Add support for OpenRouter as a language model provider (#29496)

This pull request adds full integration with OpenRouter, allowing users
to access a wide variety of language models through a single API key.

**Implementation Details:**

* **Provider Registration:** Registers OpenRouter as a new language
model provider within the application's model registry. This includes UI
for API key authentication, token counting, streaming completions, and
tool-call handling.
* **Dedicated Crate:** Adds a new `open_router` crate to manage
interactions with the OpenRouter HTTP API, including model discovery and
streaming helpers.
* **UI & Configuration:** Extends workspace manifests, the settings
schema, icons, and default configurations to surface the OpenRouter
provider and its settings within the UI.
* **Readability:** Reformats JSON arrays within the settings files for
improved readability.

**Design Decisions & Discussion Points:**

* **Code Reuse:** I leveraged much of the existing logic from the
`openai` provider integration due to the significant similarities
between the OpenAI and OpenRouter API specifications.
* **Default Model:** I set the default model to `openrouter/auto`. This
model automatically routes user prompts to the most suitable underlying
model on OpenRouter, providing a convenient starting point.
* **Model Population Strategy:**
* <strike>I've implemented dynamic population of available models by
querying the OpenRouter API upon initialization.
* Currently, this involves three separate API calls: one for all models,
one for tool-use models, and one for models good at programming.
* The data from the tool-use API call sets a `tool_use` flag for
relevant models.
* The data from the programming models API call is used to sort the
list, prioritizing coding-focused models in the dropdown.</strike>
* <strike>**Feedback Welcome:** I acknowledge this multi-call approach
is API-intensive. I am open to feedback and alternative implementation
suggestions if the team believes this can be optimized.</strike>
    * **Update: Now this has been simplified to one api call.**
* **UI/UX Considerations:**
* <strike>Authentication Method: Currently, I've implemented the
standard API key input in settings, similar to other providers like
OpenAI/Anthropic. However, OpenRouter also supports OAuth 2.0 with PKCE.
This could offer a potentially smoother, more integrated setup
experience for users (e.g., clicking a button to authorize instead of
copy-pasting a key). Should we prioritize implementing OAuth PKCE now,
or perhaps add it as an alternative option later?</strike>(PKCE is not
straight forward and complicated so skipping this for now. So that we
can add the support and work on this later.)
* <strike>To visually distinguish models better suited for programming,
I've considered adding a marker (e.g., `</>` or `🧠`) next to their
names. Thoughts on this proposal?</strike>. (This will require a changes
and discussion across model provider. This doesn't fall under the scope
of current PR).
* OpenRouter offers 300+ models. The current implementation loads all of
them. **Feedback Needed:** Should we refine this list or implement more
sophisticated filtering/categorization for better usability?

**Motivation:**

This integration directly addresses one of the most highly upvoted
feature requests/discussions within the Zed community. Adding OpenRouter
support significantly expands the range of AI models accessible to
users.

I welcome feedback from the Zed team on this implementation and the
design choices made. I am eager to refine this feature and make it
available to users.

ISSUES: https://github.com/zed-industries/zed/discussions/16576

Release Notes:

- Added support for OpenRouter as a language model provider.

---------

Signed-off-by: Umesh Yadav <umesh4257@gmail.com>
Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/open_router/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "open_router"
+version = "0.1.0"
+edition.workspace = true
+publish.workspace = true
+license = "GPL-3.0-or-later"
+
+[lints]
+workspace = true
+
+[lib]
+path = "src/open_router.rs"
+
+[features]
+default = []
+schemars = ["dep:schemars"]
+
+[dependencies]
+anyhow.workspace = true
+futures.workspace = true
+http_client.workspace = true
+schemars = { workspace = true, optional = true }
+serde.workspace = true
+serde_json.workspace = true
+workspace-hack.workspace = true

crates/open_router/LICENSE-GPL

@@ -0,0 +1 @@
+../../LICENSE-GPL

crates/open_router/src/open_router.rs

@@ -0,0 +1,484 @@
+use anyhow::{Context, Result, anyhow};
+use futures::{AsyncBufReadExt, AsyncReadExt, StreamExt, io::BufReader, stream::BoxStream};
+use http_client::{AsyncBody, HttpClient, Method, Request as HttpRequest};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::convert::TryFrom;
+
+pub const OPEN_ROUTER_API_URL: &str = "https://openrouter.ai/api/v1";
+
+fn is_none_or_empty<T: AsRef<[U]>, U>(opt: &Option<T>) -> bool {
+    opt.as_ref().map_or(true, |v| v.as_ref().is_empty())
+}
+
+#[derive(Clone, Copy, Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum Role {
+    User,
+    Assistant,
+    System,
+    Tool,
+}
+
+impl TryFrom<String> for Role {
+    type Error = anyhow::Error;
+
+    fn try_from(value: String) -> Result<Self> {
+        match value.as_str() {
+            "user" => Ok(Self::User),
+            "assistant" => Ok(Self::Assistant),
+            "system" => Ok(Self::System),
+            "tool" => Ok(Self::Tool),
+            _ => Err(anyhow!("invalid role '{value}'")),
+        }
+    }
+}
+
+impl From<Role> for String {
+    fn from(val: Role) -> Self {
+        match val {
+            Role::User => "user".to_owned(),
+            Role::Assistant => "assistant".to_owned(),
+            Role::System => "system".to_owned(),
+            Role::Tool => "tool".to_owned(),
+        }
+    }
+}
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
+pub struct Model {
+    pub name: String,
+    pub display_name: Option<String>,
+    pub max_tokens: usize,
+    pub supports_tools: Option<bool>,
+}
+
+impl Model {
+    pub fn default_fast() -> Self {
+        Self::new(
+            "openrouter/auto",
+            Some("Auto Router"),
+            Some(2000000),
+            Some(true),
+        )
+    }
+
+    pub fn default() -> Self {
+        Self::default_fast()
+    }
+
+    pub fn new(
+        name: &str,
+        display_name: Option<&str>,
+        max_tokens: Option<usize>,
+        supports_tools: Option<bool>,
+    ) -> Self {
+        Self {
+            name: name.to_owned(),
+            display_name: display_name.map(|s| s.to_owned()),
+            max_tokens: max_tokens.unwrap_or(2000000),
+            supports_tools,
+        }
+    }
+
+    pub fn id(&self) -> &str {
+        &self.name
+    }
+
+    pub fn display_name(&self) -> &str {
+        self.display_name.as_ref().unwrap_or(&self.name)
+    }
+
+    pub fn max_token_count(&self) -> usize {
+        self.max_tokens
+    }
+
+    pub fn max_output_tokens(&self) -> Option<u32> {
+        None
+    }
+
+    pub fn supports_tool_calls(&self) -> bool {
+        self.supports_tools.unwrap_or(false)
+    }
+
+    pub fn supports_parallel_tool_calls(&self) -> bool {
+        false
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Request {
+    pub model: String,
+    pub messages: Vec<RequestMessage>,
+    pub stream: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub max_tokens: Option<u32>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub stop: Vec<String>,
+    pub temperature: f32,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub tool_choice: Option<ToolChoice>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub parallel_tool_calls: Option<bool>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub tools: Vec<ToolDefinition>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum ToolChoice {
+    Auto,
+    Required,
+    None,
+    Other(ToolDefinition),
+}
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Deserialize, Serialize, Debug)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum ToolDefinition {
+    #[allow(dead_code)]
+    Function { function: FunctionDefinition },
+}
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct FunctionDefinition {
+    pub name: String,
+    pub description: Option<String>,
+    pub parameters: Option<Value>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(tag = "role", rename_all = "lowercase")]
+pub enum RequestMessage {
+    Assistant {
+        content: Option<String>,
+        #[serde(default, skip_serializing_if = "Vec::is_empty")]
+        tool_calls: Vec<ToolCall>,
+    },
+    User {
+        content: String,
+    },
+    System {
+        content: String,
+    },
+    Tool {
+        content: String,
+        tool_call_id: String,
+    },
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct ToolCall {
+    pub id: String,
+    #[serde(flatten)]
+    pub content: ToolCallContent,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(tag = "type", rename_all = "lowercase")]
+pub enum ToolCallContent {
+    Function { function: FunctionContent },
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct FunctionContent {
+    pub name: String,
+    pub arguments: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct ResponseMessageDelta {
+    pub role: Option<Role>,
+    pub content: Option<String>,
+    #[serde(default, skip_serializing_if = "is_none_or_empty")]
+    pub tool_calls: Option<Vec<ToolCallChunk>>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct ToolCallChunk {
+    pub index: usize,
+    pub id: Option<String>,
+    pub function: Option<FunctionChunk>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct FunctionChunk {
+    pub name: Option<String>,
+    pub arguments: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Usage {
+    pub prompt_tokens: u32,
+    pub completion_tokens: u32,
+    pub total_tokens: u32,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ChoiceDelta {
+    pub index: u32,
+    pub delta: ResponseMessageDelta,
+    pub finish_reason: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ResponseStreamEvent {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub id: Option<String>,
+    pub created: u32,
+    pub model: String,
+    pub choices: Vec<ChoiceDelta>,
+    pub usage: Option<Usage>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Response {
+    pub id: String,
+    pub object: String,
+    pub created: u64,
+    pub model: String,
+    pub choices: Vec<Choice>,
+    pub usage: Usage,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Choice {
+    pub index: u32,
+    pub message: RequestMessage,
+    pub finish_reason: Option<String>,
+}
+
+#[derive(Default, Debug, Clone, PartialEq, Deserialize)]
+pub struct ListModelsResponse {
+    pub data: Vec<ModelEntry>,
+}
+
+#[derive(Default, Debug, Clone, PartialEq, Deserialize)]
+pub struct ModelEntry {
+    pub id: String,
+    pub name: String,
+    pub created: usize,
+    pub description: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub context_length: Option<usize>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub supported_parameters: Vec<String>,
+}
+
+pub async fn complete(
+    client: &dyn HttpClient,
+    api_url: &str,
+    api_key: &str,
+    request: Request,
+) -> Result<Response> {
+    let uri = format!("{api_url}/chat/completions");
+    let request_builder = HttpRequest::builder()
+        .method(Method::POST)
+        .uri(uri)
+        .header("Content-Type", "application/json")
+        .header("Authorization", format!("Bearer {}", api_key))
+        .header("HTTP-Referer", "https://zed.dev")
+        .header("X-Title", "Zed Editor");
+
+    let mut request_body = request;
+    request_body.stream = false;
+
+    let request = request_builder.body(AsyncBody::from(serde_json::to_string(&request_body)?))?;
+    let mut response = client.send(request).await?;
+
+    if response.status().is_success() {
+        let mut body = String::new();
+        response.body_mut().read_to_string(&mut body).await?;
+        let response: Response = serde_json::from_str(&body)?;
+        Ok(response)
+    } else {
+        let mut body = String::new();
+        response.body_mut().read_to_string(&mut body).await?;
+
+        #[derive(Deserialize)]
+        struct OpenRouterResponse {
+            error: OpenRouterError,
+        }
+
+        #[derive(Deserialize)]
+        struct OpenRouterError {
+            message: String,
+            #[serde(default)]
+            code: String,
+        }
+
+        match serde_json::from_str::<OpenRouterResponse>(&body) {
+            Ok(response) if !response.error.message.is_empty() => {
+                let error_message = if !response.error.code.is_empty() {
+                    format!("{}: {}", response.error.code, response.error.message)
+                } else {
+                    response.error.message
+                };
+
+                Err(anyhow!(
+                    "Failed to connect to OpenRouter API: {}",
+                    error_message
+                ))
+            }
+            _ => Err(anyhow!(
+                "Failed to connect to OpenRouter API: {} {}",
+                response.status(),
+                body,
+            )),
+        }
+    }
+}
+
+pub async fn stream_completion(
+    client: &dyn HttpClient,
+    api_url: &str,
+    api_key: &str,
+    request: Request,
+) -> Result<BoxStream<'static, Result<ResponseStreamEvent>>> {
+    let uri = format!("{api_url}/chat/completions");
+    let request_builder = HttpRequest::builder()
+        .method(Method::POST)
+        .uri(uri)
+        .header("Content-Type", "application/json")
+        .header("Authorization", format!("Bearer {}", api_key))
+        .header("HTTP-Referer", "https://zed.dev")
+        .header("X-Title", "Zed Editor");
+
+    let request = request_builder.body(AsyncBody::from(serde_json::to_string(&request)?))?;
+    let mut response = client.send(request).await?;
+
+    if response.status().is_success() {
+        let reader = BufReader::new(response.into_body());
+        Ok(reader
+            .lines()
+            .filter_map(|line| async move {
+                match line {
+                    Ok(line) => {
+                        if line.starts_with(':') {
+                            return None;
+                        }
+
+                        let line = line.strip_prefix("data: ")?;
+                        if line == "[DONE]" {
+                            None
+                        } else {
+                            match serde_json::from_str::<ResponseStreamEvent>(line) {
+                                Ok(response) => Some(Ok(response)),
+                                Err(error) => {
+                                    #[derive(Deserialize)]
+                                    struct ErrorResponse {
+                                        error: String,
+                                    }
+
+                                    match serde_json::from_str::<ErrorResponse>(line) {
+                                        Ok(err_response) => Some(Err(anyhow!(err_response.error))),
+                                        Err(_) => {
+                                            if line.trim().is_empty() {
+                                                None
+                                            } else {
+                                                Some(Err(anyhow!(
+                                                    "Failed to parse response: {}. Original content: '{}'",
+                                                    error, line
+                                                )))
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    Err(error) => Some(Err(anyhow!(error))),
+                }
+            })
+            .boxed())
+    } else {
+        let mut body = String::new();
+        response.body_mut().read_to_string(&mut body).await?;
+
+        #[derive(Deserialize)]
+        struct OpenRouterResponse {
+            error: OpenRouterError,
+        }
+
+        #[derive(Deserialize)]
+        struct OpenRouterError {
+            message: String,
+            #[serde(default)]
+            code: String,
+        }
+
+        match serde_json::from_str::<OpenRouterResponse>(&body) {
+            Ok(response) if !response.error.message.is_empty() => {
+                let error_message = if !response.error.code.is_empty() {
+                    format!("{}: {}", response.error.code, response.error.message)
+                } else {
+                    response.error.message
+                };
+
+                Err(anyhow!(
+                    "Failed to connect to OpenRouter API: {}",
+                    error_message
+                ))
+            }
+            _ => Err(anyhow!(
+                "Failed to connect to OpenRouter API: {} {}",
+                response.status(),
+                body,
+            )),
+        }
+    }
+}
+
+pub async fn list_models(client: &dyn HttpClient, api_url: &str) -> Result<Vec<Model>> {
+    let uri = format!("{api_url}/models");
+    let request_builder = HttpRequest::builder()
+        .method(Method::GET)
+        .uri(uri)
+        .header("Accept", "application/json");
+
+    let request = request_builder.body(AsyncBody::default())?;
+    let mut response = client.send(request).await?;
+
+    let mut body = String::new();
+    response.body_mut().read_to_string(&mut body).await?;
+
+    if response.status().is_success() {
+        let response: ListModelsResponse =
+            serde_json::from_str(&body).context("Unable to parse OpenRouter models response")?;
+
+        let models = response
+            .data
+            .into_iter()
+            .map(|entry| Model {
+                name: entry.id,
+                // OpenRouter returns display names in the format "provider_name: model_name".
+                // When displayed in the UI, these names can get truncated from the right.
+                // Since users typically already know the provider, we extract just the model name
+                // portion (after the colon) to create a more concise and user-friendly label
+                // for the model dropdown in the agent panel.
+                display_name: Some(
+                    entry
+                        .name
+                        .split(':')
+                        .next_back()
+                        .unwrap_or(&entry.name)
+                        .trim()
+                        .to_string(),
+                ),
+                max_tokens: entry.context_length.unwrap_or(2000000),
+                supports_tools: Some(entry.supported_parameters.contains(&"tools".to_string())),
+            })
+            .collect();
+
+        Ok(models)
+    } else {
+        Err(anyhow!(
+            "Failed to connect to OpenRouter API: {} {}",
+            response.status(),
+            body,
+        ))
+    }
+}