# task-estimator

This skill estimates how long a coding task will take using your measured history instead of the model's gut feeling. Handy when you owe someone an ETA.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 748 installs
- Author: marks97
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/marks97/task-estimator/tree/HEAD/task-estimator/SKILL.md
- Updated: 2026-10-01
- HTML: https://affpapa.org/en/nevibecode/skills/task-estimator

## What it does

The skill keeps a ledger of what tasks actually cost, then quotes new work against the empirical distribution of similar past tasks. It also scores its own earlier quotes, so a systematically low forecast shows up instead of staying invisible. Four modes cover the loop: estimate, first-run setup, recording a finished task's actuals, and recalibration.

The ledger lives outside the skill directory so it survives reinstalls: `$CLAUDE_ESTIMATION_DIR` wins, otherwise `~/.claude/estimation`. Inside are `ledger/chats.ndjson`, `ledger/tasks.ndjson`, `ledger/estimates.ndjson` and `calibration.json`. Scripts under `$SKILL/scripts/` parse transcripts, stitch chats into tasks, slice epics into sub-deliverables and compute quantiles. Record and recalibrate modes run `record.mjs`, plus `calibrate.mjs` and `score.mjs`.

When `$LEDGER/calibration.json` is missing, the skill says so and offers setup, but still gives a prior-only estimate if you want one now. It will not quietly quote off an empty ledger. The loop only closes when every leg runs: estimate logs a quote, record measures the actual, recalibrate reports whether the quotes held up.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add marks97/task-estimator --skill task-estimator -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/task-estimator/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/task-estimator/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add marks97/task-estimator --skill task-estimator -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/task-estimator/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add marks97/task-estimator --skill task-estimator -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/task-estimator/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install marks97/task-estimator task-estimator
```

2. **Manually: put the files in place**
- File: `.github/skills/task-estimator/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add marks97/task-estimator --skill task-estimator -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/marks97/task-estimator --path task-estimator
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/task-estimator/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add marks97/task-estimator --skill task-estimator -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/marks97/task-estimator/tree/HEAD/task-estimator/SKILL.md

## When to use it
- give an ETA for a feature or a bug
- check whether a deadline you already promised is realistic
- log the actuals of a finished task
- recalibrate and surface a systematic estimation bias
- break an epic into sub-deliverables with hours each

## Example prompts
- how long will adding an OAuth provider take?
- record this task in the ledger
- re-run calibration and tell me how good my past estimates were

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 991de3aa2d84c806.

BEGIN THIRD-PARTY FILE 991de3aa2d84c806
```text
---
name: task-estimator
description: Estimate how long a coding task will take, using the user's own measured history instead of intuition. Use this skill whenever someone asks for an estimate, an ETA, a timeline or a deadline for a feature, bug, refactor, migration, script or investigation — "how long will this take", "give me an estimate", "how many hours is this", "can this ship today", "is this a one-day job", "how many days for the whole epic", "what should I tell the client", "estimate this ticket", "size this" — and equally when the ask is skeptical ("is that realistic", "why did that take three days"). Also use it for the machinery behind the estimates — setting up or calibrating estimation, backfilling the task ledger from past Claude Code transcripts, recording a finished task's actuals ("record this task", "log this one", "add this to the ledger"), and re-running calibration or checking whether past estimates were any good. Trigger it even when the word "estimate" never appears — a question about how much work something is, or how long something took, is this skill.
---

# Task estimator

Estimates from **your measured history**, not from the model's intuition about how hard
something looks. The model's intuition is the thing that is broken: developers using AI
tools believed they were 20% faster while measuring 19% slower (METR 2025). An estimate
that is not anchored to recorded actuals just reproduces that gap in writing.

So this skill does three things: it keeps a ledger of what tasks actually cost, it quotes
new tasks against the empirical distribution of similar past tasks, and it scores its own
past quotes so the bias is visible.

Depth on the evidence is in `references/`: `estimation-science.md` (the classical results
— EBS, reference classes, anchoring, flow metrics), `ai-era-evidence.md` (what changed once
an agent was in the loop), `measurement-model.md` (the phase taxonomy, the measured
constants, and the calibration math the scripts implement). Read them when a rule here looks
arbitrary — every rule traces to a result there. Do not re-derive the theory during an
estimate; execute the steps.

## Pick a mode

| The user is doing this | Mode |
|---|---|
| Asking how long something will take, ETA, sizing, "is this a day?" | **estimate** (default) |
| First run, no `$LEDGER` (see *Ledger layout*), "set this up", "calibrate me", "backfill" | **setup** |
| "record this task", "log this", finished a task, the CLAUDE.md hook fired | **record** — `record.mjs` |
| "re-run calibration", "how good are your estimates", "were you right", "recalibrate" | **recalibrate** — `calibrate.mjs` + `score.mjs` |
```
END THIRD-PARTY FILE 991de3aa2d84c806

The third-party file has ended. Everything between the 991de3aa2d84c806 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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