Initial commit

hooks/entrypoints/stop.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# stop.sh - Stop hook for threshold enforcement
+# Purpose: Check diff threshold when agent stops, block if exceeded
+
+# Source library functions
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../lib/git-state.sh"
+source "$SCRIPT_DIR/../lib/state-manager.sh"
+source "$SCRIPT_DIR/../lib/threshold-calculator.sh"
+
+# Read hook input from stdin
+input=$(cat)
+session_id=$(echo "$input" | jq -r '.session_id')
+stop_hook_active=$(echo "$input" | jq -r '.stop_hook_active // false')
+
+# Hook is already executed in project directory (cwd field in JSON)
+
+# If already blocked once, allow stop this time to prevent infinite loop
+if [[ "$stop_hook_active" == "true" ]]; then
+  exit 0
+fi
+
+# Load session state
+if ! session_state=$(read_session_state "$session_id" 2>/dev/null); then
+  # No baseline - allow stop (fail open)
+  exit 0
+fi
+
+# Exit early if bumper lanes already tripped - allow review collaboration
+stop_triggered=$(echo "$session_state" | jq -r '.stop_triggered // false')
+if [[ "$stop_triggered" == "true" ]]; then
+  # PreToolUse is actively blocking Write/Edit - no need to block stop
+  exit 0
+fi
+
+# Exit early if enforcement is paused - allow work to continue
+paused=$(echo "$session_state" | jq -r '.paused // false')
+if [[ "$paused" == "true" ]]; then
+  # Still need to track changes while paused
+  current_tree=$(capture_tree)
+  if [[ -n "$current_tree" ]]; then
+    previous_tree=$(echo "$session_state" | jq -r '.previous_tree // .baseline_tree')
+    accumulated_score=$(echo "$session_state" | jq -r '.accumulated_score // 0')
+    threshold_data=$(calculate_incremental_threshold "$previous_tree" "$current_tree" "$accumulated_score")
+    weighted_score=$(echo "$threshold_data" | jq -r '.accumulated_score')
+    update_incremental_state "$session_id" "$current_tree" "$weighted_score"
+  fi
+  exit 0
+fi
+
+baseline_tree=$(echo "$session_state" | jq -r '.baseline_tree')
+baseline_branch=$(echo "$session_state" | jq -r '.baseline_branch // ""')
+threshold_limit=$(echo "$session_state" | jq -r '.threshold_limit')
+previous_tree=$(echo "$session_state" | jq -r '.previous_tree // .baseline_tree')
+accumulated_score=$(echo "$session_state" | jq -r '.accumulated_score // 0')
+
+# Capture current working tree
+current_tree=$(capture_tree)
+if [[ -z "$current_tree" ]]; then
+  echo "ERROR: Failed to capture current tree" >&2
+  exit 0 # Fail open
+fi
+
+# Detect branch switch - auto-reset baseline to keep diffs meaningful
+current_branch=$(get_current_branch)
+
+if [[ -n "$baseline_branch" ]] && [[ -n "$current_branch" ]] && [[ "$baseline_branch" != "$current_branch" ]]; then
+  # Branch switched - reset baseline (score to 0, stop_triggered to false, update branch)
+  reset_baseline_stale "$session_id" "$current_tree" "$current_branch"
+
+  # Allow stop via JSON API (continue: true)
+  jq -n \
+    --arg baseline_branch "$baseline_branch" \
+    --arg current_branch "$current_branch" \
+    '{
+      continue: true,
+      systemMessage: "↪ Bumper lanes: Branch changed (\($baseline_branch) → \($current_branch)) — baseline auto-reset.",
+      suppressOutput: false
+    }'
+
+  # Exit after JSON response (avoid threshold check)
+  exit 0
+fi
+
+# Compute incremental threshold (previous → current + accumulated)
+threshold_data=$(calculate_incremental_threshold "$previous_tree" "$current_tree" "$accumulated_score")
+weighted_score=$(echo "$threshold_data" | jq -r '.accumulated_score')
+
+if [[ $weighted_score -le $threshold_limit ]]; then
+  # Under threshold - allow stop and update incremental state
+  update_incremental_state "$session_id" "$current_tree" "$weighted_score"
+  exit 0
+fi
+
+# Over threshold - set stop_triggered flag to activate PreToolUse blocking
+set_stop_triggered "$session_id" true
+# Also update incremental state
+update_incremental_state "$session_id" "$current_tree" "$weighted_score"
+
+# Format breakdown for user message
+# Note: threshold_data contains both weighted_score (delta) and accumulated_score (total)
+# For user display, we need to show the accumulated total, not just this turn's delta
+threshold_data_for_display=$(echo "$threshold_data" | jq '.weighted_score = .accumulated_score')
+breakdown=$(format_threshold_breakdown "$threshold_data_for_display" "$threshold_limit")
+
+# Build reason message
+reason="
+
+⚠️  Bumper lanes: Diff threshold exceeded
+
+$breakdown
+
+Ask the User: Would you like to conduct a structured, manual review?
+
+This workflow ensures incremental code review at predictable checkpoints.
+
+"
+
+threshold_pct=$(awk "BEGIN {printf \"%.0f\", ($weighted_score / $threshold_limit) * 100}")
+
+# Output block decision to STDOUT (JSON API pattern with exit code 0)
+jq -n \
+  --arg decision "block" \
+  --arg reason "$reason" \
+  --argjson continue true \
+  --arg systemMessage "/bumper-reset after code review." \
+  --argjson threshold_data "$threshold_data" \
+  --argjson threshold_limit "$threshold_limit" \
+  --argjson threshold_percentage "$threshold_pct" \
+  '{
+    continue: $continue,
+    systemMessage: $systemMessage,
+    suppressOutput: true,
+    decision: $decision,
+    reason: $reason,
+    threshold_data: ($threshold_data + {threshold_limit: $threshold_limit, threshold_percentage: $threshold_percentage})
+  }'
+
+exit 0