cost-gap SKILL.md skillA
cost-gap from martianmobile/backtest2live is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add martianmobile/backtest2live/cost-gap@git:20261025.6934205Pins git:20261025.6934205 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- martianmobile/backtest2live
- Path
plugins/backtest2live/skills/cost-gap/SKILL.md- Versions recorded
- 3
- Latest version
- git:20261025.6934205, committed Oct 25, 2026
- First version recorded
- Oct 14, 2026
- Size
- 3,749 bytes
- Repository stars
- 3
- License
- MIT
Check what a backtest's taker orders (market orders, or limits that cross the spread) would really have paid on the order book, with latency — the execution-cost check for bar-based backtests that fill at a bar price. Trigger with "check my slippage", "is my market-order backtest realistic?", "cost gap", "execution cost check", "my backtest fills at close", "what would my market orders have cost?".
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Cost gap — what your backtest's taker orders would have paid Runs `bt2live cost-gap` from the `backtest2live` package and interprets the result. The pricing is deterministic and lives in the CLI; your job is to get the inputs right and explain what the numbers mean for the user's strategy. ## Step 1 — Get the order log into shape One CSV row per order. Required: time (`ts`, epoch or ISO, UTC), `side` (buy/sell), `size` (base units). Recommended: `fill_price` (what the backtest booked; without it the mid at arrival is the baseline), `type` (market/limit) with `price` for limits, and per-order `pnl` (needed for a verdict). A `price` column with no `type` and no `fill_price` is read as the booked fill, with every order as a market order (a bar backtest's export); a column named `limit_price` or `limit` always means a limit. A log with no `price` column is treated as all market orders, which is what a bar-based backtest produces. If the user's engine exports a different shape, write a short conversion script and show it to them. ## Step 2 — Pick the market data …
Read the whole file at its exact version.
How to install
mdr add martianmobile/backtest2live/cost-gap@sha256:636bcc32763e024aThe line at the top of this page pins the label git:20261025.6934205, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_q4sjoy2mjxbwnvev)
1 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Oct 14, 2026 and Oct 25, 2026, about one every 5 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261025.6934205 latest | 2026-10-25 | 6934205 | 3,749 B | A | view · diff |
| git:20261015.7fe3b8d | 2026-10-15 | 7fe3b8d | 3,615 B | A | view · diff |
| git:20261014.e5f9fb0 | 2026-10-14 | e5f9fb0 | 3,346 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (3749 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
martianmobile/backtest2live · 3 stars · license MIT · pushed 2026-10-25 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_q4sjoy2mjxbwnvev GET https://markdownregistry.com/api/v1/resolve?ref=martianmobile/backtest2live/cost-gap GET https://markdownregistry.com/api/v1/blob/636bcc32763e024a208ed06d52982e47eb01d6160c670cceb70b301343f5fc95
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.