Kimi Webbridge

Kimi Browser Extension (formerly Kimi WebBridge)

Control the user's real browser (with their login sessions) via a local daemon at http://127.0.0.1:10086.

Tools

Tabs and the current tab

Single-tab tools (snapshot, click, fill, screenshot, save_as_pdf) act on the current tab — the one you most recently opened with navigate or selected with find_tab.

• Opening pages: use newTab:true when pages should coexist (comparing, cross-referencing); omit it to send the current tab to a new URL.
• Going back to an earlier tab: call find_tab to make a tab you opened earlier in this session the current one again. Pass the tab's full URL — take it from list_tabs or the earlier navigate result. A bare root domain (kimi.com) may miss a www.kimi.com tab, so prefer the exact URL. By default find_tab searches only this session's own tabs — it never reaches into the user's other tabs or windows.
• Acting on a page the user already has open: pass active:true ("use my open X tab" / "the X page I'm viewing"). It borrows the tab the user is currently viewing (returns borrowed:true); the borrowed tab is operated in place — it is not pulled into the session's tab group.
• If find_tab errors with "no tab matching … in this session", the page isn't open in this session — navigate with newTab:true instead.

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curl -s -X POST http://127.0.0.1:10086/command \
  -d '{"action":"find_tab","args":{"url":"https://www.kimi.com","active":true},"session":"k26-research"}'

Call Format

Every command carries a top-level session naming the current task — see Sessions below. The examples in later sections omit it only for brevity; in real calls always include it. The command format depends on the user's OS.

macOS / Linux — inline JSON is fine:

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curl -s -X POST http://127.0.0.1:10086/command \
  -H 'Content-Type: application/json' \
  -d '{"action":"navigate","args":{"url":"https://example.com","newTab":true,"group_title":"My task"},"session":"my-task"}'

If the inline call fails — a shell quoting/syntax error from bash, or an HTTP 400 from the daemon — do not retry the same command unchanged. Resend the request as a file body:

1. Write the JSON body to a uniquely-named temp file with your own file-write tool — never with shell echo/heredoc, which mangles the JSON the same way. Use a fresh name per request (e.g. /tmp/webbridge-req-<random>.json).
2. POST the file:

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curl -s -X POST http://127.0.0.1:10086/command -H 'Content-Type: application/json' --data-binary @/tmp/webbridge-req-<random>.json

3. Delete the temp file as soon as the request returns.

Windows (PowerShell / cmd) — the shell corrupts non-ASCII characters (Chinese etc.) carried inline in command arguments or pipes; they reach the daemon as ? and the text is unrecoverable. Send every request as a file body instead:

1. Write the JSON body to a uniquely-named temp file with your own file-write tool — never with shell echo/heredoc, which corrupts non-ASCII the same way. Give every request its own filename with a random suffix (e.g. webbridge-req-<random>.json) so concurrent requests never share a file and overwrite each other.
2. POST the file with curl.exe — always curl.exe, never bare curl, which Windows PowerShell aliases to Invoke-WebRequest:

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curl.exe -s -X POST http://127.0.0.1:10086/command -H "Content-Type: application/json" --data-binary "@$env:TEMP\webbridge-req-<random>.json"

3. Delete the temp file as soon as the request returns — don't leave request bodies on disk.

Sessions

One task = one session = one tab group. A session collects every tab the task opens into one tab group, so the user sees a single group for "what the agent is doing right now". Pass it as a top-level field of the request body (not inside args).

• Pick one session name at the task's start, put it on every command, and never switch mid-task — even across different sites. Switching session names per site is the #1 cause of fragmented tab groups.
• Name it after the task, not the site (camping-research, phone-compare). Use multiple sessions only for genuinely unrelated parallel tasks.
• group_title is the human-readable group label — write it in the user's language, on the first navigate of the task.
• When you create the group (the first navigate of a task), tell the user once that this task's pages are collected under group «title», and that you'll close them whenever they ask.

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# First tab: set session + a human label (in the user's language)
curl -s -X POST http://127.0.0.1:10086/command \
  -d '{"action":"navigate","args":{"url":"https://www.kimi.com","newTab":true,"group_title":"K2.6 feature research"},"session":"k26-research"}'
# Another site, same task → same session → joins the same group automatically
curl -s -X POST http://127.0.0.1:10086/command \
  -d '{"action":"navigate","args":{"url":"https://www.moonshot.cn","newTab":true},"session":"k26-research"}'

Closing is always user-initiated: call close_session only when the user explicitly asks ("close those", "clear the tabs"). It clears the whole group in one call.

Screenshots

The daemon writes the image to disk and returns {format, path, sizeBytes, mimeType} — never base64, since the model can't read raw image bytes. Take the .path and open it with the Read tool to actually see it.

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# Default: PNG of the visible viewport, daemon picks a temp path
curl ... -d '{"action":"screenshot","args":{}}'
# Options (each independent): JPEG quality, element-only via @e/CSS selector, custom output path
curl ... -d '{"action":"screenshot","args":{"format":"jpeg","quality":60}}'
curl ... -d '{"action":"screenshot","args":{"selector":"@e123"}}'

A caller-supplied path is honored verbatim (parent dirs created, existing file overwritten) — use a unique name to avoid clobbering. save_as_pdf follows the same rule.

Prefer snapshot over CSS/JS selectors

snapshot returns interactive elements with @e refs based on semantic role/name. Use them directly with click/fill — they survive CSS class hash changes that break manually-written selectors.

Fall back to evaluate (JS) only when:

• The target has no @e ref in the snapshot
• You need attributes not in the snapshot (e.g., href)
• You need to dispatch complex event sequences, or scroll

Evaluate Tips

• Always use compact JSON.stringify(data) — never add null, 2 formatting. Indentation and newlines can inflate the response several times over, causing truncation during transmission.
• evaluate calls share the page's JS realm — re-declaring the same const/let across two calls throws SyntaxError. Wrap in an IIFE for a fresh scope: (() => { const x = ...; return x; })().

Text input — use fill

fill (selector = CSS or @e ref, plus the value) works on <input>/<textarea> (returns mode: "value") and on [contenteditable] rich editors — ProseMirror, TipTap, Lexical, Slate, Quill, etc. (returns mode: "contenteditable"), firing the right input events so the page reacts.

fill is clear-and-insert: existing content is replaced. To append, read the current value via evaluate, concatenate, then fill with the result.

Form submit / special keys

There's no separate "press Enter" tool. To submit a form, click the submit button directly (click on the @e ref or selector). To dispatch a key event programmatically (e.g. Escape to close a modal):

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{"action":"evaluate","args":{"code":"document.activeElement.dispatchEvent(new KeyboardEvent('keydown',{key:'Escape',bubbles:true}))"}}

Save the current page as PDF

save_as_pdf renders the current page to PDF and returns the file path. All args optional:

• paper_format: letter (default) | a4 | legal | a3 | tabloid
• landscape: false (default)
• scale: 1.0 (default), range [0.1, 2.0]
• print_background: true (default) — keep background colors
• path: caller-supplied output path; if absent, daemon picks a default under OS temp dir using the page title as the filename

path semantics match screenshot: written verbatim, parent dirs auto-created, existing files overwritten.

Decoded PDF cap is 100 MB. Above that the daemon refuses; reduce scale or split the page.

Known limitations

• Sites that strictly check event.isTrusted (some banking portals, captchas) ignore click / fill because those fire DOM-level synthetic events (isTrusted=false). For these, tell the user the page needs manual interaction. (Trusted input is possible at the protocol level via the cdp escape hatch, but treat that as advanced.)
• Cross-origin iframes: fill, click, evaluate, and snapshot operate on the top frame. If a target element lives in a same-page iframe from a different origin (e.g. embedded sandbox demos), navigate to the iframe's URL directly instead.

If a tool call fails (daemon or extension not ready)

If a tool call can't reach the daemon (connection refused), start it yourself — don't ask the user. This is safe to run anytime: it no-ops if the daemon is already up.

macOS / Linux:

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~/.kimi-webbridge/bin/kimi-webbridge start

Windows (PowerShell):

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& "$env:USERPROFILE\.kimi-webbridge\bin\kimi-webbridge.exe" start

Then retry the tool call. If it still fails — or the browser extension won't connect — point the user to the help page instead of deep-troubleshooting:

• English: https://www.kimi.com/en/products/kimi-webbridge
• 中文: https://www.kimi.com/products/kimi-webbridge

Never run stop / restart / uninstall automatically — those kill a running daemon. See references/operations.md for anything deeper.

Version mismatches

If a tool returns an error containing "Please update the Kimi Browser Extension", the user's browser extension is older than this skill. Don't try to reconcile versions yourself — just tell the user, in their language, to update the extension and retry:

• English: https://www.kimi.com/en/products/kimi-webbridge
• 中文: https://www.kimi.com/products/kimi-webbridge