port-github-app-to-origin

Imported from cursor/plugins (origin-apps/skills/port-github-app-to-origin/SKILL.md). Install upstream with npx skills add cursor/plugins --skill port-github-app-to-origin. Copyright stays with the author (MIT).

Port a GitHub App to an Origin App

Run this inside the app's codebase. The output is a porting brief for the team plus a Feedback for Cursor section they can send as is (references/brief.md). This skill plans. It does not write or change code unless the user asks for that after reading the brief. Follow the origin-api skill for the docs and the rules to check first. Two more rules:

1. Find it in the code, do not ask. Read what the app uses out of its source. Anything you cannot find becomes a question for the team.
2. Feedback describes use cases, not the team's code. The team's parts of the brief may cite file:line. Feedback for Cursor says only what the app needs to do and what Origin lacks for it, in Origin terms, with no file paths, module names, framework details, or repository names.

What to find

Record file:line for each item, and note what you looked for but did not find.

• Declared permissions and events, from a manifest or infrastructure code if one is checked in. Otherwise derive them from the calls.
• Every webhook event the app handles, and every payload field each handler reads, including fields it only logs.
• Every REST and GraphQL call, with the parameters and filters the code passes, the response fields it reads, whether it runs on every webhook or in a loop, and how it paginates.
• Authentication: the JWT algorithm, how the app learns the installation ID after install, how it handles token expiry, any user sign-in and what it is for, and whether the app clones or pushes git.
• The webhook receiver: how it verifies signatures, whether it has the raw body when it verifies, and how it deduplicates deliveries.
• Calls a framework or library makes for the app. Probot's receiver, token cache, and config loader; Octokit App's installation and repository listing; app-auth libraries. Read the dependency's docs and list these calls marked "from <dependency>".

How to map

A brief needs the whole spec, but openapi.yaml and llms-full.txt are each several hundred kilobytes, too large to read into context whole. Save them locally if you can, in a temporary location outside the app's repository so nothing in the working tree is overwritten or left behind, then search them and read only the matching part:

• x-origin-scopes: in openapi.yaml marks every operation with its scopes; the operationId sits a line above.
• x-origin-webhook-events: in openapi.yaml marks every webhook payload schema with the event slugs that deliver it.
• ### <Endpoint name> and ### <Payload type> headings in llms-full.txt start the section that spells out that endpoint's or payload's fields as dotted paths; read from the heading to the next ###.

For a single question later, start at llms.txt and fetch just that section.

• A matching name is a candidate, not an answer. Read the operation's description, parameters, and response fields against what the code passes and reads. If a parameter or field the code depends on is missing, that is a workaround or a gap, not a match.
• GitHub's pull request calls that live under /issues/{n}/… (comments, labels) live under the pull request endpoints on Origin. If the code uses them on real issues, see "Where GitHub features live on Origin" in references/brief.md.
• Origin has no GraphQL. Break each query into REST calls and record the fan-out.
• The scopes to request are the union of x-origin-scopes.scopes over the operations you named. Do not translate the GitHub manifest.
• Each GitHub event and action pair maps to at most one slug in "Events". The action is part of the slug. A pair with no slug is not an event on Origin.
• For each payload field the code reads, record whether it is in the payload, in the delivery envelope around the payload (event.type carries the action), needs an extra read (say which operation and how many calls per event), can be computed from other fields, or is missing. Payloads are snapshots. A field the REST resource has but the payload lacks needs an extra read.
• A capability the docs never mention is not available today. Ask the team about it. A behavior the docs neither confirm nor deny gets a question plus a step in the end-to-end test that checks it. Do not assume it works the way it did on GitHub.

Before finishing

Every claim about Origin points at something in the saved docs. Every gap has a feedback entry that names its cost. The feedback reveals nothing about the team's internals. The summary names the native-or-mirror question.