ci: adopt rainix nix-cachix-setup composite in report-downtime, drop deprecated DeterminateSystems nix installer

[thedavidmeister]

Closes #459

What

Replaces the deprecated DeterminateSystems/nix-installer-action@main (+ flakehub-cache-action@main) in .github/workflows/report-downtime.yaml with the org-standard shared composite rainlanguage/rainix/.github/actions/nix-cachix-setup@main, which bundles nix-quick-install + Cachix + cache-nix-action and pins every third-party action to an exact SHA (single source of truth — "rainix owns shared CI"). The pre-existing actions/checkout@v4 (submodules recursive, fetch-depth 0) is kept, so the composite is called with checkout: 'false'.

This also removes the @main floating-ref supply-chain risk the roh-scan signal called out (the composite pins every third-party action to an exact SHA).

This is the same swap already applied and green on the pilot PRs rainlanguage/rain.chainlink#11, rainlanguage/rain.tier.interface#8, and rainlanguage/assemblyscript-cbor#5.

QA

CI-infrastructure-only change: it touches a single GitHub Actions workflow file and no source or test code, so there is no behavioral code surface to mutation-test.

• Scope honesty: report-downtime.yaml is a scheduled workflow (cron, once/7 days), so this PR's own CI does not exercise it — there is no PR-triggered run to observe. The change is validated by equivalence to the established pattern rather than by a PR-CI run, and I flag that explicitly here rather than implying a green run proves it.
• Independent confirmation: the identical installer → composite swap is already green on the pilots rain.chainlink#11 / rain.tier.interface#8 / assemblyscript-cbor#5; the composite's input contract (checkout, cachix-auth-token) matches nix-cachix-setup/action.yml on rainix@main.
• Equivalence: the composite provides the same capabilities the two removed steps did (Nix install + a flake/store cache) plus the org's pinned-SHA hardening. checkout: 'false' preserves the existing checkout (submodules recursive, fetch-depth 0). All downstream steps (prep-sushi.sh, nix develop -c npm install, the nix develop -c npx ts-node scripts/downtime.ts report step and its SUBGRAPHS/DURATION/THRESHOLD/TG_* env) are untouched. An empty CACHIX_AUTH_TOKEN degrades to a read-only Cachix pull (the composite's documented default).
• Category check: issue asks to replace the deprecated installer (report-downtime.yaml:18) with the org-standard install (preferred: adopt the shared composite) — done → Closes CI: replace deprecated DeterminateSystems/nix-installer-action with org-standard nix-quick-install #459.

Co-Authored-By: Claude noreply@anthropic.com

Summary by CodeRabbit

• Chores
  • Updated the downtime reporting workflow’s Nix setup and caching configuration.
  • Streamlined environment preparation for more consistent automated runs.

[coderabbitai]

Walkthrough

The downtime reporting workflow replaces the previous DeterminateSystems Nix installation steps with the shared Rainix Nix/Cachix setup action, disabling checkout and supplying the Cachix authentication secret.

Changes

CI Nix setup

Layer / File(s)	Summary
Replace Nix installer .github/workflows/report-downtime.yaml	Uses the shared Rainix setup action with checkout: 'false' and the configured Cachix authentication token.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Possibly related issues

• rainlanguage/assemblyscript-cbor#4 — Replaces the deprecated Nix installer with the shared Rainix setup action.
• rainlanguage/rain.chainlink#10 — Replaces deprecated Nix installer usage with the shared Rainix composite.
• rainlanguage/rain.local-db.remote#12 — Adopts the shared Rainix Nix setup in GitHub Actions.
• rainlanguage/rain.subgraph.docker#12 — Replaces the deprecated installer with the shared composite.
• rainlanguage/rainlang-codemirror#31 — Uses the shared Rainix Nix setup action.
• rainlanguage/rainlang.xyz#8 — Replaces deprecated Nix setup with the shared Rainix composite.
• rainlanguage/rain.subgraph.cli#12 — Adopts the shared Rainix Nix setup action.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly states the workflow now uses the rainix Nix/Cachix composite instead of the deprecated DeterminateSystems installer.
Linked Issues check	✅ Passed	The workflow change matches #459 by replacing the deprecated installer with the rainix shared setup and preserving checkout behavior.
Out of Scope Changes check	✅ Passed	The only change is the Nix setup swap in the targeted workflow, with no unrelated code or workflow edits.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ci-adopt-nix-cachix-setup-downtime

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[thedavidmeister]

🤖 ai:producer

Producer note: the red unit tests check is pre-existing and unrelated to this PR. This diff changes only .github/workflows/report-downtime.yaml, a schedule:-triggered (cron) workflow that is not run by this PR at all — it cannot affect the unit tests job. The failure is in src/logger/index.test.ts (a duration assertion: expected 10000000 to be close to 1009999990… +/- 1000), a time-dependent logger test failing independently on the base branch. This installer-modernization PR is inert on PR CI; the logger-test red needs to be resolved separately (it is not a regression from this change).

[thedavidmeister]

🤖 ai:vetter
Reviewed d3c9430: ready — closes #459 — swaps deprecated DeterminateSystems installer for org nix-cachix-setup composite in report-downtime.yaml; checkout:false + cachix-auth-token match the composite's real input contract, downstream prep-sushi/ts-node steps untouched; sole roh-scan-flagged file
cost 149 — CI installer→composite swap, scheduled wf

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.github/workflows/report-downtime.yaml:
- Line 18: Update the workflow’s rainix/cachix setup action reference from the
floating “main” ref to a full commit SHA, keeping the existing action path and
behavior unchanged.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: ea9780ce-0758-4190-91e2-457b9b78fab9

📥 Commits

Reviewing files that changed from the base of the PR and between 9031984 and b3de99b.

📒 Files selected for processing (1)

• .github/workflows/report-downtime.yaml

[thedavidmeister]

🤖 ai:vetter
Reviewed b3de99b: ready — re-vet at moved head b3de99b: closes #459 — deprecated DeterminateSystems installer swapped for rainix nix-cachix-setup composite; usage matches composite contract (checkout:'false' keeps submodules checkout, token degrades read-only); issue's single named site fully covered; red unit-tests job external to this YAML-only diff
cost 142 — one-file CI swap, org-standard composite

[thedavidmeister]

🤖 ai:vetter
Reviewed 740b5e5: ready — closes #459 — re-vet at moved head 740b5e5: only empty CI-retrigger commits since vetted b3de99b, diff identical; deprecated DeterminateSystems installer swapped for rainix nix-cachix-setup composite (checkout:'false' preserves submodule checkout, token degrades read-only); all checks green
cost 144 — one-file CI swap, retrigger-only head move

[github-actions]

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[coderabbitai]

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