feat(mcp): search tool emits search_response.v1 + budget inputs (fb-34)

SearchInput gains max_tokens / snippet_chars / cursor (all optional).
Output wrapped in search_response.v1 to match CLI; existing
tools_call_search test updated to read v["hits"] instead of the bare
array.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-mcp/src/tools/search.rs

@@ -1,5 +1,6 @@
-//! `search` tool — wraps `kebab_app::search_with_config`.
-//! Input: { query, mode?, k? }. Output: search_hit.v1 array JSON.
+//! `search` tool — wraps `kebab_app::search_with_opts_with_config`.
+//! Input: { query, mode?, k?, max_tokens?, snippet_chars?, cursor? }.
+//! Output: search_response.v1 envelope (hits + next_cursor + truncated).
 //!
 //! First tool with a non-empty `inputSchema`: `SearchInput` derives
 //! `JsonSchema` and `Tool::new` uses
@@ -17,23 +18,21 @@ pub struct SearchInput {
     /// User query (free text).
     pub query: String,
     /// Retrieval mode: "hybrid" (default), "lexical", or "vector".
-    #[serde(default = "default_mode")]
-    pub mode: String,
+    pub mode: Option<String>,
     /// Top-K results. Defaults to 10. Clamped to 1–100.
-    #[serde(default = "default_k")]
-    pub k: usize,
-}
-
-fn default_mode() -> String {
-    "hybrid".to_string()
-}
-fn default_k() -> usize {
-    10
+    pub k: Option<usize>,
+    /// p9-fb-34: cap result wire size at ~N tokens (chars/4 estimate).
+    pub max_tokens: Option<usize>,
+    /// p9-fb-34: per-hit snippet character cap.
+    pub snippet_chars: Option<usize>,
+    /// p9-fb-34: opaque cursor from a previous response.
+    pub cursor: Option<String>,
 }
 
 pub fn handle(state: &KebabAppState, input: SearchInput) -> CallToolResult {
-    let k = input.k.clamp(1, 100);
-    let mode = match input.mode.as_str() {
+    let k = input.k.unwrap_or(10).clamp(1, 100);
+    let mode_str = input.mode.as_deref().unwrap_or("hybrid");
+    let mode = match mode_str {
         "lexical" => kebab_core::SearchMode::Lexical,
         "vector" => kebab_core::SearchMode::Vector,
         _ => kebab_core::SearchMode::Hybrid,
@@ -44,11 +43,18 @@ pub fn handle(state: &KebabAppState, input: SearchInput) -> CallToolResult {
         k,
         filters: kebab_core::SearchFilters::default(),
     };
-    match kebab_app::search_with_config((*state.config).clone(), query) {
-        Ok(hits) => {
+    let opts = kebab_core::SearchOpts {
+        max_tokens: input.max_tokens,
+        snippet_chars: input.snippet_chars,
+        cursor: input.cursor,
+    };
+    let cfg_clone = (*state.config).clone();
+    match kebab_app::search_with_opts_with_config(cfg_clone, query, opts) {
+        Ok(resp) => {
             // SearchHit (kebab-core) does not carry a `schema_version` field,
             // so we tag each element inline before serialising.
-            let tagged: Vec<serde_json::Value> = hits
+            let tagged: Vec<serde_json::Value> = resp
+                .hits
                 .iter()
                 .map(|h| {
                     let mut v = serde_json::to_value(h).unwrap_or_default();
@@ -61,7 +67,13 @@ pub fn handle(state: &KebabAppState, input: SearchInput) -> CallToolResult {
                     v
                 })
                 .collect();
-            match serde_json::to_string(&serde_json::Value::Array(tagged)) {
+            let envelope = serde_json::json!({
+                "schema_version": "search_response.v1",
+                "hits": tagged,
+                "next_cursor": resp.next_cursor,
+                "truncated": resp.truncated,
+            });
+            match serde_json::to_string(&envelope) {
                 Ok(json) => to_tool_success(json),
                 Err(e) => to_tool_error(&anyhow::anyhow!(e)),
             }

crates/kebab-mcp/tests/tools_call_search.rs

@@ -1,4 +1,4 @@
-//! Integration: tools/call name=search — verify response is search_hit.v1 array.
+//! Integration: tools/call name=search — verify response is search_response.v1.
 
 use std::fs;
 
@@ -22,7 +22,7 @@ fn minimal_config(data_dir: &std::path::Path, workspace_root: &std::path::Path)
 }
 
 #[tokio::test]
-async fn search_tool_returns_search_hits_array() {
+async fn search_tool_returns_search_response_v1() {
     let dir = tempfile::tempdir().unwrap();
     let data_dir = dir.path().join("data");
     let workspace_root = dir.path().join("notes");
@@ -53,8 +53,11 @@ async fn search_tool_returns_search_hits_array() {
         handler.state(),
         kebab_mcp::tools::search::SearchInput {
             query: "kebab".to_string(),
-            mode: "lexical".to_string(),
-            k: 5,
+            mode: Some("lexical".to_string()),
+            k: Some(5),
+            max_tokens: None,
+            snippet_chars: None,
+            cursor: None,
         },
     );
 
@@ -75,16 +78,33 @@ async fn search_tool_returns_search_hits_array() {
     };
 
     let v: serde_json::Value = serde_json::from_str(text).unwrap();
-    let arr = v.as_array().expect("search returns a JSON array");
+    assert_eq!(
+        v.get("schema_version").and_then(|s| s.as_str()),
+        Some("search_response.v1"),
+        "envelope should carry schema_version=search_response.v1"
+    );
+    let hits = v
+        .get("hits")
+        .and_then(|h| h.as_array())
+        .expect("hits must be a JSON array");
     assert!(
-        !arr.is_empty(),
+        !hits.is_empty(),
         "expected at least one hit for 'kebab' in 'a.md'"
     );
     assert_eq!(
-        arr[0]
+        hits[0]
             .get("schema_version")
             .and_then(|s| s.as_str()),
         Some("search_hit.v1"),
         "first hit should carry schema_version=search_hit.v1"
     );
+    // truncated must be present (bool); next_cursor may be null on last page.
+    assert!(
+        v.get("truncated").and_then(|t| t.as_bool()).is_some(),
+        "envelope should carry truncated:bool"
+    );
+    assert!(
+        v.get("next_cursor").is_some(),
+        "envelope should carry next_cursor (possibly null)"
+    );
 }