tt_routing/
validate.rs

1//! Typed route validation shared by the gateway routes API. The capability
2//! check mirrors the runtime guard (`tt_shared::capability_check`). Cross-
3//! provider rewrites are allowed (V3d-1) — see
4//! docs/superpowers/specs/2026-06-04-v3d-1-cross-provider-routing-design.md.
5
6use tt_shared::pricing::{Capability, ModelInfo};
7
8use crate::{RouteAction, RouteConditions};
9
10#[derive(Debug, thiserror::Error, PartialEq, Eq)]
11pub enum ValidationError {
12    #[error("target_model `{target}` is missing the `{capability}` capability required by this route's content-type condition")]
13    MissingCapability {
14        target: String,
15        capability: &'static str,
16    },
17}
18
19/// When the route requires image or audio input, the target must be
20/// `Vision`-capable (the runtime guard sets `vision=true` for both). An unknown
21/// target (`lookup` returns `None`) is permissive, matching the runtime guard.
22pub fn validate_capability(
23    when: &RouteConditions,
24    then: &RouteAction,
25    lookup: impl Fn(&str) -> Option<ModelInfo>,
26) -> Result<(), ValidationError> {
27    let needs_vision = when.has_images == Some(true) || when.has_audio == Some(true);
28    if !needs_vision {
29        return Ok(());
30    }
31    if let Some(info) = lookup(&then.target_model) {
32        if !info.capabilities.contains(&Capability::Vision) {
33            return Err(ValidationError::MissingCapability {
34                target: then.target_model.clone(),
35                capability: "vision",
36            });
37        }
38    }
39    Ok(())
40}
41
42#[cfg(test)]
43mod tests {
44    use super::*;
45    use crate::{RouteAction, RouteConditions};
46    use tt_shared::pricing::{Capability, ModelInfo};
47
48    fn action(target: &str) -> RouteAction {
49        RouteAction {
50            target_model: target.into(),
51            fallbacks: vec![],
52            disable_cache: false,
53            max_cost_usd: None,
54        }
55    }
56    fn vision_model(id: &str) -> ModelInfo {
57        ModelInfo {
58            id: id.into(),
59            provider: "p".into(),
60            capabilities: vec![Capability::Text, Capability::Vision],
61            max_input_tokens: 1000,
62            max_output_tokens: 1000,
63        }
64    }
65    fn text_model(id: &str) -> ModelInfo {
66        ModelInfo {
67            id: id.into(),
68            provider: "p".into(),
69            capabilities: vec![Capability::Text],
70            max_input_tokens: 1000,
71            max_output_tokens: 1000,
72        }
73    }
74
75    #[test]
76    fn has_images_requires_vision_target() {
77        let when = RouteConditions {
78            has_images: Some(true),
79            ..Default::default()
80        };
81        let lookup = |m: &str| -> Option<ModelInfo> {
82            match m {
83                "vis" => Some(vision_model("vis")),
84                "txt" => Some(text_model("txt")),
85                _ => None,
86            }
87        };
88        assert!(validate_capability(&when, &action("vis"), lookup).is_ok());
89        assert!(validate_capability(&when, &action("txt"), lookup).is_err());
90        // Unknown target is permissive (mirrors runtime guard).
91        assert!(validate_capability(&when, &action("unknown"), lookup).is_ok());
92    }
93
94    #[test]
95    fn no_modality_condition_skips_capability_check() {
96        let when = RouteConditions::default();
97        let lookup = |_: &str| -> Option<ModelInfo> { None };
98        assert!(validate_capability(&when, &action("anything"), lookup).is_ok());
99    }
100}
tt_routing/validate.rs

tt_routing/
validate.rs
