A failed build tries again

# When CI's tests fail on a build's pull request, this starts the build again for the branch's
# issue, up to three builds since the label was last added. It reads only GitHub: the CI run that
# woke it, the build runs named for the issue, the label's events and the issue's last edit. It
# hands the build nothing but the issue's number, and the build reads why the last try failed from
# CI itself. Once a commit on the branch isn't the factory's, a person has taken the branch over:
# it's never built over again, and a new comment on the issue says so. Otherwise, after three builds,
# or if the issue was edited since the label went on, a new comment on the issue says a person must
# act. Each is said once, on the first failure of CI's tests since it came to hold. A re-run acts
# only if no earlier attempt of the run failed its tests.
awml: "0.8"
title: A failed build tries again
description: |
  The factory's retry: CI's failed tests on a build's pull request start the build again, up to
  three builds since the label was last added.
scopes:
  - { id: public, label: "public: anyone who reads the repository", processing: any }
parts:
  - { id: testsfailed, kind: trigger, label: "CI's tests fail on a pull_request run from a build/issue-* branch of this repository, whatever else failed", wait: PT1H }
  - { id: token, kind: connector, label: "The repository, through its own Actions token", in: public, ref: chrismdp/issue-to-pull-request#token }
  - { id: tries, kind: code, op: sort, cleans: true, label: "Sort by GitHub's record, passing on only the issue's number and a count: is the run at the branch's head, is the issue's lastEditedAt, from GraphQL, older than the build label's last labelled event, and how many build.yml runs for the issue have started since?", in: public }
  - { id: again, kind: code, op: do, label: "Start the build again, with only the issue's number", in: public }
  - { id: dispatch, kind: outside, label: "Start the build again: Allow", ref: chrismdp/issue-to-pull-request#dispatch, in: public }
  - { id: report, kind: code, op: do, label: "Say in a new comment on the issue, from fixed text, that the build failed three times and needs a person, linking CI's run", in: public }
  - { id: issuenote, kind: outside, label: "Comment on the issue: Allow", in: public }
  - { id: edited, kind: code, op: do, label: "Say in a new comment on the issue, from fixed text, that it was edited since the label went on, so a person must add the label again", in: public }
  - { id: editnote, kind: outside, label: "Comment on the issue that it changed: Allow", in: public }
  - { id: takenover, kind: code, op: do, cleans: true, label: "Say in a new comment on the issue, from fixed text, that a person has taken the branch over, so the build won't try again over it, linking CI's run", in: public }
  - { id: takennote, kind: outside, label: "Comment on the issue that a person took the branch over: Allow", in: public }
  - { id: takeover, kind: comment, label: "A commit since main that isn't the factory's, by the build rule's author and committer test, means a person has taken the branch over, so it's never built over again. Said once: unless an earlier CI run on a commit from the first such one on already failed its tests" }
  - { id: derived, kind: comment, label: "Decided in #160's follow-up: a try is a build.yml run for the issue since the label was last added, found by the run's name. The fixer's and the rebase's pushes don't count. Nothing is carried from one run to the next (#160 rule 3)" }
  - { id: noinputs, kind: comment, label: "It trusts nothing from inputs, and passes on nothing the build trusts: the build checks the label and the issue's last edit again, and reads CI's failed log itself (#160 rule 2)" }
  - { id: ours, kind: comment, label: "Decided in #160's follow-up: only pull_request runs count, which run once per commit, and only from a branch of this repository, since a fork's branch can carry a build's name (#153)" }
  - { id: pinned, kind: comment, label: "Decided in #160's follow-up: a retry drafts from the issue as it reads now, so an issue edited since the label went on stops here until a person adds the label again (awml #120)" }
  - { id: testsown, kind: comment, label: "Decided in #160's follow-up: the tests own a run where both they and a review failed, so this acts and the fixer doesn't. A fix commit that breaks a test lands here too, redrafts and uses a try; the tries cap stops it" }
  - { id: forperson, kind: comment, label: "New comments, since a person must act. No status comment and no marker for a later run to find (#160 rule 5)" }
lines:
  - { from: testsfailed, to: tries, kind: start, label: "CI's run and its branch" }
  - { from: token, to: tries, kind: data, label: "the build runs, the label's events and the issue's last edit" }
  - { from: tries, to: again, kind: start, label: "[unedited, fewer than three]" }
  - { from: again, to: dispatch, kind: data, label: "the issue's number" }
  - { from: dispatch, to: token, kind: data }
  - { from: tries, to: report, kind: start, label: "[three]" }
  - { from: report, to: issuenote, kind: data }
  - { from: issuenote, to: token, kind: data }
  - { from: tries, to: edited, kind: start, label: "[edited since the label]" }
  - { from: tries, to: takenover, kind: start, label: "[a commit since main isn't the factory's]" }
  - { from: takenover, to: takennote, kind: data }
  - { from: takennote, to: token, kind: data }
  - { from: takeover, to: takenover, kind: tie }
  - { from: edited, to: editnote, kind: data }
  - { from: editnote, to: token, kind: data }
  - { from: derived, to: tries, kind: tie }
  - { from: noinputs, to: again, kind: tie }
  - { from: ours, to: testsfailed, kind: tie }
  - { from: pinned, to: edited, kind: tie }
  - { from: forperson, to: report, kind: tie }
  - { from: testsown, to: testsfailed, kind: tie }
implementations:
  actions:
    label: "GitHub Actions, retry.yml"
    blocks:
      - { id: github, label: "GitHub: branches, runs and issues", parts: [testsfailed, token, dispatch, issuenote, editnote, takennote] }
      - { id: retryjob, label: "Actions job: decide, reading only GitHub, checking out nothing and running only gh, in no concurrency group", platform: actions-code, parts: [tries] }
      - { id: actjob, label: "Actions job: retry or report, running only gh, one at a time on the issue decided", platform: actions-code, parts: [again, report, edited, takenover] }
    comments:
      - { id: turns, label: "A stranger's pull request from the same branch starts CI, and so retry, too, and GitHub keeps only one run waiting in a concurrency group, so a newer one would displace the real one's. The deciding job takes no turns, and a stranger's run leaves there; the acting job takes turns per issue, never cancelled", in: retryjob, ties: [tries] }