v0.7.56

• session/list is answered by the upstream session index for a client that declares _meta.alwith.capabilities: ["sessionIndex"], with standard rows: top-level archived, _meta.codex.{projectId,nativeSessionId,forkedFromId}, titles repaired where the native preview starts with a prompt envelope. The exported client declares it. Removed: _codex/session_list, the fork's own list and rollout fork index, and threadSource on session/new, session/fork, lineage and SessionSummary. A v2 client that declares neither index gets upstream's legacy list and archive-on-delete.
• A failed turn's _meta.codex.error carries the adapter's own failure classification, the one its AIR session failures use: kind (CodexFailureKind), category and actions. The fork's second taxonomy (category such as usage_limit, retryable, stopReason) is gone; codexTurnError returns kind, category, actions and retryable derived from actions. Retrying a failed turn follows the same policy.
• Reply envelopes are parsed by upstream's parseAsyncQuestionReply; session titles are derived with upstream's attachment-envelope reader. The fork's sessionConfig.ts is gone.
• An external provider's HTTP 402 (DeepSeek's exhausted balance) reaches Codex as its usage-limit error instead of a retried connection failure. The turn error names the provider host, the 402 and the provider's message, and the thread keeps it; the proxy diagnostic records the upstream status.