fix(scheduler): #1696 — detect A2A adapter errors in 2xx response body

The scheduler recorded last_status='ok' when the adapter SDK threw
internally but still returned HTTP 200, because fireSchedule only
inspected proxyErr and statusCode.  A2A JSON-RPC errors (and plain
string error payloads) in the body were treated as success.

Changes:
- Add a2aErrorFromBody() helper that checks respBody for JSON-RPC
  {"error":{"message":"..."}} and plain {"error":"..."} shapes.
- In fireSchedule, when proxyErr is nil and status is 2xx, call
  a2aErrorFromBody; if an error message is found, set last_status to
  "error" and last_error to "A2A adapter error: <msg>".
- Add adapterErrorProxy test double + TestFireSchedule_AdapterSDKError
  regression test.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workspace-server/internal/scheduler/scheduler.go

@@ -433,6 +433,10 @@ func (s *Scheduler) fireSchedule(ctx context.Context, sched scheduleRow) {
 		lastStatus = "error"
 		lastError = fmt.Sprintf("HTTP %d", statusCode)
 		log.Printf("Scheduler: '%s' non-2xx: %d", sched.Name, statusCode)
+	} else if a2aErr := a2aErrorFromBody(respBody); a2aErr != "" {
+		lastStatus = "error"
+		lastError = fmt.Sprintf("A2A adapter error: %s", a2aErr)
+		log.Printf("Scheduler: '%s' A2A adapter error (HTTP %d): %s", sched.Name, statusCode, a2aErr)
 	} else {
 		log.Printf("Scheduler: '%s' completed (HTTP %d)", sched.Name, statusCode)
 	}
@@ -808,6 +812,32 @@ func isEmptyResponse(body []byte) bool {
 	return false
 }
 
+// a2aErrorFromBody extracts an A2A/JSON-RPC error message from a 2xx
+// response body. The adapter SDK may return HTTP 200 with an error
+// payload when it throws internally; this prevents the scheduler from
+// falsely recording last_status='ok'.
+// Issue #1696.
+func a2aErrorFromBody(body []byte) string {
+	if len(body) == 0 {
+		return ""
+	}
+	var resp map[string]interface{}
+	if json.Unmarshal(body, &resp) != nil {
+		return ""
+	}
+	// JSON-RPC style: {"error":{"code":-32603,"message":"..."}}
+	if errObj, ok := resp["error"].(map[string]interface{}); ok {
+		if msg, ok := errObj["message"].(string); ok {
+			return msg
+		}
+	}
+	// Plain style: {"error":"..."}
+	if errStr, ok := resp["error"].(string); ok {
+		return errStr
+	}
+	return ""
+}
+
 // truncation moved to internal/textutil.TruncateBytes (#2962 SSOT).
 // The original #2026 fix lives in textutil's package docs as canonical
 // prior art. Ellipsis was previously "..." (3 ASCII bytes); the SSOT

workspace-server/internal/scheduler/scheduler_test.go

@@ -256,6 +256,58 @@ func (p *successProxy) ProxyA2ARequest(
 	return 200, []byte(`{"ok":true}`), nil
 }
 
+// ── adapterErrorProxy ─────────────────────────────────────────────────────────
+
+// adapterErrorProxy is a test double whose ProxyA2ARequest returns HTTP 200
+// with a JSON-RPC error body, simulating an adapter SDK that throws internally
+// but still completes the HTTP round-trip. Issue #1696.
+type adapterErrorProxy struct{}
+
+func (p *adapterErrorProxy) ProxyA2ARequest(
+	_ context.Context, _ string, _ []byte, _ string, _ bool,
+) (int, []byte, error) {
+	return 200, []byte(`{"jsonrpc":"2.0","id":"cron-test-123","error":{"code":-32603,"message":"adapter SDK internal error"}}`), nil
+}
+
+// ── TestFireSchedule_AdapterSDKError (#1696) ──────────────────────────────────
+//
+// When the adapter SDK throws internally and returns HTTP 200 with an error
+// payload, fireSchedule must record last_status='error', not 'ok'.
+
+func TestFireSchedule_AdapterSDKError(t *testing.T) {
+	mock := setupTestDB(t)
+
+	sched := scheduleRow{
+		ID:          "55555555-dead-beef-0000-000000000005",
+		WorkspaceID: "66666666-dead-beef-0000-000000000006",
+		Name:        "adapter-err-job",
+		CronExpr:    "0 * * * *",
+		Timezone:    "UTC",
+		Prompt:      "do something",
+	}
+
+	// active_tasks check → 0 (workspace is idle; proceed to fire)
+	mock.ExpectQuery(`SELECT COALESCE`).
+		WillReturnRows(sqlmock.NewRows([]string{"coalesce"}).AddRow(0))
+
+	// Post-fire UPDATE must record last_status='error' with the adapter error message.
+	mock.ExpectExec(`UPDATE workspace_schedules`).
+		WithArgs(sched.ID, sqlmock.AnyArg(), "error", "A2A adapter error: adapter SDK internal error").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	// activity_logs INSERT must carry status='error' and the error detail.
+	mock.ExpectExec(`INSERT INTO activity_logs`).
+		WithArgs(sched.WorkspaceID, sqlmock.AnyArg(), sqlmock.AnyArg(), "error", "A2A adapter error: adapter SDK internal error").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	s := New(&adapterErrorProxy{}, nil)
+	s.fireSchedule(context.Background(), sched)
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet DB expectations — adapter error not recorded correctly: %v", err)
+	}
+}
+
 // ── TestFireSchedule_ComputeNextRunError (#722 Bug 1) ─────────────────────────
 //
 // When ComputeNextRun fails (bad cron expression), fireSchedule must NOT write