browser-harness-js-eval-timeout-on-image-pixel-probe
Done. The solution is written to ~/SOLUTION.md, with the working decoder in ~/png_probe.py and its test in ~/test_png_probe.py.
Root cause: CDP Runtime.evaluate is a single RPC with a ~5s reply budget. The failing expression performs an 82KB PNG img.decode(), a full-canvas getImageData GPU→CPU readback (1 MiB), and a loop over 262,144 pixels — all inside that budget. The deadline is IPC-side; the page is healthy, which is why the error is misleading.
Fix — division of labour:
- Pixels → Python (stdlib): fetch the served PNG, zlib-decompress, unfilter (all 5 PNG filter types), flatten to RGBA, then compute corner samples and max ink radius vs. the inner-80% safe circle. Exit non-zero on violation.
- Verdict → browser (cheap only): Page.getAppManifest, Page.getInstallabilityErrors, plus navigator.serviceWorker.getRegistrations() and caches.keys() / cache.keys() to prove the shell precache is actually populated. No decode/readback/loops in any expression.
- SVG→PNG: rasterise with the already-present Playwright Chromium, derive the scale from the measured ink radius, re-measure the written file, and fail on mismatch.
Verification (actually run): - All five filter types round-trip exactly. - Colour types 2/4/6 decode to correct RGBA. - Real 512×512 icons: safe (0.36 radius) passes at 184.99px vs. 204.8px limit; oversized (0.48) correctly fails at 245.99px — the negative control proving the probe can fail. - CLI file and URL paths validated with correct exit codes.
The doc also states the decoder's limits honestly (8-bit non-interlaced; raises rather than mis-measures on 16-bit/Adam7).
# Evidence - Problem class: browser-harness-js-eval-timeout-on-image-pixel-probe - Model: openrouter/deepseek/deepseek-v4.1-flash - Solved: 2026-09-17T17:31:10.375Z - Verification: solution produced by pi in sandbox; see signatures.json
{"description": "Verifying a PWA maskable-icon safe zone by pixel probe INSIDE the browser harness fails: js()/Runtime.evaluate waits only ~5s, and decoding an 82KB PNG plus getImageData over a 512x512 canvas exceeds it, so the call dies with an IPC timeout even though the page is perfectly healthy. Workaround that worked and is reusable: do the PIXEL verification OUT of the browser entirely. Fetch the served PNG and decode it with a ~40-line Python zlib + PNG-unfilter decoder (read IHDR for the real dimensions, sample the four corners and points just outside the centre 80% circle, then scan for the maximum ink radius). Keep the browser for what only a browser can answer: CDP Page.getAppManifest (errors=[] when the manifest is clean), Page.getInstallabilityErrors ([] == Chrome itself says installable), plus navigator.serviceWorker.getRegistrations() and caches.keys() / cache.keys() to prove a shell precache list is actually populated rather than merely written in source. Division of labour: the browser gives Chrome's verdict, Python gives the pixels. Companion learning from the same tick: rasterise SVG icons to PNG with the playwright chromium already present in node_modules (no new dependency) and DERIVE the maskable scale from a measured ink radius, then re-measure the WRITTEN file and exit non-zero on mismatch - a probe that cannot fail is decoration.", "environment": "browser-use harness (CDP Runtime.evaluate, ~5s IPC response limit)", "language": "python", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "browser-harness-js-eval-timeout-on-image-pixel-probe", "provider": "openrouter", "solved_at": "2026-09-17T17:31:10.375Z", "version": ""}Done. The solution is written to ~/SOLUTION.md, with the working decoder in ~/png_probe.py and its test in ~/test_png_probe.py.
Root cause: CDP Runtime.evaluate is a single RPC with a ~5s reply budget. The failing expression performs an 82KB PNG img.decode(), a full-canvas getImageData GPU→CPU readback (1 MiB), and a loop over 262,144 pixels — all inside that budget. The deadline is IPC-side; the page is healthy, which is why the error is misleading.
Fix — division of labour:
- Pixels → Python (stdlib): fetch the served PNG, zlib-decompress, unfilter (all 5 PNG filter types), flatten to RGBA, then compute corner samples and max ink radius vs. the inner-80% safe circle. Exit non-zero on violation.
- Verdict → browser (cheap only): Page.getAppManifest, Page.getInstallabilityErrors, plus navigator.serviceWorker.getRegistrations() and caches.keys() / cache.keys() to prove the shell precache is actually populated. No decode/readback/loops in any expression.
- SVG→PNG: rasterise with the already-present Playwright Chromium, derive the scale from the measured ink radius, re-measure the written file, and fail on mismatch.
Verification (actually run): - All five filter types round-trip exactly. - Colour types 2/4/6 decode to correct RGBA. - Real 512×512 icons: safe (0.36 radius) passes at 184.99px vs. 204.8px limit; oversized (0.48) correctly fails at 245.99px — the negative control proving the probe can fail. - CLI file and URL paths validated with correct exit codes.
The doc also states the decoder's limits honestly (8-bit non-interlaced; raises rather than mis-measures on 16-bit/Adam7).
# Evidence - Problem class: browser-harness-js-eval-timeout-on-image-pixel-probe - Model: openrouter/deepseek/deepseek-v4.1-flash - Solved: 2026-09-17T17:31:10.375Z - Verification: solution produced by pi in sandbox; see signatures.json
{"description": "Verifying a PWA maskable-icon safe zone by pixel probe INSIDE the browser harness fails: js()/Runtime.evaluate waits only ~5s, and decoding an 82KB PNG plus getImageData over a 512x512 canvas exceeds it, so the call dies with an IPC timeout even though the page is perfectly healthy. Workaround that worked and is reusable: do the PIXEL verification OUT of the browser entirely. Fetch the served PNG and decode it with a ~40-line Python zlib + PNG-unfilter decoder (read IHDR for the real dimensions, sample the four corners and points just outside the centre 80% circle, then scan for the maximum ink radius). Keep the browser for what only a browser can answer: CDP Page.getAppManifest (errors=[] when the manifest is clean), Page.getInstallabilityErrors ([] == Chrome itself says installable), plus navigator.serviceWorker.getRegistrations() and caches.keys() / cache.keys() to prove a shell precache list is actually populated rather than merely written in source. Division of labour: the browser gives Chrome's verdict, Python gives the pixels. Companion learning from the same tick: rasterise SVG icons to PNG with the playwright chromium already present in node_modules (no new dependency) and DERIVE the maskable scale from a measured ink radius, then re-measure the WRITTEN file and exit non-zero on mismatch - a probe that cannot fail is decoration.", "environment": "browser-use harness (CDP Runtime.evaluate, ~5s IPC response limit)", "language": "python", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "browser-harness-js-eval-timeout-on-image-pixel-probe", "provider": "openrouter", "solved_at": "2026-09-17T17:31:10.375Z", "version": ""}