redline-gate.yml

# Reusable readiness gate. Host in the org `.github` repo at
# .github/workflows/redline-gate.yml; repos call it from .github/workflows/redline.yml
# (see templates/redline.yml).
#
# IMPORTANT — required-status-check naming. A reusable workflow reports its check runs
# as "<caller job id> / <called job id>". templates/redline.yml names the caller job
# `redline-gate`, and the aggregate job below is `gate`, so the context a branch ruleset
# must require is exactly:
#
#     redline-gate / gate
#
# Changing either job id changes the required context and will silently block every PR
# in every onboarded repo. `npx redlinegate verify` checks the
# real name after onboarding.
name: Redline Gate

on:
  workflow_call:
    inputs:
      adr-diff-threshold:
        description: Changed lines above which an ADR link (or the no-adr label) is required
        type: number
        default: 300
      fail-on-dependency-severity:
        description: Minimum dependency-review severity that fails the gate
        type: string
        default: high
      soft-fail-labels:
        description: >-
          Comma-separated labels that downgrade the process checks (checklist, ADR) to
          warnings. Security checks are never downgraded.
        type: string
        default: redline-exempt,redline-sync
      rung:
        description: >-
          The enforcement rung this repository sits at: observe, warn, block-blocker or
          block-high. `observe` and `warn` report and never block; the block-* rungs stop a
          merge on a finding at or above their severity. Written by `redline init --rung`,
          which refuses a promotion the repository's recorded evidence does not support.
        type: string
        default: observe
      stand-down:
        description: >-
          Comma-separated gate jobs another tool in the calling repository already covers:
          `policy`, `dependencies`, `secrets`. A stood-down job is skipped and the
          aggregate below reads a skip as a pass. Written by `redline init` from the tools
          the repository DECLARED, never from detection alone — `dependencies` and
          `secrets` are the two jobs no label can waive, so a wrong guess here is the one
          that removes a security check nobody asked to remove. Empty runs every job.
        type: string
        default: ''
      exemption-enforcement:
        description: >-
          What a soft-fail label without a valid "## Redline exemption" block does.
          `warn` accepts it and says what is missing; `require` refuses it. Repos move
          from warn to require one standards version after the block was introduced, so
          nobody's open pull request is failed by a rule that did not exist when they
          opened it.
        type: string
        default: warn

permissions:
  contents: read
  pull-requests: write

jobs:
  checklist:
    name: PR checklist
    runs-on: ubuntu-latest
    steps:
      - name: Verify the launch-readiness checklist is complete
        env:
          GH_TOKEN: ${{ github.token }}
          PR: ${{ github.event.pull_request.number }}
          REPO: ${{ github.repository }}
        run: |
          set -euo pipefail
          body=$(gh pr view "$PR" --repo "$REPO" --json body --jq '.body // ""')

          # Only the Launch readiness section is enforced. "Change type" is a pick-one
          # list, so requiring every box there would make the gate unpassable.
          section=$(printf '%s\n' "$body" | awk '
            /^##[[:space:]]+Launch readiness/ { inside = 1; next }
            /^##[[:space:]]/                  { inside = 0 }
            inside                            { print }
          ')

          if [[ -z "${section//[[:space:]]/}" ]]; then
            echo "::error::No '## Launch readiness' section in the PR description. Restore .github/pull_request_template.md and complete the checklist."
            exit 1
          fi

          unchecked=$(printf '%s\n' "$section" | grep -c '^[[:space:]]*- \[ \]' || true)
          if [[ "$unchecked" -gt 0 ]]; then
            printf '%s\n' "$section" | grep '^[[:space:]]*- \[ \]' || true
            echo "::error::$unchecked unchecked launch-readiness item(s). Tick each one, or delete the line and say why in the PR description."
            exit 1
          fi
          echo "Launch readiness complete."

  adr:
    name: ADR required for significant changes
    runs-on: ubuntu-latest
    steps:
      - name: Check diff size against ADR link
        env:
          GH_TOKEN: ${{ github.token }}
          PR: ${{ github.event.pull_request.number }}
          REPO: ${{ github.repository }}
          THRESHOLD: ${{ inputs.adr-diff-threshold }}
        run: |
          set -euo pipefail
          pr=$(gh pr view "$PR" --repo "$REPO" --json additions,deletions,body,labels)
          changed=$(jq '.additions + .deletions' <<<"$pr")
          has_adr=$(jq -r '.body // ""' <<<"$pr" | grep -c 'docs/adr/' || true)
          exempt=$(jq -r '.labels[].name' <<<"$pr" | grep -cx 'no-adr' || true)
          echo "changed=$changed threshold=$THRESHOLD adr-links=$has_adr no-adr-label=$exempt"
          if [[ "$changed" -gt "$THRESHOLD" && "$has_adr" -eq 0 && "$exempt" -eq 0 ]]; then
            echo "::error::${changed} changed lines with no ADR link. Add docs/adr/NNNN-*.md and link it in the PR body, or apply the 'no-adr' label with a justification comment."
            exit 1
          fi

  policy:
    if: ${{ !contains(format(',{0},', inputs.stand-down), ',policy,') }}
    # The deterministic tier: the rules a checker can decide, evaluated with no
    # model call. They cost nothing to run and they cannot hallucinate, which is
    # the point — an author cannot argue with a model about whether the word TODO
    # appears on a line.
    #
    # Soft-fail, like the other process checks. The never-exemptible set is
    # exactly dependency-review and secrets and this does not join it: these are
    # code-standard findings, not a security boundary.
    name: Deterministic policy
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: actions/setup-node@v4
        with:
          node-version: 22
      - name: Evaluate the deterministic rules
        env:
          BASE: ${{ github.event.pull_request.base.sha }}
          HEAD: ${{ github.event.pull_request.head.sha }}
          RUNG: ${{ inputs.rung }}
          REDLINE_CLI_VERSION: '0.0.3'
        run: |
          set -euo pipefail
          # Three dots: the diff against the merge base, not against the tip of
          # the base branch. Two dots would attribute every commit that landed on
          # main since this branch started to this pull request's author.
          git diff "${BASE}...${HEAD}" > /tmp/redline.diff
          # The rung decides the floor. Without passing it, block-high behaved
          # exactly like block-blocker — the strictest rung on the ladder did
          # nothing the one below it did not already do.
          case "$RUNG" in
            block-high) fail_on=HIGH ;;
            *) fail_on=BLOCKER ;;
          esac
          npx --yes "redlinegate@${REDLINE_CLI_VERSION}" policy \
            --diff-file /tmp/redline.diff --fail-on "$fail_on"

  dependency-review:
    if: ${{ !contains(format(',{0},', inputs.stand-down), ',dependencies,') }}
    name: Dependency review
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/dependency-review-action@v4
        with:
          fail-on-severity: ${{ inputs.fail-on-dependency-severity }}
          comment-summary-in-pr: on-failure

  secrets:
    if: ${{ !contains(format(',{0},', inputs.stand-down), ',secrets,') }}
    name: Secret scan (diff)
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Scan the PR range
        # Pinned to the commit behind tag v3.97.1 (2026-08-24). This action runs with
        # access to the PR diff, so the ref must be immutable — a tag can be moved.
        # GitHub Actions does not allow expressions in a step `uses:`, so the pin is
        # reviewed here, in the org `.github` repo, which is the right place for it.
        # scripts/check-pins.mjs re-resolves it against the upstream tag in CI.
        uses: trufflesecurity/trufflehog@20652fbbdefffcdaa493a5bf57ab2ac6b1db715b # v3.97.1
        with:
          base: ${{ github.event.pull_request.base.sha }}
          head: ${{ github.event.pull_request.head.sha }}
          # verified only: `unknown` produces false positives, and this is a blocking
          # check. Unverified candidates are caught by GHAS secret scanning instead.
          #
          # No `--fail` here. The action's own entrypoint already passes it before
          # appending extra_args, and trufflehog rejects a repeated flag outright —
          # `flag 'fail' cannot be repeated` — so the scan never ran at all. This
          # job is outside the enforcement ladder and outside label exemption, so
          # that failure blocked every pull request in every onboarded repository
          # for a reason no author could act on or waive.
          extra_args: --results=verified

  gate:
    # Aggregate. The branch ruleset requires the check "redline-gate / gate".
    name: gate
    needs: [checklist, adr, policy, dependency-review, secrets]
    if: always()
    runs-on: ubuntu-latest
    steps:
      - name: Aggregate results
        env:
          RESULTS: ${{ toJSON(needs) }}
          LABELS: ${{ toJSON(github.event.pull_request.labels.*.name) }}
          SOFT_FAIL_LABELS: ${{ inputs.soft-fail-labels }}
          EXEMPTION_ENFORCEMENT: ${{ inputs.exemption-enforcement }}
          RUNG: ${{ inputs.rung }}
          # Through the environment, never interpolated into the script body:
          # `${{ github.event.pull_request.body }}` inline is a script injection
          # anyone who can open a pull request can use.
          PR_BODY: ${{ github.event.pull_request.body }}
          # Pinned, not @latest: the gate's behaviour must not change under a
          # repository because a release happened overnight.
          REDLINE_CLI_VERSION: '0.0.3'
        run: |
          set -euo pipefail

          # Security checks can never be downgraded by a label.
          HARD_JOBS='["dependency-review","secrets"]'

          # `skipped` is a pass. None of these jobs has `needs`, so the only thing
          # that skips one is its own stand-down guard above — a deliberate
          # instruction from the calling repository, not a job that fell over.
          # Without this the aggregate failed every repository that narrowed the
          # gate, which is the opposite of what narrowing it asks for.
          PASSED='["success","skipped"]'

          # `.value.result as $r` first: inside `$passed | index(...)` the input
          # is $passed, so referring to `.value.result` there indexes the array
          # with a string and jq exits 5 — which `set -e` turns into a gate that
          # fails every pull request.
          hard_failed=$(jq -r --argjson hard "$HARD_JOBS" --argjson passed "$PASSED" \
            'to_entries[] | .value.result as $r | select($passed | index($r) | not) | select(.key as $k | $hard | index($k)) | .key' <<<"$RESULTS")
          soft_failed=$(jq -r --argjson hard "$HARD_JOBS" --argjson passed "$PASSED" \
            'to_entries[] | .value.result as $r | select($passed | index($r) | not) | select(.key as $k | $hard | index($k) | not) | .key' <<<"$RESULTS")

          labelled=false
          for label in ${SOFT_FAIL_LABELS//,/ }; do
            if jq -e --arg l "$label" 'index($l)' <<<"$LABELS" >/dev/null; then
              labelled=true
              echo "Soft-fail label present: $label"
            fi
          done

          # A label alone records nothing: not who accepted the failing check, not
          # why, not until when. The pull request must also carry a
          # "## Redline exemption" block with a reason and an expiry, and the CLI
          # is what reads it — re-implementing that parse here would eventually
          # disagree with the audit that reads the same block later.
          #
          # The body is written to a file rather than passed as an argument: a
          # pull request body is attacker-controlled text full of backticks and
          # $(...), and interpolating it into a command is how one becomes a
          # command.
          exempt=false
          if [[ "$labelled" == true ]]; then
            printf '%s' "$PR_BODY" > /tmp/redline-pr-body.md
            # Every failing soft check must be covered, one at a time. Calling
            # exempt without --scope never evaluated the scope at all, so an
            # exemption written for `checklist` silently waived `adr` and the
            # deterministic `policy` job too — the field was recorded and ignored.
            exempt=true
            for check in $soft_failed; do
              if ! npx --yes "redlinegate@${REDLINE_CLI_VERSION}" exempt \
                   --body-file /tmp/redline-pr-body.md --scope "$check"; then
                exempt=false
                break
              fi
            done
            if [[ "$exempt" == true ]]; then
              :
            elif [[ "$EXEMPTION_ENFORCEMENT" != "require" ]]; then
              echo "::warning::This exemption has no valid \`## Redline exemption\` block. It is being accepted this time; once this repository moves to require, it will not be."
              exempt=true
            else
              echo "::error::A soft-fail label was applied without a valid \`## Redline exemption\` block (reason and expiry required)."
            fi
          fi

          {
            echo "### Redline gate"
            echo
            jq -r 'to_entries[] | "- \(.key): \(.value.result)"' <<<"$RESULTS"
          } >> "$GITHUB_STEP_SUMMARY"

          # The security floor is not on the ladder. Dependency review and the
          # secret scan block at every rung including observe: the ladder governs
          # how strictly a repository's own standards are enforced, not whether
          # the organisation's security minimum applies to it.
          if [[ -n "$hard_failed" ]]; then
            echo "::error::Redline gate failed on security checks (not label-exemptible, and not on the enforcement ladder): $hard_failed"
            exit 1
          fi

          # Below block-blocker the process checks report and do not block. The
          # findings are still produced, still commented, and still collected —
          # observe is not "off", it is "measured and not yet enforced", which is
          # the whole point of having a rung below blocking at all.
          # A rung this gate does not recognise is NOT enforcing. cli/config
          # reads an unrecognised value back as `observe` for the same reason: a
          # typo must never be able to make a repository stricter than anyone
          # chose, and the two halves disagreeing meant a typo blocked every pull
          # request here while the CLI reported the repository as observing.
          case "$RUNG" in
            block-blocker|block-high) enforcing=true ;;
            *) enforcing=false ;;
          esac

          if [[ -n "$soft_failed" ]]; then
            if [[ "$enforcing" != true ]]; then
              echo "::warning::Process checks failed: $soft_failed. This repository is at rung '$RUNG', which reports and does not block. The findings are recorded either way."
              echo "- **not enforced (rung: $RUNG):** $soft_failed" >> "$GITHUB_STEP_SUMMARY"
            elif [[ "$exempt" == true ]]; then
              echo "::warning::Process checks failed but a valid exemption is recorded: $soft_failed. A reviewer is accepting this deliberately, with a reason and an expiry."
              echo "- **exempted:** $soft_failed" >> "$GITHUB_STEP_SUMMARY"
            else
              echo "::error::Redline gate failed: $soft_failed"
              exit 1
            fi
          fi

          echo "Redline gate passed."