v0.4.0

🔁 Automatic provider retries

All provider clients (Gemini, Anthropic, OpenAi) — including the new embedding
clients — now retry transient failures with exponential backoff and full jitter:

• Retries 429 (honouring Retry-After up to 60s), 408/409/5xx, and
  connect/timeout transport errors. Other 4xx fail immediately.
• Defaults mirror the official SDKs: 2 retries, 500ms initial backoff, 8s cap.
• Tune or opt out per client via the new retry: RetryConfig field on each provider
  config (RetryConfig::disabled() restores the old fail-fast behaviour).
• For streaming calls, retry covers connection establishment; mid-stream failures
  still surface as stream errors.

→ https://adk-rs.vercel.app/docs/providers

🧠 Semantic memory

Memory search graduates from substring matching to embedding-based retrieval:

• New Embedder trait in adk_rs::core (plus a cosine_similarity helper).
• VectorMemoryService (adk_rs::services::mem) embeds entries at ingest time and
  ranks searches by cosine similarity, with with_top_k(n) (default 5) and
  with_min_score(s) builders. Drop-in replacement for InMemoryMemoryService —
  the load_memory / preload_memory tools work unchanged.
• Two embedders in the box: GeminiEmbedder (batchEmbedContents, e.g.
  gemini-embedding-001) and OpenAiEmbedder (/embeddings, e.g.
  text-embedding-3-small; reaches Azure/Ollama via OPENAI_BASE_URL).
• MockEmbedder under the testing feature: a deterministic hashed bag-of-words
  embedder for offline tests of semantic-memory flows.

→ https://adk-rs.vercel.app/docs/memory

🧾 Structured output on every provider

.output_schema(...) is now server-enforced on all three providers, not just Gemini:

• OpenAI-compatible — strict structured outputs
  (response_format: {"type": "json_schema", "strict": true, ...}). Optional
  properties are sent as required-but-nullable to satisfy strict mode while
  preserving the original semantics. A JSON mime type without a schema still maps
  to plain json_object mode.
• Anthropic — the Messages API's native
  output_config: {"format": {"type": "json_schema", ...}}. Requires a
  structured-outputs-capable Claude model (Claude 4.5-generation and newer).
• A shared transform converts the OpenAPI-flavoured Schema to each provider's
  JSON Schema dialect: lowercased types, nullable → ["type", "null"] unions,
  additionalProperties: false on objects, unsupported keywords stripped.

→ https://adk-rs.vercel.app/docs/structured-output

🎙 Gemini Live API (feature = "live")

Bidirectional WebSocket streaming over BidiGenerateContent:

• Gemini::connect_live(LiveConfig) → LiveSession with send_text,
  send_audio (realtime PCM with server-side VAD), send_audio_stream_end,
  send_tool_response, recv, and close.
• LiveEvent covers incremental text, decoded PCM audio, input/output
  transcriptions, tool calls and cancellations, barge-in Interrupted,
  GenerationComplete, TurnComplete, GoAway, and usage metadata.
• LiveConfig selects response modality (TEXT or AUDIO), prebuilt voice, system
  instruction, tools, and transcription flags.
• The transport-security policy carries over: wss:// always, plain ws:// only
  to loopback hosts.
• Live sessions are a model-level surface today (alongside generate_content);
  runner-loop integration is planned.

→ https://adk-rs.vercel.app/docs/live

Full Changelog: v0.3.0...v0.4.0