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Downloads

This guide describes Chromium extension mode and developer sessions. Firefox extension mode does not provide download tracking, PDF printing or network-backed domain policies. See Firefox extension limits. browser_download {action: "list", tabId} reports downloads observed while the debugger is attached to the selected shared tab. Extension mode uses tab-specific browser events, so another tab’s downloads stay private even on the same website. It reports the suggested filename and progress; the local file path is unavailable in this mode. Developer mode reports files in the context’s download directory, including their paths. browser_status shows the directory; the default is ~/.browspark/downloads/<browser>/<context>, while the compatibility choice "chromium" retains ~/.browspark/downloads/<context>. Firefox and Zen developer-mode download tracking requires a build with BiDi download events. See Firefox and Zen coverage. {action: "wait", urlContains, timeoutMs} returns a matching completed download immediately, or waits for one to complete. Use it right after clicking an “Export CSV” button; a file path is included when available.

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PDF

browser_pdf prints the current page like Print → Save as PDF: format (A4, Letter, Legal), landscape, printBackground, scale, and path to write somewhere other than the artifacts directory. Returns the file path.

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Domain policies

browser_policy restricts where a tab may navigate and load resources from. allow is an allow-list (everything else is blocked); block is a deny-list. Subdomains match, non-HTTP schemes always pass, and blocked navigations fail with ERR_BLOCKED_BY_CLIENT.
With default: true the policy applies to every tab the agent opens from now on, which is the way to keep a scraping run on the sites you intend:
status shows the active policy; clear removes it. Policies use CDP Fetch interception on Chromium and BiDi network interception in Firefox and Zen developer sessions, covering subresources as well as top-level navigation. Firefox extension tabs report an unsupported error for these policies. A default policy applies to future agent-created tabs across browsers; a tab policy applies only to its selected tabId.