- Map upstream `model_not_found` errors to HTTP 404 before evaluating generic invalid request types in Codex terminal error handling.
- Prevent treating structured model not found responses as client request faults to preserve credential rotation.
- Recognize model access denial errors to apply model-level cooldown and failover.
- Respect `disable_cooling` configuration during model-level cooldown processing.
Closes: #5635
- Broaden pattern matching for Codex model capacity errors.
- Classify model capacity rejections as overload bootstrap failures to enable failover.
Closes: #5634
- Format streaming error payloads with nested error objects matching official OpenAI Responses SSE specifications.
- Extract and propagate sequence numbers from upstream terminal events and framer states.
- Use `json.Number` to prevent precision loss for large integers and token metrics.
- Sanitize sensitive keys recursively across nested error objects without dropping custom fields.
- Retain `cache_control` blocks with 1h TTL and `extended-cache-ttl` beta header when explicitly requested by subagents.
- Detect 1h TTL configuration from request payloads and incoming Anthropic-Beta headers.
- Ensure `extended-cache-ttl` beta header is preserved or injected when 1h TTL is present.
Closes: #5629
- Register builtin model definitions for `gpt-image-2.5`, `gpt-image-2.5-flare`, and `gpt-image-2.5-sunburst`.
- Update OpenAI image handlers and request routing to recognize GPT Image 2.5 models.
- Support direct image generation and edit execution for GPT Image 2.5 variants in the Codex executor.
- Apply client visibility overrides to hide new builtin image models where appropriate.
- Initialize `util.SessionIDResolver` to resolve session IDs from request contexts, metadata, and headers.
- Ensure canonical session metadata is injected into execution options across execution flows.
- Propagate session context in executors to support `$CPA-SESSION-ID` expansion in custom headers.
- Sync cleared or updated session identities back to execution contexts during conductor execution.
Closes: #5690
- Check for \u in fast-path check to prevent JSON Unicode escapes from bypassing inspection.
- Inspect regex keys under patternProperties and drop keys with unsupported Unicode property escapes.
- Add tests covering Unicode escape representations (\u005c, \u0070, \u0050) and patternProperties keys.
- Add HasUnsupportedUnicodePropertyEscape in internal/util to detect \p{...} / \P{...} escapes that fail Python re compilation.
- Strip incompatible pattern attributes during tool parameter normalization in codex/claude and openai/claude translators.
- Provide schema-aware fallback stripping in codex executor helps to protect downstream Codex requests without mutating non-schema user data.
- Export unified schema keyword lists in internal/util to eliminate duplication.
- Add comprehensive unit tests covering Artifact fixtures, lookaheads, and user data preservation.
Closes: #5644
- Add `model-level-cooling` configuration option to Codex settings.
- Scope `usage_limit_reached` quota cooldowns to the requested model instead of the entire credential when enabled.
- Propagate model-level cooling checks across HTTP, SSE, and WebSocket execution paths.
Closes: #5619
- Emit an OpenAI-compatible trailing usage chunk with an empty choices array on `message_stop`.
- Include `cache_write_tokens` in prompt token details for OpenAI response translations.
- Parse usage from `message.usage` and buffer Claude stream usage across chunks to merge input and output token counts.
- Ensure observed streaming usage details are published on completion or stream failure.
Closes: #5617
Repair placeholder functionResponse names with part-local sjson and one
Index splice of the request body, matching the sibling content-edit path
instead of one full-body sjson.SetBytes per repaired name.
- Add shortMode, idleConnTimeout, and maxIdleConnsPerHost to antigravityTransportKey.
- Prevent stale transport reuse during hot-reload race windows under load.
- Add TestAntigravityTransportKeySeparatesPoolSettingsAcrossReload regression test.
- Route `openai-response` source format requests to dedicated streaming and non-streaming responses handlers.
- Add upstream URL resolution for Kimi Responses API endpoints based on auth attributes.
- Normalize `openai-response` provider format to codex during thinking parameter resolution.
Closes: #5400#5571
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
