mate-openspec-backfill

mate-openspec-backfill is a skill for Claude Code, Codex from uniqbit-ag/mate-cli. It costs 52 tokens per session (1,031 once invoked), scanned A, original, MIT.

A workflow that documents one existing feature in an OpenSpec specification. OpenSpec is a way to describe a software feature’s expected behavior in a standard format.

In plain words
What is it for?
Use it to trace one feature through its code and tests, check for an existing matching specification, and prepare a change containing tested, observed, and uncertain behaviors.
Why use it?
It helps bring legacy behavior under documented requirements without changing the main specifications or pretending uncertain behavior is confirmed.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/uniqbit-ag/mate-cli/mate-openspec-backfill
Any agent
npx skills add uniqbit-ag/mate-cli --skill mate-openspec-backfill
Clone the repo
git clone --depth 1 https://github.com/uniqbit-ag/mate-cli

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for mate-openspec-backfill

README.md
[![agentmods](https://agentmods.dev/badge/skills/uniqbit-ag/mate-cli/mate-openspec-backfill.svg)](https://agentmods.dev/skills/uniqbit-ag/mate-cli/mate-openspec-backfill)
Your own site
<a href="https://agentmods.dev/skills/uniqbit-ag/mate-cli/mate-openspec-backfill"><img src="https://agentmods.dev/badge/skills/uniqbit-ag/mate-cli/mate-openspec-backfill.svg" alt="Measured on agentmods" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,031 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00052 $0.01031
Opus 5 $0.00026 $0.00515
Sonnet 5 $0.00010 $0.00206
Haiku 4.5 $0.00005 $0.00103

Measured 5d ago against content hash 8baa99df7d36, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mate-openspec-backfill scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

Requirements state observable contracts, never implementation detail ("propagates the child exit code", not "uses spawnSync").
packages/mate-core/src/templates/capabilities/openspec-cap/mate-skills/agents/mate-openspec-backfill/SKILL.md · 66 lines

How it starts

The opening of the file, as written. The whole thing — 66 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Create a spec for one feature that already exists in the working repository. The run ends with a standard ready-to-finish change — it never edits main specs and never finishes.

Scope rules

  • One named feature per run. Refuse Area-wide or repository-wide sweeps; ask the user to name a single feature and run the skill once per feature.
  • Interactive by design. Every ambiguity and every suspected bug becomes a user question. Do not run this skill unattended.

Steps

  1. Scope. Map the named feature to code: entry points, callees, tests. Use whatever exploration tooling this project has enabled (code-graph or index tools when present, otherwise search and targeted reading) — assume no specific capability is installed. Then check openspec/specs/ for an existing capability covering this domain — prefer extending it (MODIFIED/ADDED deltas) over minting a new capability id.

  2. Sweep. Extract candidate behaviors and tag each finding:

    • [test-backed] — an existing test verifies it (strongest; scenarios translate almost directly from tests)
    • [code-only] — observable in code but untested
    • [inferred] — assumed intent without direct evidence

    Every candidate requirement needs at least one citation: a test name or file:line. Docs and comments corroborate but never stand alone. [inferred] findings are not requirements — they become questions for step 3.

  3. Ask. Batch the open questions to the user:

    • Behavior that looks unintended → the user rules spec the actual behavior or spec the intent (with a follow-up fix change). Suspected bugs never silently become requirements.
    • [inferred] findings → confirm, demote to out-of-scope, or convert to a question the emitted proposal records as open.
  4. Emit. Create the change and build its artifacts in dependency order:

    openspec new change "backfill-spec-<capability>"
    openspec status --change "backfill-spec-<capability>" --json
    openspec instructions <artifact-id> --change "backfill-spec-<capability>" --json
    

Read the full file on GitHub · 66 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 66 lines · 52 tokens per session scan A 8baa99df7d36

Subscribe to this mod's changes

mate-openspec-backfill is a skill published in the GitHub repository uniqbit-ag/mate-cli (11 stars, last pushed 2d ago), licensed MIT. It adds 52 tokens to every session and 1,031 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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