Who this helps: creative-ops teams that ship marketing PNGs from Figma or similar tools and must prove WCAG contrast before campaigns land in email or paid social. What you build: on a remote Mac, OpenClaw supervises a debounced folder watch on the design export inbox, runs AA or stricter AAA ratio gates from a checked-in manifest, writes JSONL evidence, applies classified retries, and hands designers a batch re-export template listing only failing SKUs. How this differs from generic export watchdogs: the unit of quality is accessibility math on declared colors, not dimensions, POT geometry, or sequence frames—pair those other pipelines when needed.
Table of Contents
Why contrast slips through static PNG QA
- Hex drift: designers tweak variables after export; the PNG on disk no longer matches the spreadsheet marketing approved.
- Silent passes: raster checks for width and ICC run nightly, but nobody scores headline color against background until legal asks.
- Retry noise: aggressive auto-retry on every failed gate hides true data faults and burns GPU time on a shared remote Mac.
Anchor the operational story in a designer handoff: every drop contains PNG bytes plus a contrast-manifest.yaml row per asset. Ops watches the folder, not the chat thread. For broader compliance overlays, see the PNG reference review pipeline; for debounce and archive discipline, reuse the watch, retry, and log archive HowTo.
Threshold and evidence matrix
| WCAG profile | Normal text minimum | Large text minimum | Typical marketing use |
|---|---|---|---|
| AA (default gate) | 4.5:1 | 3:1 | Body copy on flat brand fills |
| AAA headline | 7:1 | 4.5:1 | Regulated finance or health promos |
| Log evidence | JSONL fields: trace_id, sku, ratio, threshold_profile, pass, retry_class |
||
Reproducible setup steps
- Install and scope OpenClaw. Follow the OpenClaw install guide for all platforms, bind the Gateway to loopback, and allowlist only the export root, manifest path,
quarantine/,templates/, andlogs/. - Publish the manifest with exports. Each row lists
png_path,fg_hex,bg_hex,text_size_class(normalorlargeper WCAG), and optionalprofile(aaoraaa). Designers commit the same file to Git as the creative brief. - Create the watch loop. On APFS NVMe, ignore
*.tmpand.DS_Store, require two stable size polls, then sleep a quiet window—forty-five to ninety seconds is typical for large PNGs—before callingopenclaw job enqueuewith the manifest path. Single-flight withflockso parallel saves do not duplicate jobs. - Implement the contrast Skill. Convert hex to sRGB linear channels, apply the WCAG contrast formula, compare against the profile, and emit structured pass or fail with the numeric ratio. Keep the Skill read-only on source PNGs; move failures to
quarantine/only after the log line fsyncs. - Classify retries. Retry transient faults—file busy, Gateway five-zero-three—up to three attempts with backoff capped at ninety seconds. Route data faults, including missing manifest rows or impossible hex, to
quarantine/with no automatic retry until design updates YAML. - Emit the batch re-export template. For each failing
sku, append a CSV row consumed by a Figma plugin or a macOS Shortcut preset checked intotemplates/reexport.csv. Designers rerun only those frames; passers sync topass/YYYY-MM-DD/. Social sizing context stays aligned with the social banner PNG decision matrix. - Rotate logs. Write
logs/YYYY-MM-DD.jsonl, gzip files older than seven days, and attach the last twenty lines plus manifest hash when paging on-call.
Citable knobs for your runbook
- Quiet window: start at sixty seconds when exporters write companion previews; lower only after you measure stable close events.
- Disk floor: pause enqueue when free space on the job volume drops below fifteen gigabytes so contrast Skills never run out of temp space mid-batch.
- Trace correlation: reuse the same
trace_idacross watch enqueue, Skill invoke, and re-export CSV so designers can grep one id from Slack to disk.
FAQ
Can we auto-fix contrast inside the PNG?
Not as a silent step for brand assets. Automation should flag, log, and drive a controlled re-export with designer-approved color tokens—not mutate pixels in place without review.
What if the background is a gradient or photo?
Manifest mode still works when design declares a worst-case solid sampled from the gradient stops. For photographic heroes, add a second optional raster probe Skill and accept slower jobs; document that separately from this flat-pair recipe.
Does the Gateway need GPU access?
Contrast math from hex is CPU-only. Keep GPU scopes disabled unless you later add perceptual previews.
Summary: combine a designer manifest, a debounced watch, WCAG AA or AAA gates, JSONL receipts, and a CSV re-export template so marketing PNG drops stay provable without re-reading every pixel by hand. Browse the homepage, Tech Insights, or rent or buy a Mac node without signing in; connection steps live in the SSH and VNC help page.
Run OpenClaw WCAG contrast jobs on a dedicated remote Mac
Offload marketing PNG gates from laptops to Apple Silicon hosts with stable disks, public help docs, and a clear rent or buy path—no account wall for those entry pages.