Greptile Summary

This PR fixes a nil-pointer dereference panic in the Anthropic outbound stream transformer triggered when Claude uses server-side tools (web_search, code_execution). The root cause was that content_block_start events for server_tool_use were not tracked, so subsequent input_json_delta events dereferenced a nil map entry.

• Panic fix (streaming): isAnthropicToolUseLike replaces the exact \"tool_use\" check throughout the aggregator and outbound stream; a nil guard on state.toolCalls prevents the crash for any untracked block type.
• Non-streaming path: The previously dead case \"server_tool_use\", \"web_search_tool_result\" branch is removed; default: now routes special blocks through isAnthropicSpecialToolUseBlock / isAnthropicSpecialToolResultBlock so they become proper ToolCall + InlineToolResult entries with block-index metadata for faithful re-ordering.
• Round-trip fidelity: MessageContent.Raw passes *_tool_result content bytes verbatim through marshal/unmarshal, preserving encrypted_content and other unmodeled fields; a new orderedContentBlock sort restores the original tool/text interleaving on re-emission.

Confidence Score: 5/5

Safe to merge; the nil-pointer panic is correctly fixed in both streaming and non-streaming paths, and the server-tool round-trip is covered by comprehensive new tests.

The primary change — replacing the exact tool_use check with isAnthropicToolUseLike and adding a nil guard — is minimal, targeted, and clearly correct. The non-streaming dead-branch issue flagged in a prior review round has been addressed: the old case "server_tool_use", "web_search_tool_result" is gone and default: now handles those types properly. The block-index ordering logic and Raw byte pass-through are more complex but are exercised by the new stream-round-trip and response-round-trip tests. The one gap found (missing citation flush in the new InlineToolResults handler) is theoretical given current Anthropic API ordering and does not affect any path exercised by the tests.

The inbound_stream.go InlineToolResults handler (lines 723–737) is the only place worth a second look — it omits the flushPendingTextCitations() call that all analogous text-block-close sites include.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant A as Anthropic API
    participant OS as OutboundStream
    participant LLM as llm.Response
    participant IS as InboundStream
    participant C as Client

    A->>OS: content_block_start(server_tool_use)
    OS->>LLM: "ToolCall{id, name, anthropic_type=server_tool_use}"
    A->>OS: input_json_delta x N
    OS->>LLM: "ToolCall{partial args} x N"
    A->>OS: content_block_stop (filtered/dropped)
    A->>OS: content_block_start(web_search_tool_result)
    OS->>LLM: "InlineToolResult{tool_call_id, content Raw bytes}"
    A->>OS: content_block_start(text) + text_delta x N
    OS->>LLM: text content x N
    LLM->>IS: ToolCall chunks
    IS->>C: content_block_start(server_tool_use) + input_json_delta
    LLM->>IS: InlineToolResult chunk
    IS->>C: content_block_stop + content_block_start(web_search_tool_result) + content_block_stop
    LLM->>IS: text chunks
    IS->>C: content_block_start(text) + text_delta x N

_{Reviews (2): Last reviewed commit: "fix(anthropic): handle server-side tool ..." | Re-trigger Greptile}

Thanks for the review! The shadowing issue you identified in outbound_convert.go has been fixed in the latest push (65e2e97):

• Removed the explicit case "server_tool_use", "web_search_tool_result": that was shadowing the default handler
• server_tool_use blocks now correctly flow through isAnthropicSpecialToolUseBlock → toolCallFromAnthropicBlock to produce llm.ToolCall
• web_search_tool_result blocks now correctly flow through isAnthropicSpecialToolResultBlock → inlineToolResultFromBlock to produce llm.InlineToolResult
• The TransformerMetadataKeyAnthropicResponseContent metadata is still populated (for citation round-trip fidelity) alongside the new per-item metadata

All tests pass, including TestConvertToLlmResponse_ServerToolUse and the existing TestAnthropicTransformResponse_WebSearchBlocks_RoundTripIntegration.