plan-tools/lib/frontmatter.sh

#!/usr/bin/env bash
# frontmatter.sh — Read/write YAML frontmatter in plan files

# Read a value from YAML frontmatter
# Usage: get_frontmatter <file> <key> [default]
get_frontmatter() {
    local file="$1"
    local key="$2"
    local default="${3:-}"

    if ! head -1 "$file" | grep -q '^---$'; then
        echo "$default"
        return
    fi

    local value
    value=$(awk '/^---$/{n++; next} n==1{print}' "$file" \
        | grep "^${key}:" \
        | head -1 \
        | sed "s/^${key}: *//; s/^ *//; s/ *$//; s/^[\"']//; s/[\"']$//")
    echo "${value:-$default}"
}

# Set a value in YAML frontmatter (adds frontmatter if missing)
# Usage: set_frontmatter <file> <key> <value>
set_frontmatter() {
    local file="$1"
    local key="$2"
    local value="$3"

    # If file has no frontmatter, add it
    if ! head -1 "$file" | grep -q '^---$'; then
        local tmp
        tmp=$(mktemp)
        {
            echo "---"
            echo "${key}: ${value}"
            echo "---"
            cat "$file"
        } > "$tmp"
        mv "$tmp" "$file"
        return
    fi

    if grep -q "^${key}:" "$file"; then
        # Replace existing key (using | as delimiter to avoid path issues)
        sed -i '' "s|^${key}:.*|${key}: ${value}|" "$file"
    else
        # Insert before closing --- (second occurrence)
        awk -v key="$key" -v val="$value" '
            BEGIN { count=0; inserted=0 }
            /^---$/ { count++ }
            count == 2 && !inserted { print key ": " val; inserted=1 }
            { print }
        ' "$file" > "${file}.tmp" && mv "${file}.tmp" "$file"
    fi
}

# Check if a file has plan frontmatter
# Usage: is_plan_file <file>
is_plan_file() {
    local file="$1"
    [[ -f "$file" ]] && head -20 "$file" | grep -q "^plan: true"
}

# Initialize frontmatter on a plan file that doesn't have it
# Usage: init_frontmatter <file> [title]
init_frontmatter() {
    local file="$1"
    local title="${2:-$(basename "$file" .md)}"
    local today
    today=$(date +%Y-%m-%d)

    if head -1 "$file" | grep -q '^---$'; then
        # Has frontmatter, just ensure plan fields exist
        set_frontmatter "$file" "plan" "true"
        [[ -z "$(get_frontmatter "$file" "status")" ]] && set_frontmatter "$file" "status" "drafting"
        [[ -z "$(get_frontmatter "$file" "iteration")" ]] && set_frontmatter "$file" "iteration" "0"
        [[ -z "$(get_frontmatter "$file" "target_iterations")" ]] && set_frontmatter "$file" "target_iterations" "8"
        [[ -z "$(get_frontmatter "$file" "created")" ]] && set_frontmatter "$file" "created" "$today"
        set_frontmatter "$file" "updated" "$today"
    else
        # No frontmatter, add full block
        local tmp
        tmp=$(mktemp)
        {
            echo "---"
            echo "plan: true"
            echo "title: \"${title}\""
            echo "status: drafting"
            echo "iteration: 0"
            echo "target_iterations: 8"
            echo "beads_revision: 0"
            echo "related_plans: []"
            echo "created: ${today}"
            echo "updated: ${today}"
            echo "---"
            echo ""
            cat "$file"
        } > "$tmp"
        mv "$tmp" "$file"
    fi
}