The second renderer adapter, and the concrete case for A13's decision
to normalise in the renderer rather than on the wire. The two vendors
disagree structurally, not cosmetically: the system prompt is a
top-level field rather than a message, a tool call is a tool_use
content block rather than an array, a tool result is a block inside a
user message rather than a "tool" role, and tool schemas use
input_schema rather than parameters. A middlebox flattening those
would be lossy exactly where a long-running delegation lives.
- render_anthropic.py builds vendor-native /v1/messages bodies from
the canonical log, coalescing adjacent same-role blocks so a
tool_result lands directly after its tool_use
- Tool manifests are declared once in OpenAI shape and converted per
vendor, so adding a tool does not mean editing two places
- AnthropicPassthroughClient implements the same LLMClient protocol,
so callers pick a route rather than a different kind of client, and
maps provider tool ids to canonical ones at the boundary
- Dangling tool calls get a placeholder result here too; this API
rejects them more strictly than the OpenAI shape
- Vendor-opaque reasoning blocks are dropped for now with the reason
recorded: A10 wants them stored and never replayed across sessions,
and the canonical schema has no event for that yet
Live tests prove the body is accepted as sent, that a tool_result
turn round-trips, and — as A5 asks — that prompt cache accounting
survives the passthrough rather than being flattened by the proxy.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
dongarandClaude Opus 5