AI Chat with document

AI Chat is a sidebar where you ask questions about the PDF you are reading. Answers come from an AI agent CLI running on your computer — SumatraPDF does not send your files to its own servers.

Available in pre-release 3.7+ on Windows 10 or later.

Most often you open View → Claude chat (or another backend) and type a question. At a glance:

Four backends: Claude Code, Grok Build, OpenAI Codex, and Antigravity.
Per-tab sessions: each document tab has its own conversation.
Resume: pick a previous session from the session dropdown.
Options: model, effort level or sandbox mode, per backend.
Stop: cancel a reply in progress.

Nothing happens unless you explicitly invoke it. SumatraPDF never starts an AI agent or sends document content to an AI service on its own. An agent CLI runs only when you open a chat panel, send a message, or use an AI translate-selection command. To decide whether to show AI commands in menus, SumatraPDF only checks if the CLI executable exists on disk.

Open a chat #

Open a PDF (see Supported documents), then:

Menu: View → Claude chat (CmdAIChatWithClaudeCode), View → Grok chat (CmdAIChatWithGrokBuild), View → Codex chat (CmdAIChatWithOpenAICodex), or View → Antigravity chat (CmdAIChatWithAntiGravity).
Context menu: AI chat with document using → Grok Build, OpenAI Codex, Claude Code, or Antigravity.
Command Palette: Ctrl + K, then Claude chat..., Codex chat..., Grok chat... or Antigravity chat....
Keyboard: no default key binding; assign your own — see Customize keyboard shortcuts.

Drag the splitter between the document and the chat panel to resize the sidebar.

Ask a question #

Type a question in the input box at the bottom of the sidebar and press Enter. While the agent is working on a reply, use Stop to cancel the current request.

Each document tab has its own chat session. Switching tabs switches the sidebar to that tab’s conversation history.

Resume a previous session #

Pick a previous session from the session dropdown. SumatraPDF lists and resumes sessions for the current document’s folder. Each CLI stores history in its own location:

Claude Code: ~/.claude/projects/ (encoded by project directory)
Grok Build: ~/.grok/sessions/
OpenAI Codex: ~/.codex/sessions/ (with descriptions from ~/.codex/history.jsonl)
Antigravity: ~/.gemini/antigravity/projects/, ~/.gemini/antigravity-cli/projects/, or ~/.gemini/projects/ (encoded by project directory)

Choose model and options #

Backend-specific controls in the sidebar:

Claude Code: model, effort level, and optionally Skip Permissions (passes --dangerously-skip-permissions — use only if you understand the security implications).
Grok Build: model, effort level, and optionally Always Approve (passes --always-approve).
OpenAI Codex: model, sandbox mode, and optionally Skip Sandbox.
Antigravity: model, effort level, and Auto Approve (on by default).

Defaults are saved in advanced settings (see Settings).

Tips #

Assign a shortcut to your preferred chat command; there is none by default.
Leave Skip Permissions / Skip Sandbox off unless you understand the security implications.
Keep Auto Approve on for Antigravity; without it the agent can’t read the document.
If a CLI isn’t found, put it on PATH or in one of the folders listed for that backend below.

Supported documents #

AI Chat is available only for PDF (.pdf) files.

It is not available for single images, comic archives (.cbr, .cbz, etc.), folders of images, DjVu, ebooks (EPUB, MOBI, …), CHM, XPS, PostScript, plain text, and other formats. On those tabs the AI chat with document commands and context-menu submenu are hidden.

Set up a backend #

Claude Code #

This feature requires Claude Code to be installed and available on your system. SumatraPDF launches the claude command-line tool when you send a message.

If Claude Code is missing, the chat panel shows an error such as Cannot find claude. Is Claude Code installed?

Install and set up Claude Code using Anthropic’s official guide:

Set up Claude Code

After installation, make sure claude (or claude.exe) is on your PATH. SumatraPDF also looks in %USERPROFILE%\.local\bin\, %USERPROFILE%\AppData\Local\Programs\claude-code\, and %USERPROFILE%\AppData\Roaming\npm\.

The model picker includes Claude Code’s documented aliases: default, best, sonnet, opus, haiku, sonnet[1m], opus[1m], and opusplan. Claude Code resolves these aliases according to the user’s account and configured provider.

Grok Build #

This feature can also use Grok Build (the grok command-line tool).

If Grok Build is missing, the chat panel shows an error such as Cannot find grok. Is Grok Build installed?

Install Grok Build and sign in using xAI’s instructions. SumatraPDF looks for grok.exe on PATH, in %USERPROFILE%\.grok\bin\, and in %USERPROFILE%\.local\bin\.

Open the panel with View → Grok chat (CmdAIChatWithGrokBuild), or Ctrl + K, Grok chat... command in Command Palette.

Grok Build settings are in the GrokBuild section of advanced settings. The Always Approve checkbox passes --always-approve to Grok Build.

The first time you open the Grok chat panel in an app session, SumatraPDF runs grok models and uses the models available to the signed-in Grok CLI in the model picker. If that query fails, the picker falls back to grok-4.5.

OpenAI Codex #

This feature can also use OpenAI Codex (the codex command-line tool).

If OpenAI Codex is missing, the chat panel shows an error such as Cannot find codex. Is OpenAI Codex installed?

Install and sign in using OpenAI’s official guides:

After installation, make sure codex (or codex.exe) is on your PATH, or in %USERPROFILE%\.codex\bin\ or %USERPROFILE%\.local\bin\.

Open the panel with View → Codex chat (CmdAIChatWithOpenAICodex), or Ctrl + K, Codex chat... command in Command Palette.

Codex settings are in the CodexBuild section of advanced settings. The Skip Sandbox checkbox passes --dangerously-bypass-approvals-and-sandbox to Codex — use only if you understand the security implications.

The first time you open the Codex chat panel in an app session, SumatraPDF asks the signed-in Codex CLI which models are available and uses them in the model picker. If that query fails, the picker falls back to gpt-5.5, gpt-5.4, and o3. You can also pick a sandbox mode: Read-only, Workspace write, or Full access.

Antigravity #

This feature can also use Google’s Antigravity CLI (the antigravity or agy command-line tool).

If Antigravity is missing, the chat panel shows an error such as Cannot find antigravity. Is Antigravity installed?

Install Antigravity and sign in using Google’s instructions. SumatraPDF looks for antigravity.exe or agy.exe on PATH, in %USERPROFILE%\.local\bin\, %USERPROFILE%\.gemini\antigravity-cli\bin\, %USERPROFILE%\AppData\Local\agy\bin\, %USERPROFILE%\AppData\Roaming\Antigravity\bin\, %USERPROFILE%\AppData\Local\Programs\, and %USERPROFILE%\AppData\Roaming\npm\.

Open the panel with View → Antigravity chat (CmdAIChatWithAntiGravity), or Ctrl + K, Antigravity chat... command in Command Palette.

Antigravity settings are in the AntiGravity section of advanced settings. The Auto Approve checkbox passes --dangerously-skip-permissions to Antigravity. It is on by default: the CLI can’t ask for permissions when run non-interactively, so without it the agent can’t read the document. It also lets the agent use other tools without asking.

The first time you open the Antigravity chat panel in an app session, SumatraPDF runs agy models and uses the models available to the signed-in CLI in the model picker. If that query fails, the picker falls back to a built-in list of Gemini 3.8 / 3.7 / 3.6 Flash, Gemini 3.1 Pro, Claude Sonnet / Opus 4.6, and GPT-OSS 120B models. The default is gemini-3.8-flash-medium. Add more model IDs, comma-separated, with the Models setting.

Settings #

Sidebar width is shared by all backends via the AIChatSidebarDx advanced setting.

Backend-specific options are in advanced settings (SumatraPDF-settings.txt):

ClaudeCode — default model, effort level, Skip Permissions, background color
GrokBuild — default model, effort level, Always Approve, background color
CodexBuild — default model, extra models, sandbox mode, Skip Sandbox, background color
AntiGravity — default model, extra models, effort level, Auto Approve, background color

Requirements and limitations #

Windows 10+ only (uses WebView2 for the chat UI).
Requires a working installation of at least one supported agent CLI and network access as required by that CLI.
Each agent runs as a separate process; behavior, models, and billing follow that provider’s terms and your account.