feat(vscode): cancel in-flight requests with Escape.

[arpan7sarkar]

Description

Implements #758

Pressing Escape in the VS Code extension's chat panel now cancels an in-flight LLM request, mirroring the existing Stop button. The listener is bound on the webview's document (not just the chat input) so it fires even when focus has moved to a tool card, dropdown, or the streaming response area, and it's guarded by isProcessing so it's a no-op when idle. Also added a nanocoder.cancel command for the Command Palette.

While wiring this up, found that cancelling mid-stream surfaced as a Nanocoder prompt failed: RequestError: Internal error toast — AcpAgent.prompt was throwing a generic error on abort, and the ACP JSON-RPC layer flattened it into an opaque failure. Fixed that too: cancellation is now recognized explicitly, reported inline in the chat as "Cancelled by user", and resolved with stopReason: 'cancelled' instead of rejecting. NanocoderAcpClient also tracks an in-flight cancel client-side and suppresses the toast for it, so this holds even against a CLI build that hasn't picked up the agent-side change. Genuine errors still show the toast as before.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Changeset

• Added a changeset (pnpm changeset) describing this change for the changelog

Docs-only or internal chores need no changeset (or run pnpm changeset --empty to note that intentionally).

Testing

Automated Tests

• New features include passing tests in .spec.ts/tsx files
• All existing tests pass (pnpm test:all completes successfully)
• Tests cover both success and error scenarios

Manual Testing

• Tested with Ollama
• Tested with OpenRouter
• Tested with OpenAI-compatible API
• Tested MCP integration (if applicable)

Checklist

• Code follows project style guidelines
• Self-review completed
• Documentation updated (if needed)
• No breaking changes (or clearly documented)
• Appropriate logging added using structured logging (see CONTRIBUTING.md)

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[arpan7sarkar]

Hey @akramcodez do check it out and let me know if any changes are needed .

[arpan7sarkar]

Hey @will-lamerton , @Avtrkrb , @akramcodez , Do check this functionlity out , its perfectly working let me now if any change is needed , else merge it
Thanks

[akramcodez]

LGTM @arpan7sarkar, amazing work on this!

[arpan7sarkar]

Thanks @akramcodez , now waiting for another review :)