gh - Mirage

Mirage’s built-in gh implementation uses the vocabulary of the official cli/cli project. A repository is a tree, so mirage already reads one as files: the github mount is the read half, and ls, cat and grep are how an agent explores it. gh is the write half, plus the account-level operations a filesystem has no shape for. Licenses: The upstream cli/cli project uses the MIT License; Mirage’s independent implementation uses Apache-2.0.

Install

import { GH } from '@struktoai/mirage-core'
import { GitHubVFS, Workspace } from '@struktoai/mirage-node'

const config = { token: process.env.GITHUB_TOKEN!, repo: 'acme/tools' }
const repo = await GitHubVFS.create({
  token: config.token,
  owner: 'acme',
  repo: 'tools',
  ref: 'main',
})

const ws = new Workspace({ '/repo': repo })
ws.registerCli('gh', GH, config)

await ws.shell('gh repo view')

In YAML the same install rides the clis: section; see the CLI overview.

Field	Meaning
`token`	the API token, as `GH_TOKEN` carries for real gh
`repo`	the default repository, as `[HOST/]OWNER/REPO`
`branch`	the current branch, for `{branch}` in an endpoint
`baseUrl`	the REST API base, for GitHub Enterprise Server

An Enterprise Server base ends in /api/v3, and GraphQL (gh api graphql and the verbs that query it, such as repo view --json) then goes to /api/graphql on the same host, outside the REST base, as real gh sends it. Any other baseUrl answers GraphQL at baseUrl/graphql. repo and branch are what real gh reads off the current directory’s git remote and checkout. A workspace has neither, so the install carries them: repo answers a line that names no repository, and both feed the {owner}/{repo}/{branch} placeholders. Two installs under different head words are two accounts.

Authentication status

gh auth status checks the configured token with GET /user, reports the host and account, and exits 1 when GitHub rejects the credential. It needs no mount. The token source is reported as Mirage configuration: configuration retains the resolved secret, not the environment variable or file that supplied it. The credential itself is never printed.

Reading is the mount, acting is the CLI

ls /repo/src              # the tree, from the mount
cat /repo/README.md       # a blob, from the mount
grep -r TODO /repo        # the mount again

gh api repos/acme/tools/contents/README.md -X PUT \
  -f message='docs: fix a typo' -f content="$(base64 -w0 new.md)" -f sha=<blob-sha>

A write through gh lands on the same repository the mount reads, but it lands by repository name rather than by any vfs path, so the mount has nothing to aim a per-path invalidation at. The executor expires every mount’s caches after a write verb of an account CLI, so the next cat or ls refetches instead of serving the pre-write bytes. Nothing is required of the caller, and nothing on the spec names the mount.

Verbs

gh api       <ENDPOINT>
gh issue     list | view | create | edit | close | reopen | comment
gh pr        list | view | create | edit | merge | close | comment | diff | checks
gh repo      list | view | create | fork | rename | edit | delete
gh release   list | view | create
gh run       list | view | rerun
gh workflow  list | view | run

Every level answers --help; man gh, man gh issue, and man gh pr create render the same text from the same spec. list also accepts ls, and issue and pull request create also accept new.

Typed workflows

Typed read commands accept -R/--repo [HOST/]OWNER/REPO where applicable. Most also accept --json field1,field2 and -q/--jq EXPRESSION; --jq requires --json, so the selected field set stays explicit and bounded. List commands use -L/--limit and fetch as many pages as needed. gh issue view, gh issue list, gh pr view and gh pr list accept every --json field gh 2.85 does, and gh repo view and gh repo list every repository field. Like gh, they ask GraphQL for exactly the fields named and print each in gh’s own shape, so files, commits, reviews, statusCheckRollup and closedByPullRequestsReferences need no fallback to gh api. pr view reads reviews, comments, closing issues and checks past their first 100, and issue view its comments and closing pull requests. issue view answers a pull request’s number too, as gh does, with the fields only an issue has at their zero. The JSON prints compact, one value per line, the way gh prints it to anything but a terminal.

gh issue list --state open --label bug --limit 20
gh issue view 42 --json number,title,labels,url --jq '.url'
gh pr view 17 --json files,commits,reviews --jq '.files[].path'
gh pr checks 17 --json name,bucket,state
gh repo list acme --json nameWithOwner,visibility
gh release list --json tagName,isLatest
gh run list --workflow ci.yml --json databaseId,status,conclusion
gh run view 123456 --log-failed
gh workflow view ci.yml --yaml --ref release

Mutations never open an editor or prompt. Supply the values on the line, through a workspace file, or through stdin with -:

gh issue create --title 'Broken build' --body-file /scratch/issue.md --label bug
gh issue edit 42 --add-label confirmed --remove-assignee octocat
gh issue comment 42 --body-file - < /scratch/comment.md
gh issue close 42

gh pr create --title 'Fix build' --head fix-build --base main --body-file /scratch/pr.md
gh pr edit 17 --base release --body 'Updated scope'
gh pr merge 17 --squash --subject 'fix: build'

gh repo create acme/tools-next --private --add-readme
gh release create v1.2.0 --title '1.2.0' --notes-file /scratch/notes.md
gh workflow run ci.yml --ref main -f mode=full
gh run rerun 123456 --failed

Body and notes files are read through the workspace dispatcher, not the host filesystem. That keeps an agent inside mirage while still supporting the official CLI’s file-oriented grammar. gh workflow view --yaml prints the workflow’s file as the repository holds it at -r/--ref, a branch or tag, or on the default branch; that is the one read gh makes, and --ref without --yaml is refused as gh refuses it. gh run view --log prints a completed run’s log a line at a time, each line behind its job and step name, from the log archive GitHub ships; a job the archive has no log for is fetched on its own, and --log-failed keeps only the failed steps of failed jobs. A run still going is refused in gh’s words, run N is still in progress; logs will be available when it is complete, before any log is asked for.

repo

gh repo view                        # the install's repository
gh repo view acme/tools
gh repo view github.com/acme/tools  # the host segment is accepted
gh repo view --json nameWithOwner,defaultBranchRef,url

gh repo list acme --limit 50
gh repo create tools-next --private --description 'Next generation'

gh repo fork acme/tools
gh repo fork acme/tools --fork-name tools-patched

gh repo rename tools-v2 -R acme/tools

gh repo edit --description 'Agent tools' --homepage https://tools.example
gh repo edit acme/tools --enable-wiki=false --delete-branch-on-merge
gh repo edit --add-topic cli,agents --remove-topic legacy
gh repo edit --visibility private --accept-visibility-change-consequences

gh repo delete acme/tools-old --yes

The default view prints a name: line, a description: line, then -- and the README, with the separator omitted when the repository has none. Use --json for any of gh’s repository fields or gh api for the complete REST object. rename takes the new name as the operand and the repository to rename on -R, which is the reverse of what the shape of the line suggests; that is upstream’s grammar, not a mirage choice. edit sends the settings named on the line in one PATCH, as gh does, and reads and replaces the topic list when --add-topic or --remove-topic changes it. A switch such as --enable-wiki is on when bare and off as --enable-wiki=false. With no setting named gh would prompt, so it is refused, and --visibility needs --accept-visibility-change-consequences. delete needs --yes and a named repository, since gh only prompts for the current one; a name with no owner is the viewer’s. Both print nothing on success, as gh does when it is not writing to a terminal. [HOST/]OWNER/REPO is parsed from the right, so the owner and the repository are the last two segments and a leading host is dropped. The host is accepted for compatibility with lines copied from real gh but does not route: every call goes to the install’s baseUrl. A second host means a second install.

api

gh api reaches every endpoint that has no typed verb, which is most of them.

gh api repos/acme/tools
gh api /user
gh api repos/acme/tools/issues -f title='Bug' -f body='Steps...'
gh api -X GET search/code -f q='repo:acme/tools TODO'
gh api repos/acme/tools/issues -F draft=false -F milestone=3
gh api repos/acme/tools/issues -F 'labels[]=bug' -F 'metadata[agent]=worker'
gh api repos/acme/tools/issues --input /scratch/issue.json --silent
gh api repos/acme/tools/issues --input - < /scratch/issue.json
gh api 'repos/acme/tools/issues?per_page=50' --paginate --slurp
gh api repos/acme/tools/pulls/17 -H 'Accept: application/vnd.github.v3.diff'
gh api repos/acme/tools/contents/NOTES.md -X DELETE -f message=rm -f sha=<blob-sha>
gh api graphql -f query='{viewer{login}}'

gh api 'repos/{owner}/{repo}/releases'
gh api 'repos/{owner}/{repo}/branches/{branch}'

{owner}, {repo} and {branch} expand from the install, the way real gh expands them from the current repository. Any other brace pair is left exactly as typed and reaches the wire, which is gh’s behavior too. Quote the endpoint so the shell does not eat the braces. The rules are gh’s own:

The method is GET with no fields and POST once a field is given, unless -X says otherwise.
A GET carries its fields in the query string; every other method carries them in a JSON body.
-f/--raw-field is always a string. -F/--field reads true, false, null and integers as their JSON types. A typed value beginning with @ reads that workspace file, and @- reads stdin.
Object keys such as config[enabled] and arrays such as labels[] build nested JSON rather than flat keys.
--input FILE sends that JSON document as the body and moves any fields to the query string. --input - reads stdin.
-H/--header adds or replaces request headers.
--paginate follows REST Link headers, and pages that are arrays print as one array, joined the way gh joins them; --slurp wraps every page in one array instead.
--silent suppresses response output without suppressing the request.
-i/--include prints each response’s status line and headers before its body: HTTP/1.1 200 OK, then the headers in name order, each line ending \r\n, then a blank line. Pages print as they came, a newline between two, and --silent still prints the headers. A failing response is headed too.
A call with no fields sends no body at all, so a bare DELETE is a bare DELETE rather than an empty JSON object with a content type. Some endpoints read those differently.
The leading slash is optional.
A placeholder expands in an endpoint and in a -F value, but not in a -f one, which is the split gh’s own --help describes.
A read (GET, HEAD, OPTIONS) leaves the mount’s cache alone; only a write expires it.
A request that gets no response at all fails at once, with exit 1 and gh’s words: error connecting to HOST and a pointer at githubstatus.com for a host that does not resolve, Get "URL": dial tcp ADDR: connect: connection refused for a refused connection. It is never retried, and neither is a 500. This holds for every verb, not only api.

A response prints as the server sent it, which is how gh prints it to anything but a terminal: GitHub’s JSON arrives compact, with no newline at the end. -q/--jq evaluates in-process and prints each output as gh does: a string raw, null as an empty line, a number in fixed notation with two decimals unless it is whole (1.50, 3), and anything else as compact JSON with its keys sorted and <, > and & escaped. The rest of the shell can consume stdout just as well:

gh api repos/acme/tools | jq -r .default_branch
gh api repos/acme/tools/issues --jq '.[].title'

A --jq program that fails ends the command with exit 1, after the lines it printed first. The report follows gh’s gojq where mirage’s jq can tell what gojq would say: an error the program raises with error(v) reads error: <v>, with v as it is when it is a string and as compact JSON with sorted keys otherwise; halt_error reads halt error: <v>; and halt, like halt_error on null, only ends the output. As with every CLI failure, mirage puts the command’s name first (gh api: error: boom), where gh prints error: boom alone.

Divergences from upstream gh

gh is virtualized, not wrapped. The intentional boundaries are:

Divergence	Reason
Only the command groups listed above are installed	`auth`, `browse`, `codespace`, `extension`, `gist`, and host checkout operations do not act on virtual workspace state
Commands never prompt, open an editor, or launch a browser	agents need deterministic, noninteractive execution
`pr create` requires explicit title, head, base, and body/body-file	there is no host checkout from which to infer or fill them
`repo fork` omits clone/remote flags; release asset upload and `run watch` are absent	those require host files, checkout state, or a streaming surface not modeled here
`repo` has no `archive`, `unarchive`, `sync`, `deploy-key`, `autolink`, `gitignore`, `license`, `clone` or `set-default`	`clone` and `set-default` act on a host checkout; the others are not implemented
Outside `issue`, `pr` and `repo`, typed `--json` exposes a REST-backed field subset	upstream’s full field sets include GraphQL-only data; use `gh api` for arbitrary REST fields
`gh api --input` accepts JSON, and pagination follows REST `Link` headers only	arbitrary byte bodies and GraphQL cursor pagination are not implemented
`gh api` has no verbose/cache flags	output is optimized for agents and shell composition rather than wire debugging
`gh api -i` reports `HTTP/1.1` where gh against github.com reports `HTTP/2.0`	mirage’s clients speak HTTP/1.1; the reason phrase is Go’s for the code, as gh’s is
`gh api --slurp` also takes `--jq`, running it once on the array of pages	gh refuses the pair; the combination is the one-call way to filter every page together
A builtin’s `--jq` error keeps jq 1.8.2’s wording: `Cannot index number with string ("a")` where gh says `expected an object but got: number (5000)`	mirage evaluates `--jq` with jq, and gojq’s messages carry values jq’s leave out. The negative-count errors of `limit`, `skip` and `nth`, which gojq raises with `error`, still read `error: ...` as in gh. An `error(v)` built outside a `catch` from a value that `catch` took from another `error` also reads as a builtin’s, because the reruns that tell the two apart cannot follow it
`--jq` numbers are jq’s doubles: `nan` prints as an empty line, an infinity as the largest finite number, a negative zero as `0`, and an integer literal past 2^53 as its nearest double	jq has made `nan`, an infinity and a big literal that before mirage sees them, and jq.py hands a negative zero to Python as `0`, which TypeScript matches; gh prints `NaN`, `+Inf` and `-0` (refusing the first two inside an array or object) and keeps a big literal’s digits
A `HOST/` repository prefix is accepted but never routes	one install is one account on one host; use another install for another host

Getting Started

AI Agents

VFS

CLIs

Watch

Runtimes

gh

Install

Authentication status

Reading is the mount, acting is the CLI

Verbs

Typed workflows

repo

api

Divergences from upstream gh

​Install

​Authentication status

​Reading is the mount, acting is the CLI

​Verbs

​Typed workflows

​repo

​api

​Divergences from upstream gh

Install

Authentication status

Reading is the mount, acting is the CLI

Verbs

Typed workflows

repo

api

Divergences from upstream gh