## Summary
- **Remove `ExecuteToolResult` wrapper** — `execute_tool` is now a
transparent dispatcher that returns the raw `ToolOutput` from underlying
tools. No more `{ toolName, result }` envelope.
- **Type the entire execution chain as `Promise<ToolOutput>`** — from
`ToolExecutorService.dispatch()` through `resolveAndExecute()` to
`execute_tool.execute()`. Zero `Promise<unknown>` remaining in the tool
layer.
- **Use `Extract<ToolExecutionRef, ...>`** for dispatch methods,
enabling exhaustive switch checking and removing `as never` casts.
- **Relax `ToolOutput.result` to accept `null`** — removes `??
undefined` hacks at the boundary with logic function results.
- **Enforce 1-export-per-file** across tool type/interface files (split
`tool-descriptor.type.ts`, `tool-provider.interface.ts`, `tool.type.ts`,
`tool-output.type.ts`, `tool-executor.service.ts`).
- **Simplify error handling** — `wrapWithErrorHandler` and all
meta-errors (tool not found, tool excluded) now return consistent
`ToolOutput` shape with `error` as a plain string.
- **Frontend reads output directly** — removed `unwrapToolOutput`
utility; `ToolStepRenderer` and `ThinkingStepsDisplay` extract
`message`/`error` from the raw output with simple type guards.
- **Add permission error detection** for email tools via
`isInsufficientPermissionsError`, guiding the AI model to suggest
account reconnection instead of hallucinating about visibility settings.
## Test plan
- [ ] AI chat tool calls return visible output (not "null") in the UI
- [ ] Tool errors display correctly in the JSON tree
- [ ] Email draft/send tools return actionable permission errors
- [ ] Code interpreter output renders correctly
- [ ] Thinking steps display tool outputs properly
Made with [Cursor](https://cursor.com)
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
