Playwright Firefox boots the engine: the pref its build lags, and the error that hid it - #103
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… error that hid it Two bugs wearing one symptom. THE BOOT FAILURE: Playwright 1.57.0's Firefox build (144) ships WebAssembly JS Promise Integration DISABLED where release Firefox has it on — which is why the owner's phone runs the app while headless Firefox died at device setup. Everything else the device store needs was measured present under Gecko: module SharedWorkers, OPFS (createWritable; no sync access handles, which the store never asks for), Web Locks, non-extractable CryptoKeys through IndexedDB. The harness now launches Firefox with javascript.options.wasm_js_promise_integration=true — restoring a release default the automation build lags, not granting the page anything a real user's browser lacks — and e2e-deps probes with the same pref so the recipe cannot certify a browser the suite would refuse. THE OPACITY: the banner was honest all along (the engine's own needs-JSPI refusal reached it); the bare 'Error' was Juggler rendering a console.error(errorObject) to an out-of-process observer as the word Error and nothing else — a logging idiom that is lossless under CDP and total loss under Juggler. Boot logging now leads with the string. And the refusal got sharper: the worker probes WebAssembly.Suspending at bringUpEngine — in the SharedWorker, the realm that instantiates, since JSPI availability is per-global — and refuses with a PlatformError (code no-jspi) whose sentence names the missing capability instead of whichever import happened to suspend first. THE GATE: firefox-smoke — the suite's first non-Chromium scenario. It reads the five platform facts out of the page (so a pref that silently stops applying cannot become a green lie), runs the T0 anchor path, and survives a reload. The runner grew per-scenario engine selection with lazy launch; Firefox is ordered last so earlier failures never pay for a second browser. Deliberately not a second matrix: the visor ceremonies are engine-independent. The CI browser cache key gains a -ff suffix: the cache saves only on a miss, so the grown browser set under the old key would have hit forever with a chromium-only archive and re-downloaded Firefox every run. Gates: e2e 24/24 (firefox-smoke 3 acts), invariants 9/9, devstore matrix ALL PASS, deno checks clean.
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Two bugs wearing one symptom (the solo page dying opaquely under headless Playwright Firefox):
WebAssembly.Suspendingundefined by default; function withjavascript.options.wasm_js_promise_integration=true), and everything else the device store needs was measured present under Gecko: module SharedWorkers, OPFS viacreateWritable, Web Locks, non-extractable CryptoKeys through IndexedDB. The harness sets the pref — restoring a release default the automation build lags, not granting the page anything real users lack — ande2e-depsprobes with the same pref so it can't certify a browser the suite would refuse.Errorwas Juggler renderingconsole.error(errorObject)as the word "Error" — lossless under CDP, total loss under Juggler. Boot logging now leads with the string, and the worker refuses early with aPlatformError(no-jspi) whose sentence names the missing capability ("this browser cannot run the engine: it has no WebAssembly JS Promise Integration…") instead of whichever import happened to suspend first. Probed in the SharedWorker, the realm that instantiates — JSPI availability is per-global.firefox-smoke, the suite's first non-Chromium scenario — reads the five platform facts out of the page (a silently-lapsed pref cannot become a green lie), runs the T0 anchor path, survives a reload. Runner grows per-scenario engine selection with lazy launch, ordered last so earlier failures never pay for a second browser.-ff— the cache saves only on a miss, so the grown browser set under the old key would have re-downloaded Firefox ~90MB on every run forever.Gates: e2e 24/24, invariants 9/9, devstore matrix ALL PASS.