ra2a_ext/
activator.rs

1//! Client-side extension activator interceptor.
2//!
3//! Aligned with Go's `a2aext.NewActivator`. Requests extension activation
4//! on outgoing calls by appending supported extension URIs to the
5//! `x-a2a-extensions` header.
6
7use std::future::Future;
8use std::pin::Pin;
9
10use ra2a::SVC_PARAM_EXTENSIONS;
11use ra2a::client::{CallInterceptor, Request};
12use ra2a::error::Result;
13
14use crate::util::is_extension_supported;
15
16/// Client-side [`CallInterceptor`] that requests extension activation.
17///
18/// For each outgoing request, checks the server's [`AgentCard`](ra2a::AgentCard)
19/// for supported extensions and appends matching URIs to the
20/// `x-a2a-extensions` metadata header.
21///
22/// # Example
23///
24/// ```rust,no_run
25/// use ra2a_ext::ExtensionActivator;
26///
27/// let activator = ExtensionActivator::new(vec![
28///     "urn:a2a:ext:duration".into(),
29///     "urn:a2a:ext:custom".into(),
30/// ]);
31/// // client.with_interceptor(activator);
32/// ```
33#[derive(Debug)]
34pub struct ExtensionActivator {
35    /// Extension URIs this client wishes to activate.
36    extension_uris: Vec<String>,
37}
38
39impl ExtensionActivator {
40    /// Creates a new activator for the given extension URIs.
41    pub const fn new(extension_uris: Vec<String>) -> Self {
42        Self { extension_uris }
43    }
44}
45
46impl CallInterceptor for ExtensionActivator {
47    fn before<'a>(
48        &'a self,
49        req: &'a mut Request,
50    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'a>> {
51        Box::pin(async move {
52            // If the card has no extensions declared, skip entirely.
53            if let Some(card) = &req.card
54                && card.capabilities.extensions.is_empty()
55            {
56                return Ok(());
57            }
58
59            for uri in &self.extension_uris {
60                if is_extension_supported(req.card.as_ref(), uri) {
61                    req.service_params.append(SVC_PARAM_EXTENSIONS, uri.clone());
62                }
63            }
64            Ok(())
65        })
66    }
67}
68
69#[cfg(test)]
70#[allow(clippy::unwrap_used)]
71mod tests {
72    use ra2a::client::ServiceParams;
73    use ra2a::types::{
74        AgentCapabilities, AgentCard, AgentExtension, AgentInterface, TransportProtocol,
75    };
76
77    use super::*;
78
79    fn make_card(uris: &[&str]) -> AgentCard {
80        let mut card = AgentCard::new(
81            "test",
82            "test agent",
83            vec![AgentInterface::new(
84                "https://example.com",
85                TransportProtocol::new("JSONRPC"),
86            )],
87        );
88        card.capabilities = AgentCapabilities {
89            extensions: uris
90                .iter()
91                .map(|u| AgentExtension {
92                    uri: (*u).into(),
93                    description: None,
94                    required: false,
95                    params: None,
96                })
97                .collect(),
98            ..AgentCapabilities::default()
99        };
100        card
101    }
102
103    fn make_request(card: Option<AgentCard>) -> Request {
104        Request {
105            method: "message/send".into(),
106            card,
107            service_params: ServiceParams::default(),
108            payload: Box::new(()),
109        }
110    }
111
112    #[tokio::test]
113    async fn test_activator_filters_by_card() {
114        let activator = ExtensionActivator::new(vec![
115            "urn:a2a:ext:duration".into(),
116            "urn:a2a:ext:missing".into(),
117        ]);
118
119        let card = make_card(&["urn:a2a:ext:duration", "urn:a2a:ext:other"]);
120        let mut req = make_request(Some(card));
121
122        activator.before(&mut req).await.unwrap();
123
124        let vals = req.service_params.get_all(SVC_PARAM_EXTENSIONS);
125        assert_eq!(vals, &["urn:a2a:ext:duration"]);
126    }
127
128    #[tokio::test]
129    async fn test_activator_no_card_sends_all() {
130        let activator =
131            ExtensionActivator::new(vec!["urn:a2a:ext:a".into(), "urn:a2a:ext:b".into()]);
132
133        let mut req = make_request(None);
134        activator.before(&mut req).await.unwrap();
135
136        let vals = req.service_params.get_all(SVC_PARAM_EXTENSIONS);
137        assert_eq!(vals, &["urn:a2a:ext:a", "urn:a2a:ext:b"]);
138    }
139
140    #[tokio::test]
141    async fn test_activator_empty_card_extensions_skips() {
142        let activator = ExtensionActivator::new(vec!["urn:a2a:ext:duration".into()]);
143
144        let card = make_card(&[]);
145        let mut req = make_request(Some(card));
146
147        activator.before(&mut req).await.unwrap();
148
149        let vals = req.service_params.get_all(SVC_PARAM_EXTENSIONS);
150        assert!(vals.is_empty());
151    }
152}
ra2a_ext/activator.rs

ra2a_ext/
activator.rs
