fix(pairing): accept non-string NIP-46 params (Amber sends requested_perms as a JSON object)

RawRequest used a strict Vec<String>, so Amber's connect request —
whose params[1] is the requested_perms grant object — failed to parse
and was silently dropped. The signer saw a live session; we saw
nothing. Params now coerce non-string values to their JSON text, with
regression tests for both shapes.

src/signer/nip46_client.rs

@@ -589,9 +589,8 @@ impl Nip46ClientSigner {
             // Local-only debug capture (never leaves this machine): keep the
             // full event so a failed handshake can be dissected offline.
             {
-                let path = std::path::Path::new(
-                    "/home/avi/Tools/keynctr-debug/pairing-capture.jsonl",
-                );
+                let path =
+                    std::path::Path::new("/home/avi/Tools/keynctr-debug/pairing-capture.jsonl");
                 if let Some(dir) = path.parent() {
                     let _ = std::fs::create_dir_all(dir);
                 }
@@ -1861,10 +1860,29 @@ impl Signer for Nip46ClientSigner {
 struct RawRequest {
     id: String,
     method: String,
-    #[serde(default)]
+    #[serde(default, deserialize_with = "lenient_params")]
     params: Vec<String>,
 }
 
+/// NIP-46 params are conventionally strings, but real signers embed raw JSON
+/// objects (Amber sends its requested_perms grant object as `connect`
+/// params[1]). A strict `Vec<String>` would reject the entire request and
+/// silently drop the handshake, so non-string params are coerced to their
+/// JSON text instead.
+fn lenient_params<'de, D>(deserializer: D) -> Result<Vec<String>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    let values: Vec<serde_json::Value> = Vec::deserialize(deserializer)?;
+    Ok(values
+        .into_iter()
+        .map(|v| match v {
+            serde_json::Value::String(s) => s,
+            other => other.to_string(),
+        })
+        .collect())
+}
+
 fn response_ok(id: &str, result: String) -> String {
     json!({ "id": id, "result": result, "error": null }).to_string()
 }
@@ -1934,3 +1952,38 @@ fn percent_decode(raw: &str) -> Option<String> {
     }
     String::from_utf8(out).ok()
 }
+
+#[cfg(test)]
+mod raw_request_tests {
+    use super::RawRequest;
+
+    #[test]
+    fn parses_amber_style_connect_with_object_params() {
+        // Real signers (Amber) send requested_perms as a raw JSON object in
+        // params[1]; a strict Vec<String> used to reject the whole request
+        // and silently drop the pairing handshake.
+        let raw = format!(
+            r#"{{"id":"1","method":"connect","params":["{}",{{"sign_event":[1,7],"nip04_encrypt":true}}]}}"#,
+            "a".repeat(64)
+        );
+        let req: RawRequest = serde_json::from_str(&raw).expect("must parse");
+        assert_eq!(req.method, "connect");
+        assert_eq!(req.params.len(), 2);
+        assert_eq!(req.params[0], "a".repeat(64));
+        assert!(
+            req.params[1].starts_with('{'),
+            "object coerced to JSON text"
+        );
+    }
+
+    #[test]
+    fn parses_string_params_unchanged() {
+        let req: RawRequest =
+            serde_json::from_str(r#"{"id":"2","method":"get_public_key","params":[]}"#).unwrap();
+        assert!(req.params.is_empty());
+        let req: RawRequest =
+            serde_json::from_str(r#"{"id":"3","method":"nip44_decrypt","params":["aa","bb"]}"#)
+                .unwrap();
+        assert_eq!(req.params, vec!["aa".to_string(), "bb".to_string()]);
+    }
+}