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The hosted gateway is a byte-transparent reverse proxy. Your client sends normal provider HTTP requests; ReasonBlocks forwards them to the configured upstream with the same path and query string. There is no fixed allowlist of routes. Default product path: Anthropic Messages (POST /v1/messages) via ANTHROPIC_BASE_URL. That path has the best trace reconstruction, supports training, and relegation serving (cheaper model first, frontier fallback). It matches how most agent frameworks call Claude today. Other common endpoints (OpenAI Chat Completions, Responses API, Gemini, etc.) work for capture and passthrough when upstream routing is set correctly. Relegation serving (cheaper model + frontier fallback) applies only to POST /v1/messages.

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Upstream routing (operator / hosted config)

ReasonBlocks sets upstream routing on hosted gateways. Self-hosters configure: To forward OpenAI-shaped clients, point upstream at OpenAI:
Hosted tenants: use the dashboard gateway URL; do not change upstream unless your account supports multi-provider routing there.

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Common LLM API paths

Paths the optional client shim treats as LLM calls (for X-RB-Run / X-RB-Seq headers). All other paths still forward through the catch-all proxy.

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Anthropic (default)

Works with the Anthropic SDK, LangChain, CrewAI, and any client that respects ANTHROPIC_BASE_URL.

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OpenAI Chat Completions

Gateway upstream must be OpenAI (hosted config or self-hosted AGENTRECON_UPSTREAM_BASE):
Client calls POST /v1/chat/completions on the gateway; traffic forwards to OpenAI. Capture works; structured golden traces and relegation serving are weaker or unavailable on this path (see below).

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OpenAI Responses API

Same pattern as Chat Completions: OPENAI_BASE_URL at the gateway, upstream https://api.openai.com, path /v1/responses.

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Gemini and other providers

Point the client base URL at the gateway and set AGENTRECON_UPSTREAM_BASE to the provider origin (for example https://generativelanguage.googleapis.com). URLs containing :generateContent are recognized by the client shim for run headers.

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Framework compatibility

API keys pass through upstream and are not stored by ReasonBlocks.

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Feature matrix by endpoint

Training and relegation serving use flat Anthropic-shaped transcripts. If your workflow must use the cheaper model path, run the agent on /v1/messages even if you also capture other provider traffic.

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Relegation serving (Anthropic path only)

After training, keep the same gateway URL. Relegation routing affects only POST /v1/messages: OpenAI-shaped requests are not rewritten to the cheaper model. They passthrough to AGENTRECON_UPSTREAM_BASE. Enable relegation in the dashboard (hosted) or via gateway config (self-hosted). See Quickstart steps 5–6.

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Client shim paths

When using Tier B or C, rbtrace.client.install() stamps run headers on requests matching:
  • /v1/messages
  • /v1/chat/completions
  • /v1/responses
  • /v1/complete
  • paths containing :generateContent
Install: pip install rbtrace (when published to PyPI).

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Gateway admin endpoints

Not forwarded to upstream: Self-hosted operators: see Deployment.

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Limitations

  • Upstream failures return 502 with Anthropic-shaped error JSON regardless of client type.
  • Cheaper-model responses are synthesized Anthropic Messages JSON (or a single SSE burst), not native provider streaming.
  • Integration tests in the gateway codebase focus on POST /v1/messages; other paths are supported by architecture but less validated end-to-end.

Integrating your agent

Tier A/B/C and the optional shim.

Gateway reference

Env vars and serve contract.