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use crate::{
transform::{
Report, TransformError,
identity::{IdentityFlow, IdentityRole, OutputItemKind, SourceIdentity, TargetIdPolicy},
},
wire::{claude::content as c, openai::responses::input as r},
};
fn easy(role: r::MessageRole, content: r::MessageContent) -> r::InputItem {
r::InputItem::Easy(r::EasyInputMessage::builder(content, role).build())
}
pub(crate) fn to_responses(
messages: Vec<c::Message>,
flow: &mut IdentityFlow,
policy: &TargetIdPolicy,
report: &mut Report,
) -> Result<Vec<r::InputItem>, TransformError> {
let mut out = Vec::new();
let mut calls = std::collections::BTreeMap::new();
let mut mcp = std::collections::BTreeMap::new();
let mut ordinal = 0;
let mut used = std::collections::BTreeSet::new();
for message in messages {
let role = match message.role {
c::Role::User => r::MessageRole::User,
c::Role::Assistant => r::MessageRole::Assistant,
c::Role::System => r::MessageRole::System,
};
let blocks = match message.content {
c::MessageContent::Text(text) => {
out.push(easy(role, r::MessageContent::Text(text)));
continue;
}
c::MessageContent::Blocks(blocks) => blocks,
};
for block in blocks {
match block {
c::ContentBlock::Text(text) => {
out.push(easy(role, r::MessageContent::Text(text.text)))
}
c::ContentBlock::Image(image) => {
if role != r::MessageRole::User {
continue;
}
out.push(easy(
role,
r::MessageContent::Parts(vec![super::media::image(image.source)?]),
));
}
c::ContentBlock::Document(doc) => {
if role != r::MessageRole::User {
continue;
}
out.push(easy(
role,
r::MessageContent::Parts(vec![super::media::document(doc)?]),
));
}
c::ContentBlock::ToolUse(v) if v.toolset_name.is_some() => {
report.omitted(
"toolset_name",
"native toolset member has no target definition",
);
continue;
}
c::ContentBlock::ToolUse(call) => {
if call
.caller
.as_ref()
.is_some_and(|caller| !matches!(caller, c::Caller::Direct(_)))
{
continue;
}
if role != r::MessageRole::Assistant
|| call.id.is_empty()
|| !used.insert(call.id.clone())
|| !call.input.is_object()
{
return Err(TransformError::shape(
"tool_use",
"assistant object tool call requires unique nonempty id",
));
}
let source =
SourceIdentity::new(crate::Dialect::Claude, Some(call.id.clone()), ordinal);
let call_id = flow
.resolve_as(
IdentityRole::ToolCall,
IdentityRole::ToolCall,
source.clone(),
policy,
)
.map_err(|e| TransformError::shape("identity", e.to_string()))?
.emitted_id;
let item_id = flow
.resolve_as(
IdentityRole::ToolCall,
IdentityRole::OutputItem(OutputItemKind::FunctionCall),
source,
policy,
)
.map_err(|e| TransformError::shape("identity", e.to_string()))?
.emitted_id;
ordinal += 1;
calls.insert(call.id, call_id.clone());
out.push(r::InputItem::FunctionCall(
r::FunctionCall::builder(
r::FunctionCallType::FunctionCall,
serde_json::to_string(&call.input)?,
call_id,
call.name,
)
.id(item_id)
.build(),
));
}
c::ContentBlock::ToolResult(v) if v.toolset_name.is_some() => {
report.omitted(
"toolset_name",
"native toolset member has no target definition",
);
continue;
}
c::ContentBlock::ToolResult(result) => {
if role != r::MessageRole::User {
return Err(TransformError::shape(
"tool_result.role",
"tool results require user role",
));
}
let call_id = calls
.get(&result.tool_use_id)
.cloned()
.or_else(|| {
flow.lookup_source(
&SourceIdentity::new(
crate::Dialect::Claude,
Some(result.tool_use_id),
0,
),
IdentityRole::ToolCall,
)
.map(|v| v.emitted_id)
})
.ok_or_else(|| {
TransformError::missing_metadata("tool_result call binding")
})?;
let mut output = super::media::result_to_responses(
result
.content
.unwrap_or(c::ToolResultContent::Text(String::new())),
)?;
if result.is_error == Some(true) {
match &mut output {
r::FunctionOutput::Text(text) => {
*text = format!("Tool error:\n{text}");
report.changed(
"tool_result.is_error",
"error status represented in text",
);
}
r::FunctionOutput::Content(parts) => parts.insert(
0,
r::FunctionOutputContent::Text(
r::FunctionOutputText::builder(
r::ResponseInputTextType::ResponseInputText,
"Tool error:".into(),
)
.build(),
),
),
}
}
out.push(r::InputItem::FunctionCallOutput(
r::FunctionCallOutput::builder(
r::FunctionCallOutputType::FunctionCallOutput,
call_id,
output,
)
.build(),
));
}
c::ContentBlock::McpToolUse(call) => {
if call.id.is_empty() || !used.insert(call.id.clone()) {
return Err(TransformError::shape(
"mcp.id",
"empty or duplicate MCP call",
));
}
let id = flow
.resolve_as(
IdentityRole::ToolCall,
IdentityRole::ToolCall,
SourceIdentity::new(
crate::Dialect::Claude,
Some(call.id.clone()),
ordinal,
),
policy,
)
.map_err(|e| TransformError::shape("mcp.identity", e.to_string()))?
.emitted_id;
ordinal += 1;
mcp.insert(call.id, out.len());
out.push(r::InputItem::McpCall(
r::McpCall::builder(
r::McpCallType::McpCall,
id,
serde_json::to_string(&call.input)?,
call.name,
call.server_name,
)
.build(),
));
}
c::ContentBlock::McpToolResult(result) => {
let index = mcp.remove(&result.tool_use_id).ok_or_else(|| {
TransformError::missing_metadata("MCP result paired call")
})?;
let r::InputItem::McpCall(call) = &mut out[index] else {
unreachable!("tracked MCP position")
};
let text = result.content.map(|content| match content {
c::McpResultContent::Text(text) => text,
c::McpResultContent::Blocks(blocks) => blocks
.into_iter()
.map(|v| v.text)
.collect::<Vec<_>>()
.join(""),
});
if result.is_error == Some(true) {
call.error =
Some(Some(text.ok_or_else(|| {
TransformError::missing_metadata("MCP error text")
})?));
call.status = Some(r::McpCallStatus::Failed);
} else {
call.output = text.map(Some);
call.status = Some(r::McpCallStatus::Completed);
}
}
// A signature carried from another upstream (a Gemini thought)
// only goes back to that upstream; this one would refuse it.
c::ContentBlock::Thinking(thinking)
if crate::transform::generate::signature::is_carried(&thinking.signature) =>
{
report.omitted(
"thinking",
"a signature carried from another upstream only goes back to that upstream",
);
}
c::ContentBlock::Thinking(thinking) => {
let id = flow
.resolve_as(
IdentityRole::OutputItem(OutputItemKind::Reasoning),
IdentityRole::OutputItem(OutputItemKind::Reasoning),
SourceIdentity::new(crate::Dialect::Claude, None, ordinal),
policy,
)
.map_err(|e| TransformError::shape("identity", e.to_string()))?
.emitted_id;
ordinal += 1;
let mut item = r::ReasoningItem::builder(
r::ReasoningItemType::ReasoningItem,
id,
Vec::new(),
)
.build();
item.content = Some(vec![
r::ReasoningContent::builder(
r::ReasoningTextType::ReasoningText,
thinking.thinking,
)
.build(),
]);
report.omitted(
"thinking.signature",
"a Claude signature has no meaning to a Responses upstream",
);
out.push(r::InputItem::Reasoning(item));
}
c::ContentBlock::RedactedThinking(_) => {
return Err(TransformError::missing_metadata(
"redacted Claude reasoning has no Responses form",
));
}
c::ContentBlock::ServerToolUse(_)
| c::ContentBlock::SearchResult(_)
| c::ContentBlock::WebSearchToolResult(_)
| c::ContentBlock::WebFetchToolResult(_)
| c::ContentBlock::AdvisorToolResult(_)
| c::ContentBlock::CodeExecutionToolResult(_)
| c::ContentBlock::BashCodeExecutionToolResult(_)
| c::ContentBlock::TextEditorCodeExecutionToolResult(_)
| c::ContentBlock::ToolSearchToolResult(_)
| c::ContentBlock::ContainerUpload(_)
| c::ContentBlock::McpToolListing(_)
| c::ContentBlock::Compaction(_)
| c::ContentBlock::MidConversationSystem(_)
| c::ContentBlock::ToolAddition(_)
| c::ContentBlock::ToolRemoval(_)
| c::ContentBlock::Fallback(_) => {
continue;
}
}
}
}
Ok(out)
}