Add xAI language model provider (#33593)

Closes #30010

Release Notes:

- Add support for xAI language model provider

crates/x_ai/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "x_ai"
+version = "0.1.0"
+edition.workspace = true
+publish.workspace = true
+license = "GPL-3.0-or-later"
+
+[lints]
+workspace = true
+
+[lib]
+path = "src/x_ai.rs"
+
+[features]
+default = []
+schemars = ["dep:schemars"]
+
+[dependencies]
+anyhow.workspace = true
+schemars = { workspace = true, optional = true }
+serde.workspace = true
+strum.workspace = true
+workspace-hack.workspace = true

crates/x_ai/LICENSE-GPL

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

crates/x_ai/src/x_ai.rs

@@ -0,0 +1,126 @@
+use anyhow::Result;
+use serde::{Deserialize, Serialize};
+use strum::EnumIter;
+
+pub const XAI_API_URL: &str = "https://api.x.ai/v1";
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, EnumIter)]
+pub enum Model {
+    #[serde(rename = "grok-2-vision-latest")]
+    Grok2Vision,
+    #[default]
+    #[serde(rename = "grok-3-latest")]
+    Grok3,
+    #[serde(rename = "grok-3-mini-latest")]
+    Grok3Mini,
+    #[serde(rename = "grok-3-fast-latest")]
+    Grok3Fast,
+    #[serde(rename = "grok-3-mini-fast-latest")]
+    Grok3MiniFast,
+    #[serde(rename = "grok-4-latest")]
+    Grok4,
+    #[serde(rename = "custom")]
+    Custom {
+        name: String,
+        /// The name displayed in the UI, such as in the assistant panel model dropdown menu.
+        display_name: Option<String>,
+        max_tokens: u64,
+        max_output_tokens: Option<u64>,
+        max_completion_tokens: Option<u64>,
+    },
+}
+
+impl Model {
+    pub fn default_fast() -> Self {
+        Self::Grok3Fast
+    }
+
+    pub fn from_id(id: &str) -> Result<Self> {
+        match id {
+            "grok-2-vision" => Ok(Self::Grok2Vision),
+            "grok-3" => Ok(Self::Grok3),
+            "grok-3-mini" => Ok(Self::Grok3Mini),
+            "grok-3-fast" => Ok(Self::Grok3Fast),
+            "grok-3-mini-fast" => Ok(Self::Grok3MiniFast),
+            _ => anyhow::bail!("invalid model id '{id}'"),
+        }
+    }
+
+    pub fn id(&self) -> &str {
+        match self {
+            Self::Grok2Vision => "grok-2-vision",
+            Self::Grok3 => "grok-3",
+            Self::Grok3Mini => "grok-3-mini",
+            Self::Grok3Fast => "grok-3-fast",
+            Self::Grok3MiniFast => "grok-3-mini-fast",
+            Self::Grok4 => "grok-4",
+            Self::Custom { name, .. } => name,
+        }
+    }
+
+    pub fn display_name(&self) -> &str {
+        match self {
+            Self::Grok2Vision => "Grok 2 Vision",
+            Self::Grok3 => "Grok 3",
+            Self::Grok3Mini => "Grok 3 Mini",
+            Self::Grok3Fast => "Grok 3 Fast",
+            Self::Grok3MiniFast => "Grok 3 Mini Fast",
+            Self::Grok4 => "Grok 4",
+            Self::Custom {
+                name, display_name, ..
+            } => display_name.as_ref().unwrap_or(name),
+        }
+    }
+
+    pub fn max_token_count(&self) -> u64 {
+        match self {
+            Self::Grok3 | Self::Grok3Mini | Self::Grok3Fast | Self::Grok3MiniFast => 131_072,
+            Self::Grok4 => 256_000,
+            Self::Grok2Vision => 8_192,
+            Self::Custom { max_tokens, .. } => *max_tokens,
+        }
+    }
+
+    pub fn max_output_tokens(&self) -> Option<u64> {
+        match self {
+            Self::Grok3 | Self::Grok3Mini | Self::Grok3Fast | Self::Grok3MiniFast => Some(8_192),
+            Self::Grok4 => Some(64_000),
+            Self::Grok2Vision => Some(4_096),
+            Self::Custom {
+                max_output_tokens, ..
+            } => *max_output_tokens,
+        }
+    }
+
+    pub fn supports_parallel_tool_calls(&self) -> bool {
+        match self {
+            Self::Grok2Vision
+            | Self::Grok3
+            | Self::Grok3Mini
+            | Self::Grok3Fast
+            | Self::Grok3MiniFast
+            | Self::Grok4 => true,
+            Model::Custom { .. } => false,
+        }
+    }
+
+    pub fn supports_tool(&self) -> bool {
+        match self {
+            Self::Grok2Vision
+            | Self::Grok3
+            | Self::Grok3Mini
+            | Self::Grok3Fast
+            | Self::Grok3MiniFast
+            | Self::Grok4 => true,
+            Model::Custom { .. } => false,
+        }
+    }
+
+    pub fn supports_images(&self) -> bool {
+        match self {
+            Self::Grok2Vision => true,
+            _ => false,
+        }
+    }
+}