Chained defects made the kagane browser-fetch path completely non-functional
in Docker Compose: headless-shell's compose command re-declared
--remote-debugging-port, colliding with the image's own entrypoint/socat
proxy (EOF on every dial); the sidecar was then only reachable by Docker DNS
name, which Chrome's DevTools HTTP handler rejects with a 500
(Host-header/DNS-rebinding check); and NewBrowserFetcher's NoModifyURL option
skipped /json/version discovery entirely, dialing a bare host:port that
Chrome 404s since /devtools/browser/<uuid> is minted fresh per Chrome start.
Fixed by trimming the redundant command flags, pinning headless-shell to a
static IP so BROWSER_WS_URL can name it directly, and removing NoModifyURL so
chromedp's discovery (which echoes the request's Host back into
webSocketDebuggerUrl) does the right thing on its own.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
sulthan