Enable rubber duck and /rubber-duck command#318662
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…duck command Add chat.agentHost.rubberDuck.enabled setting (default-on for insiders/dev, hidden from stable) that gates the RUBBER_DUCK_AGENT feature flag. The flag flows from the VS Code setting through the agent host starters into the CLI subprocess environment. Add /rubber-duck slash command that invokes the critic subagent for an independent review of the current approach. The command is only visible when the feature is enabled.
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Pull request overview
This PR wires up the “Rubber Duck” critic subagent in the Agent Host by introducing a dedicated VS Code setting that controls propagation of a RUBBER_DUCK_AGENT env var into the agent-host process, and adds a /rubber-duck slash command surfaced via Copilot CLI completions and handled in the Copilot agent session.
Changes:
- Register
chat.agentHost.rubberDuck.enabled(default enabled for non-stable builds) and plumb it through both Node and Electron agent-host starters viaRUBBER_DUCK_AGENT. - Add
/rubber-duckto Copilot CLI slash-command parsing and completion, with completion visibility gated byRUBBER_DUCK_AGENT. - Add tests covering parsing, completion behavior, and env var gating.
Show a summary per file
| File | Description |
|---|---|
| src/vs/platform/agentHost/test/node/copilotSlashCommandCompletionProvider.test.ts | Adds tests for /rubber-duck parse + completion + env-gated visibility |
| src/vs/platform/agentHost/node/nodeAgentHostStarter.ts | Reads new setting and sets RUBBER_DUCK_AGENT in agent-host env |
| src/vs/platform/agentHost/node/copilot/copilotSlashCommandCompletionProvider.ts | Adds /rubber-duck command + env-gated completion visibility |
| src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts | Dispatches /rubber-duck by injecting a critic-invocation prompt |
| src/vs/platform/agentHost/node/copilot/copilotAgent.ts | Removes hardcoded RUBBER_DUCK_AGENT enablement |
| src/vs/platform/agentHost/electron-main/electronAgentHostStarter.ts | Adds the same setting→env wiring for the Electron utility-process starter |
| src/vs/platform/agentHost/common/agentService.ts | Introduces AgentHostRubberDuckEnabledSettingId constant |
| src/vs/platform/agentHost/common/agentHostStarter.config.contribution.ts | Registers the new configuration setting (non-stable only) |
Copilot's findings
- Files reviewed: 8/8 changed files
- Comments generated: 2
digitarald
changed the title
…, fix test env save/restore
…k-agent # Conflicts: # src/vs/platform/agentHost/node/copilot/copilotSlashCommandCompletionProvider.ts # src/vs/platform/agentHost/test/common/agentHostFileSystemProvider.test.ts # src/vs/platform/agentHost/test/node/copilotSlashCommandCompletionProvider.test.ts
connor4312
approved these changes
May 30, 2026
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Summary
Enables the Rubber Duck critic subagent in the Agent Host — an independent reviewer that uses a complementary model family (Claude↔GPT at the same tier) to catch bugs, logic errors, and design flaws before they ship.
https://docs.github.com/en/copilot/concepts/agents/copilot-cli/rubber-duck