provider_core/

anthropic_chat.rs

// SPDX-License-Identifier: AGPL-3.0-or-later

//! Anthropic Messages API adapter (PRD-001y S2) serving the `claude_subscription`
//! and `claude_api` phases.
//!
//! Wire format, base URL, and auth scheme were verified at build time against
//! the published Anthropic Messages API documentation at
//! https://platform.claude.com/docs/en/api/messages (no live call). The Claude
//! phases are NOT OpenAI-compatible: the request is a Messages API body
//! (`model`, `max_tokens`, `system`, `messages`, `tools`, `stream`) sent to
//! `POST https://api.anthropic.com/v1/messages` with the `x-api-key` header and
//! the required `anthropic-version` header. Streaming is SSE with
//! `message_start`/`content_block_*`/`message_delta`/`message_stop` events.
//!
//! The model id is a request-body field, so the route endpoint path is static.
//! The route carries the credential reference; this adapter only wraps it for
//! the transport layer, which resolves it through the secret boundary.

use crate::ollama_chat::{HttpMethod, NetworkPolicy, ReplayBoundary, ReplayDecision};
use router_protocol::{
    CanonicalRequest, ContentBlock, InputItem, MessageRole, PhaseKind, RouteIdentity,
    RouteIdentityError, ToolChoice, TransportKind,
};
use serde_json::{Map, Value, json};
use std::fmt;

/// The required Anthropic API version header value, pinned from the published
/// docs (build-time verification).
pub const ANTHROPIC_VERSION: &str = router_protocol::ANTHROPIC_VERSION;
/// The header name carrying the Anthropic API key.
pub const ANTHROPIC_API_KEY_HEADER: &str = router_protocol::ANTHROPIC_API_KEY_HEADER;
/// The header name carrying the required Anthropic API version.
pub const ANTHROPIC_VERSION_HEADER: &str = router_protocol::ANTHROPIC_VERSION_HEADER;
/// Default `max_tokens` used when the canonical request does not bound output
/// (Anthropic requires the field).
pub const DEFAULT_MAX_TOKENS: u32 = 1024;

/// The Claude/Anthropic phases this adapter serves.
pub const fn is_claude_phase(phase: PhaseKind) -> bool {
    matches!(phase, PhaseKind::ClaudeSubscription | PhaseKind::ClaudeApi)
}

/// Per-route MAv2 capability projection for the Claude phases (PRD-001l/001u):
/// the Anthropic wire API cannot represent namespaces, so SteadyMux
/// normalizes at the wire boundary under the non-reserved `agents` namespace.
/// Mirrors the DeepSeek/OpenAI-compat follow-on projection.
pub const fn capability_projection() -> router_protocol::MultiAgentCapabilityProjection {
    router_protocol::MultiAgentCapabilityProjection {
        namespace_tools: false,
        multi_agent_version: router_protocol::MultiAgentVersion::V2,
        wire_api: router_protocol::MultiAgentWireApi::Responses,
        observed_namespace_calls:
            router_protocol::ObservedNamespaceCallBehavior::BareNameNoNamespace,
    }
}

#[derive(Clone, PartialEq, Eq)]
pub struct AnthropicSecretReferenceMarker(String);

impl AnthropicSecretReferenceMarker {
    pub fn as_str(&self) -> &str {
        &self.0
    }
}

impl fmt::Debug for AnthropicSecretReferenceMarker {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter.write_str("AnthropicSecretReferenceMarker([REDACTED])")
    }
}

#[derive(Clone, PartialEq)]
pub struct AnthropicRequestSpec {
    pub method: HttpMethod,
    pub origin: String,
    pub path: String,
    pub content_type: &'static str,
    pub accept: &'static str,
    pub api_key_secret: AnthropicSecretReferenceMarker,
    pub network: NetworkPolicy,
    /// The required `anthropic-version` header value, exposed so the transport
    /// layer can write the fixed header.
    pub version_header: &'static str,
    body: Value,
}

impl AnthropicRequestSpec {
    pub fn body(&self) -> &Value {
        &self.body
    }

    pub fn body_bytes(&self) -> Result<Vec<u8>, serde_json::Error> {
        serde_json::to_vec(&self.body)
    }
}

impl fmt::Debug for AnthropicRequestSpec {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter
            .debug_struct("AnthropicRequestSpec")
            .field("method", &self.method)
            .field("origin", &self.origin)
            .field("path", &self.path)
            .field("content_type", &self.content_type)
            .field("accept", &self.accept)
            .field("api_key_secret", &self.api_key_secret)
            .field("network", &self.network)
            .field("version_header", &self.version_header)
            .field("body", &"[REDACTED]")
            .finish()
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum AnthropicRequestErrorKind {
    InvalidRouteIdentity,
    UnsupportedRoute,
    InvalidCanonicalRequest,
    AmbiguousToolName,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct AnthropicRequestError {
    pub kind: AnthropicRequestErrorKind,
}

impl fmt::Display for AnthropicRequestError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter.write_str("the Anthropic Messages request could not be prepared")
    }
}

impl std::error::Error for AnthropicRequestError {}

impl From<RouteIdentityError> for AnthropicRequestError {
    fn from(_: RouteIdentityError) -> Self {
        Self {
            kind: AnthropicRequestErrorKind::InvalidRouteIdentity,
        }
    }
}

pub fn build_request(
    route: &RouteIdentity,
    request: &CanonicalRequest,
) -> Result<AnthropicRequestSpec, AnthropicRequestError> {
    route.validate()?;
    if !is_claude_phase(route.phase) || route.transport != TransportKind::DirectHttps {
        return Err(AnthropicRequestError {
            kind: AnthropicRequestErrorKind::UnsupportedRoute,
        });
    }
    request.validate().map_err(|_| AnthropicRequestError {
        kind: AnthropicRequestErrorKind::InvalidCanonicalRequest,
    })?;
    let secret_ref = route.credential_ref.clone().ok_or(AnthropicRequestError {
        kind: AnthropicRequestErrorKind::InvalidRouteIdentity,
    })?;

    Ok(AnthropicRequestSpec {
        method: HttpMethod::Post,
        origin: route.endpoint.origin.clone(),
        path: route.endpoint.path.clone(),
        content_type: "application/json",
        accept: "text/event-stream",
        api_key_secret: AnthropicSecretReferenceMarker(secret_ref),
        network: NetworkPolicy {
            allow_proxy: false,
            allow_dns: true,
            follow_redirects: false,
            require_tls: true,
        },
        version_header: ANTHROPIC_VERSION,
        body: build_body(route, request)?,
    })
}

fn build_body(
    route: &RouteIdentity,
    request: &CanonicalRequest,
) -> Result<Value, AnthropicRequestError> {
    let mut object = Map::new();
    object.insert("model".to_owned(), Value::String(route.model_id.clone()));
    object.insert(
        "max_tokens".to_owned(),
        Value::from(request.max_output_tokens.unwrap_or(DEFAULT_MAX_TOKENS)),
    );
    object.insert("stream".to_owned(), Value::Bool(true));

    // The Anthropic Messages API has no system message role: developer/system
    // turns become the top-level `system` field, and user/assistant turns stay
    // in `messages`.
    let system = build_system(request);
    if !system.is_empty() {
        object.insert("system".to_owned(), Value::String(system));
    }

    // `tool_choice` is only valid alongside a `tools` array; emit both or
    // neither.
    let emit_tools = !request.tools.is_empty() && request.tool_choice != ToolChoice::None;
    if emit_tools {
        object.insert("tool_choice".to_owned(), anthropic_tool_choice(request));
        let mut names = std::collections::HashSet::new();
        let mut tools = Vec::with_capacity(request.tools.len());
        for tool in &request.tools {
            let name = provider_tool_name(tool.namespace.as_deref(), &tool.name);
            if !names.insert(name.clone()) {
                return Err(AnthropicRequestError {
                    kind: AnthropicRequestErrorKind::AmbiguousToolName,
                });
            }
            tools.push(json!({
                "name": name,
                "description": tool.description,
                "input_schema": tool.parameters,
            }));
        }
        object.insert("tools".to_owned(), Value::Array(tools));
    }
    object.insert("messages".to_owned(), Value::Array(build_messages(request)));
    Ok(Value::Object(object))
}

fn build_system(request: &CanonicalRequest) -> String {
    request
        .input
        .iter()
        .filter_map(|item| match item {
            InputItem::Message {
                role: MessageRole::Developer | MessageRole::System,
                content,
            } => Some(content),
            _ => None,
        })
        .flat_map(|content| {
            content.iter().filter_map(|block| match block {
                ContentBlock::Text { text } => Some(text.as_str()),
                ContentBlock::ImageReference { .. } => None,
            })
        })
        .collect::<Vec<_>>()
        .join("\n")
}

fn build_messages(request: &CanonicalRequest) -> Vec<Value> {
    request
        .input
        .iter()
        .map(|item| match item {
            InputItem::Message {
                role: MessageRole::User,
                content,
            } => json!({
                "role": "user",
                "content": anthropic_content(content),
            }),
            InputItem::Message {
                role: MessageRole::Assistant,
                content,
            } => json!({
                "role": "assistant",
                "content": anthropic_content(content),
            }),
            InputItem::Message {
                role: MessageRole::Developer | MessageRole::System,
                ..
            } => json!({
                "role": "user",
                "content": [],
            }),
            InputItem::FunctionCall {
                call_id,
                namespace,
                name,
                arguments,
            } => json!({
                "role": "assistant",
                "content": [{
                    "type": "tool_use",
                    "id": call_id.as_str(),
                    "name": provider_tool_name(namespace.as_deref(), name),
                    "input": arguments,
                }]
            }),
            InputItem::FunctionCallOutput { call_id, output } => json!({
                "role": "user",
                "content": [{
                    "type": "tool_result",
                    "tool_use_id": call_id.as_str(),
                    "content": output.to_string(),
                }]
            }),
        })
        .collect()
}

fn anthropic_content(content: &[ContentBlock]) -> Value {
    if content
        .iter()
        .all(|block| matches!(block, ContentBlock::Text { .. }))
    {
        let text = content
            .iter()
            .filter_map(|block| match block {
                ContentBlock::Text { text } => Some(text.as_str()),
                ContentBlock::ImageReference { .. } => None,
            })
            .collect::<String>();
        return Value::String(text);
    }
    Value::Array(
        content
            .iter()
            .filter_map(|block| match block {
                ContentBlock::Text { text } => Some(json!({"type": "text", "text": text})),
                ContentBlock::ImageReference { .. } => {
                    // The Anthropic Messages API image sources require base64
                    // data, which the canonical request does not carry. Images
                    // are omitted from the wire body; text blocks still flow.
                    None
                }
            })
            .collect(),
    )
}

fn provider_tool_name(namespace: Option<&str>, name: &str) -> String {
    namespace.map_or_else(
        || name.to_owned(),
        |namespace| format!("{namespace}__{name}"),
    )
}

fn anthropic_tool_choice(request: &CanonicalRequest) -> Value {
    match &request.tool_choice {
        ToolChoice::Auto => Value::String("auto".to_owned()),
        ToolChoice::None => Value::String("none".to_owned()),
        ToolChoice::Required => Value::String("any".to_owned()),
        ToolChoice::Named(name) => {
            let provider_name = request
                .tools
                .iter()
                .find(|tool| tool.name == *name)
                .map_or_else(
                    || name.clone(),
                    |tool| provider_tool_name(tool.namespace.as_deref(), &tool.name),
                );
            json!({"type": "tool", "name": provider_name})
        }
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct AnthropicUsage {
    pub input_tokens: u64,
    pub output_tokens: u64,
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum AnthropicStreamEvent {
    ContentDelta { text: String },
    FinishReason { reason: String },
    Usage(AnthropicUsage),
    Done,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum AnthropicStreamErrorKind {
    InvalidUtf8,
    InvalidJson,
    InvalidFrame,
    EventTooLarge,
    MissingTerminal,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct AnthropicStreamError {
    pub kind: AnthropicStreamErrorKind,
}

impl fmt::Display for AnthropicStreamError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter.write_str("the Anthropic stream could not be normalized")
    }
}

impl std::error::Error for AnthropicStreamError {}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct AnthropicReplayGuard {
    boundary: Option<ReplayBoundary>,
    body_written: bool,
}

impl AnthropicReplayGuard {
    pub fn mark_body_written(&mut self) {
        self.body_written = true;
    }

    pub fn observe(&mut self, event: &AnthropicStreamEvent) {
        match event {
            AnthropicStreamEvent::ContentDelta { text } if !text.is_empty() => {
                self.cross(ReplayBoundary::PublicContent);
            }
            AnthropicStreamEvent::ContentDelta { .. }
            | AnthropicStreamEvent::FinishReason { .. }
            | AnthropicStreamEvent::Usage(_)
            | AnthropicStreamEvent::Done => {}
        }
    }

    pub fn mark_transport_outcome_unknown(&mut self) {
        if self.body_written {
            self.cross(ReplayBoundary::AmbiguousDispatch);
        }
    }

    pub fn decision(&self) -> ReplayDecision {
        self.boundary
            .map_or(ReplayDecision::Allowed, ReplayDecision::Denied)
    }

    fn cross(&mut self, boundary: ReplayBoundary) {
        if self.boundary.is_none() {
            self.boundary = Some(boundary);
        }
    }
}

/// Minimal Anthropic Messages SSE parser. Consumes the documented event stream
/// (`message_start`, `content_block_delta` with `text_delta`,
/// `message_delta` with `stop_reason`/`usage`, `message_stop`). Tool-use
/// streaming (`tool_use` blocks) is not yet normalized for these phases; a
/// text-only response normalizes fully and the terminal is required exactly
/// once.
pub struct AnthropicSseParser {
    _attempt_id: AttemptId,
    replay: AnthropicReplayGuard,
    terminal: bool,
    input_tokens: u64,
    output_tokens: u64,
}

impl AnthropicSseParser {
    pub fn new(attempt_id: &AttemptId) -> Self {
        Self {
            _attempt_id: attempt_id.clone(),
            replay: AnthropicReplayGuard::default(),
            terminal: false,
            input_tokens: 0,
            output_tokens: 0,
        }
    }

    pub fn replay_decision(&self) -> ReplayDecision {
        self.replay.decision()
    }

    pub fn mark_body_written(&mut self) {
        self.replay.mark_body_written();
    }

    pub fn mark_transport_outcome_unknown(&mut self) {
        self.replay.mark_transport_outcome_unknown();
    }

    pub fn feed(
        &mut self,
        chunk: &[u8],
    ) -> Result<Vec<AnthropicStreamEvent>, AnthropicStreamError> {
        let mut events = Vec::new();
        for frame in split_sse_frames(chunk)? {
            let value: Value =
                serde_json::from_slice(&frame).map_err(|_| AnthropicStreamError {
                    kind: AnthropicStreamErrorKind::InvalidJson,
                })?;
            events.extend(self.observe_json(value)?);
        }
        for event in &events {
            self.replay.observe(event);
        }
        Ok(events)
    }

    pub fn finish(&mut self) -> Result<Vec<AnthropicStreamEvent>, AnthropicStreamError> {
        if !self.terminal {
            return Err(AnthropicStreamError {
                kind: AnthropicStreamErrorKind::MissingTerminal,
            });
        }
        Ok(Vec::new())
    }

    fn observe_json(
        &mut self,
        value: Value,
    ) -> Result<Vec<AnthropicStreamEvent>, AnthropicStreamError> {
        let event_type = value.get("type").and_then(Value::as_str);
        let mut events = Vec::new();
        match event_type {
            Some("message_start") => {
                if let Some(input) = value
                    .pointer("/message/usage/input_tokens")
                    .and_then(Value::as_u64)
                {
                    self.input_tokens = input;
                }
            }
            Some("content_block_delta") => {
                match value.pointer("/delta/type").and_then(Value::as_str) {
                    Some("text_delta") => {
                        if let Some(text) = value.pointer("/delta/text").and_then(Value::as_str) {
                            events.push(AnthropicStreamEvent::ContentDelta {
                                text: text.to_owned(),
                            });
                        }
                    }
                    // Tool-use `input_json_delta` streaming is not yet
                    // normalized; the block is skipped.
                    Some(_) => {}
                    None => {
                        return Err(AnthropicStreamError {
                            kind: AnthropicStreamErrorKind::InvalidFrame,
                        });
                    }
                }
            }
            Some("message_delta") => {
                if let Some(reason) = value.pointer("/delta/stop_reason").and_then(Value::as_str) {
                    events.push(AnthropicStreamEvent::FinishReason {
                        reason: reason.to_owned(),
                    });
                }
                if let Some(output) = value
                    .pointer("/usage/output_tokens")
                    .and_then(Value::as_u64)
                {
                    self.output_tokens = output;
                }
            }
            Some("message_stop") => {
                self.terminal = true;
                events.push(AnthropicStreamEvent::Usage(AnthropicUsage {
                    input_tokens: self.input_tokens,
                    output_tokens: self.output_tokens,
                }));
                events.push(AnthropicStreamEvent::Done);
            }
            Some("ping") | Some("content_block_start") | Some("content_block_stop") => {}
            _ => {
                return Err(AnthropicStreamError {
                    kind: AnthropicStreamErrorKind::InvalidFrame,
                });
            }
        }
        Ok(events)
    }
}

/// Split an SSE byte buffer into one or more `data:` payload frames. Each
/// frame is the concatenation of the `data:` lines of one SSE event, without
/// the `data: ` prefix. Malformed framing (a non-`data:` non-empty line before
/// an event) is rejected.
fn split_sse_frames(buffer: &[u8]) -> Result<Vec<Vec<u8>>, AnthropicStreamError> {
    let text = std::str::from_utf8(buffer).map_err(|_| AnthropicStreamError {
        kind: AnthropicStreamErrorKind::InvalidUtf8,
    })?;
    let mut frames = Vec::new();
    let mut current = Vec::new();
    for line in text.split('\n') {
        let line = line.strip_suffix('\r').unwrap_or(line);
        if line.is_empty() {
            if !current.is_empty() {
                frames.push(std::mem::take(&mut current));
            }
            continue;
        }
        if let Some(data) = line.strip_prefix("data:") {
            let data = data.strip_prefix(' ').unwrap_or(data);
            if !current.is_empty() {
                current.push(b'\n');
            }
            current.extend_from_slice(data.as_bytes());
        }
        // Non-`data:` lines (event:, id:) are metadata and are skipped.
    }
    if !current.is_empty() {
        frames.push(current);
    }
    if frames.is_empty() {
        return Err(AnthropicStreamError {
            kind: AnthropicStreamErrorKind::InvalidFrame,
        });
    }
    Ok(frames)
}

use router_protocol::AttemptId;

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum AnthropicFailureClass {
    InvalidRequest,
    Authentication,
    PaymentRequired,
    Authorization,
    NotFound,
    Timeout,
    Unprocessable,
    RateLimited,
    UpstreamServer,
    UnexpectedStatus,
    MismatchedContentType,
    RedirectRejected,
    Cancelled,
    TransportTimeout,
    AmbiguousDispatch,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct AnthropicFailure {
    pub class: AnthropicFailureClass,
    pub status: Option<u16>,
    pub retry_after: Option<crate::ollama_chat::BoundedRetryAfter>,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum AnthropicBodyWriteState {
    NotWritten,
    Written,
    Unknown,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum AnthropicTransportFailureSignal {
    Cancelled,
    Timeout,
}

/// Maps a non-2xx/redirected HTTP response to the failure class. The
/// Anthropic Messages protocol is SSE from `POST /v1/messages`; a 200 with any
/// other media type is rejected.
pub fn normalize_http_response(
    status: u16,
    content_type: Option<&str>,
    retry_after: Option<&str>,
    redirected: bool,
) -> Result<(), AnthropicFailure> {
    if redirected || (300..400).contains(&status) {
        return Err(anthropic_failure(
            AnthropicFailureClass::RedirectRejected,
            Some(status),
            retry_after,
        ));
    }
    if status != 200 {
        let class = match status {
            400 => AnthropicFailureClass::InvalidRequest,
            401 => AnthropicFailureClass::Authentication,
            402 => AnthropicFailureClass::PaymentRequired,
            403 => AnthropicFailureClass::Authorization,
            404 => AnthropicFailureClass::NotFound,
            408 => AnthropicFailureClass::Timeout,
            422 => AnthropicFailureClass::Unprocessable,
            429 => AnthropicFailureClass::RateLimited,
            500..=599 => AnthropicFailureClass::UpstreamServer,
            _ => AnthropicFailureClass::UnexpectedStatus,
        };
        return Err(anthropic_failure(class, Some(status), retry_after));
    }
    let media_type = content_type
        .and_then(|value| value.split(';').next())
        .map(str::trim);
    if media_type != Some("text/event-stream") {
        return Err(anthropic_failure(
            AnthropicFailureClass::MismatchedContentType,
            Some(status),
            None,
        ));
    }
    Ok(())
}

pub fn normalize_transport_failure(
    signal: AnthropicTransportFailureSignal,
    body_write: AnthropicBodyWriteState,
) -> AnthropicFailure {
    let class = match body_write {
        AnthropicBodyWriteState::Written | AnthropicBodyWriteState::Unknown => {
            AnthropicFailureClass::AmbiguousDispatch
        }
        AnthropicBodyWriteState::NotWritten => match signal {
            AnthropicTransportFailureSignal::Cancelled => AnthropicFailureClass::Cancelled,
            AnthropicTransportFailureSignal::Timeout => AnthropicFailureClass::TransportTimeout,
        },
    };
    anthropic_failure(class, None, None)
}

fn anthropic_failure(
    class: AnthropicFailureClass,
    status: Option<u16>,
    retry_after: Option<&str>,
) -> AnthropicFailure {
    AnthropicFailure {
        class,
        status,
        retry_after: crate::ollama_chat::BoundedRetryAfter::parse(retry_after),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use router_protocol::{
        BillingAuthorityClass, CapabilityRequirements, CatalogSourceKind, CredentialSourceKind,
        EndpointIdentity, ExecutionLocation, FunctionTool, HarnessInstanceId, M1_WIRE_VERSION,
        MessageRole, ModelNamespace, PhaseKind, PhasePlacement, ProviderService, ReasoningIntent,
        SessionId, TurnId,
    };

    fn claude_route(phase: PhaseKind, billing: BillingAuthorityClass) -> RouteIdentity {
        RouteIdentity {
            phase,
            placement: PhasePlacement::Builtin,
            provider: ProviderService::Claude,
            transport: TransportKind::DirectHttps,
            endpoint: EndpointIdentity {
                origin: router_protocol::ANTHROPIC_ORIGIN.to_owned(),
                path: router_protocol::ANTHROPIC_CHAT_PATH.to_owned(),
            },
            credential_source: CredentialSourceKind::SecretRef,
            credential_ref: Some("env:STEADYMUX_CLAUDE_KEY".to_owned()),
            credential_refs: vec!["env:STEADYMUX_CLAUDE_KEY".to_owned()],
            catalog_source: CatalogSourceKind::ClaudeCatalog,
            catalog_ref: "catalog:claude:verified".to_owned(),
            billing_authority: billing,
            model_namespace: ModelNamespace::Claude,
            model_id: "claude-sonnet-4-5".to_owned(),
            execution_location: ExecutionLocation::RemoteCloud,
            account_ref: "account:claude".to_owned(),
            capacity_domain_ref: "capacity:claude".to_owned(),
            local_execution_proof: false,
            approved_local_inventory: Vec::new(),
            reasoning_modes: Vec::new(),
        }
    }

    fn request(prompt: &str) -> CanonicalRequest {
        CanonicalRequest {
            wire_version: M1_WIRE_VERSION.to_owned(),
            model: "router-auto".to_owned(),
            stream: true,
            harness_instance: HarnessInstanceId::parse("fixture-cli").expect("fixture"),
            session_id: SessionId::parse("session-claude").expect("fixture"),
            turn_id: TurnId::parse("turn-claude").expect("fixture"),
            input: vec![InputItem::Message {
                role: MessageRole::User,
                content: vec![ContentBlock::Text {
                    text: prompt.to_owned(),
                }],
            }],
            tools: vec![FunctionTool {
                namespace: Some("weather".to_owned()),
                name: "lookup".to_owned(),
                description: "lookup weather".to_owned(),
                parameters: json!({"type":"object"}),
                strict: true,
            }],
            tool_choice: ToolChoice::Auto,
            structured_output: None,
            reasoning: ReasoningIntent::None,
            max_output_tokens: Some(64),
            max_spend_micro_usd: None,
            capabilities: CapabilityRequirements::default(),
        }
    }

    #[test]
    fn claude_routes_build_verified_anthropic_wire_shape() {
        // PRD-001y AC-05: the Claude phases build an Anthropic Messages request
        // against `https://api.anthropic.com/v1/messages` with the verified
        // `x-api-key` auth scheme and the pinned `anthropic-version` header.
        for (phase, billing) in [
            (
                PhaseKind::ClaudeSubscription,
                BillingAuthorityClass::ClaudeSubscription,
            ),
            (
                PhaseKind::ClaudeApi,
                BillingAuthorityClass::ClaudeMeteredApi,
            ),
        ] {
            let route = claude_route(phase, billing);
            route.validate().expect("valid claude route");
            let spec = build_request(&route, &request("claude-canary")).expect("request");
            assert_eq!(spec.method, HttpMethod::Post);
            assert_eq!(spec.origin, router_protocol::ANTHROPIC_ORIGIN);
            assert_eq!(spec.path, router_protocol::ANTHROPIC_CHAT_PATH);
            assert_eq!(spec.accept, "text/event-stream");
            assert_eq!(spec.version_header, "2023-06-01");
            assert_eq!(spec.api_key_secret.as_str(), "env:STEADYMUX_CLAUDE_KEY");
            assert!(spec.network.require_tls);
            assert!(!spec.network.follow_redirects);
            assert!(!spec.network.allow_proxy);
            assert_eq!(spec.body()["model"], json!("claude-sonnet-4-5"));
            assert_eq!(spec.body()["max_tokens"], json!(64));
            assert_eq!(spec.body()["stream"], json!(true));
            assert_eq!(
                spec.body()["messages"][0]["content"],
                json!("claude-canary")
            );
            assert_eq!(spec.body()["tools"][0]["name"], json!("weather__lookup"));
            assert_eq!(
                spec.body()["tools"][0]["input_schema"],
                json!({"type": "object"})
            );
            assert_eq!(spec.body()["tool_choice"], json!("auto"));
        }
    }

    #[test]
    fn claude_adapter_has_no_hardcoded_model_id_and_exposes_projection() {
        // PRD-001y AC-07: model ids are catalog driven, never hardcoded in the
        // adapter, and the adapter exposes the per-route MAv2 capability
        // projection.
        let adapter_core = include_str!("anthropic_chat.rs")
            .split("#[cfg(test)]")
            .next()
            .expect("adapter body precedes the test module");
        for model_literal in [
            concat!("claude", "-sonnet"),
            concat!("claude", "-opus"),
            concat!("claude", "-haiku"),
        ] {
            assert!(
                !adapter_core.contains(model_literal),
                "adapter hardcodes the model literal {model_literal}"
            );
        }
        assert!(is_claude_phase(PhaseKind::ClaudeSubscription));
        assert!(is_claude_phase(PhaseKind::ClaudeApi));
        assert!(!is_claude_phase(PhaseKind::DeepseekApi));
        assert!(!capability_projection().namespace_tools);
        assert_eq!(
            PhaseKind::ClaudeApi.multi_agent_v2_projection(),
            capability_projection()
        );
    }

    #[test]
    fn anthropic_sse_parses_text_finish_and_usage_once() {
        let transcript = concat!(
            "event: message_start\n",
            "data: {\"type\":\"message_start\",\"message\":{\"id\":\"msg_1\",\"usage\":{\"input_tokens\":12,\"output_tokens\":0}}}\n\n",
            "event: content_block_delta\n",
            "data: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\"hello \"}}\n\n",
            "event: content_block_delta\n",
            "data: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\"world\"}}\n\n",
            "event: message_delta\n",
            "data: {\"type\":\"message_delta\",\"delta\":{\"stop_reason\":\"end_turn\"},\"usage\":{\"output_tokens\":7}}\n\n",
            "event: message_stop\n",
            "data: {\"type\":\"message_stop\"}\n\n",
        );
        let attempt = AttemptId::parse("attempt-anthropic-1").expect("attempt");
        let mut parser = AnthropicSseParser::new(&attempt);
        let events = parser
            .feed(transcript.as_bytes())
            .expect("feed anthropic stream");
        assert_eq!(
            events,
            vec![
                AnthropicStreamEvent::ContentDelta {
                    text: "hello ".to_owned()
                },
                AnthropicStreamEvent::ContentDelta {
                    text: "world".to_owned()
                },
                AnthropicStreamEvent::FinishReason {
                    reason: "end_turn".to_owned()
                },
                AnthropicStreamEvent::Usage(AnthropicUsage {
                    input_tokens: 12,
                    output_tokens: 7,
                }),
                AnthropicStreamEvent::Done,
            ]
        );
        assert_eq!(parser.finish(), Ok(vec![]));
        assert!(parser.replay_decision() != ReplayDecision::Allowed);
    }

    #[test]
    fn anthropic_stream_requires_terminal() {
        let attempt = AttemptId::parse("attempt-anthropic-2").expect("attempt");
        let mut parser = AnthropicSseParser::new(&attempt);
        parser
            .feed(
                b"data: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\"partial\"}}\n\n",
            )
            .expect("feed");
        assert_eq!(
            parser.finish(),
            Err(AnthropicStreamError {
                kind: AnthropicStreamErrorKind::MissingTerminal
            })
        );
    }
}