/skill-cost-projections

name: skill-cost-projections
description: "Project remaining workflow cost from per-phase averages — warns on budget ceiling overruns"
disable-model-invocation: true

> **Host: Codex CLI** — This skill was designed for Claude Code and adapted for Codex. > Cross-reference commands use installed skill names in Codex rather than `/octo:*` slash commands. > Use the active Codex shell and subagent tools. Do not claim a provider, model, or host subagent is available until the current session exposes it. > For host tool equivalents, see `skills/blocks/codex-host-adapter.md`.

Cost Projections Skill

Overview

Projects remaining workflow cost based on per-phase averages from completed work. Displays cost data in the HUD/statusline and warns when projected totals exceed a configured budget ceiling.

**Minimum data requirement:** Needs **2+ completed steps** before projecting. With fewer than 2 data points, the average is unreliable — display actual spend only and skip projection.

Step 1: Collect Completed Phase Costs

Read cost data from `~/.claude-octopus/metrics/` or from metrics-tracker.sh output. Each completed phase/step should have an associated cost entry.

# Read metrics from the session metrics directory
METRICS_DIR="$HOME/.claude-octopus/metrics"
SESSION_METRICS="$METRICS_DIR/session-$(date +%Y%m%d).jsonl"

# Each line contains: {"phase": "discover", "cost": 0.42, "tokens_in": 12000, "tokens_out": 3400, "timestamp": "..."}
# Sum costs from completed steps
completed_costs=$(jq -s '[.[].cost]' "$SESSION_METRICS")
completed_count=$(jq -s 'length' "$SESSION_METRICS")
total_spent=$(jq -s '[.[].cost] | add' "$SESSION_METRICS")

**Data sources (in priority order):** 1. `~/.claude-octopus/metrics/session-*.jsonl` — structured per-phase cost entries 2. `metrics-tracker.sh` output — fallback for legacy sessions 3. HUD accumulated cost counters — last resort

If fewer than 2 completed steps are available, display only actual spend:

💰 Spent: $0.42 (1 step complete — need 2+ for projection)

Step 2: Compute Average Cost Per Step

Calculate the mean cost across all completed steps.

avg_cost=$(echo "$total_spent / $completed_count" | bc -l)

**Formula:**

avg_cost = total_cost / completed_steps

**Example:** If 3 steps cost $0.30, $0.50, $0.40 → avg = $1.20 / 3 = $0.40/step

Step 3: Project Remaining Cost

Multiply the average cost per step by the number of remaining steps.

remaining_steps=$((total_steps - completed_count))
projected_remaining=$(echo "$avg_cost * $remaining_steps" | bc -l)
projected_total=$(echo "$total_spent + $projected_remaining" | bc -l)

**Formula:**

projected_remaining = avg_cost × remaining_steps
projected_total     = total_spent + projected_remaining

**Step counts by workflow type:** | Workflow | Total Steps | Example Phases | |----------|-------------|----------------| | embrace | 4 | Discover, Define, Develop, Deliver | | research | 3-7 | Per-agent probe count | | review | 3 | Fleet, Verifier, Synthesis | | debate | 3 | Opening, Rebuttal, Synthesis |

Step 4: Display in HUD

Format the cost projection for the HUD/statusline display.

**Standard display:**

💰 Spent: $2.40 | Est. remaining: $3.60 | Total: ~$6.00

**Format rules:**

• All dollar amounts to 2 decimal places
• Projected total prefixed with `~` to indicate estimate
• Use `💰` prefix for the cost line
• Show in a single compact line for statusline integration

**When insufficient data (< 2 steps):**

💰 Spent: $0.42 (need 2+ steps for projection)

**Integration:** This display line is emitted by the octopus-hud hook and rendered in the statusline alongside phase progress and provider status.

Step 5: Budget Ceiling Warning

If the `OCTO_BUDGET_CEILING` environment variable is set, compare the projected total against it and warn on overrun.

if [[ -n "${OCTO_BUDGET_CEILING:-}" ]]; then
  ceiling="$OCTO_BUDGET_CEILING"
  if (( $(echo "$projected_total > $ceiling" | bc -l) )); then
    overage=$(echo "$projected_total - $ceiling" | bc -l)
    echo "⚠️ Budget ceiling: \$$ceiling — projected to exceed by \$$overage"
  fi
fi

**Display when over budget:**

💰 Spent: $2.40 | Est. remaining: $3.60 | Total: ~$6.00
⚠️ Budget ceiling: $5.00 — projected to exceed by $1.00

**Display when within budget:**

💰 Spent: $2.40 | Est. remaining: $3.60 | Total: ~$6.00
✅ Within budget ceiling: $10.00

**Note:** `OCTO_BUDGET_CEILING` is optional. When unset, no ceiling check is performed.

Step 6: Profile Suggestion

If the projected total is high relative to the task, suggest switching to the budget profile to reduce costs.

# Suggest budget profile when projected total exceeds $5.00 (configurable)
COST_THRESHOLD="${OCTO_COST_THRESHOLD:-5.00}"
if (( $(echo "$projected_total > $COST_THRESHOLD" | bc -l) )); then
  echo "💡 Tip: Switch to OCTO_PROFILE=budget to reduce costs"
fi

**Display:**

💰 Spent: $2.40 | Est. remaining: $3.60 | Total: ~$6.00
💡 Tip: Switch to OCTO_PROFILE=budget to reduce costs

The budget profile (`OCTO_PROFILE=budget`) routes to cheaper models and reduces agent count to minimize spend.

Complete Display Examples

**Normal — within budget, moderate cost:**

💰 Spent: $2.40 | Est. remaining: $3.60 | Total: ~$6.00

**Over budget ceiling:**

💰 Spent: $2.40 | Est. remaining: $3.60 | Total: ~$6.00
⚠️ Budget ceiling: $5.00 — projected to exceed by $1.00
💡 Tip: Switch to OCTO_PROFILE=budget to reduce costs

**Early in workflow (insufficient data):**

💰 Spent: $0.42 (need 2+ steps for projection)

**Low cost — no warnings:**

💰 Spent: $0.80 | Est. remaining: $0.80 | Total: ~$1.60

Integration

With octopus-hud hook

The cost projection line is rendered as part of the HUD statusline output, updated after each phase completes.

With metrics-tracker.sh

Reads per-phase cost data w