language_models: Add image support to OpenRouter models (#32012)

- [x] Manual Testing(Tested this with Qwen2.5 VL 32B Instruct (free) and
Llama 4 Scout (free), Llama 4 Maverick (free). Llama models have some
issues in write profile due to one of the in built tools schema, so I
tested it with minimal profile.

Closes #ISSUE

Release Notes:

- Add image support to OpenRouter models

---------

Signed-off-by: Umesh Yadav <umesh4257@gmail.com>
Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

crates/open_router/src/open_router.rs

@@ -52,6 +52,7 @@ pub struct Model {
     pub display_name: Option<String>,
     pub max_tokens: usize,
     pub supports_tools: Option<bool>,
+    pub supports_images: Option<bool>,
 }
 
 impl Model {
@@ -61,6 +62,7 @@ impl Model {
             Some("Auto Router"),
             Some(2000000),
             Some(true),
+            Some(false),
         )
     }
 
@@ -73,12 +75,14 @@ impl Model {
         display_name: Option<&str>,
         max_tokens: Option<usize>,
         supports_tools: Option<bool>,
+        supports_images: 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,
+            supports_images,
         }
     }
 
@@ -154,22 +158,118 @@ pub struct FunctionDefinition {
 #[serde(tag = "role", rename_all = "lowercase")]
 pub enum RequestMessage {
     Assistant {
-        content: Option<String>,
+        content: Option<MessageContent>,
         #[serde(default, skip_serializing_if = "Vec::is_empty")]
         tool_calls: Vec<ToolCall>,
     },
     User {
-        content: String,
+        content: MessageContent,
     },
     System {
-        content: String,
+        content: MessageContent,
     },
     Tool {
-        content: String,
+        content: MessageContent,
         tool_call_id: String,
     },
 }
 
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(untagged)]
+pub enum MessageContent {
+    Plain(String),
+    Multipart(Vec<MessagePart>),
+}
+
+impl MessageContent {
+    pub fn empty() -> Self {
+        Self::Plain(String::new())
+    }
+
+    pub fn push_part(&mut self, part: MessagePart) {
+        match self {
+            Self::Plain(text) if text.is_empty() => {
+                *self = Self::Multipart(vec![part]);
+            }
+            Self::Plain(text) => {
+                let text_part = MessagePart::Text {
+                    text: std::mem::take(text),
+                };
+                *self = Self::Multipart(vec![text_part, part]);
+            }
+            Self::Multipart(parts) => parts.push(part),
+        }
+    }
+}
+
+impl From<Vec<MessagePart>> for MessageContent {
+    fn from(parts: Vec<MessagePart>) -> Self {
+        if parts.len() == 1 {
+            if let MessagePart::Text { text } = &parts[0] {
+                return Self::Plain(text.clone());
+            }
+        }
+        Self::Multipart(parts)
+    }
+}
+
+impl From<String> for MessageContent {
+    fn from(text: String) -> Self {
+        Self::Plain(text)
+    }
+}
+
+impl From<&str> for MessageContent {
+    fn from(text: &str) -> Self {
+        Self::Plain(text.to_string())
+    }
+}
+
+impl MessageContent {
+    pub fn as_text(&self) -> Option<&str> {
+        match self {
+            Self::Plain(text) => Some(text),
+            Self::Multipart(parts) if parts.len() == 1 => {
+                if let MessagePart::Text { text } = &parts[0] {
+                    Some(text)
+                } else {
+                    None
+                }
+            }
+            _ => None,
+        }
+    }
+
+    pub fn to_text(&self) -> String {
+        match self {
+            Self::Plain(text) => text.clone(),
+            Self::Multipart(parts) => parts
+                .iter()
+                .filter_map(|part| {
+                    if let MessagePart::Text { text } = part {
+                        Some(text.as_str())
+                    } else {
+                        None
+                    }
+                })
+                .collect::<Vec<_>>()
+                .join(""),
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum MessagePart {
+    Text {
+        text: String,
+    },
+    #[serde(rename = "image_url")]
+    Image {
+        image_url: String,
+    },
+}
+
 #[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
 pub struct ToolCall {
     pub id: String,
@@ -266,6 +366,14 @@ pub struct ModelEntry {
     pub context_length: Option<usize>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub supported_parameters: Vec<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub architecture: Option<ModelArchitecture>,
+}
+
+#[derive(Default, Debug, Clone, PartialEq, Deserialize)]
+pub struct ModelArchitecture {
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub input_modalities: Vec<String>,
 }
 
 pub async fn complete(
@@ -470,6 +578,13 @@ pub async fn list_models(client: &dyn HttpClient, api_url: &str) -> Result<Vec<M
                 ),
                 max_tokens: entry.context_length.unwrap_or(2000000),
                 supports_tools: Some(entry.supported_parameters.contains(&"tools".to_string())),
+                supports_images: Some(
+                    entry
+                        .architecture
+                        .as_ref()
+                        .map(|arch| arch.input_modalities.contains(&"image".to_string()))
+                        .unwrap_or(false),
+                ),
             })
             .collect();