fix(mcp): preserve tool failure status and patch ExcelJS UUID

[HomenShum]

Summary

A coding agent can currently receive isError: false when a screenshot or image tool returns an explicit failure. The failure is hidden inside a successful content array, so status tracking also records success. This change returns the existing error object from those failure paths and uses the dispatcher's classified result for the MCP reply and execution records. Successful text and image blocks retain their order and bytes, including literal text that contains the word error.

The security audit now records raw tool calls before the early return, distinguishes authorization from execution outcome, and bounds buffered writes to 256 entries. Database statement/transaction failures stay inside the audit error boundary. Failed tool results no longer receive a success-only quick reference.

A separate commit scopes UUID11.1.1 to the ExcelJS development dependency. ExcelJS's actual CommonJS caller uses zero-argument v4() for workbook conditional-format IDs. The patched dependency preserves that contract and removes the two local moderate audit entries. This is not evidence that the advisory's affected buffer APIs were reachable through ExcelJS.

Two commits, nine existing files. Package version and declared Node support remain unchanged. This draft is awaiting independent final review; it is not a package release.

Validation

• MCP package build (npm run build in packages/mcp-local).
• Current ordinary MCP package suite (npm test): 390 passed, one skipped, eight files on Windows/Node22.22.2; unchanged test deadlines and worker configuration.
• Nineteen new scenarios cover missing optional dependencies, capture failures, invalid frames, controlled provider failures, successful content preservation, image recovery and repeated audit failures/recovery.
• Actual compiled stdio proof: 78 calls, 39 saved/returned PNGs, 70 expected records in each of three native databases, concurrent requests, recovery and restart. Eight deliberately failed persistence calls retain truthful replies but have no durable rows; they are not counted as successful persistence.
• Fresh exact local package installation and full audit: zero findings. This package has no committed lock; the Windows resolution and original installation are retained as local evidence.
• Workbook proof before and after UUID change: 24 exports and 120 rows per lane, six concurrent exports followed by 18 sequential exports, conditional-format IDs, ExcelJS reopen and actual compiled MCP table readback. Office-rendered visual quality was not tested.
• Independent final source/dependency review: unavailable due delegated-agent account usage limit.
• Whole application typecheck, Convex typecheck, root build and required shared checks: await this PR's actual results. Package checks do not certify the application.

The first ordinary package run had 389 passes, one XLSX timeout at 20 seconds and one skip. A selected observer passed; the current ordinary run after the dependency installation also passes. The timeout's cause remains unassigned. No claim is made that UUID repaired that timeout, and the failed run is retained.

The accepted image/protocol proof predates the UUID-only commit. Its eight source owners, 582 compiled files and seven selected native/protocol dependency files were verified unchanged; that successful proof was not replayed to change the dependency audit.

Release Notes

• Raw capture/image failures become explicit MCP failures; existing successful content is preserved.
• Security audit storage is bounded and contains write failures. Audit data can still be lost while storage is unavailable; this change does not provide durable retry.
• ExcelJS development installs use patched UUID11.1.1. No npm version bump, publication, consumer adoption or full UI/provider readiness is included.
• Required checks expected: Typecheck, Runtime smoke, Build, Tier B vs preview URL, plus the existing MCP Delta gate and repository style checks. Missing or skipped checks are not treated as passes.
• The remote fix/ review branch follows this repository's enforced branch policy; it points to the exact commits retained locally on codex/mcp-error-status-20260908.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
nodebench-ai	Ready	Preview	Sep 8, 2026 8:35am UTC