/cost

description: "Cost & capacity health — LLM router savings, run-rate, cost-per-deploy, ROI per shipped feature, WoW/MoM delta. Pairs with /digest (delivery+DORA) and /burn (reliability)."
argument-hint: "[period_days] | feature <slug> | agent <name> — default: /cost 30. Examples: /cost 7 | /cost feature stripe-subscriptions | /cost agent architect"
user-invocable: true
allowed-tools: Read, Bash, Glob, Grep
model: haiku

You are the Cost & Capacity aggregator. Multiple modes:

1. **`/cost [days]` — Aggregate health** (default mode)

• LLM router savings — measured Kimi-vs-Sonnet differential from `.great_cto/llm-router-usage.log`
• Infra cost — monthly run-rate, cost-per-deploy, WoW/MoM drift, headroom vs budget, top movers

2. **`/cost feature <slug>`** — ROI per shipped feature (NEW in v2.3.0)

• Total LLM cost broken down by agent
• Comparison to human-equivalent at $150/hr
• ROI multiplier
• Cross-reference to similar past features in same archetype

3. **`/cost agent <name>`** — Per-agent cost (NEW in v2.3.0)

• Same as `/agent-review <name>` but cost-focused

Mode dispatch

source .great_cto/env.sh 2>/dev/null || export PATH="/opt/homebrew/bin:$HOME/.local/bin:/usr/local/bin:$PATH"

# Detect mode from first arg
case "${1:-}" in
  feature)
    SLUG="${2:-}"
    [ -z "$SLUG" ] && { echo "Usage: /cost feature <slug>"; exit 2; }
    # → jump to "Feature mode" section below
    MODE=feature
    ;;
  agent)
    AGENT="${2:-}"
    [ -z "$AGENT" ] && { echo "Usage: /cost agent <name>"; exit 2; }
    # → jump to "Agent mode" section below
    MODE=agent
    ;;
  *)
    MODE=aggregate
    PERIOD=${1:-30}
    case "$PERIOD" in ''|*[!0-9]*) echo "Usage: /cost [period_days] | feature <slug> | agent <name>"; exit 2 ;; esac
    ;;
esac

COST_LOG=.great_cto/cost-history.log
DEPLOYS_LOG=.great_cto/deploys.log

Feature mode — `/cost feature <slug>`

Compute total cost of shipping a feature, broken down by agent + ROI vs human equivalent.

if [ "$MODE" = "feature" ]; then
  echo "## Cost: $SLUG"
  echo ""

  if [ ! -f "$COST_LOG" ]; then
    echo "_No cost history yet — feature ROI requires at least one shipped feature._"
    exit 0
  fi

  # Filter cost-history.log entries tagged with this feature slug
  # Format: <timestamp> agent=<name> feature=<slug> cost_usd=<n> [other tags]
  ENTRIES=$(grep -E "feature=$SLUG\b" "$COST_LOG" 2>/dev/null)

  if [ -z "$ENTRIES" ]; then
    echo "_No cost entries tagged with feature=$SLUG. Either:_"
    echo "1. Feature not yet implemented (run \`/start \"feature description\"\`)"
    echo "2. Feature uses different slug — check \`docs/architecture/ARCH-*.md\` filenames"
    echo ""
    echo "Available features in cost log:"
    grep -oE "feature=[^ ]+" "$COST_LOG" | sort -u | head -10
    exit 0
  fi

  # Aggregate by agent
  echo "### Per-agent breakdown"
  echo ""
  echo "| Agent | Invocations | Cost | Avg/inv |"
  echo "|-------|------------:|-----:|--------:|"
  echo "$ENTRIES" | awk '
    {
      for (i=1;i<=NF;i++) {
        if ($i ~ /^agent=/) { gsub(/agent=/, "", $i); agent = $i }
        if ($i ~ /^cost[-_]?usd[=:]/) { gsub(/cost[-_]?usd[=:]/, "", $i); cost = $i+0 }
      }
      sum[agent] += cost
      count[agent]++
    }
    END {
      for (a in sum) printf "| %s | %d | $%.2f | $%.2f |\n", a, count[a], sum[a], sum[a]/count[a]
    }
  ' | sort

  TOTAL=$(echo "$ENTRIES" | awk '
    { for (i=1;i<=NF;i++) if ($i ~ /^cost[-_]?usd[=:]/) { gsub(/cost[-_]?usd[=:]/, "", $i); sum += $i+0 } }
    END { printf "%.2f", sum }
  ')

  echo "| **Total** | | **\$$TOTAL** | |"
  echo ""

  # Human-equivalent comparison
  ARCHETYPE=$(grep -E "^archetype:|^primary:" .great_cto/PROJECT.md 2>/dev/null | head -1 | awk '{print $2}')
  # Default: assume 12 hours human equivalent for standard feature
  HUMAN_HOURS=${HUMAN_HOURS:-12}
  HUMAN_RATE=${HUMAN_RATE:-150}
  HUMAN_COST=$(echo "scale=0; $HUMAN_HOURS * $HUMAN_RATE" | bc)
  ROI=$(echo "scale=1; $HUMAN_COST / $TOTAL" | bc)

  echo "### vs Human equivalent"
  echo ""
  echo "- Estimated effort: ${HUMAN_HOURS}h × \$${HUMAN_RATE}/hr = **\$${HUMAN_COST}**"
  echo "- AI cost: **\$${TOTAL}**"
  echo "- **ROI: ${ROI}x**"
  echo ""
  echo "_Override estimates: \`HUMAN_HOURS=20 HUMAN_RATE=200 /cost feature $SLUG\`_"

  # Comparison to mean for archetype
  if [ -n "$ARCHETYPE" ]; then
    echo ""
    echo "### Compared to other features in archetype=$ARCHETYPE"
    grep "feature=" "$COST_LOG" | grep -v "feature=$SLUG" | awk '
      {
        for (i=1;i<=NF;i++) {
          if ($i ~ /^feature=/) { gsub(/feature=/, "", $i); feat = $i }
          if ($i ~ /^cost[-_]?usd[=:]/) { gsub(/cost[-_]?usd[=:]/, "", $i); cost = $i+0 }
        }
        sum[feat] += cost
      }
      END {
        for (f in sum) printf "- %s: $%.2f\n", f, sum[f]
      }
    ' | sort -t '$' -k2 -n | head -5
  fi
  exit 0
fi

Agent mode — `/cost agent <name>`

Quick per-agent cost summary (lighter than /agent-review):

if [ "$MODE" = "agent" ]; then
  echo "## Cost: $AGENT"
  echo ""

  if [ ! -f "$COST_LOG" ]; then
    echo "_No cost history yet._"
    exit 0
  fi

  ENTRIES=$(grep -E "agent=$AGENT\b" "$COST_LOG" 2>/dev/null)
  COUNT=$(echo "$ENTRIES" | grep -c .)

  if [ "$COUNT" = "0" ]; then
    echo "_No cost entries for agent=$AGENT._"
    exit 0
  fi

  TOTAL=$(echo "$ENTRIES" | awk '{ for (i=1;i<=NF;i++) if ($i ~ /^cost[-_]?usd[=:]/) { gsub(/cost[-_]?usd[=:]/, "", $i); sum += $i+0 } } END { printf "%.2f", sum }')
  AVG=$(echo "scale=2; $TOTAL / $COUNT" | bc)

  echo "- Total invocations: $COUNT"
  echo "- Total cost: \$$TOTAL"
  echo "- Avg cost/invocation: \$$AVG"
  echo ""
  echo "_For full performance review: \`/agent-review $AGENT\`_"
  exit 0
fi

Aggregate mode (default — original behaviour)

You are the Cost & Capacity aggregator. Two parts:

1. **LLM router savings** — measured Kimi-vs-Sonnet differential from `.great_cto/llm-router-usage.log`. This is the data behind the README