2.1.258 attaches x-client-request-id only when the base URL is
api.anthropic.com. Since the helper check made this header optional, a
helper that arrived without one gained a freshly generated UUID on a
custom upstream. Attach it only for a first-party upstream or when the
caller actually sent one, and otherwise keep the header absent as the
real client would.
advanced-tool-use-2025-11-20 is sent only while tool search or another
advanced tool-use feature is on the wire, or when the caller asks for it;
2.1.258 no longer attaches it to plain tool declarations (measured: 158
inline tools, no beta). A caller-supplied afk-mode-2026-01-31 is forwarded
between fast-mode and extended-cache-ttl and is an insertion boundary for
the advisor beta.
2.1.258 Haiku helpers offer the same full compression set as the main
thread and never send X-Stainless-Async. x-client-request-id is attached
only when the client's base URL is api.anthropic.com, so the helper
transport check accepts an empty value or a valid UUID and rejects only a
malformed one.
- Check `error.message` and `message` for retry advice on upstream `server_error` responses.
- Treat server errors indicating the request can be retried as eligible overload bootstrap failures.
- Normalize complex constant `oneOf` and `anyOf` tool parameter schemas into equivalent enums to prevent upstream aborts.
- Escape property keys containing dots and colons during schema updates to prevent invalid path splitting.
- Identify terminal `response.incomplete` events with zero output tokens and no content as upstream failures.
Closes: #5551
- Configure upstream connection pool under antigravity.connection-pool with enabled: false by default.
- In short connection mode, set MaxIdleConnsPerHost = -1 with DisableKeepAlives = false, ensuring immediate TCP termination after response body completion without leaking Connection: close request headers.
- When pooling is explicitly enabled (enabled: true), cap idle-conn-timeout at 210s (leaving a 30s safety buffer below Google Frontend's 240s Keep-Alive cutoff) and default max-idle-conns-per-host to 2 (bounded at 100).
- Refactor TransportCache to execute CloseIdleConnections outside the mutex lock during LRU eviction and matching closes.
- Proactively evict and close idle connections on 429 quota exhaustion across Execute, ExecuteStream, and CountTokens.
- Wire hot-reload diff detection and server reload purge hooks for graceful transport pool updates.
- Detect `collaboration-optimize.` tool conflicts during multi-agent v2 request optimization.
- Restore dot-prefixed tool calls back to the collaboration namespace and base tool name in responses.
Closes: #5524
- Ensure Gemini, AI Studio, Vertex, and Antigravity requests end with a user turn to prevent upstream errors when trailing with model content.
- Preserve trailing turns that contain a function response and skip trailing adjustments for `countTokens` actions or Claude models.
- Introduce boundary normalization helpers to validate both leading and trailing turn roles.
Closes: #5358
- Fall back to request payload input items or `previous_response_id` during websocket compaction when transcript snapshot is empty.
- Preserve `previous_response_id` in prepared request body for xAI execution.
Closes: #5205
- Add payload detection and preparation helpers for compaction triggers and summary generation.
- Implement AES-GCM sealing and unsealing to store and restore opaque compaction capsules across turns.
- Support expanding compaction capsules into developer context for downstream turns.
- Provide summary text extraction across Gemini, Claude, and OpenAI response formats.
- Add builders for compaction non-stream JSON responses and SSE stream frames.
Closes: #5094
- Reuse coresession.ExtractSessionInfo across HTTP headers and request payloads to unify canonical session prefix namespaces with the scheduler.
- Extract hierarchical session identities in two phases: initial extraction from request headers on entry, and authoritative deep extraction once request payloads and metadata are available.
- Support Claude Code multi-level subagents (X-Claude-Code-Agent-Id, metadata.agent_id) and Codex thread fork lineages.
- Propagate SessionID and ParentSessionID across ClientRequestMetadata, UsageReporter, and coreusage.Record without root_session_id.
- Include session_id and parent_session_id in queuedUsageDetail for Home LPushUsage forwarding and Redis consumption with self-loop guards.
- Add comprehensive test coverage for canonical headers, body extraction, ghost parent elimination, and self-referential loop guards.
- Mark Codex usage limit errors as credential-scoped across HTTP and WebSocket executors.
- Support both top-level and nested error structures with case-insensitive matching when parsing retry-after resets.
- Propagate prevalidated candidate context to session affinity and built-in selectors during auth selection.
Closes: #5529
- Detect advisor tool calls and advisor results in conversation history.
- Preserve forwarded system prompt blocks in top-level system instead of splicing them into message turns or prepending reminders.
- Prevent message index shifts that break layout bindings for encrypted advisor results and trigger upstream 400 errors.
Closes: #5470
- Require exactly one non-reminder text block matching quota/test/probe/./Hi for probe request matching.
- Identify title helper requests via expanded session title patterns.
- Implement post-payload bidirectional probe reclassification: strip CPA diagnostics and billing tags on probes, while restoring continuity if declassified.
- Preserve caller-owned and payload-supplied diagnostics on probe requests.
- Gate late sensitive-word obfuscation strictly on cloaked requests in Execute and ExecuteStream.
- Add comprehensive end-to-end tests for probe classification, diagnostics isolation, and late cloaking.
- Inject '# Reporting outcomes' system block for Fable 5.1 / Mythos 5.1 models matching Claude Code 2.1.258 tengu_dapper_lagoon behavior.
- Support both string-format and block-array system prompts for Fable reporting injection.
- Add reconcileClaudeCodeFableModelAfterPayload to reconcile model additions when payload rules override model or thinking.
- Reliably re-add reporting block if omitted after payload rules modify system blocks.
- Drop injected thinking.display on Fable models when payload changes thinking type from adaptive to disabled.
- Enhance payload rule path tracking with ancestor target matching in ApplyPayloadConfigWithTrackedPaths.
- Introduce 2.1.258 dynamic betas: thinking-display-updates-2026-08-18, server-side-fallback-2026-06-01, and fallback-credit-2026-03-24.
- Prune effort-2025-11-24 on Haiku models, probes, and when thinking is disabled.
- Prune thinking-display-updates on disabled thinking and probe/helper turns.
- Identify Fable 5.1 / Mythos 5.1 models with boundary checks and inject default fallbacks and adaptive thinking display.
- Strictly pair 1h cache control with extended-cache-ttl-2025-04-11, stripping TTL on probes and subagents.
- Assemble x-anthropic-billing-header strictly following official 2.1.258 binary sequence: cc_version -> cc_entrypoint -> cch -> cc_workload -> cc_is_subagent -> cc_prev_req -> cc_prompt_id.
- Track upstream request-id in thread-safe bounded session continuity state and inject into subsequent turns as cc_prev_req.
- Generate and enforce RFC 4122 UUIDv4 cc_prompt_id per user prompt turn, preserving it across tool continuations while suppressing it on probes and title helpers.
- Detect subagents via agent headers and session metadata to emit cc_is_subagent=true.
- Harmonize diagnostics and continuity lifecycles to prevent uncommitted or truncated streams from corrupting state.
- Exclude x-anthropic-billing-header system blocks from sensitive-word zero-width space injection.
Enforce strict monotonic offset ordering (replacement.start <= last) when
splicing degraded tool provenance IDs to reject unknown zero offsets and
prevent overwriting the payload prefix.
- Map Claude `max_tokens` stop reason to `response.incomplete` with `max_output_tokens` incomplete details.
- Propagate `incomplete` status to trailing output items across streaming and non-streaming responses.
- Defer and track output item finalization to ensure correct status and arguments when turns are truncated.
Closes: #5439
- Add `codex.orphan-delegation-compatibility` configuration option and mirror it to SDK configuration.
- Convert orphan Codex delegation outputs into standard user messages for requests with `X-Openai-Subagent: collab_spawn`.
- Integrate orphan delegation rewriting into OpenAI responses request handling pipeline.
Closes: #5401
- Bump default Claude Code version baseline from 2.1.220 to 2.1.258 to resolve upstream 400 version gate error
- Update Stainless SDK package version to 0.112.1 and runtime version to v26.3.0
- Refresh default device profile, billing header build hashes, and cloaking signatures
- Decouple unconfirmed client OS/Arch test assertions from host runner platform
- Update config.example.yaml and test suites across executor and helps packages
- Bypass short cooldown checks and recording in execution flows when cooling is disabled globally or per auth.
- Skip marking credits permanently disabled and refreshing credit hints when cooling is disabled.
- Export quota cooldown status helper functions for auth and configuration evaluations.
Closes: #4793
- Introduce `HTTPStatusError` to retain upstream HTTP status codes across Antigravity OAuth and project lookup calls.
- Propagate status codes and retry-after metadata from cause errors in `missingAntigravityProjectIDError`.
Closes: #5368
- Preserve pending tool use IDs across message-level system reminders to maintain tool call and result alignment.
- Merge adjacent Gemini request contents for consecutive user and system reminder turns.
- Relax tool response reordering condition and preserve non-response parts in Antigravity executor.
- Align tool results and buffer pending system reminders in OpenAI translator.
Closes: #5354
Close go-git repository handles across store operations and tests to avoid
leaked handles blocking recovery cleanup. Abort recovery before mutating the
worktree when close failures occur and retain backups when rollback fails.
- Add `ParsePluginExecutorResponseUsage` to extract token usage from non-streaming plugin responses across Claude, Gemini, Interactions, Antigravity, and OpenAI/Codex protocols.
- Add `ObservePluginExecutorStreamUsage` to observe and aggregate token usage across streaming chunks.
Closes: #5340
- Route image and video generation requests through `xaiChatBaseURL` so OAuth credentials default to the CLI chat proxy endpoint.
- Update `using_api` and base URL definitions to apply to both HTTP chat and media requests.
Closes: #5335
- Add `advisor-tool-2026-03-01` beta header support when advisor server tools are declared or explicitly requested.
- Ensure proper ordering of the advisor tool beta before advanced tool use and effort betas.
- Inject and preserve advisor tool beta across token counting and fingerprint preservation paths.
Closes: #5330
Track when executor calls cross an upstream transport boundary and use that
signal to keep model/provider errors from being replaced by later local
preparation, selection, or internal failures.
Mark HTTP, websocket, relay, and usage-tracked transports as upstream
attempts, while avoiding marks for local validation, logging, missing
sessions, and successful websocket handshakes before request send.
Parse relative auth expiry metadata and adjust Antigravity refresh timing.
- Inline local `$ref` pointers and strip `$defs` and `definitions` from tool parameter schemas for Moonshot compatibility.
- Ensure tool parameter root objects declare an explicit `type: "object"`.
Closes: #5316
- Support CRLF line endings and skip hidden dot directories in nocopy invariant tests.
- Handle environment variable overrides and skip case-sensitive token priority tests on Windows.
- Use static OS and architecture values in Claude header fingerprint assertions for deterministic test results.
Closes: #5295
- Treat `allowed_warning` status as allowed for shared 5h and 7d rate limit windows.
- Ensure Fable-only rejections with warning-level shared windows remain model-scoped instead of credential-scoped.
Closes: #5275
- Use `newCodexStatusErr` when handling HTTP handshake rejections in WebSocket execution and streaming.
- Ensure rate limit retry-after metadata and error payload details are properly parsed from handshake responses.
Closes: #5270
- Introduce `WebSocketResponseObserver` capability and bump plugin ABI schema version to 4.
- Forward upstream WebSocket response frames from Codex and xAI executors to configured observers.
- Wire `WebSocketResponseObserver` across API handlers and plugin host dispatchers.
Closes: #5248
