Clean up tool output architecture: remove wrappers, enforce ToolOutput everywhere (#19321)

## 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)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/twenty-server/src/engine/metadata-modules/ai/ai-agent-execution/services/agent-async-executor.service.ts

@@ -12,7 +12,7 @@ import { type ActorMetadata } from 'twenty-shared/types';
 import { isDefined } from 'twenty-shared/utils';
 import { type Repository } from 'typeorm';
 
-import { type ToolProviderContext } from 'src/engine/core-modules/tool-provider/interfaces/tool-provider.interface';
+import { type ToolProviderContext } from 'src/engine/core-modules/tool-provider/interfaces/tool-provider-context.type';
 
 import { isUserAuthContext } from 'src/engine/core-modules/auth/guards/is-user-auth-context.guard';
 import { type WorkspaceAuthContext } from 'src/engine/core-modules/auth/types/workspace-auth-context.type';

packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/services/chat-execution.service.ts

@@ -17,7 +17,7 @@ import { getAppPath, isDefined } from 'twenty-shared/utils';
 
 import { UsageOperationType } from 'src/engine/core-modules/usage/enums/usage-operation-type.enum';
 
-import { type CodeExecutionStreamEmitter } from 'src/engine/core-modules/tool-provider/interfaces/tool-provider.interface';
+import { type CodeExecutionStreamEmitter } from 'src/engine/core-modules/tool-provider/interfaces/code-execution-stream-emitter.type';
 
 import { CodeInterpreterService } from 'src/engine/core-modules/code-interpreter/code-interpreter.service';
 import { WorkspaceDomainsService } from 'src/engine/core-modules/domain/workspace-domains/services/workspace-domains.service';

packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/services/system-prompt-builder.service.ts

@@ -10,7 +10,7 @@ import {
   LEARN_TOOLS_TOOL_NAME,
   LOAD_SKILL_TOOL_NAME,
 } from 'src/engine/core-modules/tool-provider/tools';
-import { type ToolIndexEntry } from 'src/engine/core-modules/tool-provider/types/tool-descriptor.type';
+import { type ToolIndexEntry } from 'src/engine/core-modules/tool-provider/types/tool-index-entry.type';
 import {
   AgentActorContextService,
   type UserContext,