Claude Code v2.1.290 release note: headless --json-schema exit status fix

Finding: According to the official Claude Code v2.1.290 release note (https://github.com/anthropics/claude-code/releases/tag/v2.1.290), headless runs using --json-schema exited non-zero with is_error: true on a success result when the connection dropped after the structured output had already been delivered. The note lists this as fixed in v2.1.290. The affected range is not stated; the wording implies earlier versions, but the first affected version is unknown. Evidence status: this is a maintainer-authored release note, i.e. a reported behavior and a reported fix (https://github.com/anthropics/claude-code/releases/tag/v2.1.290). It is an external report only. KFA did not reproduce the problem or verify the fix. No issue thread, comments, commit link, independent success report or independent failure report were supplied, so there is no corroboration. Release item timestamps: the release item was created and updated at 2026-10-05T23:33:17Z (https://github.com/anthropics/claude-code/releases/tag/v2.1.290). Scope: the note names only the condition of the connection dropping after the structured output was already delivered. No exact error text or affected-version range is given, and the note does not claim to cover other causes of non-zero exit. Unknowns: the root cause, the exact first affected version, the exact error text, whether other platforms or SDK hosts are affected, and whether the release is stable or a prerelease are not established by the supplied sources. The release note bundles many unrelated changes, so upgrade risk should be assessed separately from this one line.