.polychat File Extension

What kind of file is a .polychat?

A .polychat file represents a conversation with Poly's built-in agent. Poly identifies it with the application/vnd.polyapp.conversation MIME type. The conversation behaves like a file in Poly, with a title, location, timestamps, permissions, and searchable content.

The file shown in Finder or File Explorer is normally a zero-byte placeholder, not a transcript container. Poly keeps the conversation turns and state with the synced file record. Because the placeholder is empty, it has no magic number, header, or text encoding to inspect.

How do I open a .polychat on my computer?

Open it with Poly on Windows or macOS. The desktop app registers .polychat as a Poly Conversation and resolves a placeholder in the Poly sync location to the corresponding conversation record. Windows applications can register filename extensions, while macOS apps declare proprietary file types with Uniform Type Identifiers.¹²

A text editor, browser, or generic conversion tool cannot recover the conversation from the empty file. If a copied placeholder does not open, return to the original Poly workspace and locate the synced conversation there.

Poly support for .polychat

Poly provides its complete conversation experience for .polychat. Opening the file displays the stored user and agent turns. Poly indexes the filename and readable conversation text for full-text search, and the agent can use the transcript as context when the conversation continues.

Those capabilities come from the conversation record, not from parsing the local placeholder. The empty file itself contains no searchable transcript. Structured tool activity is not presented as ordinary conversation text.

History of .polychat

Poly introduced the .polychat suffix and its canonical conversation MIME type in 2026. The vnd. part of application/vnd.polyapp.conversation follows the vendor-tree naming convention that RFC 6838 defines for product-associated media types.³ The type is not listed in IANA's media-type registry, so it is a Poly-specific identifier rather than an open interchange standard.⁴

Working with .polychat and alternatives

Treat .polychat as a doorway into a synced Poly conversation, not as a portable chat archive. It is useful for opening, organizing, syncing, and searching conversations inside Poly, but its zero-byte placeholder is not an independent backup.

For a portable record:

• Copy the visible conversation into Markdown or plain text.
• Print the rendered conversation to PDF when your browser or operating system offers that workflow.
• Open the exported file and confirm that it contains the expected text before relying on it.

Renaming discussion.polychat to discussion.txt does not convert it. The renamed file remains empty and contains no transcript to recover.