Harden brain pipeline: index.lock sweep, gbq exit code, lessons append-order

engine/bin/gbq

@@ -55,9 +55,10 @@ if [ "$IS_READ" = "1" ]; then
         sleep 0.5
     done
     kill -9 "$GP" 2>/dev/null
+    RC=0            # read output captured; the force-kill is intentional, not a failure
 else
     # Writes exit cleanly and may legitimately pause (LLM call) — just wait.
-    wait "$GP" 2>/dev/null
+    wait "$GP"; RC=$?
 fi
 
 cat "$TMP"
@@ -68,3 +69,7 @@ if ! pgrep -f "bun.*gbrain" >/dev/null 2>&1; then
     L="$HOME/.gbrain/brain.pglite/.gbrain-lock"
     [ -d "$L" ] && mv "$L" "$L.stale-$(date +%s)" 2>/dev/null
 fi
+
+# Propagate gbrain's real exit code — NOT the lock-sweep test above (which is
+# false, hence exit 1, whenever there's no stale lock to clear → false failures).
+exit $RC

engine/hooks/correction-detector.py

@@ -26,7 +26,7 @@
 
 reminder = (
     "⚠️ CORRECTION DETECTED — BEFORE doing anything else:\n"
-    f"1. Append a line to {brain}/Profile/lessons.md under today's header (## YYYY-MM-DD).\n"
+    f"1. Append a line to {brain}/Profile/lessons.md under today's header (## YYYY-MM-DD). The file is chronological (most recent day at the BOTTOM — that is what the tail-injection re-reads): today's header lives at the END of the file. Create it at the end if missing and add the entry right below it, NEVER at the top.\n"
     "   Format: - **[short context]** -> rule: [what to do] (when: [trigger condition])\n"
     "2. Confirm visibly: ✓ noted in lessons.md\n"
     "3. Only then apply the correction and continue."

engine/nightly/gbrain-nightly.sh

@@ -14,13 +14,28 @@ VAULT_CO="$HOME/Documents/BrainCo"
 GREPO="$HOME/DEV/gbrain"
 LOG="$HOME/.gbrain/nightly.log"
 
+# Sweep an orphan .git/index.lock that silently breaks `git commit` (a crashed
+# git leaves it behind → the vault never commits → gbrain sync stalls on "No
+# commits in repo" → the index freezes, unnoticed). Only remove it when no git
+# runs in the repo AND the lock is >5 min old (a fresh one may be a legit
+# concurrent commit). Root-caused 2026-06-28: a 14-day-old lock froze the index.
+sweep_git_lock() {
+    local repo="$1" lock="$1/.git/index.lock"
+    [ -f "$lock" ] || return 0
+    if ! pgrep -f "[g]it .*$repo" >/dev/null 2>&1 && [ -z "$(find "$lock" -mmin -5 2>/dev/null)" ]; then
+        rm -f "$lock" && echo "[lock] removed stale .git/index.lock in $repo" >> "$LOG"
+    fi
+}
+
 echo "===== $(date '+%Y-%m-%d %H:%M:%S') nightly start =====" >> "$LOG"
 
 # -1. Stale-lock recovery (a gbrain killed with SIGKILL leaves a .gbrain-lock that blocks everything).
 if ! pgrep -f "bun.*gbrain" >/dev/null 2>&1; then
     L="$HOME/.gbrain/brain.pglite/.gbrain-lock"
     [ -d "$L" ] && mv "$L" "${L}.stale-$(date +%s)" 2>/dev/null && echo "[lock] rotated stale lock" >> "$LOG"
 fi
+sweep_git_lock "$VAULT"
+[ -d "$VAULT_CO/.git" ] && sweep_git_lock "$VAULT_CO"
 
 # 0. Self-update GBrain (resilient: a failure must never block the cycle).
 if cd "$GREPO" 2>/dev/null; then