fix(adapters): honor paused overrides and isolate UI parser state

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/adapters/transcript.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
 import { buildTranscript, type RunLogChunk } from "./transcript";
+import type { UIAdapterModule } from "./types";
 
 describe("buildTranscript", () => {
   const ts = "2026-03-20T13:00:00.000Z";
@@ -27,4 +28,46 @@ describe("buildTranscript", () => {
       { kind: "stderr", ts, text: "stderr /Users/d****/project" },
     ]);
   });
+
+  it("creates a fresh stateful parser for each transcript build", () => {
+    const statefulAdapter: UIAdapterModule = {
+      type: "stateful_test",
+      label: "Stateful Test",
+      parseStdoutLine: (line, entryTs) => [{ kind: "stdout", ts: entryTs, text: line }],
+      createStdoutParser: () => {
+        let pending: string | null = null;
+        return {
+          parseLine: (line, entryTs) => {
+            if (line.startsWith("begin:")) {
+              pending = line.slice("begin:".length);
+              return [];
+            }
+            if (line === "finish" && pending) {
+              const text = `completed:${pending}`;
+              pending = null;
+              return [{ kind: "stdout", ts: entryTs, text }];
+            }
+            return [{ kind: "stdout", ts: entryTs, text: `literal:${line}` }];
+          },
+          reset: () => {
+            pending = null;
+          },
+        };
+      },
+      ConfigFields: () => null,
+      buildAdapterConfig: () => ({}),
+    };
+
+    const first = buildTranscript(
+      [{ ts, stream: "stdout", chunk: "begin:task-a\n" }],
+      statefulAdapter,
+    );
+    const second = buildTranscript(
+      [{ ts, stream: "stdout", chunk: "finish\n" }],
+      statefulAdapter,
+    );
+
+    expect(first).toEqual([]);
+    expect(second).toEqual([{ kind: "stdout", ts, text: "literal:finish" }]);
+  });
 });