Terminal Duck
A runtime-aware rubber duck for VS Code. @duck is a chat participant that sees the commands you actually ran in the integrated terminal — with their exit codes and output — and grounds its answers in that history instead of making you copy-paste.
How it works
Terminal Duck subscribes to VS Code's terminal shell integration events and keeps a rolling buffer of your last 20 commands (command line, working directory, exit code, captured output). When you ask @duck something in Copilot Chat, it includes the most recent executions as context for the LLM.
Requirements
- VS Code
^1.95.0
- GitHub Copilot Chat installed and signed in — Terminal Duck uses the
vscode.lm API, which routes through Copilot's entitlement
- An integrated terminal with shell integration active (default for bash, zsh, fish, and pwsh in recent VS Code)
Install
Install from the VS Code Marketplace:
- From VS Code: open the Extensions view, search for
Terminal Duck, and click Install.
- From the command line:
code --install-extension DarrenJaworski.terminal-duck
Or grab the .vsix from the latest GitHub release and use Extensions view → ... (More Actions) → Install from VSIX....
Usage
- Run some commands in the integrated terminal.
- Open Copilot Chat and type
@duck why did my last test fail? (or any follow-up question).
- Duck cites the specific command and exit code when relevant.
Example prompts:
@duck what's going wrong with my build?@duck the last command hung — what should I try?@duck I ran three things, give me a summary
Slash commands
| Command |
What it does |
@duck /fix |
Finds the most recent failing command and proposes a single concrete fix. |
@duck /rerun |
Suggests the next command to run — retry with different flags, or the natural follow-up step. |
@duck /explain |
Explains what the most recent command did and what its output means. |
Terminal Duck also registers a #duck tool via the lm.tools API. Any chat participant or Copilot agent-mode session can call it to fetch your recent terminal activity.
In Copilot Chat, reference it explicitly with #duck to include recent commands in the prompt:
#duck why might the test runner be picking up the wrong config?
Agents can invoke terminal-duck_getRecentCommands programmatically; accepts an optional limit (1–20, default 6).
Commands
| Command |
Description |
Terminal Duck: Clear captured shell history |
Wipes the in-memory command buffer. |
Caveats
- Shell integration must be active. If your terminal is a plain PTY (or you're running inside a shell VS Code doesn't recognise), Duck has nothing to work with and will say so.
- Output is truncated at ~8 KB per command to keep the LLM context tight.
- History lives in memory only — it resets when the extension reloads.
Development
npm install
npm run kitchen-sink # format:check, lint, typecheck, test, compile, package
Press F5 in VS Code to launch an Extension Development Host with Terminal Duck loaded.
License
MIT — see LICENSE.
