VS Code Copilot Chat

  • ID: copilot-chat
  • Store: VS Code User folder workspaceStorage/<hash>/chatSessions/<sessionId>.jsonl (flat .json on older builds); empty-window chats under globalStorage/emptyWindowChatSessions/. Code, Code Insiders and VSCodium hosts. Not Copilot CLI (copilot).
  • Read override: DEJA_COPILOT_CHAT_ROOTS (path list of User folders)
  • Format: JSONL mutation log (kind 0 initial / 1 set / 2 push / 3 delete) or whole-file JSON; full re-parse per pass. Compaction rewrites the file, so a byte-offset resume would apply deltas to state it never saw.

workspace.json next to chatSessions holds {"folder":"file:///…"} (or workspace for a multi-root .code-workspace); the project name is the last path segment. Empty-window sessions take workingDirectory the same way, or -. inputState is not read (it carries the GitHub account label).

User turns are message as a string or {text}. Assistant speech is bare {value} markdown chunks (and a plain string in old files); thinking and UI chrome (progressMessage, warning, info, systemNotification) are skipped. Tool paths come from toolInvocationSerialized.resultDetails and inlineReference; terminal commands from toolSpecificData.commandLine.

  • MCP: deja install vscode writes the user mcp.json VS Code reads in agent mode (top-level servers, type: stdio). Verified on VS Code 1.134.0: Copilot Chat started the server and called the deja tool with mode: recall.
  • Skill: the same install writes <User>/prompts/deja.instructions.md with applyTo: "**", VS Code's custom instructions, which are in front of the model on every chat. Verified on 1.134.0: with that file and no mention of deja in the question, Copilot Chat called recall on its own.
  • Command: not wired. Copilot Chat has no user-level command file deja knows how to write; the MCP prompt deja serves is listed (prompts/list) but its slash form is unverified.
  • Auto-recall: none in the hook sense — Copilot Chat has no session-start or per-prompt event. The instructions file is what makes recall arrive without being asked for.
  • Resume: Chat: Show Chats… in the editor, not a command.
  • Handoff: paste.

Last verified: 2026-09-06

deja reads this format and twenty-four others, and turns what it finds into memory your agents can search. See the harness matrix for what is wired where, or install it and search your own history.