dsh-browser-view · Live Browser View for DeepSeek Harness (DSH)

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A browser the agent drives, watched from a tab beside the chat. The host half owns a dedicated Chromium over the devtools protocol; the browser half contributes one right-sidebar tab type, so the page stays in view while the agent verifies it.

This package is an external plugin for DeepSeek Harness (DSH), structured as a cordis bundle: src/index.ts is the host half (Chrome process, CDP sessions, tab registry, WebSocket fan-out, agent tools) and src/client/ is the browser half (the sidebar tab body and its chip).

What it does

• A live tab, not a screenshot poll: CDP Page.startScreencast frames arrive over one WebSocket and are painted as they come. The tab shows the active page, its URL and title, and what the agent last did.
• Eleven agent tools: browser_navigate, browser_click, browser_type, browser_press, browser_scroll, browser_snapshot, browser_screenshot, browser_console, browser_network, browser_tabs, browser_close (closes only the tabs this session opened).
• Evidence in the conversation: every browser_screenshot result carries the image, so the transcript keeps the picture the agent acted on instead of only a sentence about it.
• One dedicated browser: the plugin launches its own Chromium with a throwaway profile. It never attaches to a browser you are signed into.
• Signs itself in to this host's own GUI: a fresh profile has no session cookie, so the viewer would only ever see the 401 challenge. When a navigation lands on that challenge over loopback, the plugin asks the host's connection service for the same ticketed URL dsh web printed, and retries once. The cookie that mints lives in the throwaway profile and dies with it.

How it works

agent tool call ──► host half ──► CDP ──► dedicated Chromium
                        │
                        └─ screencast frames ──► WebSocket ──► sidebar tab body

The host half starts Chrome lazily on the first tool call or the first tab mount, pins a viewport, and keeps a ring of console entries and network requests per tab so a verification can be read back without re-running the page. A top-level document replacement clears both rings; a same-document navigation (hash, query, SPA pushState) keeps them.

Interface seats

Seat	Kind	What lands there
sidebar.right.pane.tab	keyed, session	the tab body
sidebar.right.pane.tab.title	keyed, session	the chip text and glyph

The conversation header carries no entry for this tab: the column's own tab strip and the guide capsule already open it, and a third place to click was only crowding that row.

The tab type is registered with ctx.sidebarRightTabs.register and opened with ctx.sidebarRight.openTabIn. Its kind is browser-view, deliberately not browser: the shipped @deepseek-ai/dsh-client-ui-sidebar-browser owns that kind, and a second registration in the extension band takes a kind over, which would shadow the shipped tab out of existence.

The single-occupant rightbar / rightbar.session seats are still not touched: they belong to the column itself, not to the tabs inside it.

Security model

• Loopback only: the panel socket is fenced to loopback requests; a non-local client is rejected before the upgrade.
• Throwaway profile: Chrome runs on a fresh --user-data-dir under the system temp directory with a random debugging port, so no cookie, session or extension of the user's real browser is reachable.
• Headless by default: nothing pops up on the desktop; the tab is the only view.
• Process lifetime: the Chromium child is killed when the plugin disposes. Nothing is left running behind a closed session.
• Token handling: the launch token is minted per navigation, held in memory, and never written to disk; the retry only happens on a loopback target whose document is DSH's own challenge, so no other local service is ever handed the token.

Known limits

• The tab is a view. Input comes from the agent through the tools; it does not forward your mouse or keyboard.
• The tab lives inside the right sidebar, so it needs that column; a layout that hides the column hides the tab.
• Frames are produced when the page changes, so a static page holds the last frame instead of streaming duplicates.
• Switching chips keeps the body mounted (keepMounted), so the socket survives; the frame still waits for the next change.
• The token top-up only covers the site root, because DSH answers the challenge with a 303 to ./ for GET / alone.
• One browser process per host; tabs are isolated CDP targets, not separate profiles.
• Chrome must be installed at a standard location (or named by CHROME_PATH).

Install

dsh plugin --profile web add link:<this repo>/packages/dsh-browser-view

The plugin row is read at startup, so a DSH restart is required after installing or changing it.

Development

pnpm --filter @linxin666/dsh-client-ui-browser-view typecheck
pnpm --filter @linxin666/dsh-client-ui-browser-view test
pnpm --filter @linxin666/dsh-client-ui-browser-view build