Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Stacked on #1441 (McpClient). Part of the codemode rip-out sequence
(itx-next.md §4).

## What

The two-event execution record that replaces codemode's six-event
protocol:

- `events.iterate.com/itx/execution-requested` `{ executionId, code,
vars, context }`
- `events.iterate.com/itx/execution-completed` `{ executionId, ok,
result | error+stack, durationMs, context }`

Both land on the owning project's `/itx` stream (D9-consistent: context
id in the payload).

**Record-only mode**: the events are the durable history, not the
transport — callers get the outcome from the return value/HTTP response,
and everything between the two events is invisible to the stream.
Appends are best-effort, matching the registry's audit posture. Recorded
results are bounded (64k chars, truncated with a preview beyond that);
the full value still returns to the caller.

Mechanically: the loader harness moves out of `fetch.ts` into a shared
`src/itx/run.ts` (`runItxScript()`), `/api/itx/run` becomes a thin
resolve-and-delegate shim, and the response now includes the
`executionId` for correlation. Global-context scripts record no events
(no owning project stream).

The shared runner is the function the upcoming codemode-drop PR points
the inbound-MCP `exec_js` and agent execution paths at.

## Testing

typecheck / lint / format green. New e2e test runs a script via
`/api/itx/run` and asserts both events land on the `/itx` stream with
the returned `executionId` and the correct outcome payload.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Touches dynamic code execution and stream audit payloads; auth stays
at the existing `/api/itx/run` boundary, but execution records and API
response shape change for all script runs.
> 
> **Overview**
> Introduces **record-only** script execution auditing: each
project-context run appends **`execution-requested`** then
**`execution-completed`** on the project **`/itx`** stream (replacing
codemode’s six-event protocol), while callers still get the outcome from
the HTTP/return value.
> 
> The loader harness moves from **`fetch.ts`** into shared
**`runItxScript()`** in **`run.ts`**; **`POST /api/itx/run`** only
resolves access and delegates. Responses now include **`executionId`**
(and on errors too) for correlation. The runner captures isolate
**console** lines, **truncates** large results on the stream (64k),
always emits **completed** even on loader failures, and skips stream
writes for **global** (admin-only) scripts.
> 
> A new e2e test runs a script via **`/api/itx/run`** and asserts both
events match the returned **`executionId`** and result.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
f43fee8. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

<!-- CLOUDFLARE_PREVIEW -->
## Environment Config Lease
<!-- CLOUDFLARE_PREVIEW_STATE -->
<!--
{
  "apps": {
    "os": {
      "appDisplayName": "OS",
      "appSlug": "os",
      "status": "deployed",
      "updatedAt": "2026-06-10T14:04:25.235Z",
      "headSha": "f43fee8b69ae70c6889cdd236fd568c1eab9b671",
      "message": null,
      "publicUrl": "https://os.iterate-preview-7.com",
"runUrl": "https://github.com/iterate/iterate/actions/runs/27281391307",
      "shortSha": "f43fee8"
    },
    "semaphore": {
      "appDisplayName": "Semaphore",
      "appSlug": "semaphore",
      "status": "deployed",
      "updatedAt": "2026-06-10T14:00:32.897Z",
      "headSha": "f43fee8b69ae70c6889cdd236fd568c1eab9b671",
      "message": null,
      "publicUrl": "https://semaphore.iterate-preview-7.com",
"runUrl": "https://github.com/iterate/iterate/actions/runs/27281391307",
      "shortSha": "f43fee8"
    }
  },
  "environmentConfigLease": {
    "dopplerConfig": "preview_7",
    "leasedUntil": 1781103456147,
    "leaseId": "2790f185-d4dc-4d47-8791-eab94eb3ac31",
    "slug": "preview-7",
    "type": "environment-config-lease"
  }
}
-->
<!-- /CLOUDFLARE_PREVIEW_STATE -->
Lease: `preview-7`
Doppler config: `preview_7`
Type: `environment-config-lease`
Leased until: 2026-06-10T14:57:36.147Z

### OS
Status: deployed
Commit: `f43fee8`
Preview: https://os.iterate-preview-7.com
[Workflow
run](https://github.com/iterate/iterate/actions/runs/27281391307)
Updated: 2026-06-10T14:04:25.235Z

### Semaphore
Status: deployed
Commit: `f43fee8`
Preview: https://semaphore.iterate-preview-7.com
[Workflow
run](https://github.com/iterate/iterate/actions/runs/27281391307)
Updated: 2026-06-10T14:00:32.897Z
<!-- /CLOUDFLARE_PREVIEW -->

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>