lean_ctx/proxy/
anthropic.rs

1use axum::{
2    body::Body,
3    extract::State,
4    http::{Request, StatusCode},
5    response::Response,
6};
7use serde_json::Value;
8
9use super::ProxyState;
10use super::compress::compress_tool_result;
11use super::forward;
12use super::tool_kind::{self, ToolResultKind, should_protect};
13
14pub async fn handler(
15    State(state): State<ProxyState>,
16    req: Request<Body>,
17) -> Result<Response, StatusCode> {
18    let upstream = state.anthropic_upstream.clone();
19    forward::forward_request(
20        State(state),
21        req,
22        &upstream,
23        "/v1/messages",
24        compress_request_body,
25        "Anthropic",
26        &[],
27    )
28    .await
29}
30
31fn compress_request_body(parsed: Value, original_size: usize) -> (Vec<u8>, usize, usize) {
32    let mut doc = parsed;
33    let mut modified = false;
34
35    if let Some(messages) = doc.get_mut("messages").and_then(|m| m.as_array_mut()) {
36        // Resolve tool-call id → tool name so file/source reads can be protected
37        // from lossy compression that would force the model to re-read mid-task.
38        let tool_names = tool_kind::anthropic_tool_names(messages);
39
40        // Prune at a frozen, cache-aware boundary by default: Anthropic's
41        // prompt cache matches exact prefixes, so the boundary must not move
42        // every turn (see `history_prune::prune_boundary`).
43        let mode = crate::core::config::Config::load()
44            .proxy
45            .resolved_history_mode();
46        let boundary = super::history_prune::prune_boundary(mode, messages.len());
47        modified |= super::history_prune::prune_history(messages, boundary, &tool_names);
48
49        for msg in messages.iter_mut() {
50            let role = msg.get("role").and_then(|r| r.as_str()).unwrap_or("");
51            if role != "user" {
52                continue;
53            }
54
55            if let Some(content) = msg.get_mut("content").and_then(|c| c.as_array_mut()) {
56                for block in content.iter_mut() {
57                    if block.get("type").and_then(|t| t.as_str()) != Some("tool_result") {
58                        continue;
59                    }
60
61                    let name = block
62                        .get("tool_use_id")
63                        .and_then(|v| v.as_str())
64                        .and_then(|id| tool_names.get(id))
65                        .map(String::as_str);
66                    let kind = name.map_or(ToolResultKind::Other, tool_kind::classify_tool_name);
67
68                    if let Some(inner_content) = block.get_mut("content") {
69                        modified |= compress_content_field(inner_content, name, kind);
70                    }
71                }
72            }
73        }
74    }
75
76    let out = serde_json::to_vec(&doc).unwrap_or_default();
77    let compressed_size = if modified { out.len() } else { original_size };
78    (out, original_size, compressed_size)
79}
80
81/// Compresses a tool_result `content` field unless it is a protected file/source
82/// read, which must reach the model intact (it is what gets edited).
83fn compress_content_field(
84    content: &mut Value,
85    tool_name: Option<&str>,
86    kind: ToolResultKind,
87) -> bool {
88    match content {
89        Value::String(s) => {
90            if should_protect(kind, s) {
91                return false;
92            }
93            let compressed = compress_tool_result(s, tool_name);
94            if compressed.len() < s.len() {
95                *s = compressed;
96                return true;
97            }
98            false
99        }
100        Value::Array(arr) => {
101            let mut modified = false;
102            for item in arr.iter_mut() {
103                if item.get("type").and_then(|t| t.as_str()) == Some("text")
104                    && let Some(text) = item
105                        .get_mut("text")
106                        .and_then(|t| t.as_str().map(String::from))
107                {
108                    if should_protect(kind, &text) {
109                        continue;
110                    }
111                    let compressed = compress_tool_result(&text, tool_name);
112                    if compressed.len() < text.len() {
113                        item["text"] = Value::String(compressed);
114                        modified = true;
115                    }
116                }
117            }
118            modified
119        }
120        _ => false,
121    }
122}
123
124#[cfg(test)]
125mod tests {
126    use super::*;
127
128    fn source_file_body() -> Vec<u8> {
129        let code = (0..60)
130            .map(|i| format!("    let binding_{i} = compute_value_{i}(context, options);"))
131            .collect::<Vec<_>>()
132            .join("\n");
133        let body = serde_json::json!({
134            "model": "claude-opus-4-8",
135            "messages": [
136                {
137                    "role": "assistant",
138                    "content": [{"type": "tool_use", "id": "toolu_1", "name": "Read", "input": {"file_path": "src/app.rs"}}]
139                },
140                {
141                    "role": "user",
142                    "content": [{"type": "tool_result", "tool_use_id": "toolu_1", "content": code}]
143                }
144            ]
145        });
146        serde_json::to_vec(&body).unwrap()
147    }
148
149    #[test]
150    fn read_tool_result_is_never_truncated() {
151        let bytes = source_file_body();
152        let body: Value = serde_json::from_slice(&bytes).unwrap();
153        let (out, _orig, _comp) = compress_request_body(body, bytes.len());
154        let parsed: Value = serde_json::from_slice(&out).unwrap();
155        let content = parsed["messages"][1]["content"][0]["content"]
156            .as_str()
157            .unwrap();
158        assert!(
159            content.contains("binding_59"),
160            "the full source body must survive — refactors need it intact"
161        );
162        assert!(!content.contains("lines omitted"));
163    }
164
165    fn forge_log_body(tool_name: &str) -> Value {
166        // Generic, highly-repetitive log with no `$ cmd` hint, so routing falls
167        // back to the tool name (exercising the foreign-tool classification)
168        // and the generic compressor (not a command-specific pattern).
169        let mut log = String::new();
170        for i in 0..90 {
171            log.push_str(&format!(
172                "INFO  processing item {i}: ok, latency={i}ms, queue depth normal, retries 0\n"
173            ));
174        }
175        serde_json::json!({
176            "messages": [
177                {"role": "assistant", "content": [{"type": "tool_use", "id": "f1", "name": tool_name, "input": {}}]},
178                {"role": "user", "content": [{"type": "tool_result", "tool_use_id": "f1", "content": log}]}
179            ]
180        })
181    }
182
183    #[test]
184    fn forge_shell_tool_result_compresses() {
185        // A vendor-prefixed foreign shell tool reaches the proxy; its log output
186        // must still be compressed (rtk/ctx_* never see another server's tools).
187        let body = forge_log_body("forge_shell");
188        let bytes = serde_json::to_vec(&body).unwrap();
189        let (_out, orig, comp) = compress_request_body(body, bytes.len());
190        assert!(comp < orig, "foreign shell output must be compressed");
191    }
192
193    #[test]
194    fn foreign_read_tool_protects_source() {
195        // `forge_read` is classified FileRead via the segment fallback, so the
196        // source body must reach the model intact (it is what gets edited).
197        let code = (0..60)
198            .map(|i| format!("    let binding_{i} = compute_value_{i}(context, options);"))
199            .collect::<Vec<_>>()
200            .join("\n");
201        let body = serde_json::json!({
202            "messages": [
203                {"role": "assistant", "content": [{"type": "tool_use", "id": "r1", "name": "forge_read", "input": {"path": "src/app.rs"}}]},
204                {"role": "user", "content": [{"type": "tool_result", "tool_use_id": "r1", "content": code}]}
205            ]
206        });
207        let bytes = serde_json::to_vec(&body).unwrap();
208        let (out, _orig, _comp) = compress_request_body(body, bytes.len());
209        let parsed: Value = serde_json::from_slice(&out).unwrap();
210        let content = parsed["messages"][1]["content"][0]["content"]
211            .as_str()
212            .unwrap();
213        assert!(
214            content.contains("binding_59"),
215            "source body must survive intact"
216        );
217    }
218
219    #[test]
220    fn compress_request_body_is_deterministic() {
221        // #498: the proxy rewrite must be a pure function of the body so the
222        // provider prompt-cache prefix stays byte-identical across turns.
223        let bytes = serde_json::to_vec(&forge_log_body("Bash")).unwrap();
224        let a = compress_request_body(serde_json::from_slice(&bytes).unwrap(), bytes.len()).0;
225        let b = compress_request_body(serde_json::from_slice(&bytes).unwrap(), bytes.len()).0;
226        assert_eq!(a, b, "identical input must yield byte-identical output");
227    }
228
229    #[test]
230    fn bash_tool_result_still_compresses() {
231        let log = {
232            let mut s = String::from(
233                "$ git status\nOn branch main\nYour branch is up to date with 'origin/main'.\n\nChanges not staged for commit:\n  (use \"git add <file>...\" to update what will be committed)\n",
234            );
235            for i in 0..90 {
236                s.push_str(&format!("\tmodified:   src/module_{i}/file_{i}.rs\n"));
237            }
238            s.push_str("\nno changes added to commit (use \"git add\" and/or \"git commit -a\")\n");
239            s
240        };
241        let body = serde_json::json!({
242            "messages": [
243                {"role": "assistant", "content": [{"type": "tool_use", "id": "t1", "name": "Bash", "input": {}}]},
244                {"role": "user", "content": [{"type": "tool_result", "tool_use_id": "t1", "content": log}]}
245            ]
246        });
247        let bytes = serde_json::to_vec(&body).unwrap();
248        let (_out, orig, comp) = compress_request_body(body, bytes.len());
249        assert!(comp < orig, "shell output must still be compressed");
250    }
251}
lean_ctx/proxy/anthropic.rs

lean_ctx/proxy/
anthropic.rs
