fix(agents): parse JSON configuration with serde_json before json5

src-tauri/src/agents/discovery.rs

@@ -1577,7 +1577,7 @@ pub(crate) fn agent_has_connection_evidence(
             )
             .map_err(|e| e.to_string())?,
             Some("yaml" | "yml") => serde_yaml::from_str(content).map_err(|e| e.to_string())?,
-            _ => json5::from_str(content).map_err(|e| e.to_string())?,
+            _ => super::transactions::parse_json_or_json5(content)?,
         };
         let provider_present = client != AgentClient::Codex
             && [
@@ -3587,7 +3587,8 @@ pub(crate) fn read_agent_json5_or_empty(
         return Ok(serde_json::json!({}));
     }
     let value: serde_json::Value =
-        json5::from_str(&content).map_err(|error| format!("Failed to parse {label}: {error}"))?;
+        super::transactions::parse_json_or_json5(&content)
+            .map_err(|error| format!("Failed to parse {label}: {error}"))?;
     if !value.is_object() {
         return Err(format!("{label} root must be an object"));
     }

src-tauri/src/agents/transactions.rs

@@ -1171,6 +1171,15 @@ pub(crate) fn text(bytes: Option<&[u8]>) -> Result<Option<&str>, String> {
         .transpose()
 }
 
+/// Parses JSON configuration, accepting JSON5 syntax (comments, trailing commas) as well.
+/// Strict JSON is tried first: the json5 (pest) parser needs about 80x the input size in memory,
+/// so a 64 MB generated Codex model catalog took more than 5 GB at every start.
+pub(crate) fn parse_json_or_json5(content: &str) -> Result<Value, String> {
+    serde_json::from_str::<Value>(content)
+        .or_else(|_| json5::from_str::<Value>(content))
+        .map_err(|e| e.to_string())
+}
+
 pub(crate) fn parse(path: &Path, content: Option<&str>) -> Result<Value, String> {
     let Some(content) = content else {
         return Ok(serde_json::json!({}));
@@ -1181,7 +1190,7 @@ pub(crate) fn parse(path: &Path, content: Option<&str>) -> Result<Value, String>
             .map_err(|e| e.to_string())
             .and_then(|v| serde_json::to_value(v).map_err(|e| e.to_string())),
         Some("yaml" | "yml") => serde_norway::from_str::<Value>(content).map_err(|e| e.to_string()),
-        _ => json5::from_str::<Value>(content).map_err(|e| e.to_string()),
+        _ => parse_json_or_json5(content),
     };
     let value = result.map_err(|_| {
         format!(

src-tauri/src/agents/transactions/tests.rs

@@ -122,3 +122,24 @@ fn relocated_configuration_root_accepts_writes_but_nested_links_do_not() {
         "a nested configuration link targeting the temp root must stay rejected"
     );
 }
+
+#[test]
+fn parse_json_or_json5_reads_strict_json_and_json5() {
+    let strict = parse_json_or_json5(r#"{"models":[{"slug":"a","n":1}]}"#).unwrap();
+    assert_eq!(strict["models"][0]["slug"], "a");
+
+    let json5 = parse_json_or_json5("{\n  // comment\n  models: [{slug: 'b',},],\n}").unwrap();
+    assert_eq!(json5["models"][0]["slug"], "b");
+
+    assert!(parse_json_or_json5("{\"models\":").is_err());
+}
+
+#[test]
+fn parse_keeps_json5_config_files_working() {
+    let value = parse(
+        Path::new("opencode.jsonc"),
+        Some("{\n  // keep comments working\n  \"provider\": {\"cpa-gui\": {},},\n}"),
+    )
+    .unwrap();
+    assert!(value["provider"]["cpa-gui"].is_object());
+}