#!/usr/bin/env bash
# PreCompact hook: export critical session state before context summarization.
# Saves investigation progress so findings survive context window compression.
set -euo pipefail

REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || echo ".")"
SESSION_DIR="$REPO_ROOT/.session"
COMPACT_LOG="$SESSION_DIR/pre-compact-state.md"

mkdir -p "$SESSION_DIR"

TIMESTAMP=$(date -u +"%Y-%m-%dT%H:%M:%SZ")

# Read the dead-ends file if it exists
dead_ends_summary=""
DEAD_ENDS_FILE="$SESSION_DIR/dead-ends.md"
if [[ -f "$DEAD_ENDS_FILE" ]]; then
  dead_ends_summary=$(tail -30 "$DEAD_ENDS_FILE" 2>/dev/null || true)
fi

# Check for active investigation files (exclude those already marked complete)
investigation_summary=""
EXPLORATIONS_DIR="$REPO_ROOT/docs/explorations"
if [[ -d "$EXPLORATIONS_DIR" ]]; then
  inv_files=$(find "$EXPLORATIONS_DIR" -name "*.md" -not -empty 2>/dev/null || true)
  if [[ -n "$inv_files" ]]; then
    active_files=$(echo "$inv_files" | while read -r f; do
      if ! grep -qi '^\*\*Status\*\*.*complete\|^Status:.*complete' "$f" 2>/dev/null; then
        echo "$f"
      fi
    done || true)
    if [[ -n "$active_files" ]]; then
      investigation_summary=$(echo "$active_files" | xargs -I{} basename {} .md | sed 's/^/- /' || true)
    fi
  fi
fi

# Write the pre-compact state file
cat > "$COMPACT_LOG" << STATEEOF
# Pre-Compact State Export
Exported at: $TIMESTAMP
Trigger: context summarization

## Active Investigations
$investigation_summary

## Recent Dead Ends (do NOT re-test these)
$dead_ends_summary

## Reminders
- Hypothesis + falsification criterion BEFORE any diagnostic test
- Record WHY failures failed, not just WHAT was tried
- Check AGENTS.md and package-level AGENTS.md for implementation guidance
STATEEOF

# Inject context for the summarized conversation
context="[HOOK INJECTION: pre-compact] System reminder — injected before context compaction, not part of any user message or tool output:\n\n"
context="${context}CONTEXT PRESERVATION (pre-compact): Critical state exported to .session/pre-compact-state.md."
context="${context} After summarization, re-read this file to restore investigation context."
context="${context} Key: do NOT re-test eliminated hypotheses from the dead-ends file."
context="${context} TODO LIST SYNC: After resuming, update the chat todo list to reflect actual progress."

cat <<EOF
{
  "hookSpecificOutput": {
    "hookEventName": "PreCompact",
    "additionalContext": "$(echo "$context" | sed 's/"/\\"/g')"
  }
}
EOF