1.9.1: upload files through the sandbox browser's live view

[TonsOfFun]

Release: 1.9.1. This PR changes browser-sidecar/, and @activeagents/browser-sidecar@1.9.0 is already on npm, identical to main's browser-sidecar/. So it bumps activeagent, actionagent and the sidecar to 1.9.1 (CI requires the sidecar's version to equal ActionAgent::VERSION). The 1.9.1 release must publish the sidecar, as a staged npm publish (#585) that a maintainer approves.

Stacked on #584 (base feat/claude-code-boot-setup). Retarget to main once #584 merges.

File upload in the sandbox browser's live view

• Before this, clicking a page's file input while driving the live view opened a chooser inside the headless Chromium that nobody could see.
• Sidecar (browser-sidecar/lib/file-upload.mjs, FileChooserRelay): listens for Playwright filechooser events. A chooser opened while a person holds control is offered to the live view as { type: "file_chooser", chooser: { id, multiple, accept, max_files, max_file_bytes } }, and it's included in ready for viewers who join later. A chooser opened while nobody drives is left to Playwright MCP's browser_file_upload, so agents behave as before. The listener is attached only while someone drives, so a headed window's native dialog still opens the rest of the time.
• Transport: the existing live-view WebSocket, with the same ticket auth and control lock. The client sends file_upload { chooser, files }, then file_chunk (base64, 32 KiB per message, under the 64 KiB cap) or file_cancel. Replies report progress, done, or failed with a code.
• Storage: files go to a per-chooser directory under the sidecar's workdir (0700 directories, 0600 files, one subdirectory per file), then fileChooser.setFiles(paths). They're kept until the browser stops, because the page reads them from disk lazily.
• Withdrawn when: the driver cancels, hands back control, or sends nothing for 5 minutes.
• Playwright MCP modal state: when a person answers or cancels, the relay clears the MCP "File chooser" modal state so later agent tool calls aren't blocked. This reaches into MCP through a private symbol, best-effort, and the real-Chromium smoke test covers it.
• Dashboard (LiveView.jsx, utils/liveView.mjs): the driver gets an overlay with a real <input type=file> (honouring multiple and accept) plus Cancel, and can drop files on the frame while the chooser is open. Counts and sizes are checked before sending, sending waits when more than 1 MiB is queued, and progress shows as a percentage. Other viewers see "The page is asking for a file."
• Project page: the Browser tab's copy mentions uploads again (1.9.0: fix a failed boot with Claude Code, and the sandbox browser on the project page #584 removed it).

Limits (sidecar live config; Ruby doesn't set these yet)

Key	Default
upload_max_file_bytes	25 MiB
upload_max_files	10 per chooser (0 turns uploads off; a single-file input takes 1)
upload_max_session_bytes	250 MiB per browser session

Security

• Only the connection holding control can answer, and only the chooser currently offered. Watchers never receive file bytes.
• File names are reduced to their last segment with control and reserved characters and leading dots removed, capped at 200 bytes. Names and contents are never logged or recorded; the recording gets a file_uploaded marker with the count and bytes.
• accept is advisory, as it is in browsers.
• Uploaded files live outside Playwright MCP's uploads directory.

Tests

• browser-sidecar: 145 pass, 0 skipped, including a real-Chromium run: click through the live view, upload, the page reads the file, and the agent isn't blocked.
• frontend: 591 pass.
• actionagent (Ruby 4.0.6): 1688 runs, 0 failures, 7 skips.
• rubocop: clean.

Open questions

• Should a person be able to answer a chooser an agent opened? Today it's left to the agent.
• Dropping files on a page's own drop zone isn't supported; drop works only while a chooser is open.
• Ruby can't pass the upload_max_* limits to the sidecar yet, in either the local or the Incus backend.

🤖 Generated with Claude Code

https://claude.ai/code/session_01CJAKwnkBaCGr5qjCcmc3kh