Authoring CI Workflows

Authoring CI workflows

Before you propose a change to CI, check things already tried for the idea. It records what was measured, and why some good-sounding changes were reverted or rejected.

Conventions for .github/workflows/** and .github/actions/**. The linters own the mechanical rules (below); this skill is the judgment calls they can't enforce.

Before you write

• Copy from a canonical file rather than from memory. ci-paths-filter.yml is the smallest complete example (triggers, concurrency, timeout, app token, Depot runner); ci-backend.yml is the reference for the heavy patterns (bounded-depth checkout, per-SHA concurrency, draft/ready, sharding).
• Related skills — reach for these instead of duplicating them here:
  • /gating-production-deploys — any job that pushes a prod image or dispatches a Charts deploy.
  • /managing-github-actions-secrets — creating the GitHub App / secret a workflow reads.
  • /depot-github-runners — Depot runner labels and sizing.
  • /debugging-ci-failures — CI is red and you need to know why.

What the linters already enforce

Run bin/hogli lint:workflows and actionlint before pushing — they gate CI, and they (not this list) are the source of truth for what's enforced. Today that's: timeout-minutes on every job, the canonical PR concurrency block, a repo-wide budget for unscoped PR event dispatches, dorny/paths-filter negation safety, justification for full-depth checkouts, cache-write gating, semgrep service coverage, MCP path-filter coverage of the trees the MCP build compiles, required-check gate hygiene, and generic GHA correctness (bad secrets.* / needs: refs, deprecated ::set-output, unknown runner labels). Third-party action digests are bumped by Renovate.

The dispatch budget (500 runs / 10s / repo)

GitHub caps workflow-run dispatch at 500 runs per 10s per repo; overflow fails as startup_failure and takes unrelated runs in the same window down with it (a stack restack pushing many branches is the usual trigger). Minimize runs dispatched, not just work done — draft status doesn't help, runs dispatch before skip logic applies.

• A reusable-workflow call counts as one run. Small always-fire PR workflows should be jobs under a single workflow_call parent, not their own dispatches (see pr-updated.yml / pr-opened.yml folded behind their parent — fold pr housekeeping into one dispatch). Event-type scoping moves to job-level if: guards:

  jobs:
    turbo:
      if: contains(fromJSON('["opened", "synchronize", "reopened"]'), github.event.action)
      uses: ./.github/workflows/ci-turbo.yml
  

• Prefer a trigger-level paths: filter over dispatch-then-skip: a run that only starts to no-op still spends a dispatch (gate container workflows on trigger paths).

  on:
    pull_request:
      paths:
        - '.github/workflows/ci-x.yml'
        - 'path/to/product/**'
    workflow_dispatch:
  

• Judgment call — trigger paths: vs a runtime dorny/paths-filter job. Use trigger paths: for a workflow that is skippable as a whole. Never put a trigger paths: on a workflow whose check is required by branch protection: a required check that doesn't dispatch on a PR leaves it stuck "waiting for status" and unmergeable. Keep those firing on every PR and gate internally with a changes job (also the right call when several jobs branch on different path sets). Heavy matrices (ci-backend, ci-nodejs) do exactly this — deliberate.

• Delete dead dispatchers outright. A disabled-but-still-triggered workflow keeps dispatching no-op runs against the cap — remove the trigger, don't just disable it.

• A filter has to cover what the job actually compiles, not just where the code lives. A build that reaches out of its own tree — through a tsconfig paths alias, a workspace dependency, a generated file — breaks when a filter lists only the service directory. The PR touching the imported tree skips the job, the merge-queue run skips it too, and the break lands on master, where it then fails every later PR whose diff does match. Cover the enclosing directory, not the imported file: the module drags its own relative imports along. When the imported tree is busy, give it a second filter output and gate only the jobs it can actually break, rather than widening the one that also fires an expensive suite. WF009 derives the MCP filters' required trees from the MCP sources and fails when one is uncovered; a build with the same shape wants the same treatment.

Concurrency

Every PR-triggered workflow gets the canonical block:

concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

• Cancel superseded PR runs; never cancel across master pushes. WF002 rejects a bare cancel-in-progress: true on any push-triggered workflow. Where latest-wins is genuinely right (a cache warmer), say so with # hogli-lint: allow-master-cancel -- <reason>.

• Use github.ref as the fallback, never github.run_id — run_id is unique per run, so it silently gives every push its own group and dedup is lost.

• Publish-on-push workflows must not let two master pushes race :latest / a deploy dispatch. Key the push arm per-SHA (see ci-backend.yml):

  group: ${{ github.workflow }}-${{ github.event_name == 'push' && github.sha || github.head_ref || github.ref }}
  

Required-check gates

The "gate" is the collate job that emits the required status check by reading needs.*.result. By convention its display name ends in Pass (Django Tests Pass, Visual regression tests pass), but WF007 also finds gates structurally when a step reads needs.<dep>.result, because the convention is not universally followed. A job that inspects results without gating anything opts out with # hogli-lint: not-a-required-gate — <reason> above the job key. Gates and the workers they inspect share the same condition:

The gate condition must contain !cancelled(), with optional ${{ }} wrapping. always() is rejected: it is identical to !cancelled() on any run that is not cancelled, but on a superseded run it runs the gate after the cancel and reports failure, which inflates every CI failure-rate metric with runs a developer merely pushed over.

Extra predicates may only be OR-ed on, never AND-ed. This is a correctness rule, not a style one. A conjunction gives the gate a second way to be false, and a job skipped by its own condition records skipped, which branch protection reads as a pass. Both conclusions occur in the same cancelled run: in run 33496887370 Calculate running time recorded cancelled while Backend coverage report recorded skipped, because an AND-ed predicate of its own was already false. A disjunction cannot be false while !cancelled() is true, so cancellation stays the gate's one false predicate and the conclusion stays cancelled.

Cancellation still fails closed. A gate on !cancelled() that never starts records conclusion cancelled, never skipped. Measured on a superseded run (evidence): the gate recorded cancelled with zero steps, while the always() control ran after the cancel and recorded failure. GitHub's status checks reference lists success/neutral/skipped as passing and never places cancelled among them, and a commit whose only checks are cancelled rolls up to FAILURE (evidence). That is inference rather than a documented guarantee, which is the reason for the next rule.

A workflow that cancels its own run must OR that signal onto its gate. ci-backend cancels itself when repo checks or OpenAPI types fail deterministically, to stop paying for runners on a failure a retry cannot fix. Under a bare !cancelled() those real failures would report cancelled too, which both hides them from the failure-rate metric and rests merge safety on the inference above. OR-ing the deterministic-failure output back on keeps the honest verdict, because the disjunct is true, so the gate dispatches despite the cancel:

if: >
  !cancelled()
  || needs.repo-checks.outputs.deterministic_failure == 'true'
  || needs.check-openapi-types.outputs.deterministic_failure == 'true'

Measured on a self-cancelled run (evidence): the bare !cancelled() gate recorded cancelled, the OR-ed gate ran and recorded failure. Only superseded runs then report cancelled, and every real failure keeps a failure conclusion.

A failure-rate metric keyed on a gate job must exclude cancelled. Only success and a decisive failure are a verdict, so a denominator that counts cancelled measures push behavior, not test health. Find those rows through the run's conclusion, not the gate job's. The gate job's own conclusion changed on 2026-09-04: a superseded gate recorded failure before that date and records cancelled after it. A metric that drops the superseded rows from the numerator and the denominator stays comparable across that date. One that filters on the gate job's conclusion alone does not. The run's conclusion lives in the warehouse table github_workflow_runs. The posthog-ci-running-time event cannot supply it: the action fills that event's conclusion property from the job named in its status-job input, and every caller passes a gate job name. It writes the same value to the workflow_run group, so both of those fields carry a gate conclusion under a run-shaped name. A metric keyed on jobs joins github_workflow_jobs to that table on run_id, then scopes the job side to a single run_attempt. The runs snapshot keeps one row per run id, at its newest attempt, so an unscoped read stamps that conclusion onto every earlier attempt's gate and counts the gate once per attempt. Do not enforce that scope by joining run_attempt equality: it blanks or drops every earlier attempt, which is the population that actually ran after a partial re-run (products/engineering_analytics/backend/logic/views/job_costs.py records that decision). Reuse the canonical predicates instead of writing a new denominator: CONCLUSIVE_RUN_CONDITION in products/engineering_analytics/backend/logic/queries/_workflow_filters.py, and computeHealthSummary in products/engineering_analytics/frontend/lib/runHealth.ts. That run-level key identifies superseded runs only where the workflow never cancels its own run. Where it does (the rule above), a deterministic failure records run conclusion cancelled too, so the canonical predicates drop that honest failure together with the superseded rows. Measured on Backend CI run 34204389260: the run recorded cancelled while the Django Tests Pass gate recorded failure. Keep those rows in the numerator and the denominator, and find them through the cancel jobs: each one dispatches only on its deterministic-failure signal, so a success from any of them marks that population on both sides of 2026-09-04.

Four rules for the gate body:

1. Allowlist every dependency, never denylist. Assert success/skipped and fail everything else. A dependency tested only against == 'failure' lets cancelled through, and one bad dependency is enough — a gate that clears four correctly and one with a bare failure test is still wrong. The trap is the changes detector: clearing it with == 'failure' and then reading needs.changes.outputs.* reports green on cancellation, because those outputs are empty and the gate takes its "nothing to test" exit.
2. needs every job that produces coverage. If a job's failure would only cascade into a downstream job being skipped, the gate reads that as a pass and you get a green check with zero tests run. Name the upstream job explicitly.
3. Legitimate skips must still pass. A frontend-only PR skips backend jobs by design.
4. Every dependency's result must reach a fail-closed allowlist guard. One inline if per dependency is the clearest form, but a shared shell helper or an env: block is equally fine: WF007 traces each result through assignments, ${!var} indirection, and helper argument positions within that step. The guard must compare with !=, join multiple allowed values with &&, and unconditionally exit 1 when entered. Comparisons in another step, comments, logs, or branches that do not exit nonzero prove nothing and are rejected. A result whose guard WF007 cannot follow is reported rather than assumed safe, so an unusual routing may need the checks moved inline.

WF007 enforces 1, 4, and the !cancelled() condition, and it takes the dependency list from needs: as well as the step body, so a job you wired into needs: and then forgot to test is reported rather than silently trusted. The half of rule 2 it cannot check is whether you named the right jobs in needs: to begin with: "reporting job" and "coverage job" look identical to a linter, so that one is on you and the reviewer.

What GitHub does with each conclusion

Rule 3 works because a skipped check run satisfies a required context, in the Trunk queue as well as on GitHub. Build Docker image rides on that: it concludes skipped on most PRs and they merge anyway.

Three cases behave in ways the name does not suggest:

• A required context that no check run reports stays pending and blocks. A trigger-level paths: filter that silences the whole workflow produces exactly this.
• A job-level continue-on-error: true posts a failure check run even though dependents read success and the run goes green. Use step-level continue-on-error plus an explicit verdict step instead.
• A matrix that expands to zero cells fails its dependents on GitHub Actions and posts no check run at all. Guard any fromJSON matrix with an if: that skips the job when the list is empty.

Required contexts are pinned to one app: every entry in this repo's master ruleset carries integration_id: 15368, the github-actions app, so a check run from any other app never satisfies one however exactly the name matches. /depot-ci has the measurements, the rulesets query, and how Depot CI differs.

Checkout / clone — sparse first, then shallow

This repo is 45k tracked files and 4.6 GiB of packed objects, so what you materialize costs more than how much history you fetch. Measured checkout-step durations, from the GitHub API on real runs:

• Biggest lever: check out only the paths the job reads. Sparse-checkout is not just for single files — a job that runs a local composite action, reads a JSON config, or lints one directory should name those paths and nothing else.

  - uses: actions/checkout@<sha> # v6
    with:
      sparse-checkout: |
        .github/actions/paths-filter
        .github/clickhouse-versions.json
      sparse-checkout-cone-mode: false
  

• Always set sparse-checkout-cone-mode: false. Cone mode additionally materializes every file in the repo root — here 70 files and 21.5 MB, .test_durations alone 18.5 MB — which is most of what you were trying to avoid. Cone mode also only takes whole directories, so it drags in all of bin/ when you wanted one script.

• filter: blob:none is counterproductive if the job then materializes the tree. It removes blobs from the fetch, but git checkout immediately lazy-fetches every blob in HEAD in a second round trip, which is slower than having fetched them in the pack. That lazy fetch also intermittently fails its per-blob credential lookup with could not read Username for github.com (#59779, blocked a merge until retried). Pair blob:none with sparse-checkout so the lazy fetch is a handful of blobs, or drop it and take the plain depth-1 checkout.

• Default: plain actions/checkout (depth 1). Add nothing.

• Diffing against the PR base: you need real history, so bound the depth, filter blobs, and sparse-checkout the files the job reads:

  - uses: actions/checkout@<sha> # v6
    with:
      fetch-depth: 1000
      filter: blob:none
      sparse-checkout: .github/actions/paths-filter
      sparse-checkout-cone-mode: false
  - name: Fetch PR base for affected diff
    if: github.event_name == 'pull_request'
    env:
      BASE_REF: ${{ github.event.pull_request.base.ref }}
    run: git fetch --no-tags --depth=1000 --filter=blob:none origin "$BASE_REF:refs/remotes/origin/$BASE_REF"
  

  A sparse working tree does not affect git merge-base, git diff <a>...<b>, git log --name-status, git ls-tree, git ls-files, or git show <rev>:<path> — those read the object database or the index. Only commands that compare against the worktree (git diff HEAD, git status) see the skip-worktree entries. One caveat when blob:none is also set: git show <rev>:<path> still needs that blob, and a sparse checkout never downloaded it, so the read becomes a lazy fetch that can fail. Name any file a step reads that way in the sparse set — ci-dagster.yml does this for docker-compose.base.yml, whose contents feed a cache key.

• changes / paths-filter gating jobs: on pull_request the vendored .github/actions/paths-filter diffs via the GitHub API and never touches the tree. The only reason to check out is that a local action must exist on disk, so sparse-checkout .github/actions/paths-filter plus any file the job's own steps read. Never pass base: HEAD to paths-filter from a sparse job — that routes it to git diff HEAD, which a sparse worktree makes return nothing, so every downstream job silently skips green.

• Foot-gun: git fetch --deepen=N with no refspec falls back to the wildcard refs/heads/* and pulls every branch. Always pass an explicit, --no-tags, --filter=blob:none refspec scoped to the base ref. (Bumping actions/checkout's own fetch-depth is safe — it uses a scoped refs/pull/N/merge refspec.)

• The linter rejects fetch-depth: 0 unless you add filter: blob:none, use sparse-checkout, or justify it with # hogli-lint: allow-full-depth-checkout -- <reason>. Genuinely full-history jobs: repo mirroring (foss-sync.yml), tag/submodule version math (release-cli.yml, desktop-tag.yml). Most base-diff jobs should use bounded 1000 + blob:none plus a sparse set.

Pinning and tool versions

• Pin every third-party action to a full 40-char commit SHA with a # vX.Y.Z comment. A moved tag can ship malicious code; pinning is also reproducible and skips a per-run GitHub-API version lookup. The only sanctioned exception is a debug-only action. In-repo composites use a local path with no ref (uses: ./.github/actions/pnpm-install).
• Node version comes from .nvmrc — node-version-file: .nvmrc, never a hardcoded node-version:. Sparse-checkout .nvmrc if the job has no checkout.
• Pin setup-uv's version: — an unpinned setup-uv calls the GitHub API on every job and burns the rate limit.

Network fetches

Downloads from outside the runner need retries, or a transient reset becomes a red check with no findings (actionlint died on curl: (35)).

curl -fsSL --retry 5 --retry-all-errors --retry-max-time 60 --connect-timeout 10 -o "$out" "$url"

• --retry-all-errors is the part that catches a reset; plain --retry covers only timeouts and 408/429/5xx, and --retry-connrefused adds ECONNREFUSED, not ECONNRESET.
• Drop it on GitHub API calls: with -f it also retries 403 and 404, spending five more requests on an already-empty token bucket.
• No --retry-delay (it replaces exponential backoff with a fixed wait). Keep -f, or an error page lands in your output file at exit 0.
• Don't retry anything non-idempotent (webhook posts, telemetry), or where a shell loop or readiness wait already retries.

Tokens — dedicated App tokens for high-volume calls

GITHUB_TOKEN shares one ~15k req/hr bucket across every job of every run in the repo; it goes hot at merge peaks and change-detection jobs fail before real work starts. A dedicated GitHub App installation is its own bucket — rate-limit headroom plus blast-radius isolation.

- uses: actions/create-github-app-token@<sha> # v3.1.1
  id: app-token
  # forks can't read org secrets — fall back to github.token
  if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
  with:
    client-id: ${{ vars.GH_APP_POSTHOG_PATHS_FILTER_APP_ID }}
    private-key: ${{ secrets.GH_APP_POSTHOG_PATHS_FILTER_PRIVATE_KEY }}

# a later step consumes the token (falling back to github.token on forks):
- uses: some-action@<sha>
  with:
    token: ${{ steps.app-token.outputs.token || github.token }}

• Right-size, don't over-isolate. One heavy consumer (change detection on a hot matrix) deserves its own app; a long tail of light workflows can share GITHUB_TOKEN. Convention: GH_APP_<PURPOSE>_APP_ID (an org variable — app IDs are not sensitive, and org secret slots are capped at 100) + GH_APP_<PURPOSE>_PRIVATE_KEY (an org secret).
• Cross-repo tokens set explicit owner: + repositories: (least privilege).
• Creating the app + secret is out of scope here — use /managing-github-actions-secrets.

Forks and untrusted PRs (public repo)

Fork pull_request runs (and Dependabot) get a read-only GITHUB_TOKEN and no secrets. Make those runs pass, and never let untrusted code reach a secret.

• Guard secret-needing steps with if: github.event.pull_request.head.repo.full_name == github.repository, and degrade rather than fail (|| github.token, or the raw test outcome).
• Secret-injecting builds (BuildKit --secret, registry login) must skip forks — gate both the changes job and any always() build job (block fork PRs from rust image build).
• Comment or label only on same-repo PRs — the fork token can't write.
• To act on a fork PR with secrets/write (reviewer or label bots), use pull_request_target: base-repo permissions, but it must never check out and run fork code. That's why those workflows can't fold into a pull_request parent.
• First-time contributors need maintainer approval before workflows run (action_required) — expected.

Timeouts

Every job sets timeout-minutes, sized ~2-3x observed max; gate/aggregation jobs get ~5m. The default is 6 hours — a hung job burns paid minutes silently. Caveat: timeout-minutes is invalid on a job that only uses: a reusable workflow — put the timeout inside the called workflow instead.

Caching

Route through the shared composites rather than hand-rolling actions/cache: ./.github/actions/pnpm-install (single pnpm-<os>-<lockhash> key, restore only; pnpm-store-cache.yml writes it on master), astral-sh/setup-uv with enable-cache: true, Depot cache via ./.github/actions/build-n-cache-image. One canonical key per artifact; gate saves to master or key deliberately per-ref. PR-scoped cache writes nobody else can read just fragment the 10 GB LRU cap.

Any job that runs manage.py migrate against a fresh Postgres must restore the master schema dump first, keeping the migrate as a seconds-long top-up. A from-scratch replay of the full migration history grows with every migration merged and already costs more than most jobs' timeout-minutes, so an uncached migrate is a timeout that hasn't fired yet (agent-skills cancelled at 30 min with the checks green). Copy the three steps (compute keys, actions/cache/restore, prime) from ci-agent-skills.yml for compose-stack jobs or ci-rust-flags-integration.yml for service-container jobs; hogli db:restore-schema-fresh reads TARGET_DB to pick the database. A miss falls through to the full migrate, so the restore is never a correctness risk. The only sanctioned exception is a job whose purpose is validating the migration history itself (ci-backend's check-migrations), where a restored dump would mask what it checks.

Runners

depot-ubuntu-<version>[-<vCPU>] for build/compute-heavy jobs (the -4/-8 suffix bumps CPU from the 2-vCPU default); GitHub-hosted for light jobs. New Depot labels must be added to the allow-list in .github/actionlint.yaml or actionlint fails. Details: /depot-github-runners.

Draft vs ready-for-review

The merge gate is the merge queue's run on a trunk-merge/ branch. So a heavy suite runs its narrowed subset on drafts and on ready PRs, and only the queue run takes the full matrix. ci-backend.yml, ci-frontend.yml, ci-storybook.yml, and ci-e2e-playwright.yml all work this way. Exclude the queue with !startsWith(github.head_ref, 'trunk-merge/'), or with draft != true since those PRs open as drafts — not with draft == true.

Still add ready_for_review to the pull_request types — a no-ci draft skips the workflow outright, and that event is what gives it a run — and make aggregator "... Tests Pass" jobs treat skipped as success so drafts still report.

What draft state does decide is the fallback when a selection cannot be trusted (config change, oversized diff, selector crash):

• draft → skip the suite. Its own ready run selects again, so nothing is lost.
• ready → full matrix. No later run on that PR would cover it, and a narrowed run the selector can't vouch for is false confidence.

The real test is not draft-vs-ready, it is whether a later run on this PR exists to defer to. So draft → skip is only valid when the workflow lists ready_for_review in its pull_request types and its "... Tests Pass" aggregator treats skipped as success. Otherwise the fallback is full on drafts too: ci-nodejs.yml has a bare pull_request: trigger, so a skipped draft would never get a second run, and ci-e2e-playwright.yml skips drafts entirely, so there is no draft run to fall back from.

turbo-discover.js (draft ? 'skip' : 'full') and ci-frontend.yml's fall_back are the two reference implementations of the draft/ready split; ci-nodejs.yml and ci-e2e-playwright.yml are the reference for always-full. Foot-gun: if the job that selects tests is cancelled mid-flight, its mode output is empty — normalize empty-mode on a draft to skip, or the draft grabs the full matrix and serializes the ready run behind it.

A selector needs telemetry, or nobody knows whether it bites

A narrowing that falls back on most runs looks identical in the YAML to one that works. The Playwright selector was eligible on 2,783 runs over two weeks and narrowed on 167 of them; the rest fell back, most often on one glob. That is unreadable without an event, so every selector emits one to the DevEx project (347861): posthog-ci-test-selection, posthog-ci-e2e-spec-selection, posthog-ci-jest-selection, posthog-ci-nodejs-selection.

Copy the shape from capture-jest-selection in ci-frontend.yml:

• Emit on full runs too, tagged so they are distinguishable. They are the baseline a narrowed run is measured against.
• Give the fallback a closed category plus an unbounded detail. The category is what you group by; the detail is what tells you which glob to attack.
• Emit the counts from every branch of the selector, including the ones that narrow to nothing.
• continue-on-error, github.run_attempt == '1', and the same-repo if: — telemetry never reds CI, never double-counts a re-run, and forks have no secret.
• Do not duplicate timings. posthog-ci-running-time-job already carries each job's duration; join it on run_id.

What this still does not answer is whether a narrowed run would have caught what broke. Only backend scores that, in tools/test_selection_verdict.py, which reads the run's JUnit and reports recall. The cheap oracle for the rest is the queue: the trunk-merge/** run tests the same code with the full suite, so a failure there whose file was reachable from the diff and was not selected is a miss, at no extra compute.

The hourly master lane

The merge queue's trunk-merge/** run tests every commit before it lands, so re-running a heavy suite on the master push tests a commit that CI already covered. Those suites skip push and take their master coverage — and their Trunk flaky-test baseline — from an hourly schedule: instead.

Crons are offset so the runs do not all fire at once, and the offsets live here rather than in the workflows:

Adding a seventh: pick an unused minute, add the row, and keep the gap at ten minutes.

ci-backend-update-test-timing.yml sits in the table too. It is one small job that merges the artifacts of the hourly runs, not a suite, so it does not need the ten-minute gap.

Give the cron its own concurrency group. cancel-in-progress is false outside pull requests, but GitHub still keeps at most one pending run per group, so a newer run replaces an older pending one. An hourly run that shares the ref group with master pushes therefore holds the group for its whole duration while pushes queue behind it, and each new push discards the previous pending one along with whatever per-commit checks it carried.

group: ${{ github.workflow }}-${{ github.event_name == 'schedule' && 'scheduled' || github.head_ref || github.ref }}

That keeps hourly runs queueing behind each other rather than stacking, and leaves push behavior untouched. ci-backend.yml reaches the same place from the other side: its push arm is already keyed per SHA, so pushes never share a group with the cron. Prefer the 'scheduled' key when the push lane still runs real per-commit work, because a per-SHA push arm also gives up the deduplication that collapses a burst of master pushes into one run.

The paths filter must be skipped on schedule, and every output it feeds must default to true. On a cron the action has nothing to diff against: it gets no base input, so base resolves to the default branch and equals head, and before is set only on push events. It falls back to the last commit alone, so one docs-only commit narrows the hourly run to nothing and reports green having tested almost nothing — a silent failure, not a red one. Guard the step with if: github.event_name != 'push' && github.event_name != 'schedule', and give each consumed output a || 'true' default.

Any step that reads a filter output needs the same schedule arm. ci-dagster.yml's build-matrix is the cautionary case: without it the matrix is [] and the hourly run passes having run no tests.

A lane that stops producing runs is invisible to the master-red alerter: it reads run completions, so a dropped cron reads as unreadable and drops out of evaluation rather than paging. Add every converted workflow to SCHEDULED_GATING_WORKFLOWS in ci-alerts-devex.yml in the same change, or its failures stop paging altogether.

Backwards-compat with unrebased PRs

A workflow edit hits every open PR the instant it merges (it runs against PR-merged-with-master), but companion changes — a new dependency, file, or config — only reach a branch when it rebases. If the workflow starts requiring something unrebased branches lack, every in-flight PR fails before its tests run. Make new behavior degrade gracefully when the prerequisite is absent, or gate it. Roll out a new blocking lint the same way: ship continue-on-error, clear the inbox, promote to blocking.

New-workflow checklist

• Triggers scoped: trigger paths: where the whole workflow is skippable; a required check must still fire on every PR (never paths-gate it into never dispatching).
• Canonical concurrency: block (per-SHA push arm if it publishes on push).
• timeout-minutes on every job (except reusable-caller jobs).
• Checkout names only the paths the job reads (sparse-checkout + cone mode off), or is shallow; bounded 1000 + blob:none only for base diffing.
• Third-party actions SHA-pinned; Node from .nvmrc; setup-uv version pinned.
• External fetches retry (--retry-all-errors), except where a repeat has a side effect.
• High-volume API calls on a dedicated App token with || github.token fork fallback.
• Fork PRs handled: secret-needing steps guarded with the same-repo if:; no secret-injecting build runs on forks.
• Caching through the shared composites; writes gated to master.
• Any job running manage.py migrate restores the master schema dump first, with the migrate as top-up (see Caching).
• Prod image push / deploy dispatch gated per /gating-production-deploys.
• bin/hogli lint:workflows and actionlint pass locally.