IS_FIRST_EVER" = "true" ] && echo "true" || echo "false")" > "$LESSON_FILE"
+then
+  log_error "$SCRIPT_NAME" "Failed to write pending lesson: $LESSON_FILE"
+fi
+
+# --- Delegation hint: delegate teaching to sensei subagent --- (DOJ-2436)
+CONTEXT="CodeSensei: New teaching moment detected ($DISPLAY_TOPIC, $SAFE_CMD). If the user is not in the middle of a complex task, use the Task tool to invoke the 'sensei' agent. Pass it the latest pending lesson from ~/.code-sensei/pending-lessons/."
+
 ESCAPED_CONTEXT=$(json_escape "$CONTEXT")
 printf '{"hookSpecificOutput":{"hookEventName":"PostToolUse","additionalContext":%s}}\n' "$ESCAPED_CONTEXT"
 
diff --git a/tests/test-hooks.sh b/tests/test-hooks.sh
new file mode 100755
index 0000000..d46d15c
--- /dev/null
+++ b/tests/test-hooks.sh
@@ -0,0 +1,256 @@
+#!/bin/bash
+# CodeSensei — Hook Regression Tests
+# Validates that hook scripts produce valid JSON output and write
+# structured pending lessons to the queue directory.
+#
+# Usage: bash tests/test-hooks.sh
+# Requirements: jq
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")/.." && pwd)"
+TEST_HOME=$(mktemp -d)
+export HOME="$TEST_HOME"
+
+PASS=0
+FAIL=0
+
+# Colors
+GREEN='\033[0;32m'
+RED='\033[0;31m'
+NC='\033[0m'
+
+pass() { PASS=$((PASS + 1)); echo -e "  ${GREEN}✓${NC} $1"; }
+fail() { FAIL=$((FAIL + 1)); echo -e "  ${RED}✗${NC} $1: $2"; }
+
+cleanup() {
+  rm -rf "$TEST_HOME"
+}
+trap cleanup EXIT
+
+# --- Setup: create a minimal profile ---
+setup_profile() {
+  mkdir -p "$TEST_HOME/.code-sensei"
+  cat > "$TEST_HOME/.code-sensei/profile.json" <<'PROFILE'
+{
+  "belt": "yellow",
+  "xp": 100,
+  "session_concepts": [],
+  "concepts_seen": ["html"],
+  "streak": {"current": 3}
+}
+PROFILE
+}
+
+echo ""
+echo "━━━ CodeSensei Hook Regression Tests ━━━"
+echo ""
+
+# ============================================================
+# TEST GROUP 1: track-code-change.sh
+# ============================================================
+echo "▸ track-code-change.sh"
+
+# Test 1.1: Output is valid JSON
+setup_profile
+OUTPUT=$(echo '{"tool_name":"Write","tool_input":{"file_path":"src/App.tsx"}}' \
+  | bash "$SCRIPT_DIR/scripts/track-code-change.sh" 2>/dev/null)
+
+if echo "$OUTPUT" | jq . > /dev/null 2>&1; then
+  pass "stdout is valid JSON"
+else
+  fail "stdout is valid JSON" "got: $OUTPUT"
+fi
+
+# Test 1.2: Output contains hookSpecificOutput with PostToolUse event
+EVENT=$(echo "$OUTPUT" | jq -r '.hookSpecificOutput.hookEventName')
+if [ "$EVENT" = "PostToolUse" ]; then
+  pass "hookEventName is PostToolUse"
+else
+  fail "hookEventName is PostToolUse" "got: $EVENT"
+fi
+
+# Test 1.3: additionalContext is a delegation hint (not verbose teaching)
+CONTEXT=$(echo "$OUTPUT" | jq -r '.hookSpecificOutput.additionalContext')
+if echo "$CONTEXT" | grep -q "Task tool" && echo "$CONTEXT" | grep -q "sensei"; then
+  pass "additionalContext is a delegation hint (mentions Task tool + sensei)"
+else
+  fail "additionalContext is a delegation hint" "got: $CONTEXT"
+fi
+
+# Test 1.4: additionalContext does NOT contain old verbose teaching patterns
+if echo "$CONTEXT" | grep -q "Provide a brief"; then
+  fail "additionalContext has no verbose teaching" "still contains 'Provide a brief'"
+else
+  pass "additionalContext has no verbose teaching content"
+fi
+
+# Test 1.5: Pending lesson file was created
+LESSON_COUNT=$(find "$TEST_HOME/.code-sensei/pending-lessons" -name "*.json" 2>/dev/null | wc -l)
+if [ "$LESSON_COUNT" -ge 1 ]; then
+  pass "pending lesson file created ($LESSON_COUNT file(s))"
+else
+  fail "pending lesson file created" "found $LESSON_COUNT files"
+fi
+
+# Test 1.6: Pending lesson file is valid JSON
+LESSON_FILE=$(find "$TEST_HOME/.code-sensei/pending-lessons" -name "*.json" | head -1)
+if jq . "$LESSON_FILE" > /dev/null 2>&1; then
+  pass "pending lesson file is valid JSON"
+else
+  fail "pending lesson file is valid JSON" "file: $LESSON_FILE"
+fi
+
+# Test 1.7: Pending lesson has required fields
+LESSON_TYPE=$(jq -r '.type' "$LESSON_FILE")
+LESSON_TECH=$(jq -r '.tech' "$LESSON_FILE")
+LESSON_BELT=$(jq -r '.belt' "$LESSON_FILE")
+if [ "$LESSON_TYPE" != "null" ] && [ "$LESSON_TECH" != "null" ] && [ "$LESSON_BELT" != "null" ]; then
+  pass "pending lesson has type=$LESSON_TYPE, tech=$LESSON_TECH, belt=$LESSON_BELT"
+else
+  fail "pending lesson has required fields" "type=$LESSON_TYPE tech=$LESSON_TECH belt=$LESSON_BELT"
+fi
+
+# Test 1.8: First encounter for new tech creates micro-lesson
+setup_profile
+rm -rf "$TEST_HOME/.code-sensei/pending-lessons"
+echo '{"tool_name":"Write","tool_input":{"file_path":"main.py"}}' \
+  | bash "$SCRIPT_DIR/scripts/track-code-change.sh" > /dev/null 2>&1
+LESSON_FILE=$(find "$TEST_HOME/.code-sensei/pending-lessons" -name "*.json" | head -1)
+LESSON_TYPE=$(jq -r '.type' "$LESSON_FILE")
+FIRST=$(jq -r '.firstEncounter' "$LESSON_FILE")
+if [ "$LESSON_TYPE" = "micro-lesson" ] && [ "$FIRST" = "true" ]; then
+  pass "first encounter creates micro-lesson with firstEncounter=true"
+else
+  fail "first encounter creates micro-lesson" "type=$LESSON_TYPE firstEncounter=$FIRST"
+fi
+
+# Test 1.9: Already-seen tech creates inline-insight
+setup_profile
+rm -rf "$TEST_HOME/.code-sensei/pending-lessons"
+echo '{"tool_name":"Edit","tool_input":{"file_path":"index.html"}}' \
+  | bash "$SCRIPT_DIR/scripts/track-code-change.sh" > /dev/null 2>&1
+LESSON_FILE=$(find "$TEST_HOME/.code-sensei/pending-lessons" -name "*.json" | head -1)
+LESSON_TYPE=$(jq -r '.type' "$LESSON_FILE")
+FIRST=$(jq -r '.firstEncounter' "$LESSON_FILE")
+if [ "$LESSON_TYPE" = "inline-insight" ] && [ "$FIRST" = "false" ]; then
+  pass "already-seen tech creates inline-insight with firstEncounter=false"
+else
+  fail "already-seen tech creates inline-insight" "type=$LESSON_TYPE firstEncounter=$FIRST"
+fi
+
+echo ""
+
+# ============================================================
+# TEST GROUP 2: track-command.sh
+# ============================================================
+echo "▸ track-command.sh"
+
+setup_profile
+rm -rf "$TEST_HOME/.code-sensei/pending-lessons"
+
+# Test 2.1: Output is valid JSON
+OUTPUT=$(echo '{"tool_input":{"command":"npm install express"}}' \
+  | bash "$SCRIPT_DIR/scripts/track-command.sh" 2>/dev/null)
+
+if echo "$OUTPUT" | jq . > /dev/null 2>&1; then
+  pass "stdout is valid JSON"
+else
+  fail "stdout is valid JSON" "got: $OUTPUT"
+fi
+
+# Test 2.2: additionalContext is delegation hint
+CONTEXT=$(echo "$OUTPUT" | jq -r '.hookSpecificOutput.additionalContext')
+if echo "$CONTEXT" | grep -q "Task tool" && echo "$CONTEXT" | grep -q "sensei"; then
+  pass "additionalContext is a delegation hint"
+else
+  fail "additionalContext is a delegation hint" "got: $CONTEXT"
+fi
+
+# Test 2.3: Pending lesson file for command
+LESSON_FILE=$(find "$TEST_HOME/.code-sensei/pending-lessons" -name "*.json" | head -1)
+if jq . "$LESSON_FILE" > /dev/null 2>&1; then
+  pass "pending lesson file is valid JSON"
+else
+  fail "pending lesson file is valid JSON" "file: $LESSON_FILE"
+fi
+
+# Test 2.4: Command lesson has concept field
+CONCEPT=$(jq -r '.concept' "$LESSON_FILE")
+if [ "$CONCEPT" = "package-management" ]; then
+  pass "command lesson detected concept=package-management"
+else
+  fail "command lesson detected concept" "got: $CONCEPT"
+fi
+
+echo ""
+
+# ============================================================
+# TEST GROUP 3: session-stop.sh (cleanup)
+# ============================================================
+echo "▸ session-stop.sh (pending lessons cleanup)"
+
+setup_profile
+rm -rf "$TEST_HOME/.code-sensei/pending-lessons" "$TEST_HOME/.code-sensei/lessons-archive"
+
+# Create some pending lessons
+mkdir -p "$TEST_HOME/.code-sensei/pending-lessons"
+echo '{"timestamp":"2026-03-09T12:00:00Z","type":"micro-lesson","tech":"react"}' \
+  > "$TEST_HOME/.code-sensei/pending-lessons/test1.json"
+echo '{"timestamp":"2026-03-09T12:01:00Z","type":"inline-insight","tech":"css"}' \
+  > "$TEST_HOME/.code-sensei/pending-lessons/test2.json"
+
+# Add a session concept so we can verify the full flow
+jq '.session_concepts = ["react","css"]' "$TEST_HOME/.code-sensei/profile.json" \
+  | tee "$TEST_HOME/.code-sensei/profile.json.tmp" > /dev/null \
+  && mv "$TEST_HOME/.code-sensei/profile.json.tmp" "$TEST_HOME/.code-sensei/profile.json"
+
+# Run session-stop
+bash "$SCRIPT_DIR/scripts/session-stop.sh" > /dev/null 2>&1
+
+# Test 3.1: Pending lessons directory was cleaned
+REMAINING=$(find "$TEST_HOME/.code-sensei/pending-lessons" -name "*.json" 2>/dev/null | wc -l)
+if [ "$REMAINING" -eq 0 ]; then
+  pass "pending lessons cleaned after session stop"
+else
+  fail "pending lessons cleaned" "$REMAINING files remaining"
+fi
+
+# Test 3.2: Archive file was created
+TODAY=$(date -u +%Y-%m-%d)
+ARCHIVE_FILE="$TEST_HOME/.code-sensei/lessons-archive/${TODAY}.jsonl"
+if [ -f "$ARCHIVE_FILE" ]; then
+  pass "archive file created at lessons-archive/${TODAY}.jsonl"
+else
+  fail "archive file created" "file not found: $ARCHIVE_FILE"
+fi
+
+# Test 3.3: Archive contains the lessons (each line is valid JSON)
+ARCHIVE_LINES=$(wc -l < "$ARCHIVE_FILE")
+VALID_JSON=0
+while IFS= read -r line; do
+  if echo "$line" | jq . > /dev/null 2>&1; then
+    VALID_JSON=$((VALID_JSON + 1))
+  fi
+done < "$ARCHIVE_FILE"
+if [ "$VALID_JSON" -eq "$ARCHIVE_LINES" ] && [ "$ARCHIVE_LINES" -ge 2 ]; then
+  pass "archive has $ARCHIVE_LINES valid JSON lines"
+else
+  fail "archive has valid JSON lines" "total=$ARCHIVE_LINES valid=$VALID_JSON"
+fi
+
+echo ""
+
+# ============================================================
+# SUMMARY
+# ============================================================
+TOTAL=$((PASS + FAIL))
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+if [ "$FAIL" -eq 0 ]; then
+  echo -e "${GREEN}All $TOTAL tests passed!${NC}"
+else
+  echo -e "${RED}$FAIL/$TOTAL tests failed${NC}"
+fi
+echo ""
+
+exit "$FAIL"