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Title: fix(mcp): stabilize authenticated tool discovery by j15z · Pull Request #5754 · simstudioai/sim · GitHub

Open Graph Title: fix(mcp): stabilize authenticated tool discovery by j15z · Pull Request #5754 · simstudioai/sim

X Title: fix(mcp): stabilize authenticated tool discovery by j15z · Pull Request #5754 · simstudioai/sim

Description: Summary Authenticated MCP servers that advertise OAuth can now be added and refreshed with an explicitly configured static Authorization: Bearer ... credential without being diverted into OAuth. The previous fix made the pre-save connection test try the configured header, but runtime discovery still mapped every SDK UnauthorizedError to “authorization required.” This PR makes that classification depend on the server's configured auth type, so static-header servers stay on the normal credential path and only OAuth-configured servers enter OAuth. OAuth-pending connections now remain actionable in Workspace Settings: the persistent server status says OAuth authorization required, and a refresh that cleanly returns to that state says Authorization required instead of the generic Failed / Not Connected. Concrete connection errors still take precedence, so timeouts and other failures are not mislabeled as an OAuth prompt. Discovery publication is ordered end to end. Redis and memory cache adapters allocate a monotonic millisecond mutation token; conditional cache publication and the database lastToolsRefresh compare-and-swap use that same token, so retries, failures, successes, and invalidations choose one winner across both layers. A credential-safe discovery revision covers every connection-affecting field, preserving valid tools across metadata-only edits while failing closed after URL, credential, auth-type, or transport changes. Each retry acquires fresh mutation ownership. Successful, failed, and OAuth-pending status publication share a bounded retry for metadata-only edit races: every attempt rechecks cache ownership and the discovery revision before publishing against the latest row token. If ordering or an atomic cache transition is unavailable, freshly fetched tools may be returned to the current caller but unordered cache/database state is not persisted. Successful discovery returns its exact publication token, so workflow schemas sync only while the post-discovery reread still belongs to that winning published refresh; later success, failure, or invalidation barriers take precedence, and winner-cache, superseded, and degraded unavailable results cannot propagate as winners. Cache invalidation retries reacquire fresh ownership, publish a database barrier only after an atomic delete wins, and never fall back to an unordered delete that could erase a newer discovery. Refresh responses now prove that a newer successful discovery actually won before preserving connected state after a failure: both lastToolsRefresh and lastConnected must advance beyond the request's original snapshot. Invalidation advances the publication token but not lastConnected, so it can no longer hide a real discovery failure behind a stale connected row. Failure counters also recompute through an optimistic JSONB compare-and-swap when success races them. Security-sensitive paths remain bounded: MCP targets still pass domain and SSRF validation, public targets are DNS-pinned when policy permits, and HTTP/2 negotiation does not relax that pinning. Logs contain header names and structural diagnostics but never values, session IDs, or raw upstream bodies, while UI/API errors come from an allowlist. OAuth servers without dynamic client registration return an actionable 422 that directs users to configure a token. The settings copy change consumes only the existing auth type and sanitized error state; it does not alter or expose credentials, headers, tokens, or upstream responses. Related: #5665 and #5595. Type of Change Bug fix New feature Breaking change Documentation Other: ___________ Testing bun run --cwd apps/sim test -- lib/mcp app/api/mcp 'app/workspace/[workspaceId]/settings/components/mcp' — 454 tests passed across all 29 MCP suites, including static Bearer classification, concurrent publication, repeated metadata-only races, ownership-safe invalidation retries, degraded-cache behavior, publication-token-gated workflow sync, secret-safe diagnostics, SSRF pinning, invalidation-only refresh races, and OAuth-specific settings status behavior. bun run check:api-validation:strict — passed with all 964 routes Zod-backed and no boundary-policy drift. Biome on the final review files and git diff --check — passed. Direct GitHub Copilot MCP probes completed initialize and tools/list with 47 tools using both normal and SSRF-pinned transports; the SDK transport carried the session ID without logging it. A full app-suite baseline recorded 10,715 passing tests and 41 known failures in unrelated workflow, webhook, chat, and UI tests. The final review changes were revalidated in the focused suite above. bun run --cwd apps/sim type-check reaches only unrelated shared-worktree dependency errors in fork audit events, recordAuditBatch, and @google-cloud/storage; no MCP TypeScript errors are reported. Reviewer focus: auth-type-aware handling of typed 401s, OAuth-pending UI status with concrete-error precedence, unified cache/database mutation ownership, bounded same-revision status retries, fresh-token invalidation retries, Redis conditional-mutation scripts, winner-only workflow synchronization, fail-closed degraded-cache behavior, and the two-timestamp proof for a racing successful refresh. Checklist Code follows project style guidelines Self-reviewed my changes Tests added/updated and passing No new warnings introduced I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA) Screenshots/Videos N/A — status-copy-only UI change with no layout change.

Open Graph Description: Summary Authenticated MCP servers that advertise OAuth can now be added and refreshed with an explicitly configured static Authorization: Bearer ... credential without being diverted into OAuth. Th...

X Description: Summary Authenticated MCP servers that advertise OAuth can now be added and refreshed with an explicitly configured static Authorization: Bearer ... credential without being diverted into OAuth. Th...

Opengraph URL: https://github.com/simstudioai/sim/pull/5754

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