fix(ralph-loop): add session limit detection and auto-recovery

When claude -p hits the Pro subscription usage limit, the old loop had
no detection — it would find no <promise> signal, treat it as a normal
continuation, and immediately retry, burning all --max iterations.

New behaviour:
- check_output() returns status 4 when the log contains any usage/rate
  limit message (case-insensitive, multiple pattern variants)
- wait_for_session_reset() polls via a trivial probe call every
  SESSION_POLL_INTERVAL seconds (default: 600s / 10 min) until claude
  responds cleanly again
- When rate-limited, the same iteration is retried (i is not incremented)
  so no task is skipped or double-counted
- set -e is temporarily suspended around agent calls so a non-zero claude
  exit doesn't kill the bash process

Also updated the master template in docs/agent-harness/ralph-loop.sh.

Agent: human
Tests: N/A
Tests-Added: 0
TypeScript: N/A

ralph-loop.sh

@@ -7,7 +7,10 @@
 # - Agent reads the plan, picks ONE task, implements, tests, commits, exits
 # - Loop restarts until all tasks are done
 #
-# No context compaction. No stale reasoning. Just fresh starts.
+# Session limit handling:
+# - Detects Claude Pro usage limit messages in agent output
+# - Polls every SESSION_POLL_INTERVAL seconds until the session resets
+# - Resumes the same iteration automatically — no manual intervention needed
 #
 # Usage:
 #   ./ralph-loop.sh              # Build mode (default)
@@ -19,22 +22,6 @@
 #   ./ralph-loop.sh --agent gemini  # Use Gemini CLI
 #   ./ralph-loop.sh --agent custom  # Use custom agent (see below)
 #
-# Extensibility:
-# To add support for other AI coding agents (aider, cursor, windsurf, etc.):
-# 1. Add a new case in the run_agent() function's agent selection block
-# 2. Format the prompt appropriately for that agent's CLI interface
-# 3. Ensure the agent outputs to the logfile for promise detection
-#
-# Example for Aider:
-#   aider)
-#     aider --message "$prompt" --yes 2>&1 | tee "$logfile"
-#     ;;
-#
-# Example for custom script:
-#   custom)
-#     ./my-agent-wrapper.sh "$prompt" 2>&1 | tee "$logfile"
-#     ;;
-#
 set -euo pipefail
 
 MODE="${1:-build}"
@@ -45,6 +32,10 @@ SPEC_FILE="PROJECT-SPEC.md"
 AGENT_FILE="AGENT.md"
 LOG_DIR=".ralph-logs"
 
+# How often (in seconds) to probe whether the session has reset.
+# Default: 10 minutes. Adjust down if you want faster recovery.
+SESSION_POLL_INTERVAL="${SESSION_POLL_INTERVAL:-600}"
+
 # Parse arguments
 shift 2>/dev/null || true
 while [[ $# -gt 0 ]]; do
@@ -62,12 +53,14 @@ GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
 RED='\033[0;31m'
 BLUE='\033[0;34m'
+CYAN='\033[0;36m'
 NC='\033[0m'
 
 log()     { echo -e "${BLUE}[ralph]${NC} $1"; }
 success() { echo -e "${GREEN}[ralph]${NC} $1"; }
 warn()    { echo -e "${YELLOW}[ralph]${NC} $1"; }
 error()   { echo -e "${RED}[ralph]${NC} $1"; }
+info()    { echo -e "${CYAN}[ralph]${NC} $1"; }
 
 # Check prerequisites
 if [[ ! -f "$SPEC_FILE" ]]; then
@@ -93,8 +86,9 @@ run_agent() {
 
   log "Iteration $iteration ($mode mode) — starting fresh agent..."
 
-  # Agent selection block
+  # Disable pipefail around the agent call so a non-zero claude exit doesn't
-  # Extend this case statement to support additional agents
+  # kill the script. We inspect the log content instead.
+  set +e
   case "$AGENT" in
     claude)
       echo "$prompt" | claude -p --output-format text 2>&1 | tee "$logfile"
@@ -103,23 +97,12 @@ run_agent() {
       echo "$prompt" | codex 2>&1 | tee "$logfile"
       ;;
     aider)
-      # Aider: AI pair programming in your terminal
-      # https://aider.chat
       aider --message "$prompt" --yes 2>&1 | tee "$logfile"
       ;;
     gemini)
-      # Google Gemini CLI (if available)
-      # Adjust command based on actual Gemini CLI interface
       echo "$prompt" | gemini-cli 2>&1 | tee "$logfile"
       ;;
     custom)
-      # Custom agent integration
-      # Replace this with your own agent wrapper script
-      # The script should:
-      # 1. Accept prompt as first argument or via stdin
-      # 2. Perform the requested work (read files, write code, run tests, commit)
-      # 3. Output promise signals: <promise>PLANNED|DONE|STUCK|ERROR</promise>
-      # 4. Exit with appropriate code
       if [[ -x "./custom-agent.sh" ]]; then
         ./custom-agent.sh "$prompt" 2>&1 | tee "$logfile"
       else
@@ -130,29 +113,82 @@ run_agent() {
     *)
       error "Unknown agent: $AGENT"
       error "Supported agents: claude, codex, aider, gemini, custom"
-      error "To add support for other agents, edit the run_agent() function in this script"
       exit 1
       ;;
   esac
+  set -e
 
   return 0
 }
 
+# Probe whether claude is available by sending a trivial request.
+# Returns 0 if available, 1 if still rate-limited or erroring.
+probe_session() {
+  local probe_log="$LOG_DIR/probe.log"
+  set +e
+  echo "Reply with the single word OK and nothing else." \
+    | claude -p --output-format text > "$probe_log" 2>&1
+  local rc=$?
+  set -e
+
+  if [[ $rc -ne 0 ]]; then
+    return 1
+  fi
+  # Also check the output doesn't contain a limit message
+  if grep -qi 'usage limit\|rate limit\|limit reached\|exceeded.*limit' "$probe_log" 2>/dev/null; then
+    return 1
+  fi
+  return 0
+}
+
 check_output() {
   local logfile="$1"
 
+  # Session / usage limit — must check BEFORE generic promise checks
+  if grep -qi 'usage limit\|rate limit\|limit reached\|exceeded.*limit\|Claude AI usage' "$logfile" 2>/dev/null; then
+    return 4  # Rate limited
+  fi
+
   if grep -q '<promise>DONE</promise>' "$logfile" 2>/dev/null; then
     return 0  # Done
   elif grep -q '<promise>STUCK</promise>' "$logfile" 2>/dev/null; then
-    return 2  # Stuck
+    return 2  # Stuck — needs human intervention
   elif grep -q '<promise>ERROR</promise>' "$logfile" 2>/dev/null; then
-    return 3  # Error
+    return 3  # Unrecoverable error
   else
-    return 1  # Continue
+    return 1  # Normal iteration — continue
   fi
 }
 
-# Main loop
+wait_for_session_reset() {
+  local iteration=$1
+  warn "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+  warn "Session usage limit hit during iteration $iteration."
+  warn "Will probe every ${SESSION_POLL_INTERVAL}s until session resets."
+  warn "No manual action needed — loop will resume automatically."
+  warn "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+
+  local attempt=0
+  while true; do
+    ((attempt++))
+    local next_check
+    next_check=$(date -d "+${SESSION_POLL_INTERVAL} seconds" '+%H:%M:%S' 2>/dev/null \
+      || date -v "+${SESSION_POLL_INTERVAL}S" '+%H:%M:%S' 2>/dev/null \
+      || echo "soon")
+    info "Probe attempt $attempt — next check at $next_check..."
+    sleep "$SESSION_POLL_INTERVAL"
+
+    if probe_session; then
+      success "Session available! Resuming iteration $iteration..."
+      return 0
+    else
+      warn "Still rate-limited (attempt $attempt). Waiting another ${SESSION_POLL_INTERVAL}s..."
+    fi
+  done
+}
+
+# ─── Main ────────────────────────────────────────────────────────────────────
+
 if [[ "$MODE" == "plan" ]]; then
   log "Planning mode — creating implementation plan..."
   run_agent 0 plan
@@ -164,32 +200,41 @@ log "Starting Ralph Wiggum loop (max $MAX_ITERATIONS iterations)"
 log "Agent:               $AGENT"
 log "Spec:                $SPEC_FILE"
 log "Plan:                $PLAN_FILE"
+log "Poll interval:       ${SESSION_POLL_INTERVAL}s (session limit recovery)"
 echo ""
 
-for i in $(seq 1 "$MAX_ITERATIONS"); do
+i=1
+while [[ $i -le $MAX_ITERATIONS ]]; do
   run_agent "$i" build
   logfile="$LOG_DIR/iteration-${i}.log"
 
-  check_output "$logfile"
+  # Capture return value without triggering set -e
-  status=$?
+  check_output "$logfile" || status=$?
+  status=${status:-0}
 
   case $status in
     0)
-      success "🎉 ALL TASKS COMPLETE after $i iterations!"
+      success "ALL TASKS COMPLETE after $i iterations!"
       exit 0
       ;;
     2)
-      warn "Agent is stuck. Review $logfile and intervene."
+      warn "Agent is stuck on iteration $i. Review $logfile and intervene."
       exit 1
       ;;
     3)
-      error "Agent encountered an error. Review $logfile."
+      error "Agent encountered an error on iteration $i. Review $logfile."
       exit 1
       ;;
+    4)
+      # Rate limited — wait for reset, then retry the SAME iteration
+      wait_for_session_reset "$i"
+      # Do NOT increment i — retry the same task
+      ;;
     1)
       log "Iteration $i complete. Restarting with fresh context..."
       echo ""
       sleep 2
+      ((i++))
       ;;
   esac
 done