Changelog

Docs updates for the smallestai 5.5.0 release, plus the sibling platform fix for crew transfer audio.

Typed errors with actionable hints. Plan or entitlement-gated requests (HTTP 400 with “…upgrade to a higher plan…”) now raise PlanNotEntitledError (subclass of BadRequestError), importable from smallestai or the new smallestai.errors module. Error messages carry an actionable hint: 401 points at SMALLEST_API_KEY, plan-gated 400 points at upgrading, org-gated 403 points at the account team.

Waves helpers. smallestai.waves.helpers ships synthesize_to_file, synthesize_bytes, and synthesize_with_expiry for the common one-shot TTS shapes. Setting expire_content=True on the helpers sends the Enterprise-only x-expire-content header; synthesize_with_expiry also reads back the x-content-expiry outcome so callers can log or surface it.

CLI reference expanded. client-libraries/overview.mdx now lists all seven smallestai command groups: auth, agents, agent-crew, calls, and the three added in 5.4.2 (waves, campaigns, phone-numbers). Billable and destructive subcommands prompt for confirmation unless --yes is passed.

Custom-LLM crew gotcha. The BYOM page now warns against pointing a crew’s OpenAIClient at Anthropic’s OpenAI-compatible endpoint (https://api.anthropic.com/v1/). That URL truncates streaming replies and drops tool-call turns, which surfaces as the agent going silent mid-conversation. For Claude on a crew, use a gateway that stabilizes the stream (LiteLLM, OpenRouter, Portkey), or the platform model. The page also gets a ngrok note (ERR_NGROK_8012 when the local process is down surfaces as a fatal agent_error and hangs up) and a tool_choice note (crew chat() forwards extra kwargs, so tool_choice="required" works for deterministic transfer decisions).

Call Transfer guide. The cold-vs-warm section on dev/build/phone-calling/call-features/call-transfer.mdx now has separate subsections for each method, spells out that warm is a private briefing (with the “please hold” announcement on the caller side and the whisper on the destination side), and lists the three audio slots warm supports (on_hold_music, whisper, three-way). Cold stays a direct connect with no audio window. Also adds two new Troubleshooting entries from customer debug: transfer fires but the far end rejects in ~2s (destination not answering), and the agent says “let me transfer you” without ever firing the tool (LLM determinism; prompt fix + tool_choice="required").

Cookbook cross-link. The voice-agents/call_transfer sample covers cold, warm, inbound, and agent-to-agent shapes and now ships an AGENTS.md so a coding agent can consume it directly.