RFC: reusable GitHub Action for storyboard non-regression gating

[bokelley]

Motivation

Every seller that integrates the AdCP compliance suite wants a CI gate that fails a PR if it regresses storyboard pass-rate. The pattern is simple but non-obvious: run storyboards, parse the output, compare against a rolling floor, fail if below.

Our training-agent workflow at `.github/workflows/training-agent-storyboards.yml` has the shape:

```yaml

• name: Run storyboards
  id: run
  run: |
  npx tsx server/tests/manual/run-storyboards.ts 2>&1 | tee /tmp/storyboards.log
  clean=$(grep -oE 'storyboards: [0-9]+/[0-9]+' /tmp/storyboards.log | tail -1 | grep -oE '^storyboards: [0-9]+' | grep -oE '[0-9]+$')
  echo "clean=${clean}" >> "$GITHUB_OUTPUT"

• name: Enforce non-regression
  env:
  CLEAN: ${{ steps.run.outputs.clean }}
  MIN_CLEAN: ${{ matrix.min_clean_storyboards }}
  run: |
  if [ "${CLEAN}" -lt "${MIN_CLEAN}" ]; then
  echo "::error::Regression: ${CLEAN} clean storyboards is below the ${MIN_CLEAN} floor."
  exit 1
  fi
  ```

Plus the matrix of legacy/framework modes, the ratcheting floor comments explaining each bump, and the `paths:` filter. Every seller is going to need ~60 lines of this.

Proposal

Ship a reusable composite action at `adcontextprotocol/adcp-client/.github/actions/storyboard-gate`:

```yaml

• uses: adcontextprotocol/adcp-client/.github/actions/storyboard-gate@v1
  with:
  agent-url: http://localhost:4444/api/mcp
  min-clean: 45
  min-passing: 324
  mode: json # table | json | junit
  ```

Assumes the CLI from the companion RFC is installed. Emits `::error::` annotations on regression so the PR comment is structured.

What the action does

1. Install `@adcp/client` (or use a pre-installed one via `skip-install`).
2. Invoke `npx @adcp/client run-storyboards --format json` (or local equivalent).
3. Parse the JSON output for `clean_count` + `passing_count`.
4. Compare to `min-clean` / `min-passing` inputs.
5. Upload the full run report as a workflow artifact.
6. Emit a GH check summary with the ratchet comment (if floor bumped upward, suggest a follow-up PR to bump the input).

Ratcheting helper (optional)

Separate action `adcontextprotocol/adcp-client/.github/actions/storyboard-ratchet` that bumps the floor when the main branch pass-rate exceeds it for N consecutive runs. Reduces human toil on the "we added a fix, now bump the floor" PR.

Why separate from the CLI RFC

The CLI is where the work is; the action is a thin wrapper. Keeping them as separate issues lets the CLI land first and sellers adopt with bespoke workflows in the meantime.

Reference implementation

`adcontextprotocol/adcp`'s training-agent workflow, specifically the `min_clean_storyboards` / `min_passing_steps` matrix entries with their floor-bump comments that document each compliance milestone.

Complementary RFC: `@adcp/client` CLI (separate issue).