fix: client-cancelled GET /v0/servers returns 499 without error log#1335
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rdimitrov merged 3 commits intoJun 5, 2026
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Avoid error-level logs and double WriteHeader when GET /v0/servers clients disconnect mid-stream. Closes modelcontextprotocol#1323. Co-authored-by: Cursor <cursoragent@cursor.com>
Export ListServersError, use errors.As and v0_test package. Co-authored-by: Cursor <cursoragent@cursor.com>
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…#1338) ## Summary Fixes the information-disclosure regression introduced by #1335 (item 1 of #1337). `ListServersError` passed the raw `err` into `huma.Error500InternalServerError(...)`. huma serializes extra error args into the response body's `errors` array (`ErrorModel.Errors`, `json:"errors,omitempty"`), so on the **public, unauthenticated** `GET /v0/servers` endpoint a genuine DB failure echoed the internal wrapped error from `internal/database/postgres.go` (`error iterating rows: <pgx error>`) back to the client. pgx/pgconn errors can carry SQLSTATE codes, constraint/table/column names, and internal messages (CWE-209). ## Change - Drop `err` from the 500 call so only the generic message is returned; keep `log.Printf` for the server-side detail — matching the sibling handlers (`servers.go:190/220`, `edit.go`, `status.go`). - Add a regression test (`TestListServersError_realFailureDoesNotLeakDetail`) that marshals the 500 error and asserts the internal detail is absent from the client-visible body. Existing tests only asserted status codes, which is why the leak slipped through. The 499 client-cancelled path is unchanged (the client has already disconnected, so nothing is leaked there). ## Test plan - [x] `go test ./internal/api/handlers/v0/... -run ListServersError` (3/3 pass) - [x] `go build ./...`, `go vet`, `golangci-lint` (no new findings in changed files) ## Note This leaves the non-security items in #1337 (correcting the `superfluous WriteHeader` claim, `statusClientClosed` const reuse, broader cancellation-guard scope) for separate follow-up. Closing #1337 here since the only security-impacting item is addressed; reopen/split if you'd prefer to track the nits independently. Closes #1337 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
context.CanceledfromListServersto HTTP 499 instead of 500list servers failederror-level logging when the client disconnects mid-streamsuperfluous response.WriteHeaderwarnings on closed socketsCloses #1323
Test plan
go test ./internal/api/handlers/v0/... -run ListServersErrorMade with Cursor