feat: source navigation echoes and guarded fork-prefix inheritance

crates/core/src/prefix_cache.rs

@@ -712,7 +712,11 @@ impl PrefixStabilityManager {
 /// Serialize a tool to the same JSON shape the chat API receives,
 /// excluding internal-only fields like `allowed_callers`, `defer_loading`,
 /// `input_examples`, and `cache_control` that are never sent to DeepSeek.
-fn tool_to_api_json(tool: &Tool) -> Option<String> {
+///
+/// Shared by the fingerprint manager and fork-prefix inheritance: both
+/// need byte-equality against provider-cached prefixes, and raw `Tool`
+/// serialization would false-negative on internal-only flag skew.
+pub fn tool_to_api_json(tool: &Tool) -> Option<String> {
     let mut value = serde_json::json!({
         "type": "function",
         "function": {

crates/runtime/Cargo.toml

@@ -47,6 +47,7 @@ codewhale-palette = { path = "../palette", version = "0.10.2", default-features
 colored = "3.0.0"
 fd-lock = "4.0.4"
 lru = "0.18"
+parking_lot = "0.12"
 regex = "1.11"
 serde.workspace = true
 serde_json = { workspace = true, features = ["preserve_order", "raw_value"] }