Treat OpenCode abort as cancellation, not error (#1169)

OpenCode emits session.error with MessageAbortedError when the user
interrupts a running turn. Paseo was mapping every session.error to
turn_failed, which set the agent lifecycle to error and appended a
raw JSON system error message to the timeline.

Now MessageAbortedError translates to turn_canceled (same as an
explicit cancel), so the agent returns to idle with no error state.
Real errors still produce turn_failed.

packages/server/src/server/agent/providers/opencode-agent.ts

@@ -1691,14 +1691,7 @@ export function translateOpenCodeEvent(
       }
       break;
     case "session.error":
-      if (event.properties.sessionID === state.sessionId) {
-        resetOpenCodeTurnTrackingState(state);
-        events.push({
-          type: "turn_failed",
-          provider: "opencode",
-          error: toDiagnosticErrorMessage(event.properties.error),
-        });
-      }
+      appendOpenCodeSessionError(event, state, events);
       break;
     case "session.status":
       appendOpenCodeSessionStatus(event, state, events);
@@ -2294,6 +2287,36 @@ function appendOpenCodeQuestionAsked(
   });
 }
 
+function appendOpenCodeSessionError(
+  event: Extract<OpenCodeEvent, { type: "session.error" }>,
+  state: OpenCodeEventTranslationState,
+  events: AgentStreamEvent[],
+): void {
+  if (event.properties.sessionID !== state.sessionId) {
+    return;
+  }
+  resetOpenCodeTurnTrackingState(state);
+  const error = event.properties.error;
+  if (
+    typeof error === "object" &&
+    error !== null &&
+    "name" in error &&
+    error.name === "MessageAbortedError"
+  ) {
+    events.push({
+      type: "turn_canceled",
+      provider: "opencode",
+      reason: "interrupted",
+    });
+  } else {
+    events.push({
+      type: "turn_failed",
+      provider: "opencode",
+      error: toDiagnosticErrorMessage(error),
+    });
+  }
+}
+
 function appendOpenCodeSessionStatus(
   event: Extract<OpenCodeEvent, { type: "session.status" }>,
   state: OpenCodeEventTranslationState,

packages/server/src/server/agent/providers/opencode/event-translator.test.ts

@@ -924,4 +924,52 @@ describe("translateOpenCodeEvent", () => {
     ]);
     expect(second).toEqual([]);
   });
+
+  it("translates session.error with MessageAbortedError as turn_canceled, not turn_failed", () => {
+    const state = createState();
+
+    const events = translateOpenCodeEvent(
+      {
+        type: "session.error",
+        properties: {
+          sessionID: "session-1",
+          error: {
+            name: "MessageAbortedError",
+            data: { message: "aborted" },
+          },
+        },
+      },
+      state,
+    );
+
+    expect(events).toEqual([
+      { type: "turn_canceled", provider: "opencode", reason: "interrupted" },
+    ]);
+  });
+
+  it("translates session.error with a real error as turn_failed", () => {
+    const state = createState();
+
+    const events = translateOpenCodeEvent(
+      {
+        type: "session.error",
+        properties: {
+          sessionID: "session-1",
+          error: {
+            name: "UnknownError",
+            data: { message: "something broke" },
+          },
+        },
+      },
+      state,
+    );
+
+    expect(events).toEqual([
+      {
+        type: "turn_failed",
+        provider: "opencode",
+        error: '{"name":"UnknownError","data":{"message":"something broke"}}',
+      },
+    ]);
+  });
 });