fix: use Effect.flatMap for decodeJjCurrentChange to route errors to typed channel

decodeJjCurrentChange was throwing VcsOutputDecodeError inside Effect.map,
which causes the error to become an unrecoverable defect rather than a typed
error in the VcsError channel. Changed the function to return an Effect and
use Effect.flatMap at the call site so errors properly land in the typed
error channel as the type signature promises.

Author: cursoragent

apps/server/src/vcs/JjVcsDriver.ts

@@ -80,27 +80,32 @@ function parseNullRecord(record: string): string[] {
   return record.split("\0").map((value) => value.trim());
 }
 
-function decodeJjCurrentChange(raw: string, cwd: string): JjCurrentChange | null {
+function decodeJjCurrentChange(
+  raw: string,
+  cwd: string,
+): Effect.Effect<JjCurrentChange | null, VcsOutputDecodeError> {
   const trimmed = raw.trim();
   if (trimmed.length === 0) {
-    return null;
+    return Effect.succeed(null);
   }
 
   const [changeId, commitId, description] = parseNullRecord(trimmed);
   if (!changeId) {
-    throw new VcsOutputDecodeError({
-      operation: "JjVcsDriver.currentChange",
-      command: "jj log",
-      cwd,
-      detail: "jj current change output did not include a change id",
-    });
+    return Effect.fail(
+      new VcsOutputDecodeError({
+        operation: "JjVcsDriver.currentChange",
+        command: "jj log",
+        cwd,
+        detail: "jj current change output did not include a change id",
+      }),
+    );
   }
 
-  return {
+  return Effect.succeed({
     changeId,
     commitId: commitId || null,
     description: description || null,
-  };
+  });
 }
 
 function decodeJjBookmarkList(raw: string): ReadonlyArray<JjBookmark> {
@@ -370,7 +375,7 @@ export const makeVcsDriverShape = Effect.fn("makeJjVcsDriverShape")(function* ()
         timeoutMs: 5_000,
         maxOutputBytes: 64 * 1024,
       },
-    ).pipe(Effect.map((result) => decodeJjCurrentChange(result.stdout, cwd)));
+    ).pipe(Effect.flatMap((result) => decodeJjCurrentChange(result.stdout, cwd)));
 
   const listBookmarks: JjVcsDriverShape["listBookmarks"] = (cwd) =>
     jjCommand(